Running rough

[Sidd]

I bought this truck it is a 1990 extended cab C 3500 Dually would they automatic 400 and a 454 TBI motor. It's the first big block I've ever owned and I'm not quite sure what I'm doing here it didn't have a distributor shaft in it so I bought a brand new one but Indian put a new cap new plug wires new rotor new spark plugs new injectors on the tbi and a regulator a new starter and a new map sensor. It doesn't smoke when I do get it started but it has a dead missing it if you rev the motor up its moves out but you can still hear this dead mess and feel it. I have checked the plug wires and the plugs the plug wires all seem to be good the bugs had been fouled out I cleaned them up and put them back but still have this dead Miss the vacuum lines all seem to be good I've sprayed starter fluid around the base to the tbi and around all of the vacuums and it did not change the tone of the motor. Can anyone tell me what to check next I am lost at this point not sure what to do and running out of money

 

[Sidd]

Wow, I guess no one on this site has a clue about what might be causing my truck to run rough or I'm not in the right group, but either way no one seems to be offering any help with my problem or if I'm not in the right group. Well back to the drawing bored.

 

[Nov93]

Try giving a bit more time. Someone will surely answer.

 

[studigggs]

Do a cylinder drop test to determine which one is missing. Look closely at the ignition system on that cylinder. Swap plugs and wires with a neighbor and see if the miss moves with the hardware. If it doesn’t, do a compression test on that cylinder. If low, do a leak down test.

 

[kennythewelder]

Do a cylinder drop test to determine which one is missing. Look closely at the ignition system on that cylinder. Swap plugs and wires with a neighbor and see if the miss moves with the hardware. If it doesn’t, do a compression test on that cylinder. If low, do a leak down test.

Yes, I agree. To add to this, get a set of spark plug wire plyers. Pull off the plug wires one by one with the engine running. As you pull off one wire, the miss should increase. then put that wire back on and move on to the next one. When and if you find one that diesnt change then there is your issue. You are going to want to ware a leather, or maybe a rubber glove for this.

 

[Sidd]

Ok

Yes, I agree. To add to this, get a set of spark plug wire plyers. Pull off the plug wires one by one with the engine running. As you pull off one wire, the miss should increase. then put that wire back on and move on to the next one. When and if you find one that diesnt change then there is your issue. You are going to want to ware a leather, or maybe a rubber glove for this.

Ok I will try that. Thanks everyone, I do I apologize for being so hasty there is no excuse for it but I am just so flabbergasted that I cannot get this thing running right thanks again for the info I will try that tomorrow and let you know how things

 

[studigggs]

The good news is that your problem is persistent so finding the fault should be straight forward. Watch some videos from South Main Auto or Scanner Danner on misfire diagnosis. The basics you learn there will assist greatly.

 

[udidwht]

A bad or failing CTS (cooling temp sensor) will do what you prescribe. Only use AC Delco/Delphi parts whenever possible. Don't not skimp for a few extra dollars saved on aftermarket parts.

 

[Schurkey]

but Indian put a new cap new plug wires new rotor new spark plugs new injectors on the tbi and a regulator a new starter and a new map sensor.

Be sure to thank the Indian. That was very nice of him.

the bugs had been fouled out

I hate mosquitoes most of all.

still have this dead Miss

My condolences to her family.