What now? Engine missing/fluctuating at Idle/Part throttle....injection pump going?

[Wwalden]

This has gotten worse, so I think its time to post and ask. The motor RPM will fluctuate, almost like its 'missing' at idle and at part throttle. When you lay into the throttle, the engine smooths out. When you're decelerating, or just lightly accelerating, with your foot on the throttle 1/4 or less it seems, it will do it. Wah wah wah wah wah wah wah... . then give it throttle and it smooths out.



I thought that the 'ticking/tapping' noise might be related to an injector pump problem, what does this sound like? The fuel filter is fairly new, and the K&N isn't dirty yet. I changed the f/f and cleaned the K&N when it first started doing this, off and on, about 2 months ago.



Please help, much appreciated.



Wes

 

[Dfeland]

Just a thought but the same thing happened to me and it turned out to be water in the fuel. It would buck at idle and off idle and then when you would give it throttle it would run smoother. All I had to do was to drain some fuel from the seperator and that fixed it. Sorry to here your troubles.

 

[nascar mark]

Water or air in lines. As Dfeland said try drain at seperator. If miss is still there try bleeding lines first as it is easier then draining tank. Don't just try draining by hose. Pull tank.



Most likely water and noise in pump might be lack of lube, as fuel lubes or pumps. As you know water isan't a very good lubricant.



mark

 

[CrewCabDiesel]

Did you check your lift pump ? the 1st gens will still run without it, but will cause some of the same problems you are listing, including having a noisy injection pump.

Kyle

 

[A Johnson]

Do the simple stuff first, filter, check lift pump pressure(3psi min) check for air in fuel.

Another thing you could do is pull your shutdown solenoid and check it for slivers of metal from internal pump pieces going south.

If you have some one that could help you check pump timing get it checked, sometimes it will walk all over the place indicating a faulty pump.

I have had a couple of pumps that had these symptoms and I could move the pump shaft in and out probably 1/2" and while I was doing this the pump timing was wandering all over the place. A new injector pump cured these. I cant give you a spec for pump shaft end play as I have never seen it published. --A Johnson

 

[jmtandem]

idle miss, surge

On my 91. 5 at about 130,000 miles it began to surge slightly when idling but ran fine at any speed. It was the lift pump that was weak and the fuel injection pump. Fixed the problem but lightened the wallet a lot. Lift pump at Dodge installed was $340 and the injection pump is about $1600. But, it ran good after that and would probably go another 130,000 miles no problem. I won't know, I purchased a 2001.