91 B2600 runs rough on start
 

My 1991 B2600 5spd 4x4 misses on one or two cylinders for a second or two to a couple of min when I start it. After this, it runs well. I had the ECM rebuilt by AvPro and this didn't help. I changed the cap, rotor, plugs and wires and this seemed to help for a couple weeks but now the it is back to running rough on start. I have seen a few posts on here that say there is a chip in the distributor that can go bad, I don't know anything about this but I guess it could be an option. I was also thinking the coil could be going bad since this is about the only ignition component I have not replaced yet, however at ~$80 I don't want to get a new one if there is no need. I have a multimeter and could test the coil if anyone knows how. Thanks, any advice is appreciated.

When started cold an engine needs to run a rich fuel mixture until warmed up. I assume your truck is fuel injected so this is achieved by bumping up the fuel pressure/volume and advancing the timing a bit.
That said a lot of things can cause what you describe. A vacuum leak/inoperative vacuum advance/inoperative fuel pressure regulator/excessive carbon on the valves/intake/pistons/inacurate ECT/etc. The carbon issue is easily fixed with a gas tank additive. Techron or Seafoam work well. Just add to the gas tank and drive. The others listed will have to be checked handson.

Thanks a lot, I will take a look.

Checking for vacuum leaks is a good idea. I used one of those small propane bottles with a long rubber hose attached. I moved the hose all over the intake manifold area. I discovered a bad spot with the intake manifold gasket on the under side, completely out of site. My B2600i will sometimes miss after it has been parked for a few days. I'm thinking I may have an injector that is sluggish and eventually loosens up and starts working.

The fuel pump has a check valve inside it to retain residual fuel pressure when the truck is not running. Obviously if you turn the truck off and all the fuel in the syatem drains back to the tank it will have a long crank time and run rough until all the air in the fuel system is gone. The fuel system should retain 20 psi for 5 minutes after shutting the engine off and should never go to zero psi.

testing the ignition coil
 

Nobody answered the question of how to test the ignition coil.
I cannot start my 1991 B2600i and would like to test the coil befor I pay $80 for a new one.

should help.
http://www.autozone.com/addVehicleId...00c152800769e3

Thanks
 

Very Nice
Thank you!!