Fuel Pressure Bounce

[Lefty257]

Was going to help do a FPR shim on a friends 95PSD and when we put the gauge on to get an initial reading, it was bouncing between 35 and 70 psi. Went ahead and put the Ford kit (as per wiki article) and now it bounces between 45 and 85. I would suspect the pump but the truck runs too good. Any ideas gang? Thanks ahead of time
It's a 95 cc 2wd auto

 

[95_stroker]

Its normal, to read the fuel pressure accurately you need a liquid filled guage.

 

[Lefty257]

just talked to him a bit ago. Gauge was liquid filled(summit racing). After 2 days of driving needle was bent from hitting the stop, so we are getting some over 100psi spikes. My 99 sits rock steady at 72 (after shim) so the fluctuation was surprising to me but I know the regulators are different.

 

[95_stroker]

The pumps are different as well. We have a mechanical diaphragm pump.

 

[Lefty257]

Thanks for the info 95 Stroker. Put a second gauge on just to make sure it wasnt the problem, but same deal. Just used a 300 psi instead of a 100psi.

 

[95_stroker]

You are welcome Lefty, I think if he was having pump issues he would'nt see the fuel pressure at all. I dont want to minimize a potential problem, but I really think that the fluctuation you are seeing on the guage is normal. I ran a liquid filled gauge on my FPR for a while full time, it eventually ruptured and began leaking.

 

[Big K]

The pump is probably fine if the truck is running good.

I would be worried if there is something else that was noticed.

 

[Lefty257]

95 Stroker, Again Thank you, This is what is great about this site. I hope I can help in the future.

 

[Lefty257]

Big K
Thanks for your reply too.
I kinda thought that but my experience goes from all gassers to IDI 6.9 to99 psd. ALL FOMOCO. AM always open to enlightenment