Looking for a possible diagnosis of a rail pressure issue. Last year I installed an lbz fuel pump and ordered a tune to go with it and since then I have been chasing a problem with low fuel rail pressure. When ever I pull anything even as small as 2000lbs on the interstate I can’t keep rail pressure and almost all the time my rail pressure lags behind my desired pressure. I have a race plug in place of the pressure relief, a ported rail fitting, lift pump, and my balance rates are within +-3. Does this seem like a bad cp3(I bought used) and a bad tune? It will get up to 23.1kpsi.
LLY: Fuel Issue
- Thread starter shotgunwilly1117
- Start date
Could be either the tune or the CP3. Who did you get the tune through?
If you log the regulator duty cycle / % while this is happening and see it opening more and more without increasing fuel pressure then I would say you may have a bad pump.
You can also unplug the regulator connector and the pressure should go up to maximum.
There is also the possibility that you have air getting into the fuel lines or there is a restriction like a collapsed fuel line. Start with the easy stuff assuming the pump is ok.
If you log the regulator duty cycle / % while this is happening and see it opening more and more without increasing fuel pressure then I would say you may have a bad pump.
You can also unplug the regulator connector and the pressure should go up to maximum.
There is also the possibility that you have air getting into the fuel lines or there is a restriction like a collapsed fuel line. Start with the easy stuff assuming the pump is ok.
Bottle test it first... Many a race plug has made it into the trash because it leaked. Keep it simple first.
True, I don’t remember where I got the tune, it may have been ridge runner. I’ll start by unplugging it and then checking all my supply hoses for restrictions. I added the lift pump since the problem started thinking if there was a restriction or air it would help and it didn’t make any difference.
Thanks,
Worse comes to worse I’ll drop it off at the shop
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Thanks,
Worse comes to worse I’ll drop it off at the shop
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I think my regulator on the old pump was going bad cause I had surging and I was doing heads so I went ahead and changed pumps too
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Correct but I’ve been having them ever since because I was dumb and Tried the shim kit At the same time, couldn’t get it to seat again so I put a plug and it got way better but has been doing this now for about a year
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Ended up being fuel leaking past the plug, got an extra 1/4 turn and sealed up. Wish I checked that last year
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