89 YJ stalls / won't start - JeepForum.com
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post #1 of 10 Old 08-10-2010, 06:26 PM Thread Starter
Drakkhen
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89 YJ stalls / won't start

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

Drak

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post #2 of 10 Old 08-10-2010, 06:57 PM
Old4X
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Put a new mechanical fuel pump on it, along with a new 3 line fuel filter (original type). Run like that without the elect pump, see if your problem goes away.

BTW, my 4.2 never gets over 3,000 RPMS, that is really cranking for a stroker style motor like the 4.2.

418 miles on 19 gallons of gas. Can't beat the BBD !
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post #3 of 10 Old 08-10-2010, 09:41 PM
NonRubicon
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Next time this happens check to see if your gas tank is venting when it gets hot - you could be experiencing intermittent vapor lock. Remove the gas cap - if you hear any air escaping or being sucked in, your gas tank is not venting properly.

Take a look at the carb and clean it up if it looks dirty. Check the carb plate bolts and make sure they are tight, and check the gasket for leaks.

Either go with a electric pump or the stock mechanical. I'm not sure why there are two pumps installed but all you need is one. The electric pump must have a properly calibrated pressure regulator. If it doesn't appear to be vapor lock, and the carb is clean, replacing the fuel pump and filter as Old4X suggested would be the next thing to do. I'd also replace the damaged connector at the distributor - it may look OK but could have internal damage.

FYI: Opening up the exhaust will open up the top end but you will lose the bottom end torque that the 4.2 was built for - Replace the cat and muffler if you want the low end torque.


If you are running the 4.2 and the Carter BBD (bone stock unmodified) then you have the stepper motor coming into play. If it is getting occasional wrong signals it could be tweaking the carb and causing a problem.

Here's two resources to look over if you have the unmodified Carter BBD:

Jeep Adventures Under the Hood

Jeep Carter BBD carburetor Fix



Quote:
Originally Posted by Old4X View Post
...BTW, my 4.2 never gets over 3,000 RPMS, that is really cranking for a stroker style motor like the 4.2.
If you do the Team Rush upgrade you may be surprised to find that the 4.2 can actually rev under load up to 4000 RPMs (with a stock exhaust system in place) and it'll feel strong without feeling like it's going to explode under the stress (whether a worn stock clutch can handle it without occasionally slipping at 4k is another story ) The crappy stock distributor cap cripples the engine. The TR upgrade results in a smoother idle and better acceleration by getting the spark to the right cylinder when it is needed over a wider RPM range, unlike the stock cap/rotor. Before I did the TR upgrade my 4.2 would struggle to get to 3000 RPMs and above that would miss enough to hold herself back. Not that I always rev up to or past 3k, but sometimes you gotta get up and go, or give an unsuspecting Ram Hemi a run for it's money
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post #4 of 10 Old 08-10-2010, 10:04 PM Thread Starter
Drakkhen
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Thank you for the advice, I will attempt to perform what is suggested at,
Jeep Adventures Under the Hood
and
Jeep Carter BBD carburetor Fix

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!
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post #5 of 10 Old 08-11-2010, 06:47 PM Thread Starter
Drakkhen
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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.

Also, made sure fuel filter was clear of junk.

Drak
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post #6 of 10 Old 08-11-2010, 07:17 PM
NonRubicon
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From what I understand about the computer controlled Carter BBD, is that once a certain temperature is reached, the computer will take over and start to operate the stepper motor. If the computer is getting bad signals or isn't working properly, then the stepper motor will not adjust the mixture correctly.

Are you able to put an aftermarket carb on your Jeep in Nevada or do you have to keep the Carter BBD for smog purposes like some regions of California?
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post #7 of 10 Old 08-11-2010, 07:42 PM
Old4X
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From your last post it is obvious the computer is still controlling the engine. If allowable in your area, Nutter the ignition and remove the computer from the Jeep (hang it on the wall next to your tool box).

418 miles on 19 gallons of gas. Can't beat the BBD !
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post #8 of 10 Old 06-16-2019, 06:50 PM
WyattEarpp
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I was reading this post,but am confused. Having a similar problem when the weather is hot in the summer (above 80 F). 1988 YJ 4.2L 258 CI. When it get's hot cannot accelerate, and will not go uphill, like it was either getting flooded or not enough gas....
If I back off the accelerator a bit, it will run, but cannot accelerate...starts to "bog down". Runs perfect in cool weather.
Has good fuel line pressure, so mechanical fuel pump working. Did notice all spark plugs (about 1 yr old) had lots of carbon on them. Cleaned them.
Spark seemed weak.
Just replaced ICM (under wiper fluid reservoir) and did a Nutter By-pass.
Any suggestions ? Trying to get this right, as I am on a VA pension, so money is limited. Please help.
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post #9 of 10 Old 06-16-2019, 07:43 PM
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Quote:
Originally Posted by WyattEarpp View Post
I was reading this post,but am confused. Having a similar problem when the weather is hot in the summer (above 80 F). 1988 YJ 4.2L 258 CI. When it get's hot cannot accelerate, and will not go uphill, like it was either getting flooded or not enough gas....
If I back off the accelerator a bit, it will run, but cannot accelerate...starts to "bog down". Runs perfect in cool weather.
Has good fuel line pressure, so mechanical fuel pump working. Did notice all spark plugs (about 1 yr old) had lots of carbon on them. Cleaned them.
Spark seemed weak.
Just replaced ICM (under wiper fluid reservoir) and did a Nutter By-pass.
Any suggestions ? Trying to get this right, as I am on a VA pension, so money is limited. Please help.
Clogged CAT.

FYI, you'll likely get better responses starting a new thread. Many times people read the original post and respond without reading the remainder of the thread, plus this is a nine year old thread so....

Quote:
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post #10 of 10 Old 06-16-2019, 07:49 PM
gutthans
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Quote:
Originally Posted by WyattEarpp View Post
I was reading this post,but am confused. Having a similar problem when the weather is hot in the summer (above 80 F). 1988 YJ 4.2L 258 CI. When it get's hot cannot accelerate, and will not go uphill, like it was either getting flooded or not enough gas....
If I back off the accelerator a bit, it will run, but cannot accelerate...starts to "bog down". Runs perfect in cool weather.
Has good fuel line pressure, so mechanical fuel pump working. Did notice all spark plugs (about 1 yr old) had lots of carbon on them. Cleaned them.
Spark seemed weak.
Just replaced ICM (under wiper fluid reservoir) and did a Nutter By-pass.
Any suggestions ? Trying to get this right, as I am on a VA pension, so money is limited. Please help.
First thing to check is plugged up cats or muffler. Rust debris clogs and creates backpressure which shows up under accelerating or loading ...usually in 3rd/4th/5th gears.
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