Hello,

This is my first post on this forum. I know very little about cars and am trying to learn. I was having some issues with my truck not starting and when I could get it to start not staying running. This issue was intermittent so I took the truck to a mechanic. He told me that it was my thermostat and I asked him to replace it.
$90 later the truck would start and run but every once in a while the truck would seem to lose power and the RPM’s would drop down to 500 for a few seconds and then the truck would backfire 3 or 4 times and everything would go back to normal.

I asked the mechanic how much a tune up would cost and he told me $400. So I decided to tackle the tune up myself. A friend of mine who works on cars pointed me in the right direction to do research and get all the parts and tools I would need. I spent about 2 and ½ hours in the cold last weekend replacing plugs, wires, distributor cap, rotor, and PCV valve. The truck seemed to be running fine after all of this.

But since the tune up the truck has done the same backfiring deal about 4 or 5 times. It just happens out of the blue. So my friend suggested that I buy a timing light and check the timing. I got the light off ebay for $17 shipped. This morning I went out to figure out the timing and it took me forever to find the TDC line. In the process I found this site and downloaded the repair manual. After reading the manual I find out that you cannot change the timing via the distributor.

So I called up my friend and told him this info and he is stumped.

Can anyone tell me what might be causing this and how I can fix it?

I would really appreciate it…

Thanks,

P.

 

You may have gotten a couple of wires crossed when you did this.

 

I was very careful about this, I drew the distributor cap on a piece of paper and traced all the wires to the plugs and marked each one on the paper to insure that I would not cross any wires.

Also as I mentioned before, the problem was happening before the tune up and seems to have gotten better after the tune up.

 

bump

 

That does not mean the plug wires were not wrong to start. I crossed two wires and had the same problem. Since you have the book double check the firing order. 18436572 I believe. Take your AIC off the throttle body and clean it with some brake or carb cleaner.

 

I will check it... but the truck ran fine for 2 years and then started acting up...

 

I dont believe a thermostat has ever caused your problems. Sorry but that is funny. While your at it might as well clean all the sensors on your t/b. How many miles on the truck?

 

110,500 miles.

The wires appear to be right.

 

Is it backfiring through the intake or the exhaust?
Does it just pop once or does it happen for a few seconds then clear up.
A back fire through the intake could be a lean fuel condition. Vacuum leaks, blown plenum gasket, plugged injectors, failing fuel pump. or a lazy O2 sensor can all cause these conditions.

Good luck

 

It sounds like its coming from the exhaust.

it pops anywhere from once to 4 times in a row and then it clears up.