Just ask the Fiero guys, it seems (Page 1/2)
weaselbeak JUL 24, 04:23 PM
Fifteen different surefire opinions from the Ford guys. So, I just turn to the best. On an F-250, 2000 model year with a 5.4, I'm trouble shooting fuel pressure. Turning the key on yields zip, until it's been done 6-8 times. Finally, up around 10 lbs, it will start and idle, climbing to and maintaining 32 psi. While this sounds low to me, the Ford guys are sayinf 30-45 at idle. I didn't know anyone used as low as 30 psi with individual injectors. Filter is OK, so with the slow pressuring I'm thinking surely the pump, unless I can find hose problems inside the tank. Any oddball ideas that I'm overlooking? It is a Ford, after all....
Raydar JUL 24, 04:34 PM
Don't know what to tell you about the "slow to build pressure" problem, but 30 lbs sounds okay.
All the Ford injectors I found, when I was doing things with my 3.4, specified the injector flow rates at 30 lbs.
carnut122 JUL 24, 06:59 PM
Playing devil's advocate...how do you know the filter is OK and installed in the correct direction? After that, I'd say it's time to pull the tank. I agree with Raydar that 30 is OK (I'd assume a bit higher would be better), but taking 6-8 tries to get there obviously is not ok.
weaselbeak JUL 24, 08:40 PM
We took the filter off, you can blow thru it easily. A new one goes on anyway. I'm surprised to hear 30 lbs, tho.

[This message has been edited by weaselbeak (edited 07-24-2012).]

weaselbeak JUL 24, 08:41 PM
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[This message has been edited by weaselbeak (edited 07-24-2012).]

Jr86GT JUL 24, 10:43 PM
Here you are, straight from the Ford PTS Website (online workshop manual, and I highlighted the important parts):



As for your lack of building fuel pressure, I'd make sure you have power and ground at the connector at the fuel tank EVERY time you turn the key on (rule out electrical). Sounds like your fuel pump is going out.
weaselbeak JUL 25, 02:48 AM
You can hear the pump run every time you turn the switch on, it even sounds good. But it barely budges the pressure gauge. With constant juice it will climb to 32#, but it takes 5-7 seconds to get there. Tomorrow will tell.
crashyoung JUL 25, 03:10 PM
I had a similar problem, it was the hose that connected the pump to the tubing.
I had to drop the tank and put in a submersible hose, as the other hose was nothing but threads!
GreenPlatypus JUL 25, 04:21 PM
The pump is most likely on it's way out. However, if possible, block off the return line, see if that helps. May just have a bad pressure regulator. I don't remember if the 5.4's use a returnless system or not, though. Been awhile since I seen one last. Or disconnect the fuel line and turn the key on and off, see if fuel is actually flowing out of the line - JUST BE CAREFUL doing it that way.

If you do get a new pump, I'd get one from Ford. Haven't had much luck with after market pumps lately, on anything.

[This message has been edited by GreenPlatypus (edited 07-25-2012).]

weaselbeak JUL 25, 05:35 PM
New pump cured it, for now. It came from O'Reilly's, the brand is Precision, 226 bucks out the door, and it says "Made in the USA". Time will tell. Since the pump was not that old, the owner took the easy way out for fear of another big expensive job. He cut an access hole in the bed, and plated over it. It's asking too much for easy access from the factory.