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Lost lift pump prime cycle?

SupaDave
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SupaDave

SupaDave

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98 1/2 2500 2wd 5.9L auto. Normally, turning ignition switch to run position and waiting for the WTS to go out, starts a prime cycle on the lift pump that I can hear,  lasts a few seconds and turning key to start position starts this truck immediately, I mean in like half a crank. Lately, I have had intermittent issues where the WTS lights normally and goes out, but I never hear any lift pump prime and the truck has an extended crank time of 5-10 secs before it starts. Once it starts, it runs great, fuel pressure great. But the problem is intermittent. It will work normally for a week or so, and then exhibit this problem..... I know Mike said in previous posts that a missing WTS light is a possible ECM. My WTS is not missing, just the lift pump prime. Could this still be the ECM? BTW, new IP and new lift pump have less than 10K on them. Appreciate any ideas anyone may have. Thanx, Dave.

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dripley

dripley

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The ECM also controls the the short cycle of the LP at key on and the continued operation of the pump. The WTS light and the LPare 2 seperate functions of the ECM as I inderstand. We have seen many here with that issue over the years. What kind of lift pump do you have?

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dripley

dripley

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2 hours ago, SupaDave said:

Got any suggestions on a quality rebuild ECM? Lift pump is newest version available, installed new with IP less than 10K ago, not sure of brand. When it runs well, (which is always) this truck runs like a dream. I love it. :cummins:

Is your lift pump the OE style pump on the block?

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dripley

dripley

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Did you ever check the to see if the ECM was was powering the pump? The initial prime at key on should only last maybe a second. But if you bump the starter, no engine start, it should run the lift pump for 20 or so seconds. I am thinking that you a leak somewhere causing the long starts. The return line from the VP and the back the head tie together at a tee back behind the fuel filter. The sealing washers and grommets in the tee are prime candidates for that leak. You may or may not see any fuel leaking. But air can get and drain the high pressure lines of more fuel than the little prime you get from the lift pump. Try parking the overnight with the nose pointed down hill and see if stops. 

 Do you have a fuel pressure gauge?

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SupaDave

SupaDave

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Dripley-

Thanks for getting back to me. Busy time here for us. In addition to the holidays, we have just sold our home and are looking for a new one here in Georgia. We are currently in an apartment ( try THAT after owning your own home for 30 years... ) and they are very strict on working on your vehicle on the property. So, it looks like I will have to take my truck to someone. I can tell you this. I still have no lp activation that I can hear at the WTS lite. I also have no lift pump activity I can hear after bumping the starter. If I continue to crank for 10 secs or so, the truck starts and runs. As far as leak theory, coincidentally, I actually have the truck parked nose down rite now, does not seem to make a difference. I don't have a fuel pressure gauge as such, I have the Edge Insight Digital Pod on the dash for all my gauges. My fuel pressure is consistently around 12 or so. Do you think you, or one of the other fantastic members here could direct me to someone in the Lawrenceville, Ga. area that I could trust to work on my baby? I mean someone who KNOWS these 2nd gen CTD's like you guys do. Not impressed with the dealer's "diesel guys".

Appreciate any direction you could offer. Wishing you and yours a happy and safe holiday. :USflag:

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dripley

dripley

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Food for thought on hearing the pump. I just put a new pump head on my AD and i cannot hear it run. The only way I know its running is the my pressure gauge shows the pressure. I have not had an oe pump pump since 06 to remember how much noise they make.

 Even with my pump blown the truck would fire right off. The VP will pull its own fuel though it is not good for it. I still think you have a small loss of prime somewhere. Still going to be hard to find the problem if you cant work on it. Wish I knew some body to take it to but I dont.

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