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89 YJ stalls / won't start

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Joined: 10 Aug 2010

PostPosted: Tue Aug 10, 2010 4:47 pm    Post subject: 89 YJ stalls / won't start Reply with quote

Please, HELP! I have been all over the internet and tried sooo many things. The only solution I have at this point is putting a .45 in my skull.

I have a 1989 YJ, 4.2L, and for the longest time has worked smoothly. Once 4 years ago it died when hot, and after a few minutes I tried to start it, and worked perfectly. I noticed the more i stepped on the gas, the more it was almost like drowning itself and gasping for air. I took this as a sign the ICM was going out and was warned by the previous owner that it does happen frequently. For many 2 years no problems, but it was only being driven to and from work during the spring and fall. Now its my primary/only vehicle and has been getting much worse. During hot days it was dieing while driving and forcing my to pull over and wait for it to cool down. Now sometimes even only when its warm it acts that way! This morning it appeared the jeep was working great again, then out of no where it started to try and stall/die while going about 40mph / ~2000 rpms. As a reaction i pushed in the clutch and left off the gas, and it stuttered then came right back to life. I released the clutch, shift up to the next gear to lower the rpms, and continued on. It hiccuped like that two more times on the way back home.

What I have down, (sigh),
Replaced Spark plugs, Spark plug cables, Distributer cap, Rotor, Fuel Filter, Coil, ICM, blew fuel lines and vent line to tank, PCV, Coolant, and checked connectors.

I have noticed a crack on the connector coming from three wires from the bottom of the distributor, but it still appears to be a solid connection. I have also scrapped/cleaned the connectors on the coil.

It also appeared as if my exhaust was plugged. After a VERY LOUD backfire, I had a nice hole made at the top of the muffler, and notice rattling inside the muffler. I took this as a sign that Cat blew chunks all over the muffler and may be clogging the exhaust. I cut the pipe between the Cat and Muffler. I did notice a much faster response time when accelerating and it felt as if there was a lot more torque above 3000 RPMs. In the past when at 3000 RPMs I would notice a HUGE drop in power but always figured it was because of the engines age. It also appears the engine is running a bit cooler now, and has a nice monster truck sound (which I am sure will get annoying VERY fast).

EVERYTHING is original, and 150,000 miles. I know, I know, drop a new engine in, except I am a bit strapped for cash and it is my ONLY vehicle at the moment and I am far from a mechanic. I guess I am doing something right, it hasn't burst into flames yet or given my a blue screen of death.

I have noticed what appears to be a second fuel pump, below the driver side and bolted to the frame. It sounds as if it is working correctly, the moment the key is turned a vibration and hum comes from it. I did disconnect the power to this pump and the car started even without this pump going but still died a few minutes after.

Any thoughts, ideas, prays are welcome! lol

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Joined: 10 Aug 2010

PostPosted: Tue Aug 10, 2010 8:05 pm    Post subject: Reply with quote

My reply to advice from another website:

Thank you for the advice, I will attempt to perform what is suggested at,

I have replaced the fuel filter already with the exact same type. I have noticed after blowing out the lines the jeep now will stall after it has warmed up. I have a video but not able to convert it at the moment. The video shows an nice smooth but LOUD idle (remember no muffler), and then after warm up, the idle drops, and the device on the side of the carb that has one wire to it, and a vacuum line starts going crazy going back and forth pushing on the throttle as the jeep starts to die. It appears the more the throttle opens, the more it wants to die. What usually happens after this is, the jeep will be dead for about 15 mins as it cools down, so it goes back to the whole cold startup cycle. Then start right back up. Because of this, I don't believe it could be a fuel pump. I can stomp on the gas, and get the RPMs way up, right till the jeep "thinks" its warmed up, and dies. Its repeatable as well.

(sigh) MEDIC! I need a medic, or a bullet to the head! drool:
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Joined: 10 Aug 2010

PostPosted: Wed Aug 11, 2010 4:48 pm    Post subject: Reply with quote

Reply from another website, suggesting to replace mechanical pump and bypass after market electrical pump:

I bypassed the after market fuel pump, and replaced the mechanical fuel pump. Jeep would not start at all. It appeared to be no gas was getting to the carb at all.

Swapped everything back to the way it was and still same problem. The Jeep will start up, and as soon as it "thinks" its warmed up, dies. Attempting to start it again right away sounds for about 1 second like it might start, and then nothing till an hour later.

I also disconnected the O2 sensor, and watched the reading on it. It appears to be working correctly, however with the jeep never fully warming up, so its a bit hard to tell. The numbers were within range, and slowly climbing as it warmed up.

The lines off the distributer are the crank cam position sensor, as i mentioned before it "looks" like it is a solid connection. Also I noticed the wires on the coil cap appear a bit brittle. I am going to return the mechanical fuel pump for an electrical one and replace the coil cap. I do hear a noise from the electrical pump that is not always consistent and looking at the wire, appears as if it was replaced before. Besides, I don't stink enough of gas already, whats another litter or two on me. laugh:

Also, made sure fuel filter was clear of junk.

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Joined: 29 May 2007
Location: Benicia Ca.

PostPosted: Thu Aug 12, 2010 10:12 am    Post subject: Reply with quote

Years ago a buddy chased a small rock through his fuel system, it was doing the same thing you described. You might have some kind of trash in the tank, that the suction from the pump pulls against the pick up tube in the tank.
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