Fuel Pressure Regulator

[Bwana Bob]

I think my FPR is going west. It was replaced a few years ago. Now I have jerking and hesitation under hard acceleration and hard starting when it sits for an hour or two (Ok sitting overnight). From posts I've read, it sounds like the FPR pressure is low or is not increasing when the vacuum drops.

I want to replace the FPR. Where's the best place to get one? Ford Parts Network shows the list price as $138.84 and their price as $115.24. Is that a fair price? Is Ford Parts Network good to deal with?



Thanks,


Bob

 

[Chew_12]

Get a price on the local Auto Zone just to see. Im not too sure what a good price is, but if you shop around im sure you will get a good idea.

 

[Opera House]

If FPR was replaced a few years before

I wouldn't expect it to be bad this soon. Has the fuel pump also been replaced? I have my doubts about the FPR. I would do a pressure and leakdown test first. Leakdown would explain hard starting but not hesitation. Old pump might explain both. I would consider other things besides fuel system.

 

[james t]

before you replace it without knowing that is the problem, go rent a fuel pressure guage at autozone (free) and see what kind of fuel pressure you have. do the leakdown test as operahouse suggested.

 

[Bwana Bob]

Thanks for the suggestions.

Both the FPR and fuel pump were replaced about 50,000 miles ago, in January 2000. The FPR had failed.

I suspect the FPR now because the truck jerks and hesitates only under hard acceleration when the RPM's are below 2000. So, I'm guessing (maybe an educated guess) that when the vacuum drops under acceleration, the FPR is not increasing the pressure as it should. Sometimes the jerking is accompanied by pinging, which I think could indicate a lean mixture. Hovever, I don't get a check engine light as I did when the last FPR failed.

I can't think of anything else that would cause this problem. I recently replaced the fuel filter, but the problem remains.

The other symptom is that it takes a bit of cranking to start the engine when its been sitting a while, but it fires off immediately after sitting for several hours or overnight.

Thanks again.

Bob

 

[Rhett]

Are your plug wires good?

 

[Garth]

Whats a leak down test? Is a 35 reading when you turn the key, good for a V8?

 

[SVO]

If the FRP was bad (diaphram ruptured) vacuum would suck fuel into the intake and excessive fuel would also be forced on the injectors causing an over rich condition, hence black exhaust smoke, and the smell of raw fuel being expelled through the tail pipe.


Plus the vehicle would feel slow and very sluggish, bogging down like.

 

[Opera House]

Pressure should be around 39# with no vacuum (you can remove it with the engine running) and 33-34# at idle. Accuracy of many gauges is poor. If you can hold 30# for 15-30 minutes then leakdown isn't a problem.

 

[Garth]

Would a diagnostic machine find problems like these or its something that you have to find manually?

 

[SVO]

Process of elimination, you will have to do this one manually.

 

[MattPersman]

the hard starting when cold is typically the check valve in the fuel pump, when it fails it allows the fuel to drain out of the rail and high pressure line so the fuel has to go from the tank again after sitting a while to get to the injectors. you have to replace the pump to fix that, or just prime the pump 3 times each time before you start it if it bothers you. it will last a long time that way still if thats the only thing wrong with the pump. try that and see what happens

if you get a fuel pressure gauge, get a vacuum pump too. you can check the integrity of the FPR diaphram to see if its working or defective.

diagnostic machine will be a waste of money in this case, get or borrow a fuel pressure gauge, one that has a ford adapter not just a standard one cause that will not fit, autozone sells them so does sears it also has a clear house that you can check volume of the system with also like I mentioned vacuum pump, its amazing what you can diagnose with one of these in a short amount of time on a vehicle

 

[Garth]

Questions: How do I perform the vacuum test? I will check with auto zone for a pump in the morning. Should I ask for a particular vacuum pump or is there only one?

 

[Opera House]

The vacuum pump would allow you to suck gas if the diagphram was leaking, something you could do with the engine running. It would also allow you to change the fuel rail pressure manually. Pressure drops with the amount of vacuum. Perfect vacuum is about 30" of mercury or 15#. Idle is about 15-17" so the pressure drops about 7#. You can see that by just pulling off the vacuum line at idle. I would get a cheap digital volt meter and measure the pump current by pulling the pump fuse and measuring the current there. Should be about 5A. This might give an indication of the pump condition. You could also do a flow test on the regulator return line.

 

[Garth]

Thanks for that heads up! I did the tap start and it works all the time. I will have to change the regulator because it wont remote start in the condition that its in. I can smell the Gas at times too but I use to think it was the other car that was infront of me.