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And once again....

Discussion in 'Chevy Trucks' started by jrm123180, Nov 11, 2005.

  1. jrm123180

    jrm123180 Senior Member
    Messages: 156

    And once again, I am seeking your wisdom and knowledge.

    I can't start my truck....It was running, but back firing. When I listened closely, it sound as thought it was coming from cylinders 6 and or 8. I put new wires on the truck and have not been able to start it since.

    I've both advanced and ******** the timing to about a total of 45 degs. All I get is the carb popping. I've tripled checked the wires to make sure they are all on correctly and they are. I'm about stumped. Any help would be appreciated.

    Thanks once again.

  2. douglasl330

    douglasl330 Senior Member
    Messages: 356

    New wire Eh? Correct firing order is is stamped on intake (18654372) thats from memory don't hold me to it. Start with #1 and work your way clock wise. It sounds like you havew a couple of wires out of sequence. Have fun!:rolleyes:
  3. Mowerpan

    Mowerpan Senior Member
    Messages: 305

    Yup, first start by verifying each wire is connected to the right plug. Then retime it to factory specs. If you still have a problem, verify spark is getting to the plus by taking a wire off one at a time and using a spare plug ground the spark out to the block. If ya get spark you know its getting spark. Continue for all plugs, wires. check plugs? Gap correctly?
  4. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    An SBC firing order is 18436572. Always. They are all the same.

    Why would you monkey with the timing after changing the wires? If it ran before you changed them, and not after, there is (extremely likely) an error in the wiring.

    #1 on the distributor basically points to the #1 cylinder on the engine.... the left front corner of the truck. Going clockwise, verify the order one wire at a time. It NEEDS to be in this position, or the distributor needs to be turned to suit. Sometimes people do this to gain a little clearance for the vaccuum advance--did you note where #1 was before you started?

    Now unless you have taken the distributor OUT, the positioning should still be correct, and with a little fiddling you should be able to make it fire.

    Still can't find it? Next issue: Was it backfiring BEFORE you changed them, and that was why you changed them? Sounds more like the HEI module (under the cap) dying slowly and painfully. I had one even that ran perfectly when I shut it off, then wouldn't restart. It would spit and pop like it was trying to, and even seemed to have spark when we tested everything, but couldn't catch and run. We changed the module and it fired immediately. PS if you buy one, spend the little bit extra and buy an original AC Delco one rather than an aftermarket... they last a lot longer.

    If you are going that far, maybe change the cap and rotor too. You did the plugs themselves already, right?

    Good Luck, keep us informed.

  5. jrm123180

    jrm123180 Senior Member
    Messages: 156

    So i haven't tried to start it yet, but I did figure my problem; I had the wiring order correct...but only if it was setup to go counter clockwise. I have to redo them, but going clockwise.

    Thanks again for you help.

  6. jrm123180

    jrm123180 Senior Member
    Messages: 156

    Fixed it!!

    Turned out to be the fuel pump. I swapped out the carb and put on a clear filter and noticed that it wasn't filling completely with fuel the way it should be. I swapped out the pump with a spare, and it cranked right over.

    Thanks again.