Hey everyone this is my first post here and im hoping you guys can help me out. I bought a 1984 gmc k1500 last summer which ran fine. I went away to school and it sat without being started so when i was finally home it would not turn over. I put the battery on a charger it would not hold a charge so i replaced the battery. I let me friend hook up the new battery which he did backwards. After this it would not crank, i checked the fuses all fine, i checked if battery voltage was getting to the starter it was so now the starter is currently jumped straight from the battery. The truck cranks now but will not fire. I checked fuel which it is getting i then grounded out a spark plug wire got nothing. I took the cap off the distributor and the rotor is turning so i checked how many volts was getting to the distributor. When cranking the volts drop to about 8, 8.5 so i jumped directly from the battery to the distributor still got the same voltage. What do you think the problem is would hooking the battery backwards go all the way back enough to screw up the ignition coil or the distributor or even fry the ecu. Is the ignition switch the problem any input would be appreciated.

 

It was sitting for a while and if you are sure there is no water in your fuel, I would guess ignition wires. They go bad pretty easily even if they look good and will give you all kinds of trouble if they are shot. Plugs also get crappy when they have sat for a long time, even tho they look good.

Try new wires and plugs and fresh gas....when you step on the throttle can you see the accelerator jets squirt? If so, just a couple of shots of gas and turn it over. Put a timing light on it; the timing should be fine...nobody broke in at night and moved your distributor...but you want to make sure you are getting a good spark as it spins over. It should run.

BTW: In the old days all cars were positive ground and there may still be a few overseas models built that way. Reversing polarity can zap the diodes in your alternator, but I don't think it will fry any other circuit. But if it will kill one set of diodes it could kill another and it is possible that you lost something off the board in your distributor. As I recall, an 84 has wires going to the carb and if you fried any electronics, it will effect your metering and make it run bad, but it should at least run somewhat.

 

i do have new plugs and wires laying around so i guess i could try that but i put fresh gas right into the carb and got nothing. As far as the ignition wires go i did check the power wire to the distributor and it was getting power are there any other ones i should look at it and you think possibly something in the distributor itself is bad i guess i could look at the ignition module too. The guy i bought this truck from didnt really know what he was doing theres splices and tape all over the wires in the bay which makes me kinda nervous.