Hey Guys! I'll try to make this brief.

Background: The car was pulled off the road for winter 2011. About 40L in the gas tank, I added a stabilizer and half a liter of methanol. Brought home in May 2012, engine seized. Spun rod bearing from the cap being on backwards. Engine out, rebuilt with a .020 bore, same compression ratio. The engine was reassembled in fall 2012, primed with the oil pump and the cylinders got a quick oil bath to prevent rust. Engine back in a couple months ago. First start today.

Fuel system: Walbro 255 with rewire, hardline to Russel filter, braided stainless from filter to Magnus fuel rail to Aeromotive FPR to return hardline. PTE 780CC injectors. Everything at the engine was disassembled and cleaned, but the only thing replaced was the fuel pump's inline fuse (the old one broke on the way out). AEM EMS for a brain.

Today: Primed the engine with a hand pump and a tube stuck into the filter housing. Put a bottle of Lucas octane booster in the tank to help the 2 year old fuel. Pushed it into the driveway to fire it up. It took awhile to be able to hold enough fuel pressure to run (which I figured was just air). Eventually it fired up but would not stay running without help at the gas pedal. Fuel pressure at idle was over 50psi, wideband was stuck on 10.0, though it was still burning through a decent amount of oil. I pulled the vacuum line off the regulator and plugged it, which changed nothing.

My conclusions: Something's fucked! When the fuel pump primes (yes, my fuel pump primes..), the fuel pressure goes right to 43.5psi and holds. Cranking is when it seems to jump up. It seems weird to me that after all the work I did, the FPR would sh!t the bed even though I didn't touch it, and it worked fine before. That and it seems to have its base pressure set. I'm breaking for dinner but I'm at a loss. For those of you who made it through the whole post... any ideas?!

I can't comment on the AEM EMS, but just a couple things here.
Lets go through a list of things with a simple Y/N answer.
Plugs ok? (condition, gap, etc)
Wires on correct cylinders?
Injectors properly compensated for?
I have no idea why you'd be pushing 50psi of fuel pressure unless something is messed with the lines on the AFPR. You should be running ~30psi at idle with 20inhg of vac. (judging from my numbers)
Boost leaks?

Interesting issue though.

I know when I was running link, I forgot to simulate narrow band operation which caused a no start. Would peg at 10 for AFR, run for 5 seconds then putt and die.

AFPR doesn't have wiring

I recall reading a post somewhere on Link Forums from the Link guys saying that your idle fuel pressure should be approximately equal to this formula --> IFP = BFP (= 43.5) - (Idle Vacuum/2).

So if vacuum is 20, IFP should be no higher than around 33.5, possibly lower.

Have you made sure all your settings look good? Make a list of what items have been changed since you took her off the road and which, if any, of those items would possibly affect fuel pressure, AFR, etc. Have you changed your EMS files whatsoever?

Lines. I was thinking about lines. Fixed now

Fuel pressure on a 2G should be 43psi with the car running and vacuum line removed. If you set your fuel pressure with the car off, you've not compensated for the drop in pressure due to the injectors opening/closing.

If your car won't stay running unless you have your foot on the pedal I'd say you have either an injector compensation or airflow calculation wrong.

Great ideas guys, I appreciate the input. Keep it coming!

The tune on the car has not been changed. It was originally tuned by Marco and nothing in the fuel system has been changed since.

Johnny, for your list:
-New plugs, double checked the gap
-As far as I know the wires are hooked up properly. I have a 6 bolt with 1g coil packs and igniter, and have kept the same wire configuration as to when I got the car, which was double checked against the Haynes manual
-Injectors should be properly compensated for on the existing tune
-Intake seems to be leak-free. I managed to build 30psi of pressure in it with my piece of sh!t BLT. It didn't hold the 30psi, because my POS BLT leaks. It's on the to do list...

Pulling the vacuum line off of the pressure regulator seemed to make it harder for the engine to start and get itself running. So even though it's wonky, it DOES appear to be trying to compensate for it's vacuum signal.

My dad (who's been with me all day) offered a simple solution: a plugged up fuel return line, acting as an extra restriction that the FPR can't compensate for.

I really didn't muck around with the fuel system, as it's never given my problems. Even the usual issue with Aeromotive FPRs losing pressure right after shutdown has never showed up. She's still pegged at 43.5 now, after 2 hours of not being touched.

If you pinch your return line at the rubber section. You pressure should rise if it doesnt you dad may just be correct.

It may be the coolant temp sensor.






lol.




Actually Id start by running an extra bit of line off your return line and into a bucket and purging all the 2 year old gas out of the tank. And if you can purgethe entire fuel line then you will see if there are any clogs. I did this on my 2g with 2 year old gas and it started right up with some fresh high octane gasoline!

The more I think about all the symptoms, the more I'm confident that there is additional restriction after the rail. Which leaves only a couple options; I may just owe the old man a beer on this one







First thing on the to do list for tomorrow night!

Few questions, sorry if they're a bit stupid:

Can an FPR seize up if left sitting for an extended period of time? I've never actually opened one up; I'll probably be able to find the answer with some searching..

Also, since I'm AEM-illiterate, I can make my fuel pump run by pulling off the relay and jumping the connector, right? I suppose I'll need to slap some flat terminals on the end of some spare wire.

If the key is out (and therefore ECU is off) the injectors will all stay closed, correct? Just making sure I don't do something stupid because I assumed I was right

The 2g has a fuel pump wire on the fire wall by the battery. jump 12v to that connector and the pump will run without the key. The injectors will stay closed.. I thoight Aem had a manual fuel pump control.

the fpr is sorta like a wastegate or bov. spring loaded And the vacuum or boost pushes or pulls a diaphram that opens or closes a valve. It wont sieze But it does go bad.

The valve could sieze are you able to adjust pressure if you try?
No the injectors will stay closed with the key off aslong as you dont a leaky one.
You can jump the pump either at the relay or at the connector like Jay said. I have no clue about AEM.
Flushing out that old fuel is probably the best idea.
If you a compress blow some air thru the return line see if it fliwd with the gas off of course.

I'm going to look into controlling the fuel pump with AEM tomorrow while I'm at work. Just getting backup plans ready

Thanks for the tip on the connector on the firewall, and the info about FPRs!

I was thinking of running the pump first to see what comes out the return, and then going to compressed air if I think something's afoul.

If I don't get any tangible results there I'll go to playing with the FPR. One way or another, I agree that the old fuel won't help when there's a fuel system problem. That sh!t's gotta go!

Remember that 140psi from a air compressor is alot more powerfull then the 50psi of fuel. You fuel system may not handle it. Keep it regulated.

If the line is clogged. then I would start with a new filter.. then fpr.. then replace the lines. But I think something is not set up right. Or got bumped.

Then one would ask the question, "How did the line get clogged?!"
I'd recommend opening up your AFPR for a closer inspection and checking your filter before messing about with your line.
But either way, interested to see what the issue is.


Time for a bonfire!

I would just be taking the AFPR and opening it up and checking it.

Did you confirm that you are getting vacuum to that line that is on the AFPR?

I set my AFPR with the car off so I don't think it's a huge issue.

Well, I want to purge out the old gas, so I'll likely be leaving the system intact until I run at least 30L through. I don't think the line is BLOCKED, just restricted. Although I would be more inclined to think that the FPR didn't like sitting, doing nothing for two years.

When the pump primes, pressure shoots up to like 55psi and then backs off to 43.5psi before cranking. So I think the FPR knows what pressure to get to and is able to get it there, but there's something slowing the fuel's return to the tank. With the pump running constantly, the FPR is doing its best but can't drop the pressure low enough.

Once the old fuel gets flushed through, I'll pull apart the FPR and dig the filter out. I think I remember opening the filter and cleaning the element, but that was back before Christmas.

Well whatevery you are doing you better hurry up the KW Meet is in 10 days!

I didn't have time to get at her tonight, but I've got all weekend free to get this mitsubitchy running

Okay, I've got my AFPR out and apart. The spring has some corrosion and can't be compressed very far by hand, but everything else appears to be fine.

How will I know if this thing is causing my problems?

I don't know forsure but if the spring wont compress it wont lift seat or valve which would cause higher fuel pressure

Well I really don't know what else it could be at this point... if everything after the regulator is clean and clear, and the fuel pressure is wonky at a constant RPM even with the vacuum line off, I feel like it would have the be the regulator that's causing the problem..

And since the diaphragm seems fine, I have to think there's a problem with the spring.


Thinking about it from a different angle though: what if it's just the gauge that's fucked? Would the fact that the engine's burning off some oil and assembly lube be enough to keep the wideband buried on rich?

Do you have a cat? Do you have any bluey smoke out the tail pipe? I would asume if you cant change the fuel manually with the set screw that there is somethin wrong with the spring.

No cat, and the smoke is a lot more grey than blue. Everything appears to me as if it's running really rich (because of way too much fuel pressure). But I've checked everything at the regulator back and can't see any obvious issues.

My Dad's new suggestion is that the tank's ability to vent is compromised, and excess pressure in the tank is what's slowing the return. That really doesn't seem feasible to me, but once I get everything back together and fire it up, if the problem persists I'll try leaving the gas cap off.

Gonna shoot down to Ziggy in the morning and grab some parts just in case. Performance parts available on the Sunday of a long weekend at great prices...the man is a saint!

You will still change the pressure with the set screw if the spring is for some reason .. not working the way it should. Altho I think the spring would have to be heated up alot... or really old to ever not hold a steady pressure. Aftermarket fuel regulators may leak..but they dont normally wear out.
I still thinkyou should purge the old stuff first and start from there. Old gas wont burn and will give you a rich reading... cause its not burning. The car may start but as soon as tries to idle It cant find stoich with weak gas.

Jesus if i knew he was open i would of grabbed new fuel lines aswell. Oh well winter project now.

I dont think fuel thank venting is your issue but no harm in checking. You could run seperate return into a jerrycan see if that helps. But my guess is the regulator

Well the regulator is about 8 years old I believe... and it has spent the last 2 sitting doing nothing, often without any fuel in it.

I have purged most of the old stuff out and have been filling jerry cans with some fresh 94 octane. I agree the old fuel didn't help, but old fuel won't cause fuel pressure to be all over the place.



I'm not sure if he's really open or just doing me a favour because I asked really nicely and am a pain in the ass like that

I figured taking the cap off would act as a vent, avoiding the need for a separate return. My guess is also the regulator at this point.

The regulator spring in my 1g sat dry for 4;years and its 20 years old and works fine. But you never know. Do you have a stock you can replace it with?

Unfortunately not, but the 255 with rewire would overrun a stock regulator anyway so I'd still have too much fuel pressure..

Of course there will be some that last longer without a problem, but my point was that the FPR isn't new

And my hands still smell like gas because of it...

Ah yes, a big "thank you" to Salomon who helped me keep about 20L of fuel away from the environment (and into the tank of my shitbox Rio!)

So, a new AFPR from Ziggy changed nothing. Not exactly the cheapest way to rule it out, but I knew it was a gamble..

With the FPR cranked down to 28 base pressure, it fluctuates between 30 and 40 psi while running with the vacuum line detached. When it was at 43.5 base pressure, it was spiking in the high 40s-low 50s (vacuum line detached).

The symptoms are seriously baffling...

where is the vacuum source?

Bottom of the manifold, split to the boost gauge (same as it was before). But it's the behaviour of the fuel pressure with the line disconnect that is truly confusing me...

What happens if you pinch off the return?

I'll have to try again tomorrow; there are too many families around. I waited for them to go inside to eat earlier and then had at it. I'm not sure I'll go back at it tonight, but tomorrow I'll try running the pump with the car off and pinch the return to see what happens.

Might also be time to get the car jacked up and have a real close inspection of the lines, but I feel like I would have gotten some feedback while pumping 100psi through the line if it was kinked or crushed anywhere..

Are you only using the fpr guage or do you have another guage you can plumb in? I could lend you a guage set. Like if you plumbed it before the rail and pinch the hose after the guage you see if was a bad pump.

I wouldnt concern yourself with the vacuum portion on the reg.

I'm going up to Loo tomorrow and heading back home tomorrow as well, so I can grab and drop off the gauge set/anything else at Jeremy's.

I don't have any extra gauges that I can plumb in. I have a car until tomorrow night so I could drive out myself to borrow them.

But I'm not sure how a bad pump could cause this issue.. the gauge certainly seems to be working. Even if the pump was all over the place, the regulator should be able to hold reasonably constant fuel pressure. The fact that it can't suggest to me that the problem has to be at or after it...

Edit: When I searched around about this, I saw many people mentioning that they had to drill out a portion of the fuel return on the 2g sending unit when they went to a Walbro 255 with rewire. The fact that this setup ran fine for 2 years leaned me away from it; the fact that the return going into the tank seemed unrestricted pushed it right out of my mind. But I'm wondering if there's dirt or something in there plugging things up.

I'll probably pull my sending unit out for inspection after trying a few other tests..

Well a weak pump will run poorly untill you adjust the pressure to get it up to stock. but when the pump gets a surge of energy then it will raise the pressure higher then whatvyou set it to.

If the pump is running at half effieciancy and the regulator is set to create 45psi...then when it gets a sudden surge. It will spike the fuel pressure.

But the pressure doesn't spike from 43.5psi. It NEVER gets down to 43.5psi once the engine starts running. It fluctuates between like 48-55..

Jeremy I am with you on this one, I say after the regulator, seeing as you have now rules out the regulatore.
I would do what Jay initially suggested and hook up a return line into a bucket and then run some fuel into there and see what the pressure is like, that way you know for sure it's after the regulator.

So not much progress yesterday. I needed tools and some more fuel line and everybody was closed for the holiday... so I just cleaned the frack out of my garage, bathing in fumes

What I did manage to find out though: With the fuel system hooked up and the car off, the fuel pressure jumps about 10-12 psi when the pump turns on. It holds constant pressure with the pump running, then drops the 10-12 psi when the pump shuts off and holds again at the lower pressure.

Then, if I pull the return line off where it attaches to the sending unit and run a line out to a bucket, with the car off, and run the pump, it only jumps 3-4psi when the pump turns on. This suggests to me that there is some sort of restriction inside the return portion of the sending unit.

For tonight (time permitting):

-Try to get the sending unit out (I hear this is easier said than done... and the 14mm tube nut at the bottom of that rubber feed line from the sender was rounded by the previous owner)
-Disconnect the return line at the FPR and run a line from there to a bucket and see how fuel pressure behaves

Removing the sender is very easy. It's cracking those nuts that's a PITA. Vise grips are your best friend

Get a move on things! You're falling behind

Yeah, no sh!t. Unfortunately, moving into a new house, finishing up research while starting full time work, and having to juggle a half dozen family obligations in the past few weeks has really taxed my free time. Especially since I have to rely on Guelph Transit to get me around.

If I had a car, I would have had the time to fix the car. Catch 22 is a much funnier book than reality

I feel your pain, House projects taxed all my 'DSM' time

Didn't make it to the garage until about 9 (I had soccer after work). Ran the fuel pump with a line off the regulator straight into a bucket, and it acted the same as when the return was hooked up but not attached to the sending unit. So I'm quite confident that my return line is fine.

Pulled the sending unit out. Got the feed line apart at the sending unit (a day soaking in mouse milk and it was cake), and actually managed to get it off without ripping the rubber section. Since I really see no easy way of putting that piece back on, and I've already got everything apart anyway, I'm thinking of having the sending unit welded for -AN lines.

Took a look at that plastic piece where the fuel drains back in, and WOW is it small. Gave it a shot of air, and a little black something-or-other came out (I proceeded to burn it while cackling maniacally over the pitifully small flame). Again, since I'm already in there, I think I'm going to drill that little return hole out a bit.

Hopefully that was the issue. I won't have it ready for welding tomorrow, and my Thursday night is full, so it may not be reassembled until Friday...

I've tried searching a bit on this subject, to no avail:

Is there an easy way to get the white plug out on a 2g sending unit? It looks like the metal is crimped on the sides to hold the plug in, but I don't like bending things out of shape if I don't have to.

Nevermind, got 'er out..

like this?

Try building a DSM from the ground up with the car 2.5 hours from home. Quit yer belly aching

I don't envy your situation either, but I do love your work.

Progress!

Got the fuel system back together last night with the new feed and return line. As soon as I tested the pump, it was obvious that the return had lost a significant amount of restriction.

Fired her up, she ran SIGNIFICANTLY better, with the fuel pressure acting absolutely as it should. It sounds like the engine is quite a bit out of time though, and it had trouble running below 1500 or above 5000 RPM.

I'm trying to figure out exactly how to do my base timing. Apparently the '95s DID have a plug that you could ground to put the ECU into base timing mode, but I'm not sure if that works with the AEM EMS. From what I gather so far, I need to figure out what my base timing is set to in my tune, and then match the actual base timing to it. I may have to do the "set-timing-while-cranking" method, and just hope my starter keeps running like a champ.

Hell, it managed to survive me trying to start a seized motor with it..

Good stuff!! What are you using for air measurement?

There might be an option in AEM to set your base timing, I think I would look for that first before trying to ground stuff.

Lets see some picture of the fuel sending unit!

GM IAT and AEM MAP sensor for SD (as far as I know), and yes I'll be digging through the AEM stuff tonight and poking around on their forums.

I'll see if I can get a pic of the sending unit.

Oh ok, when my car had a leaky 3' maf it was having the same symptoms.

I'm thinking the timing being out has something to do with it.

If not, I'm guessing the problem will be easier to find once the timing is right

Okay, so the problems persist. The fuel pressure is acting perfectly normal after the new lines, but the engine still seems like it's getting way too much fuel. It takes a ton of cranking to get it running, and once it's running the AFRs stay pegged on rich, it stalls if you try to idle, and it can't get past about 4500 RPM before it starts misfiring and popping away...

I'm going to try and get a log of it while it's running, and I'm awaiting approval to begin using the AEM forums. I really feel like it's not going to be a tuning thing though; it ran fine on the same tune before the rebuild. I'm sure it will need some tweaking but it should be close enough for the car to run.

Not even sure where to go from here. Maybe pull the injectors and test them... I'm really starting to get frustrated though.

I'm sure you have but did you do a BLT?

There could be an issue with the tune now that youve fixed the fuel issues, after an engine rebuild there will be a difference in compression and vacuum due to the new parts, your old tune was smoothed out to another engine basicly (as far as the ecu thinks)

My tune was perfect for my engine before it went in for a rebuild but the ecu was tuned around cracked valves and a blown HG, when I finally get the engine back it would be in my best interest to go over the tune from the start and make adjustments to dial it in for the new conditions.

Yeah, BLT was fine. I know the tune will need to be changed for the new engine, but the old engine held compression fine, had the same compression ratio, same cams, same valves. It should need smoothing out, but I can't see it needing to be redone from scratch..but we'll see what the logs say when I get a chance.

How does AEM adjust fuel? Is it like Link? By that I mean you set your base Global and deadtime then tweek from there. I remember mentioned the front wiring just laying there, Is your WB installed in the front O2 or downstream? Is there a NB sim in AEM?

I know that AEM read WB natively, huge plus I think.
Did you change injectors, I am sure AEM would be total dead time and not just the stock plus what ever you enter.

Found this, does it look like this:

I don't think there's a need for NB sim as there's no stock ECU to keep happy. As Bryan said, AEM reads the WB natively. I'm not sure exactly how fuel is managed (haven't gotten that far yet..), but there are big charts like what Bryan linked where you can adjust the numbers (and when you put in a bigger number, it puts in more fuel).

I've made adjustments to the fuel map before but all I did was click on the boxes in the chart and fiddle with the numbers a bit..

Edit: To answer your question Bryan, it looks similar to that. That's AEMTuner, I'm on AEMPro (I think the Version2 guys use AEMTuner).

Oh right AEM is a stand alone... I have seen alot those (in the honda world) that over the winter didnt keep settings. I have even seen them lose everything if you turn off the key, but that of been incorrect wiring.

Probably AEM forums are your best advise or join the sheep and buy link... (still don't know how to put in emoticons)

The thought crossed my mind too. I reflashed the ECU last Tuesday, and again yesterday before firing it up.

I want to get on the AEM forums but you have to wait for approval, so I'm guessing that won't be until tomorrow. I may try to make a new base map just to see if I can get it running better; if I can, then I know it's in the tune.

when writing a post at the bottom of the screen it will have a button that says 'switch to full screen reply' click that and at the top left of your new window it will have a smiley face button...click it and chose what emoticon you wish to use.

I always thought emoticons were for teenage girls.

...wait I don't get it. This sentence is completely free of grammatical or spelling errors.

Who's on Jay's account?

Hahaha!.. ''

I am actually killing myself right now

All in good fun Jay

I think while I wait on approval for the AEM forums I'm going to go back to basics. Check spark, check injectors for leaks/spray pattern...

Make sure the coolant temp sensor is plugged in

If you need Injector testers. I can lend you one.

What does the tester do/how does it work?

It test resitance and flow in conjuction with a fuel pressure gauge to check for leakage and flow balance.

So, I went about checking the basics tonight. I got the plugs out and laid them across the valve cover with wires attached, pulled the CAS and put my key in. Gave her a spin, and watched the pairs of spark plugs fire away, happy as can be. Gave her a couple more spins, and noticed something. The second and third plug were firing as the CAS was passing by the position that you set it to when installing it for #1 TDC.

So.....


......out of curiosity...


..can these cars run if the plug wires are on opposite coils? That is, cylinders 1 and 4 are firing when 2 and 3 should be, and vice versa?

It was too late for me to be able to switch them back and fire it up to try.

CLICK ME!

I set mine up according to how you're supposed to if you have a 6bolt in a 2g using the 1g coil pack and igniter. But with AEM you can set it up either way, and I'm too AEMtarded to know how to check.


P.S. Dick

Hey that was cool

It's never too late to buy LINK..... JK.

Ive seen 4g's run as you describe before, all timing related. I havent read the whole thread to its entirety, but have you checked the timing? Im certain your symptoms are timing related.

It really sounds like an engine that's out of time when it's running. I've adjusted the CAS fully to either side while the car was running and it didn't change whatsoever, but it seemed like the more advanced I put it, the better it ran.

The problem is that I can't really set the timing properly until it will idle, or can at least hold a constant RPM for a bit.


When I mentioned the idea of backwards plug wires to my dad, he just started laughing. He did the same thing on his Norton once, and had the exact same symptoms that I'm having. His Norton ran on a waste spark system.

I'm going in for surgery in a few hours, and I know this will be bugging me until I can get back to Guelph and try it!

Quick update: switching the plug wires did nothing. The car farted a couple times but didn't run. I did find that the wires weren't seating all the way down on the plug though. With that fixed, the car was able to rev to 6000RPM+ without misfiring. It still won't idle.

I did manage to get a log of it though, and it's showing my injector duty ranging from 40-65% as my RPM ranges from 1000-3000. The measurement which I believe is the MAP sensor is pegged up high.

So, new theory: I think my ECU is seeing a steady 5V from the MAP sensor and is trying to compensate by dumping way too much fuel. Comments, ideas?

Edit: I also pulled off the timing cover to double check that everything is lines up properly under there, which it is.

Alright, so my MAP sensor's ground was kafuct. I pulled the electrical tape back about a foot to find some shotty wiring, and even after that point I still didn't have a ground. So I chopped the wire before the shotty-ness and grounded it to a bolt on the firewall.

Fast forward an hour, and I'm screaming down Victoria at full boost. What a fracking feeling!

A HUGE thanks goes out to Stephen Richardson, who walked me through the electrical diagnosis over the phone this afternoon, as well as bouncing ideas with me the last few weeks. Thanks for the rest of you guys for your ideas, and Salomon, Rob, and Ryan who I also bugged directly for some insight! Boost on!

About time I have to stop dealing with your endless pestering!

Haha...kidding, but I'm glad she's finally come to life. About damn time...just when she comes to life mine has lost hers...I guess the grudge-teasing begins, eh?

Glad to hear you got it sorted out man! Sometimes, it's the simplest thing.

I think you get the beer for this one

Goes to show how important it is to know your tuning software, or at the very least how to monitor your car. The problem was fixed within 48 hours of me finally looking at a log.

And Salomon, I know better than to fling poo when my car is running right(ish). It's only a matter of time

Yay! No more texts and calls while Im driving! LOL

Kidding bud, glad your running.

I really am good at that... haha

Woo! Wicked man!

Glad to hear you're moving.

Larmond and Eng both know very well how good I am at texting hehehe

lol. Yup!
not so much recently... Does that mean all is going well Mike?!

Slide texting is where it's at.

Haha, no, not really, but she's acting as a grocery getter at the moment.

Slide texting? Oooooooh, Eng is all up in the Android world now, no more stuttery Blackberry Torch

Black who? Loool