fuel pressure problem

ldclark

Registered User
Just a quick question to doublecheck my diagnosis. I hooked up a fuel pressure gauge to schrader valve on the fuel rail and there was no pressure (zero). When I turned on the key, the pressure went up to about 10 pounds and then went immediately back to zero (the pump only ran for a few seconds). When the car is running the pressure stays at 20 pounds, and yes it takes about 10 seconds of cranking to start it. I think this sounds like a bad pressure regulator, what do you guys think?

PS: the symptom that caused me to start diagnosis was the car sputters and dies when you step on the gas enough to get the boost gauge to the "0", or straight up position. The car seems to idle fine. Before you ask, new plugs and wires, new TPS, MAF sensor cleaned, one new oxygen sensor. It was misbehaving before those were changed but I wanted to get the obvious out of the way (and clear the codes for the O2 sensor).
 
You didn't mention the fuel filter. If it hasn't been changed recently that would be the first place to look. Fuel pump could also be failing. Basically the regulator probably is ok if the diaphram is not ruptured. If you pull the vacuum hose of the regulator while engine idling and no gas comes out of the vacuum port it's probably ok. John
 
AnnivSpeCpe said:
You didn't mention the fuel filter. If it hasn't been changed recently that would be the first place to look. Fuel pump could also be failing. Basically the regulator probably is ok if the diaphram is not ruptured. If you pull the vacuum hose of the regulator while engine idling and no gas comes out of the vacuum port it's probably ok. John

Sorry, fuel filter has less than 1000 miles. I'll pull off the vacuum hose and see what happens tomorrow. I'm actually hoping it's the pump, that looks easier to change out than the pressure regulator.
 
re-fuel preasure

My 91 has 40 psi at the fuel rail and drops a littlle bit when I give it gas. Sounds like your fuel pump is going out. Is your battery fully charged? If you change your fuel pump make sure you disconnect your battery. good luck
 
mine holds around 30 pounds fuel press while idleing , i think it holds 20 when i shut it off , it sounds like regulator or bad injector , did you try stp gas treatment that fixed mine in about a mile of driving onetime . i had an injector stick open it was missing and throwing black smoke i stopped at 7 11 and bought stp gas treatment it fixed it right away i believed in it ever since . once in a while my pressure regulator will stick a little bit when the engine is cold you can feel it hesitate a bit . i checked my fuel pressure cause my car started running like junk but it was the harmonic balancer broke and twisted enough to spark the plugs late. it had no wobbles or other symptoms so im glad the guys here on the forum helped me with that one the last time my balancer broke it broke bolt and all off
 
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pressure

I'm going through the same thing. Hard starting at times. I did a pressure test yesterday and it was at 34 at idle but would drop to almost nothing in about 30 minutes after cutting it off.

I was told by Paul at BTM, that it should hold most of the pressure for at least an hour, only dropping a couple. After testing mine, we concluded that it's the injectors that are causing the problem. They are sticking open due to being gummed up and thus leaking fuel into the heads and giving it a flooding situation, making it hard to start.

I had already replaced the filter, the pump died, so got a new one and replaced the fuel pump relay. The pressure at idle should be around 35-40.
If you don't have more than 20 pounds of pressure, I would think your pump might need replacing. Good luck with it.

David
 
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