Fuel Pressure ??

[mhochman]

What should my fuel pressure be on the valve at the fuel rail with Key on Engine off and Key On Engine On. The first time I turned key on it went to 25 the next it was 42 then the last was 62. After I start the engine it stays at about 62-64. In between the first 3 tests with the key on I did start the engine. Anotherwords key on, check dial, start check dial, off.
Thanks for your time,
Mark

 

[Maniak]

I belive the 62 is high.. but I'd have to look in a book.. I "think" 40's is closer to correct...

But.. the low pressures in teh beginning sound like a bad check valve in the fuel pump.. It lets the pressure back into the tank over time.. It means longer starting times..

It it takes a while to start (a few cranks) in the morning, try this trick.. Turn the key on, wait, turn off.. turn on, wait, turn off.. then start. if it starts much faster and Your fuel pressure in the morning (on first turn on) is always low then it should be the fuel pump...

It is possible you are loosing pressure from somewhere else (leaking injector etc), but normally you can hear those when the vehicle is off (but key on)..

~Mark

 

[aldive]

The specs on my '99 SOHC are as follows:

Fuel Pressure 65 +/- 8 psi

 

[mhochman]

Thanks for the info. Yeah sometimes at the end of the day after my car has been sitting it will crank over and almost start, sputter and die. Or crank over and over and over then start and run rough for about 5 seconds then normal. I also have a rough or miss at idle. I noticed that with key on engine off after pressure goes up it starts to fall and continues even if the key is on. Could the high pressure cause the rough idle?
Thanks Again,
Mark

 

[aldive]

Your symptoms are similar to a fuel pump failing.

 

[mhochman]

I do have a bad habit of running on empty, I heard that it is not good for the fuel pump, runs hot???
The hard to start has been going on for about 8 months but it does it like maybe once or twice a month. Are there any other tests I can do to the fuel system?
-Mark

 

[Maniak]

Looks like your pressure is right. Its the dropping pressure that is bad. If you aren't leaking fuel anywhere (leaky injector, leak at the fuel filter etc) then it is your fuel pump that is going. It is allowing pressure to leak. I don't know about the 2nd gen.. but on the first gen you drop the tank to change the fuel pump.. and if your going to change it.. spend a little extra to get a better quality one and get the assembly (fuel pump with sending unit). You don't want to have to go back in there to change the sending unit later or have to change it again becuase you got a bad/cheap pump..

It took me 4 hours to change my fuel pump (tank was near empty).. Most of the time was trying to get the skid plate off. The skid plate/mounting strap was slightly modified from an EF run (I fit a round tree root into the square hole on the bottom of the skid plate while at crown king).

~Mark

 

[mhochman]

Thanks Maniak, it drops down slowly and steadly with the key on engine off. With the key on engine on it seems to stay steady. Should it stay steady with Key on engine off?
-Mark

 

[Maniak]

It should stay the same.. once you know you aren't leaking anywhere else I would start saving for a fuel pump assembly...

~Mark

 

[mhochman]

How would I know that the fuel injectors are not leaking? Everywhere else looks ok.