It bounces up and down 6psi or so I cant get an accurate pressure. Its between 42/48 psi, It did this once and awhile before, now its constant. I can almost feel the pressure pulsating in the line. I did leave it connected for a couple days under the hood. I dont think the heat could have hurt the gage.

Could this be a sign of a bad pressure regulator? The one I have is a crane.

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90 IROC
SuperRamed 406
Trickflow 23* heads

 

You need to unhook the vacume line from the AFPR when checking the psi. I think it still bounces around a bit, but to get the proper psi, unhook your vacume line when checking the psi.

 

Yeah...thats how I set my fuel pressure.It does it with the line diconnected also.

 

not that i have any proof or info to base it on, but if its bouncing around that much could it be the pump going bad? like its pulsing or something?

 

hey, i have the exact same problem, i wondered at first if maybe it could be because we have batch fire, but one day i was testing it, and it was perfectly steady. and like you, i can feel it pulsing in the line also. Im thinking it might be a bad injector maybe, one of these days im gonna pull the plugs off the injectors one by one until i see if any are bad (when the pressure smooths out)..

i also noticed that sometimes when reving the engine, after i let off the throttle, i coudl hear a single loud tick coming from the passenger side of the car, and i thought maybe an injector is sticking open or closed or something.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

 

I hope its not the pump or injectors both are new. I just installed a walbro 255lph pump. It just started doing this,I tried disconnecting the gauge and hooking it backup. It seemed to smooth out some but still fluctuates. I cant get a steady reading to see where its at. I taped the gage to the windshield and went for a drive. It still bounced but it would stop and hold steady as I accelerated. The pressure would rise under acceleration. Its running rich at idle I dont know if that matters or not.

Maybe the underhood heat damaged the gauge.

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90 IROC
SuperRamed 406
Trickflow 23* heads

 

The fuel pressure should be steady and not bounce around at all. If it moves at all w/out touching anything then you have a problem somewhere. Sorry I don't know where you should start. Good luck.