I have good spark. If the Crankshaft position sensor was bad I would not get a spark at all. So I’m told. Also if the PCM was bad I would not get signal to the Injectors which I am getting a good signal. What about a faulty ground somewhere?
@RobertB4
What do you consider a “good spark” . . . ?
You need a bright blue spark from the spark plug tester tool
I remember one time I worked on a truck with a spark, but it was weak. Because the distributor gear was worn.
Make sure the distributor rotor doesn’t have a lot of slop. If it does, you may want to do some further investigating
My first guess was that not fuel is getting injected. Are you certain the injectors are being pulsed during the start process? Edit: Do you have a visual confirmation that fuel is getting injected?
And here’s something worth trying, as it happened to me one time on my VW Rabbit and caused me a lot of grief. Sometimes by replacing the right stuff you actually fix the original problem, but it still won’t start no matter what you do. Why? B/c during the process of trying this/trying that/ lots of attempted starts you’ve injected a bunch of gasoline into the cylinders. So it won’t start b/c the engine is thoroughly flooded.
The solution is to remove all the spark plugs and let it sit open like that for a few days for all the gas to evaporate. Cranking it once in a while (with the spark plugs out) can help get the gas out too. But remove the fuel pump relay first.
OK, so I had a friend of mine over to lend a hand. After telling him about everything I’ve done and a with a little time for him to think about it. He asked if I tried to start it without the exhaust. I said no. So we unhooked the pipes just past the manifold. Surprisingly, it started right up and ran loud but great. Turned out to be a clogged muffler or Cat. 450.00 bucks later. At least its all tuned up now.
Thank you all for the help. I learned a lot more than I thought I would on this project. Hopefully some of you did too.
Enjoy
That is wild. To finish our learning, could you answer:
- When was the last time this truck ran well?
- Were there any starting or running problems before the no-start condition?
Thanks.
I wouldn’t be surprised if your compression reading wasn’t higher now. We all missed this one, including what I had poster for a minute or two
Good for you. An intake manifold vacuum reading (during cranking) might have zeroed in as this being an exhaust restriction problem. Goes to show, that’s one simple measurement worth taking when a car won’t start or has very poor performance. It sounds like you have a car-knowledgeable friend. Taking him out for lunch seems in order. Glad you got the problem solved.
Here’s a link.
I would suggest that you revisit the compression issue which can be affected by a clogged converter.
However, a clogged converter is generally not the cause of a problem; it’s a symptom of something else.
If it’s clogged then it would more than likely be due to:
Long time operation of a poorly running engine or one not up to par.
An engine that consumes oil.
Congratulations!
That said, I’d look into WHY the cat was plugged
Oil consumption
Rich mixture
head gasket blown
leaking injecto
etc.
Any of that sound familiar?
What was the last thing done to it.It was running fine…then what? Was the front main seal replaced? You have a timing chain so I don’t think that’s the problem.I’ve said this at another post but if the crank pulleys were taken off for any reason, it’s possible it wasn’t tightened enough, shimmied back n forth, and started cutting the keys that hold the timing gear and the crank pulley in place.This would give an odd reading from the crank angle sensor to the ECM.
I had similar problems with mine (same year and engine). Replaced one electrical part after another. Each time I replaced a part the code would show another electrical part being the culprit. Finally found out it was the ECM. Found a place in Chicago on Ebay that rebuilds them and warrants the rebuild for life. Cost me about $120. Takes 5 minutes to remove it. You send it in. They fix it and send it back to you. 5 minutes it’s back in and no more sporadic problems!
Thanks for coming by and sharing that info.