Lately, I been having some hard starting and hesitation problems. I believe the problem is my fuel pressure regulator. When I turn the key the pump energizes and the fuel pressure jumps to about 50 psi but as soon as the fuel pump turns off the pressure rapidly decreases back to zero. Even a leaky injector wouldn't drop the pressure that fast.

So today after work I changed out my fuel pressure reg with the one that I had bought just a year ago and the samething happen. Up to 50psi and down to 0 psi. I still have the old fuel press reg that I swapped out when I first got the engine and I will check that tomorrow.

The problem seemed to start after a was running low on fuel one day.

I replaced the fuel pump and fuel filter less then 3 months ago. Fuel injectors are less then 1 1/2 years old.

Any suggestions if the other fuel pressure regulator doesn't work? I can't see all three being bad.

Thanks,
JAy

 

Most likely the check valve in the fuel pump.

 

I'm still having the same problems. Although, now it seems to be worst. When I turn the key it goes to about 20psi and when I turn it again it goes to about 35psi. Basically it takes 3 turns of the key to build up pressure. However it keeps dropping back down. When I changed the pump two months ago I had no split lines or anything. If the check valve in the pump is bad would it cause hesitation at higher speeds? Also the pump is whining like crazy. I can hear it over the exhaust. When I crank the engine the fuel pressure is low holding steady around 35psi. Anything suggestions, I would hate to cut my exhaust back down to change the pump again...

Thanks,
Jay

 

I was having a similar problem after replacing a fuel pump. My mistake was using the cheap little plastis clamps supplied with the pump for the outlet hose in the tank. They allowed leakage, similar to what a bad check valve would do. They just didn't hold up to TPI line pressure.

I replaced them with screw on type clamps in stead and got rid of the problem. Nothing like having to tear out the tank twice!

 

Turn your key on to get rail pressure.. Pinch off both return and inlet hose's to isolate system and see if it still bleeds down. If it dont you know its your fuel pump bleeding down. If you had a bad fyel pressure regulatos two things could happen. You would have a hole in the diapram and start sucking fuel in your intake cause rough running,rich cond. If the little seat/spring wears out that you'll have low pressure cause its sending it all back to tank. Good luck!

 

Yesterday after work the pump started whining so loud I could hear it over the exhaust. Next came the hesitation and stalling. The pressure continously dropped down while driving and engine started bogging down. Looks like I'll be getting another fuel pump.

Jay

 

How long does it normally take for the fuel pressure to go down after you turn the engine off? It does having a way of relieving presssure right?

Thanks,
Jay

 

Well, when my car's fuel system was mostly stock, it would hold pressure for several hours, at least...

 

I cut a access hole in the rear floor right above the fuel pump. Beats dropping down exhaust, rear, and all that other crap
http://www.taekwondoplus.org/z28/fuelpump.html

 

I'm very impressed with the trap door!!!!!! I have an 1989 5.0...........I replaced my fuel pump after old fuel pump would not hold pressure..My new pump however, is not holding pressure- it builds up to 35 lbs then right back down to 0lbs when i turn it off..........Iroc86, i saw your pics, and noticed that you had two O-rings side by side. I only put one of the orings on the cover, the smaller one; what is the bigger oring for? was that suppose to go on also?