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6.5 rpm issues

J

John1992

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Beckley wv
I just bought a 1995 6.5 from a friend of mine who thought the lift pump was bad so I installed a new one along with a new filter. The issue I'm having is the truck won't rev over 2000 rpm. I started the truck and unhooked the lp to see if the injector pump would keep it running and it did so that makes me think the ip is good. It doesn't puff any smoke which makes me think the injectors are fine. I'm just really stumped on this one, and new to Diesel engines any tips would be greatly appreciated thanks in advance.
 
Besides the filter there is a sock on the pickup in the tank, a screen on the shaft in the fuel filter, and a screen on the fitting going into the IP.
 
Welcome John.
Your talking no load, right?
Only thing I would do different is put a fuel pressure gauge between the Lp and ip. If it drops below 1 lbs, then chase the fuel system like AK mentioned. Ideally 9 psi is what you want there, below 5 is not good, but as long as you have over 1 psi, it should rev up to 3,200 no problem.

If you dont have a pressure tester, most auto parts stores have a loaner program where you buy, then return for full refund. Or this one is not bad at all:
http://m.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html
 
You do not necessarily ave to change the OPS.

In my opinion. the first thing to be done along that line would be to make up a dual lift pump relay upgrade - or just buy one from leroydiesel.com

If you make your own, make it plug and play like Leroy does his. Do not cut and splice things.

With your truck running check for juice at the lift pump plug. If you have juice there, skip the OPS and use that money and time for the lift pump relay upgrade. Even if your tester says 12 volts, you may still not be getting enough juice to run the lift pump.

The lift pump relay is a must do on 1995 and older 6.5's

I have 2 vehicles running fine on OPS's that would not run a lift pump - but they throw enough juice to trigger a relay
 
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