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tanbuddy 09-09-2004 04:47 PM

Fuel Pressure
Hey guys My truck has been running crappy lately. When its above 1200 rpm I cna only give it maybe 1/4 throttle or it stumbles. Put a fuel pressure tester on hte rail. 30 psi idle. WOT it goes to 3 grand, then stumbles to 1500 rpm. Pressure drops to 20 psi. Any ideas, pump, computer bad? Thanks

BigNorm 09-10-2004 12:48 AM

Re: Fuel Pressure
Check your vacuum lines. Sounds like you may have a Vacuum leak.

havack 09-10-2004 01:58 PM

Re: Fuel Pressure
I would think the pressure regulator is bad and your pump sounds a bit weak.

BigNorm 09-10-2004 05:40 PM

Re: Fuel Pressure
Havack's right. I just focussed on the stumbling part. Drop in pressure was the key to what you said.

Jacob_Royer 09-11-2004 06:52 PM

Re: Fuel Pressure
I'd try a fuel filter they are cheap and you most likely need a new one anyway. Then I would pick up a Ford code reader. They are only $19/$25 at autozone and will help diagnose what is giving you problems. Alot of times it will spit out a code for somemthing (ie map sensor) and the vacuum line is shot or unpluges. Much easier to have the reader to narrow down the problem plus its somthing everyone that has an EFI truck should have. The are very universal and work on just about all 80's through 96 ford vehicles.

havack 09-13-2004 09:35 AM

Re: Fuel Pressure
With the thing droping 10 PSI on pressure I would not pass go until I bought a pressure regulator. You could pull the vacuum from the current one and see if the pressure still drops. If it does then r&r. Might not see any codes and there is no need for a code reader to pull them anyway. You can do it from my site or someplace like the 'Zone will do it for free and I am all about free.

tanbuddy 09-14-2004 10:01 PM

Re: Fuel Pressure
Just replaced the filter, and she runs a little better, but not like she should. I can get a pressure regulator for free [img]images/graemlins/cool.gif[/img], so i guess that'll be the next step.

JWharden 09-15-2004 08:29 AM

Re: Fuel Pressure
Did you check the fuel pressure after you changed the filter ?
Pressure should be @45 psi at idle and hold with in 5 pounds for 1 mintue after shut down. Always change the filter after you replace pump, they collect the piece of the bad pump.
best way to keep your electic fuel pump alive is to change the fuel filter often.
Good luck

Steve83 09-26-2004 07:51 PM

Re: Fuel Pressure
Changing the FPR is a PITA, and it probably won't help you. Pull the vacuum line to it & see what your pressure is at idle, then Key On Engine Off. If it's low for EITHER test, you need a pump.

tanbuddy 09-27-2004 08:56 PM

Re: Fuel Pressure
I Pulled the vacume line, the pressure was still low, so I changed pump. What PITA. Took all day sunday, my dad helped me get the tank back up today. Too much rust one of hte stupid lines broke off the assemble aso had to spend another 20 bucks. Oh well she starts every time and runs good again [img]images/graemlins/cool.gif[/img] well as good as a 2.9 can run [img]images/graemlins/crazy.gif[/img]

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