u have an intake valve bent or sticking open. run a compression check with all the plugs out and butterfly to carb open.
Not definite, but possibly wrong timing when reinstalling cams and chain and heads, etc. other option is wrong spark plug wiring. spark plug wires on the wrong plug!
A backfire is when the ignition of fuel doesn't take place in the ignition/combustion chamber, it(a backfire) can take place in the intake or exhaust. It can be caused by a fuel to air ratio not being correct, also if the timing of the spark is not just right that could cause it to back fire. It could be running lean with not enough fuel and too much air, or could have too much fuel and not enough air. It could be because the intake valves are not shut when the combustion takes place, therefore the combustion would take place in the wrong spot. The most likely cause are from: 1. Incorrect timing, the timing issue could be caused by bad wiring/ or bad ignition. 2. Incorrect fuel to air ratio, bad fuel filter, low fuel pressure-caused by weak fuel pump. Most cars will have the same reason to backfire, as long as it's an internal combustion engine it shouldn't differ...
On GM trucks, you need to look under the glove compartment for the wiring harness. look for a single wire with a brown tracer that has a black connector. This is the electronic timing connector. Start the truck, unplug connector, set the distributor timing at zero, tighten distributor, reconnect wire.
timing is computer controled base timing is done when gears are put on and timing marks are allined. there is not normally a timing problem there can be problems with sensors and wiring or pcm/ficm.
disconnect the tan wire connector on the passenger side wiring harness , that puts it in bypass mode, unlock dist. bolt and adjust timing. when set reconnect wiring connector.
wiring order tune up
A backfire is when the ignition of fuel doesn't take place in the ignition/combustion chamber, it(a backfire) can take place in the intake or exhaust. It can be caused by a fuel to air ratio not being correct, also if the timing of the spark is not just right that could cause it to back fire. It could be running lean with not enough fuel and too much air, or could have too much fuel and not enough air. It could be because the intake valves are not shut when the combustion takes place, therefore the combustion would take place in the wrong spot. The most likely cause are from: 1. Incorrect timing, the timing issue could be caused by bad wiring/ or bad ignition. 2. Incorrect fuel to air ratio, bad fuel filter, low fuel pressure-caused by weak fuel pump. Most cars will have the same reason to backfire, as long as it's an internal combustion engine it shouldn't differ...
That year did not have a EST/ electronic spark timing connector. The timing is controlled by the PCM / Powertrain Controll Module. It requires a engine scanner to ajust the timing. You can not use a timing light.
Possible causes include a failed cam sensor, broken wiring, broken timing belt, failed computer.Possible causes include a failed cam sensor, broken wiring, broken timing belt, failed computer.
18436572 0 degrees BTDC The base timing must be set to 0 degrees with the timing connector conduit disconnected to bypass automatic timing. With timing set to 0 degrees, reconnect the conduit and the computer controles the timing. This conduit is located on the wiring harness on the right side of the firewall, under a Y shaped plastic cover. It is a one wire connection that protrudes from the wiring harness. It is a tan/black stripe wire.
It should be 6 degrees before tdc, just make sure you disconnect the distributor's computer control wiring harness before you adjust, and check the timing with a timing gun.
Backfiring in a nutshell: A backfire is when the ignition of fuel doesn't take place in the ignition/combustion chamber, it(a backfire) can take place in the intake or exhaust. It can be caused by a fuel to air ratio not being correct, also if the timing of the spark is not just right that could cause it to back fire. It could be running lean with not enough fuel and too much air, or could have too much fuel and not enough air. It could be because the intake valves are not shut when the combustion takes place, therefore the combustion would take place in the wrong spot. The most likely cause are from: 1. Incorrect timing, the timing issue could be caused by bad wiring/ or bad ignition. 2. Incorrect fuel to air ratio, bad fuel filter, low fuel pressure-caused by weak fuel pump. Most cars will have the same cause for backfiring, as long as it's an internal combustion engine it shouldn't differ...