Won`t start when hot

The car will start with no problems when it`s cold.It ran fine all winter,and has only acted up on hotter days like today.Basically,it runs perfect,but on a hot day(such as right now),if i park it for a while at a store,etc,it doesn`t want to start.An little while later,after it cools,it`s start right up.It`s stock with just a hacked MAS(going to be unhacked soon),fuel pump rewire(i did try to bypass the rewire with no change),and 12psi(although i only go into boost every few days).It`s a 90TSI,the caps are new also fwiw.
It runs prefectly,the only problem is geting it started when it`s hot,on a hot day.

For your reference, I had the same problem a couple of weeks ago. It was my aged starter. You could open the hood, let someone listen the starter when you try to start up. If it crank very weak, you should check the battery and starter.

HEAT SOKE. Do you let the car idle a few minutes after you drive it letting the fan kick in to cool things off? That was the only way I could cure my 1G when I had it as I did not have a turbo timer. Once the turbo timer is installed, it will never happen. IT is also good for the turbo to cool it off. My present 2G has always had one so I have not experienced that at all.

I beleive the starter is fine,it does turn over just fine.The heat soak is something i had already concidered,knowing these cars run hot.I did not let it run after driving.I don`t go into boost after every ride,so i though the turbo would be alright,but i didn`t think of using it to cool the motor.What i had planned is to rewire the a/c fan(the a/c doesn`t work)with my Flex a Lite fan controller to come on a 185° to help cool things down.I also want to rig an intercooler/radiator sprayer to bring the temps down quicker.Hopefully the heat soak is my problem,i`ll let you know.As of now,it`s about 85° out,so it`s not cooling too fast.

Thanks for the FAST replies,any other input is welcome of course.

More than 4 hours later,it won`t start at all this time.After some research,i see that the stock boost guage should go to "0" with the ignition on,mine doesn`t.Is it likely my ECU is bad again?

Sorry for the triple reply to myself.
I just went out again,fiddled with a few things.When i turned the key,the stock guage read "0",and sure enough it started right up.What`s the thinking,ECU problem when hot?

ECU caps!

I`ll have to take a look at the ECU.The caps were replaced 1k ago by an experienced DSM`er who does then regularly.

Jeremy, it sounds like the infamous "hot start" problem which plagued the early 1Gs. There's reference to it in the 1000AAQs and maybe the VFAQs. I've had versions of it on both my 90 TSis (I only have one of them now). Once you learn how to deal with it (I just held my foot on the gas for about a minute) it becomes nothing more than a nuisance.

I checked out the write up on it,i`m going to follow up with it`s suggestions this week.I agree it really sounds like the hot start problem.I did just check the ECU,it looks and smells fine,which is what i suspected.Look for a cooling fan question in the appropriate section.

EDIT:again the stock boost guage won`t "0" when keyed,and it won`t start.It must the the ECU afterall.

After a few attempts this afternoon,i got the guage reading with a key on,and of course it started.I went for a quick spin around the block(1/4 mile).Afterwards,several key on/key off`s,it would register fine.I shut it down for about 20 seconds,heard the ECU click,and then no start.Does this point to a specific part of the ECU itself?

No. The "click" is the relay for the ECU shutting off - it is normal.

The first thing to check/replace are the ECU capacitors. <a href="http://members.shaw.ca/costall/1000Q/answers-ECU.htm#IsthereanECUproblem">Info here.</a>

The caps were replaced 3/22/04,they don`t look to be leaking,and smell fine.A possibility given to me is that the MPI relay has a break in it somewhere.When it heats up,it can`t close enough to turn the ECU back on,which would explain why i can constantly restart when hot only until the relay shuts the ECU off.I have the schematic of the relay and harness so today i can check voltage coming out of it while it won`t start.If that checks out fine,the ECU is the last link and will be shipped off.

I had the same problem yrs ago when I bought my Talon...Just wouldn't start when hot...I would have to let it sit for 20 mins or so every time...

The problem that I was told was the fuel pump or something to do with it...I took it back to where I had purchased it and they fixed the problem...I don't know how though as it didn't appear as they had replaced the pump (bolts still dirty etc.).

Now when hot, my car starts but wants to stall...This goes on for about 30 secs or so...

I'm just saying that you shouldn't write off your ECU yet...Check the fuel system first..

Hope that's a lil help...

I did think about the fuel pump since i did the rewire a while ago.I bypassed the relay with no change.However,i was more looking into the ECU because the stock boost guage is affected.If it reads "0",it starts,if it doesn`t register,it doesn`t start.Today i put a meter on the power wires from the MPI relay,it read 12v.On/off kept showing the 12v.After a short ride,a shut off and quick start showed still 12v.So i shut it down,let the MPI relay close power to the ECU,it of course dropped to 0v.A turn of they key showed no power(also the stock boost guage had no reading,as it`s been when it won`t start).It seems that when the relay gets hot,it can`t close the circut,so the ECU isn`t getting any power.

What i`d like to know is,does any 1g DSM(turbo or n/a) have the same MPI relay,or is it year/aspiration specific?I`d like to grap 1 or 2 out of the junkyard to try the theory before i get into other options of the problem.So far this seems the most logical and cost effective to try.

Btw,thanks,i`m open to any ideas.I hate to say it,but this problem isn`t getting me down too much because it`s helping me to learn more about this car specifically.I always stinks to buy a new car and know nothing about it.