73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 86charcoalsierra on June 04, 2010, 06:16:15 pm
-
I got a 86 gmc sierra with the stock 305 it recently started to miss fire when i step on the gas it has only been about 2 months since i changed the spark plugs i changed the spark plug wires and the distributer cap but it still misfires what else should i check.
-
Misfire, do you mean a popping sound? Could mean a lobe down on the cam. One of the spark plugs could be bad as well unless when you changed them the problem didn't go away... My $.02
-
make sure a plug wire doesn't have a bad connection, could of had a good one but just popped off
-
Go through and double check everything in the ignition system. Plugs, gap, wires, cap, rotor, firing order, timing. Is it backfiring or misfiring?
-
if it is a backfire wheres it coming from carb or tail pipe?
-
It sounds like it is backfiring from the tail pipe.
-
check the wires (inside of your distributor) leading up to your vacuum advance.
-
Check all you wires. Is it only when you get on it?
-
It does it when i get past about 20 mph if im just cruising slow it runs good but when i push the gas it starts to misfire.
-
Did you change the rotor
-
sounds like it is misfiring when the vacuum is pulling on the vacuum advance causing the wires inside of your distributor connecting to your vac.-adv. to seperate. this is a very common wear point. take off your dist cap and rotor and you will see what to check.