Since I didn't get much replies from fullthrottletech.com I'll try this here.

I got their bolt on AFPR and have experienced the following problem. After setting the base pressure with the vacuum line off (37psi) I went for a spin. When I came back the engine was nice and warm, and the pressure dropped to 28psi with the vacuum line off. I have readjusted the base pressure and left the car for the night. Next morning I the pressure was higher around 45 psi or so (when the engine was cold). Is this normal or the thing is busted?

IM using summit racing 0-60 liquid filled gas pressure gauge. The gauge is attached to the AFPR. Also IM using a walbro 255 hp that was installed at the same time as the AFPR. Could it be that the fuel pump is producing less PSI after it warms up? If yes would that matter?

I've had trouble with FP gauges..

You can get a cheap one for $10 at CISCO (they're in the book).
It'll be an easy way to confirm or deny that there is something "special" happening.

I got a reply from Mike from Fulltrhottle, and he sugests the same thing (bad gauge or fuel pump). It could be the gauge, hopefully not the fuel pump since it is brand new. Does heat effect gauges hat much? I did a litle experiment today.

Pressure measured with vacuum line disconnected.

1) Start idling from cold, pressure 47psi (yesterday it was set at 37psi when the engine was hot) Voltage at the pump is 13.72V

2) Engine warmed up idling (at 192 deg), AFPR and gauge is still cool to touch (the hood was open), pressure 46.5psi.

3) Went for a spin, AFPR and gauge is warm to touch, pressure 39psi. Voltage at pump 13.5v

The pressure did not come back to 37psi as yesterday but it was colder outside, and the AFPR was warm to touch, not hot like it was yesterday.

I had the same symptons with my spoolinup afr(it was made by the same people who made the fullthrottle afr), i was re-adjusting the fuel pressure everyday for like a week, eventually it settled down and everything was fine.

Interesting. Dave did you readjust when engine was cold or warm? Did you see such a big difference in psi between one adjustment and the other?

Rob, did it end up being the FP gauge that was the problem you described in <A HREF="http://www.ca.dsm.org/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=000782">this thread</A>? Or was it the FPR adjustment?

I'm still pointing my finger at the Autometer gauges.
This is based on the fact that turning the fuel pressure up (not even close to where it was on the Autometer gauges) creates a VERY rich condition.
And my plugs are fine at this low pressure (which apparently I am tuned for).

Both, when it was cold and warm. It was around a 5-7psi drop.

I tested another fuel gauge with my AFPR, and it was reading very close to my gauge, maybe 2psi less. (not to sure since this gauge had worse scale). In any case it was reading 45Psi instead of 39psi like the night before. I have readjusted it again. The saga continues . Dave how long did it take you to get it right? Any other people with this AFPR?

It took around a week for it to settle down.
Is the screw backing out maybe? Or you can try a stiffer spring.

Update: Problem solved!

Someone at Fullthrottle tech forum suggested to do a vacuum test on the AFPR. It turned out my AFPR was leaking from the set screw area. I have fixed the leak for now with some Teflon tape. Mike from Fullthrottle said to send the unit back for repair/exchange. Overall Fullthrottle guys have provided great support, so they are still good guys in my books.