running out of fuel?? Lift pump?

kasey200

kasey200

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Sep 24, 2006
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my 97 12v acts like it's running out of fuel at about 2500 rpm on the road. if you ease into it doesn't do it as bad. If you step on it.... it falls on its face. My fuel pressure gauge is reading about 25 psi at an idle but as soon as you touch the accelerator it drops to zero fast. Does this sound like a lift pump failure?? if so how does it keep running? This happened about 300 miles form home yesterday, and i was able to drive it the rest of the way home.
 
Did you test the overflow valve by pinching the return line off and seeing if the pressure rises or holds steady through the rpm range?
 
a P-7100 needs about 40-45 PSI if i remember correctly. mine only drops to about 33-35 psi WFO
 
Just went through this on mine. Would drive/tow with no problem.
Hold it to the floor and it would die/bog bad.
checked pressure 30 at idle, 0 at 2500.
My fix, fuel filter!!! now 45 idle,55 at 2500
I'am still using the stock 95 filter setup. Hope this is of help.
TOMMY
 
I usually run my airdog/ Fass pumps at 35-50 psi but as long as you have more than 20 at full load you won't notice a power difference. My truck dropped to 15 psi at full load with the mechanical pump and dropped to 35 with an airdog. I dynoed the truck back to back after switching to the airdog and there was no difference in power.
 
TOMTOM said:
Just went through this on mine. Would drive/tow with no problem.
Hold it to the floor and it would die/bog bad.
checked pressure 30 at idle, 0 at 2500.
My fix, fuel filter!!! now 45 idle,55 at 2500
I'am still using the stock 95 filter setup. Hope this is of help.
TOMMY
Click to expand...

This is exactly what it's doing. I Might give that a try.

I pinched the return line and pressure went up to about 60psi?!?! I pulled the OFV apart and stretched the spring and started it up and the fuel pressure was at 40psi at an idle for a bit. As soon as i gave it throttle it dropped back to 0 and wouldn't go back up to 40. It almost seems like the OFV is messed up.
 
I need to Check my OFV. I ordered a new one, and I'm going to replace mine anyway. My truck Is doing something similar.
 
Got the same problem with a truck at work.
FP is good and changed the FF and the overflow valve but it still runs out of fuel crusing down the interstate at @70mph.
Problem comes and goes. It's got me baffled.......:bang

One diesel shop I talked to said it could have a "barrell" hanging up and one shop said the rack could be "catching/sticking". IDK anymore.......

Good luck with yours.
 
hmmmm I ordered a new ofv and i am going to replact the fuel filter. we'll see what happens i guess.
 
Also, I pinched the overflow line with a vicegrip and the fuel pressure rose to about 60 psi and it held there throught teh RPM range. It actually increased to about 70-75 depending on the load on the engine at that given moment. I sure am hoping the new OFV solves the problem.
 
Instead of buying a new OFV, get a click-stick pen and take the spring out of it. Cut it to the length of the spring in the OFV and run both springs. Took my FP from 14 to 45 at idle. Been running great since then.
 
Well the new OFV didn't solve the problem... fuel filter next?? i don't get it because if i pinch the return line it runs great??!?!?!
 
Can you do the click pen spring? If it doesn't work, it only cost you 10-20 minutes and the price of the pen.
 
i'll give it a try but i don't think it's the OFV anymore... i'm going to put in a new fuel filter today.
 
I also checked my fuel stop selenoid, when i click on the ignition, it doesnt go all the way up, i have to manually lift it up. once i do that, it will run great. You might want to check yours.
 
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