Rough Idle with new injector pump

[Idaho460]

I had a new injector pump put on my 1987 6.2 which has 150K miles. The truck starts better, has more power and now I can actually see smoke when I accelerate heavily. Overall it runs great at the higher RPM.
However, at idle it runs rough and runs rough up to say 1200 rpm. A slow acceleration produces a shakey takeoff. JUst like it is missing on a cylinder or more. It ran smooth before I took it to the shop, it was just hard starting. I had just put in rebuilt bosch injectors four months before I had the injector pump replaced.

The shop pulled all the injectors and had them tested. All were fine. They said the pump rebuild shop insists it could not be their pump rebuild. I asked for the pump rebuild set up flow sheet. So far they have not delivered. I suspect they simply replaced parts.

Any ideas ?

[Robyn]

Welcome to TDP :)

With the info you have listed it could be that the IP has issues or one or more of the injectors are getting goofy under actual load.

Do you see any puffs of smoke, possibly white while its running rough ??

If it was smooth before you had the IP worked on and now runs rough then the finger certainly points at the IP.

The exception could be that some dirt found it's way into the system (injector line or two) during the reinstall and is causing issues.

With the rough idle there is a quicky check.

Go through and crack each injector line loose at the injector until there is enough leakage to kill that cylinder.

Do this until you find the one that's causing the roughness.

If it is pretty plain as to which cylinder it is just swap in another injector and see what happens.

Sort of like locating a bad spark plug in a gasser.

Give this a go and let us know

Good luck

Robyn

[john8662]

Does it do it hot or cold or all the time?

Usually ones with a rough idle (lots of them do) perform best cold, as they warm up they get worse.