Injection pump de-fueling too soon

[k2diesel]

Well, I think I might be yanking the ol' injection pump sooner than expected. Just recently, without provocation, my governed speed dropped to about 1900-2200 rpm. Previously, it was about 2800 rpm ( I had adjusted the high idle screw up). Whats weird is that while driving, occaisionally my normal 2800 rpm speed will come back, boost will be normal i. e. app. 18-20 psi under load, then all of a sudden it falls on its face at 1900-2000 rpm with boost topping out at only 10-12 psi. Very strange. Any theories on what might cause this? I'm also getting some intermittent blue smoke. I'm getting full linkage travel @ pump, and I've pressure tested the charge air plumbing. Me thinks the pump is on its way south. K2

 

[1stgen4evr]

going south

Pleasant thought if you only meant to warm weather. My approach on the pump is this; if it will work right some of the time, there is a good chance that the problem is with some thing other than the pump. The things that do go wrong in the pump will never 'heal themselves'. And the smoke that is intermittent leads me to think you have a filter problem. Had a similar problem once in Missouri. It got rapidly worse till I had to unhook my trailer and limp to a truck stop where I bought a horribly overpriced fuel filter. Changed it out and back on the road.



Good luck with whatever you encounter.



James

 

[JLEONARD]

I agree with James in that the first thing you should check/change is the fuel filter.

Then make sure the rest of the fuel delivery system is up to snuff... . as in rubber hoses and lift pump if the problem continues.

Hope it's an easy one.

Jay

 

[k2diesel]

Thanks for the input James & Jay. I've already changed out the fuel filter twice ( cut them open, both times clean inside ) and the lift pump. And that was my sentiment too, these things don't usually self heal, so I pressure washed the engine in preparation for pulling the injection pump. Well, lo and behold I ran the truck one more time before I was going to work on it, and my rpm was back ! For a while . Now it comes and goes. Oh ya and one more anomally, when the truck is pointed nose downhill, my rpm increases slightly ( maybe 50 rpm or so ) and when it's pointed nose uphill, the rpm DECREASES, about the same amount. These observations are at idle, in or out of gear, backing out of my driveway to my street ( both about a 20 % grade ). It seems to be related proportionally to fuel tank head pressure, or the lack thereof. Whadddya think? K2

 

[JLEONARD]

Perhaps time to install a fuel pressure gage, at least a temporary one, to learn a little more.

I would also check for leaks in the fuel lines between the tank and pump. If you pressurize the tank to about 5 to 10 psi using an air gun and a rag to seal it, leaks should be easy to spot.

Anybody else??

Jay

 

[cojhl2]

Seemingly running low on fuel

As we speak,, I have this problem, but I am sure I know the answer. . I suspected(for quite some time) an air leak in the hose above the tank. This is tough to get to so I tested my hypothesis by using a 5 gal can as a fuel tank. The problem goes away as I bypass the suction line completely.



Remember you can only run for a few minutes on 5 gal as the return is still to the main tank!!



But my problem is now definded, only now I gotta get some energy to pull the tank down.

 

[TKingsbury]

If you have access to a helper or two, you can undo the bed and slide it back instead of dropping the tank and making a mess.

Travis. .