rcurrier44

My 1991.5 CTD (200K mi, stock) has been developing a problem and none of us are really sure what it is? It has started idling rough in the mornings... it acts like it is trying to start at -20F. Now that's not all there is to it...

It starts great fires right up and will usually idle great for 10-30 seconds in the morning. Then the idle drops and it chugs heavily. If you ever so slightly touch the gas it cleans right up and purrs away like there is nothing wrong. Even when cold when driving it she runs great and feels like it has the same amount of power it has always had (it might be smoking a little more when it's building a lot of boost but other than that it's good). When the temp needle gets just beyond the first tick mark on the gauge it starts to idle good again (gets slowly better right around that point). When I get in it later in the day it still runs good...

I have replaced the fuel filter and the air filter looks good.

It's like it has a cold start/high idle sol that has gone out... but I am told that 12V's don't have this like the fords do.

We were thinking a lift pump but that would get worse at high rpm/ high boost.

We were thinking it might be loosing its prime below the injector pump and take a bit to re-prime but that should also get worse with a higher fuel demand.


I am kind of stumped and looking for some direction or someone who has run across this before.

Thanks
ROB

wannadiesel

I think you're getting air. Check the fuel heater gasket.

rcurrier44

Well I didn't have time to check for leaks last night but I did add a full bottle of Power Service; plus it was in the 40's this morning instead of the 30's. The truck started just fine this morning... so I am guessing it's some bad fuel. I'll update this thread if I found out something different.

I realy should look over my lines and maybe get another lift pump to have in the truck just in case...

Thanks
ROB