Something is wrong, need some advice. My lift pump went south, had the bd kit installed (all I could find in town other than dodges in tank kit).It was good for awhile then it would not idle. Found that they left the old dead lift pump in place, got the adaptor plate got rid of the old pump. Its been good until today. As soon as you get of the skinny pedal it drops to about 500rpm then back up to about 800rpm. It only does it when you let off the pedal.Now it is running good again.I noticed the other day when it was idling in high idle it was surging, maybe about 25-50rpm. It does not do it consistantly.

 

check for any codes yet?
fuel filter dirty?

 

fuel filters not that old maybe 12000 kms but maybe I will change it anyway. No codes come up.

 

The change in rpm at idle is that what they call looping? I my searching the solution to looping was usually the fuel control actuator. I am wondering how to confirm this?

 

Several ways of checking the FCA. Easy way is draining the fuel out of the filter canister. Then fill up the canister with 2 stroke mixture oil. Start the engine. Idle is ok then its the FCA.
Other way is removing the FCA and shaking it. If it rattles it's ok. If not it's stuck and needs to be replaced.

First thing I would do is run a heavy dose of diesel fuel additive and see if the lope goes away.

MikeyB

 

If the lope goes away with a heavy dose of additive then on the next couple tanks of fuel do NOT add anything.If lope returns its also a bad FCA.The additive lubes it up.

 

Make sure you arent sucking any air into your fuel system. If you have a bad gasket or o-ring or a rusty fuel line they will loop.