Yj starting Problem

[pyagid]

The photographer for wedding called yestrday saying his jeep wont start. It is a 88 Sahara 4.2 automatic. This summer i installed a weber carb and it ran great since then up until a couple of weeks ago. It started to sputter while he was driving it . And then it was hard to start after sitting for a couple of days. I thought it may be the choke not working properly since it had started once it got cold. I checked that last week and it was workng properly and it looked like it could use a tune up. And he said he would take care of that. Then he called saturday and said it would not start at all. I asked if he did a tune up yet he saidno. So i went over tonight watched him do the tune up. and it still would not start. The old plugs were shot. and need replacing. When he pulled the out of cylinder 6 it seemed like there was fur on the plug. not sure if it came out like that or if he hit something in the engine bay.

Put all new plugs wires cap and rotor and went to start it and no go. Loosened the distr. adjusted it and got it started. It was running rough. Adjusted the timing. got it to run ok but it seemed to miss at 1100 rpm.

Got it to idle ok and stay idling by itself turned it off and tightend down the distr. Went to start it to take it for a test ride and it would not start agan. No matter what we did with the dist.

When we first got it running it seemed like there was excesive vacum in the carb...just by feeling it with my hand. Also it smells like it had a bad cat.

What should i look at?

Should I bypass the computer b/c of the weber carb?
Could the cat be partially clogged and causing these problems?
Do these motors have the vinyl timing chain like the older ones? should i check that?

I was also thinking of doing a compression test?

Thanks for your help
Paul

[RandyJ]

My first guess, based on your description, would either be a bad fuel pump, frozen fuel line (water in the gas), or a clogged CAT.

You can check the timing chain by rotating the engine clockwise to the timing mark, note the rotor location, and start rotating slowly counter clockwise until the rotor just starts to turn. I think the speck is no more than 5¬? slop... but you should verify that with a shop manual.

To check the CAT, just un-bolt the exhaust pipe at the manifold and see if it starts and runs. If it runs OK there could be a block in the exhaust system somewhere.

Take the air filter off open the choke and push the accelerator pedal to see if it is pumping gas, this could indicate that the fuel isn't getting to the carburator, which was my first thought.

[pyagid]

I know it is definatly getting fuel. The Fuel pump was new a few months ago. I ran out of time last night but i need to go back and check the Timing Chain and I will try to free up the exhuast and see if that helps.

Also when i originally tried to start it after the plugs and wires it blew a puff or air through the Carb. Like the timing was off and it was backfiring but this was different then a back fire. It was only air.

Thanks
Paul

Randy where are you located so I could come take a look at that scout? How far from west hartford?

[Redemption]

Dont know if this help but my javelin was doing something simular, the air sound in the carb. i'd try to start it and you'd here a puff sound. it ended up being the timing. I think it was advanced. My friend brought over his timing gun thing(dont know what they are called exactly) and after he did, whatever you do with those gun things, it turned over on the first try.

[mrtazwrench]

with the having to adjust timing etc, i'd look at the chain, dont keep cranking it though, bent pushrods in a sm block chev that way.

[pyagid]

with the having to adjust timing etc, i'd look at the chain, dont keep cranking it though, bent pushrods in a sm block chev that way.

Yeah i am always carefull about that.

Timing CHain is what i was thinking b/c we had it set and running ok...not great once we turned it off then went to start it again it was a no go.

[pyagid]

*****UPDATE******

Went back today to check the chain...it was tight........did a compression test 130ish across the board except #4 was at 40. What should i look for next. I checked it 3 times to be sure i got a good seat with the compression tester. Either way i guess the head is coming off......but shouldn't it still start even though there is 1 bad cylinder???? Could it be something simple like the neutral saftey switch not allowing it to start

Thanks in advance
Paul

[jeepsr4ever]

pull the vlave cover and inspect the valves on top the 40psi cylinder. Look for a broken spring or a slightly dropped valve....chances are you can save this one from the top end

[Rocky]

Also check for bent pushrods. A cylinder w/ a bent exhaust pushrod will show full compression, but will misfire, or not fire at all.

[pyagid]

Ok I took the valve cover off and every thing seemed to be moving properly. I pulled all the push rods nothing seemed like it was really bent. But when we looked at the valves the got progessivly worse towards the back of the motor. WIth the way they were firing. Plugs as well. Could this be caused by a crack?

Once the exhaust manifold and intake manifold were off it looked like some of the valve stems had a lot more build up on them like there were not moving almost? There is definalty a ridge in the cylinder walls and some scoring not really bad though.

The bottom of the 3 lifters i pulled did not have a wear mark on them but the sides did and they also seemed to have a little bit of a ridge built up on them and the cam looked like it had a little wear on it. What would you suggest i check from here. #4 was the cylinder with 40psi the rest read about 120-130. Could the ridge on the lifters not allow it to open the valves all the way? Also all the rockers had oil in them except for the ones for #4 Those were pretty dry.

Here are some pictures of everything. My site has gone down a few times today so the pictures will be back up as soon as the site it.

Thanks
Paul