jeep wont start

[dave123]

1975 Jeep cj with 304 and stock carb. (mc2100) and ignition. emmissions have been removed.

started normally, then died after about 10 seconds. got it to start once or twice, ran a few seconds. I had to have the gas all the way to the floor just to keep it running at about 1200 rpm. then it died again and won't start now. I checked and it has good spark from the coil. It appears to be getting gas. It cranks freely. the ignition module is only a few weeks old, but since i'm getting good spark, I don't think that would be it anyway? can't find any vaccum leaks. choke not sticking. battery good. starter good. the cap, rotor, and wires have 100 miles or less on them. haven't checked for spark after distributer yet (had to leave jeep at work, and it was dark. It appeared to be getting fuel. i could hear it squirting (too dark to see). I also tried pouring some fuel in the carb. but it would not start. always the chance i flooded it, but i don't really think so.

any ideas appreciated!

 

[dave123]

Here is an update. We think we know what it is, but still want opinions and advice on doing the job.

Checked, engine. It has good spark, it's getting fuel, no vacuum leaks, electrical timing seems right. Cap, rotor, plugs, wires seem ok. Still would not start. Tried a compression test on 3 cylinders, all were at 50lbs. Remember, this was a very strong running engine that had no problems 24 hours before. No smoking, easy start, ran hard, never overheated, no backpressure problems, etc.

The only thing we can think of is that the timing chain must have jumped a few teeth. If you read my first post, you will see it happened when starting, they say that's a common time for the timing chain to slip.

It seems like the valves are opening at the wrong times, and the compression is way below where it should be on such a strong engine. No evidence of head gasket problems either.

You guys agree? It's a big job that I have never done before, not looking forward to pulling it all apart. Any tips on doing the job (assuming you agree)?
thx

 

[PS89YJ]

You may be able the check the timing by moving #1 to top and seeing where the timing marks are, must be on the compression stroke.

 

[dave123]

Tore it open yesterday. The chain had a TON of slop, and one tooth was broken off, several more damaged. The timing marks look like it slipped 2, maybe 3 teeth. So, I'm now in total agreement with those who told me that was what happened.

Expect my parts today or tomorrow, then the fun begins!

 

[dave123]

Well, some friends from JeepTalk helped me do the work. The old timing gear had several broke teeth and some cracks. It had slipped a couple teeth.

Anyway, We looked at the valve train with the covers off and were in agreement that I had been lucky and no damage was done.

Got the Jeep started last night, purrs like she did before. I would have had to take it to a shop and had a big bill without JeepTalk and floridajeepers guys giving good advice.

Only issue was that one waterpump bolt broke as i was tightening it. It doesn't leak, but I guess I better do it right and pull the waterpump and get what's left of the bolt out of there and a new one in. Much better than cracking the timing cover, but kinda a bummer to have to go back. I think I will drive it a few times around town first just because I don't feel like wrenching today!

I guess that's what it's all about, 4wheelers helping 4wheelers.

I think any engine this old should be checked for problems like this, it could have been very expensive if it had slipped more.

dave