Engine/Transmission (1994 - 1998) Lift Pump Internal Construction

[MasonM]

Hey people. I guess I should introduce myself. My name is Matt and I purchased a '94 2500 5spd 4x4 reg cab about a year ago. For the last month or two there has been a large fuel leak near the lift pump and it appears to be coming from behind the gasket. My question is what long term damage can fuel in oil do and if it goes one way, can it go the other? I ask because I've also got a leak at an injector that casually paints the driver's side of my engine comparment and I've noticed the residue to appear darker as if oil is present in the fuel. On top of all of this, there is an oil leak at the front of the engine somewhere that I have yet to find. All in all it uses about a quart of oil every 400 miles. I guess this kind of maintanance should be expected in a truck with 240,000+ miles on it. Any suggestions or common experiences?



Thanks!

 

[Signal73]

if your LP is leaking into the crankcase it will fill your whole motor up before it were to laek past the gasket between the LP and block. Depending how bad it were leaking, it would fill it quite fast also. As far as oil getting into the fuel through the lift pump not likely.

As far as the front oil leak, only good way to tell is clean it up, and look for freash oil. could be front crank seal, loose timing case bolts, killer dowel pin let loose etc... .

 

[Joe G.]

Matt,



What ever is leaking on the driver's side of the engine is not an injector. They are on the passenger's side. A lot of things can leak that cause fuel to drip from the lift pump. Check the input to the fuel filter. There is a double banjo fitting there that can leak. The water in fuel sensor in the bottom of the fuel filter can leak. The push button on the lift pump can leak (about 50 cents to fix that).



If the front oil leak is a failed dowell pin you have an expensive repair to do.



Where do you live? Maybe some TDR member with a 12 valve can take a look at it for you.

 

[fglidden]

Does the 94 have the p7100 fuel pump with the fuel return line undre the intake manifold? If so that is a short rubber line and it can leak fuel down the left side of the engine. Its under the intake and behind the fuel filter.

 

[MasonM]

It drips regularly and putting my hand above the pump against the block I can't feel it, only around and below it. I live north of Austin, Tx. Luckily, my friend is a diesel mechanic and loves the cummins motor, but as he owns a professional shop I hate to play the friend-card for free work. However, I recently spoke to him about doing some recording for his country band in turn for service work! Hopefully he goes for it and I'll let a pro take care of it.



What is this dowell pin and what does it do?



Thanks!!

 

[Joe G.]

Look here:

http://www.cumminsdatabase.com/read.php?id=111

 

[pwerwagn]

Hey Joe, how do you fix the leax at the primer on the lift pump?



I put a new lift pump on yesterday (not new, but good used) and when I prime it is seems like the primer has some fuel come out when I get it primed up and hard...



thanks,

Jeff

 

[Joe G.]

Take the cover off the button. Unscrew it from the lift pump. There is a large O-ring. It's the problem. Get another from NAPA. About 50 cents. You can do this job without removing the lift pump.

 

[pwerwagn]

Cool, thanks Joe.

 

[cruiser_2]

I just repaired a fuel leak problem with mine. Yes it appeared to be coming from the lift pump area. Get a mirrir, take off the fuel filter and look up under the intake manifold. There is a rubber hose about 5" long that is a drain from the Injection pump back to the fuel tank. It is VERY hard to see without a miror, and not easy to access. Take the fuel filter mount off and you can get to the clamps in both sides.



Since it is a drain, it usually only does it when it is a t idle or when you are priming it as that line is an overflow which is why You only see it at idle or when priming it.



For what it's worth.