1991 GMC S-15 V6 2WD 4.3L

Im installing spark plug wires. I have a good idea what the firing order is and need to know how to tell which spark plug wire goes to which spark plug so its the correct length. I bought the truck with the wrong wires apparently because when matching wires up to replace old ones none of my new wires matched the same length of the old wires. In fact the only wire that was the same length was the coil wire. One wire was visibly different from the rest. It was a red 8mm wire and the rest were all black 7mm gauge wires. So I have no idea what goes where and have been told to just start with the shortest wire first and so on but I am still confused on which run is longer then the next. Would it be helpful top take a measuring tape and go about judging which wire that way? I believe the correct firing order is 165432 clock wise from what I’m reading from other forums, if this is false then please inform me of this. Ok while standing in front of the truck the #1 would be to the right and closest to you, #5 being closest to drivers seat or steering wheel. And on the opposite side near the trucks battery or passenger side the #2 would be closest to you on your left, and #6 being closest to the passenger seat . Please help in desperate need to get this truck running right, broke and started new job and at the end of the line for help on this even autozone couldn’t tell me the firing order and they sold me the wires, wanted to slap the kid.

13 thoughts on “1991 GMC S-15 V6 2WD 4.3L”

  1. You came to the right place, soon to be your first stop next time(We Hope).

    On some the distributer cap is numbered. Attach the corresponding plug wire to the number on the cap, starting at the front of the engine 1,3,5 on driverside and 2,4,6 on passenger side

    Firing order: 1-6-5-4-3-2 Distributor rotation: clockwise
    spark plug wires 4.3 engine

    4.3L Engine
    Firing order: 1–6–5–4–3–2
    Distributorless ignition system

    4.3L distributorless timing

  2. In most cases you can remove one wire at a time and match up the closest one. Another way is to lay out all your wires and start with the shortest one and place it in the shortest distance plug from the distributor. Then move to the next shortest and so on. The wires are all made the same on the inside, the only difference is the length.

  3. The number one can be anywhere on your distributor cap. If you look closely at the cap in most cases the cap has the number 1 molded on to it. Follow the #1 plug wire from the spark plug to the distributor, this is the number one location on your distributor.

    If they were moved. You would need to rotate the engine till the piston is at TDC on Number 1 cylinder and then remove the distributor cap and look at where the rotor is pointing, this is the number one location.

  4. Double check that you have the plug wires in the right place. Make certain each spark plug is good and didn’t accidentally get dropped and closed the gap. Check the cap and rotor button. Replace as needed.

    If the engine sounds like it is running on all 6 cylinders but just doesn’t want to hold an idle, check for vacuum leaks.

  5. Thank you for clarifying that for me, also I need to know how to judge which wire goes to which plug, each wire is a different length and could use an idea on how to go about using the right wire on the right plug at the right length.

  6. also on your picture the #1 location on the distributor is practically dead center of the engine if you will…is this the correct positing of it?

  7. I’m confused how can the #1 be any where? So in the photo the #1 can be at the back of the distributor nearest the dog house and still run right? Or does what you mean if the timing is synced that way it would run right no matter where you timed the #1 at? This is causing me to think more may be wrong with who ever installed the distributor. I’m going to post a photo maybe that will help some what.

  8. Abd I’ll wanna go clock wise from there #1#6#5#4#3#2…And as I’m looking and typing I noticed the #3 and #1 are crossed and need corrected might have just solved my problem, might not have been wrong wire from coil to plug, was just wrong connections in first place…

  9. Ok I have every thing ran to the right plug, and I’m still getting some sputtering and it won’t stay running unless I feather the gas. And its idling is not consistent, wants to rev up and down and it will do it 3 or 4 times till it’s so low that it dies.

  10. Thanks for the responses. I’ll make sure I come back with the final results if not more questions lol thank you again I’ve been calling and searching for 2 weeks and have yet to get anyone to respond with any help or information what so ever.

  11. Ok I figured out I had at least one spark plug bad. The first spark plug I pulled was the #6 plug and it was bad engine didn’t change at all, and when I pulled the next plug #4 and it died. So I just went bought new plugs instead of going any further. I bought a cap and rotor but mine looked done what fine but have that as naval up in car out layer down the line already have new plug wires. The trouble inn having now I’d finding the correct gaping. Im getting two different gaping suggestions equally so it’s hard to make a choice. .35 and .45 are the two gaps I’m getting, the new plugs are already at .45 so I’m unsure in where to go?

  12. Glad you found the bad spark plug. Spark plug gap should be listed on the under-hood decal(Gap .035 ; OE Type). Spark Plugs are to be replaced every 30k miles according to the manual.

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