Engine/Transmission (1994 - 1998) White smoke after new lift pump

[cumminsram95]

Hi everyone. The lift pump on my 95 12v was making a "ticking" noise and I replaced it with a Cummins lift pump from Geno's. While I was at it, I removed and by passed the fuel heater and clean the strainer. Everything went good. The first time I started the truck, nice puff of black smoke and immediately cleared. Took her for a test run and all seemed good. Not missing, normal power, smooth idle, all seemed good. I got on it and looked in the rear view mirror, the smoke started coming out black( it normally does) but the turned white. Before the pump, it would only smoke black. When I say smoke I do not mean excessive smoke, just a good puff. I did get fuel from a small station that I normally never use immediately after the repairs and before the road test. Any ideals? Could the pump timing be off because of the new lift pump? What about deleting the fuel heater? It was burned up. Could air in the system cause white smoke? The truck is all stock except for a 4" muffler delete exhaust and has 430,000 miles on it. Thanks.

 

[GAmes]

Installing the new lift pump did not change the timing. I suspect you are getting a tiny bit of air when you are hammer down. Did you replace the 90 degree hose? Did you replace the square cut seal that goes onto the fitting in the top of the prefilter?

 

[cumminsram95]

Sorry for taking so long to reply. I did change the 90 degree hose. I also change the pre filter seal. Today it was blowing more black smoke that white but I have noticed a strong diesel smell from the exhaust. Almost like there's unburnt fuel in the exhaust.

 

[GAmes]

Sorry for taking so long to reply. I did change the 90 degree hose. I also change the pre filter seal. Today it was blowing more black smoke that white but I have noticed a strong diesel smell from the exhaust. Almost like there's unburnt fuel in the exhaust.

That was my best guess. Most people are not aware there is a square cut seal on the end of the supply line, and it isn't shown on Cummins quickserve. I don't have another guess.

 

[fest3er]

Black smoke in partially burned fuel. White smoke is unburned fuel. Unburned fuel can be caused by far more fuel being injected than can be burned for many reasons: the charge air can be too cold (as in winter); you could have one or more injectors that leak or don't atomize the fuel well enough; the barrels and plungers in the p-pump could need work; the p-pump's overflow/bypass regulator could be set too high; the pistons might not be generating enough compression, the fuel plate could be set too close. By increasing pressure and flow to the p-pump, you might've caused the system to inject more fuel than you expect. And as GAmes said, you could have entrained air in the fuel; when injected, the sudden decompression of the air could cause it to cool the fuel too much and, thus, cause it to not burn in time. It could even simply be that you haven't given the engine enough time to work that plug of air through the injectors, or given the engine enough time to properly warm up. Or as you said, you might've gotten a batch of fuel that just doesn't want to burn under normal (standard) conditions.

 

[cumminsram95]

Before the lift pump the truck ran perfect. The only reason I replaced it was because it was making a ticking noise. Could deleting the fuel heater cause this? Where is the square cut seal, Is it at the banjo fitting on the filter housing? I use a Fleetguard strainer kit from Genos and did away with the fuel heater. I am leaning towards the heater being deleted.

 

[GAmes]

Before the lift pump the truck ran perfect. The only reason I replaced it was because it was making a ticking noise. Could deleting the fuel heater cause this? Where is the square cut seal, Is it at the banjo fitting on the filter housing? I use a Fleetguard strainer kit from Genos and did away with the fuel heater. I am leaning towards the heater being deleted.

Unless the o-ring for the prefilter is damaged the heater delete will not cause a problem, in fact, it eliminates a potential problem. The square cut seal is on the end of the supply line that goes into the top of the prefilter housing. I even supplied a picture.