quinn132 Posted February 25, 2021 Share Posted February 25, 2021 I recently purchased an 86 comanche after wrecking my 2000 xj.. oh do I miss her. Anyways when I was driving back about an hour in the engine just stopped while driving. Power steering was off but all the lights stayed on and the radio kept playing. After letting it sit for 10 minutes it started back up with an extremely long crank time. I had to give it a little gas with the pedal as it wanted to die in idle. Got it home after this happened a couple times. (it was a 4 hour drive). The next day she didnt even want to idle. The engine would fire up just fine with a super short crank time then shut off as soon as I let the key off. I could keep the engine going if i pumped a little gas and then it would idle fine, once I put it in reverse the engine would turn off, all power stayed on though, no flickering of lights or anything. I was able to get it running and took it about 10 minutes to a friends house, on the way back I stopped for food and turned the car off. When I tried to turn it back on it cranked for ever and took quite a few tries to start. Which leads me to believe this problem becomes worse when the car is warm. The next day I cleaned some grounds and found a connection that was pretty bad, cleaned it all and the car started up and ran fine. I took her around the block and no dying. Everything seemed to be fine. I started it again later that day and it was idling at a higher rpm than normal, it sounded like someone was pressing on the gas... but only when idling in park, when switched to drive it would idle fine. No dying right after the start though which was nice. The next day I cleaned some more grounds I could find and the icm connection points and she would start fine and idle fine. The previous owner said it could be a failing icm as he just put one in and it fixed that problem about 700-800 miles ago. I'm not sure if this is it as it was just replaced. On the way to work everything was smooth, the idle, the engine, until I got about a block away from my work when she just died again.. lights stayed on same thing. I pulled over and tried to start it but it had a stupid long crank time so I let it sit and opened the hood to maybe let some air in and help it cool off as I think its partially heat related. After holding it in crank position for 20-30 seconds and a finess of the gas pedal I got it started. Anyone have any tips? I think Ill start by replacing the ICM then clean the egr and iac valve. Maybe the ignition switch/cylinder? It can start without a key and will crank just by rotating the cylinder so maybe thats going bad? Link to comment Share on other sites More sharing options...
quinn132 Posted February 25, 2021 Author Share Posted February 25, 2021 I posted a video on youtube as well, maybe this could help someone help me Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted February 25, 2021 Share Posted February 25, 2021 Hadn’t looked at the video yet but it’s factory carburetor is a POS. Could be fuel filter or junk in the carb jets , I’ll look again laterSent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Pete M Posted February 25, 2021 Share Posted February 25, 2021 does the carb have an IAC? it's been a few years since I owned a 2.8, but I remember only an idle set screw of some kind. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted February 25, 2021 Share Posted February 25, 2021 Easy test if you have spark when it does this Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted February 26, 2021 Share Posted February 26, 2021 Ok probably fuel related.When it does this spray starting fluid or WD-40 down the carburetor and see if it tries to run, if it does until the what you sprayed runs out it’s fuel problem, meaning you have spark from the ignition coil , distributor is working as is the ignition module or whatever they call it inside the distributor.What I didn’t notice as if this is a California emission engine which has more electronics to screw up. Federal emission has some crap but I can’t think of anything that’d keep it from running. Electric coil to adjust the choke, a poor idea of a pre heater underneath the carb. Honestly the factory carb is garbage, I ditched mine a long time ago.The loose the alternator belt is either too long or not adjusted , I’d take it off and get a slightly shorter one and install it. Take it to Napa or autozone they should be able to match it up. You could just ask for the proper belt but the jeeps of these years have poor parts catalogs sometimes wrong. Basically the Jeep is running a 1985 Chevy s10 2.8 engine, but because of the Chrysler takeover 1987 most of the books are incorrect and nobody cares to go back and fix them. If all else fails 1984-85 Chevy 2.8 s10 pickup is the same engine. Far as trouble shooting Start simple and go from there. Even with a new fuel pump and rebuild carb it could be fuel related. I don’t want to overwhelm with a bunch of things I’d test so start with a few easy tests to see where the problem leads. Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
zomeizter Posted February 26, 2021 Share Posted February 26, 2021 4 hours ago, quinn132 said: I posted a video on youtube as well, maybe this could help someone help me Ain't no map sensor on there, seems you're having trouble starting it when cold which means your choke is not working or needs some adjustment. Carbed engines will not start without a couple accelerator pedal "pumps"... Link to comment Share on other sites More sharing options...
quinn132 Posted February 26, 2021 Author Share Posted February 26, 2021 On 2/25/2021 at 4:38 PM, Pete M said: does the carb have an IAC? it's been a few years since I owned a 2.8, but I remember only an idle set screw of some kind. I don’t know, I have a friend who’s good at tuning carbs coming to teach me how to tune her up next week, Monday or so, I’ll ask him and let you know! Link to comment Share on other sites More sharing options...
quinn132 Posted February 26, 2021 Author Share Posted February 26, 2021 22 hours ago, zomeizter said: Ain't no map sensor on there, seems you're having trouble starting it when cold which means your choke is not working or needs some adjustment. Carbed engines will not start without a couple accelerator pedal "pumps"... Got a friend coming over next week to help me tune it! Thanks for the tip! Link to comment Share on other sites More sharing options...
quinn132 Posted February 26, 2021 Author Share Posted February 26, 2021 22 hours ago, Green Mesa XJ said: Ok probably fuel related. When it does this spray starting fluid or WD-40 down the carburetor and see if it tries to run, if it does until the what you sprayed runs out it’s fuel problem, meaning you have spark from the ignition coil , distributor is working as is the ignition module or whatever they call it inside the distributor. What I didn’t notice as if this is a California emission engine which has more electronics to screw up. Federal emission has some crap but I can’t think of anything that’d keep it from running. Electric coil to adjust the choke, a poor idea of a pre heater underneath the carb. Honestly the factory carb is garbage, I ditched mine a long time ago. The loose the alternator belt is either too long or not adjusted , I’d take it off and get a slightly shorter one and install it. Take it to Napa or autozone they should be able to match it up. You could just ask for the proper belt but the jeeps of these years have poor parts catalogs sometimes wrong. Basically the Jeep is running a 1985 Chevy s10 2.8 engine, but because of the Chrysler takeover 1987 most of the books are incorrect and nobody cares to go back and fix them. If all else fails 1984-85 Chevy 2.8 s10 pickup is the same engine. Far as trouble shooting Start simple and go from there. Even with a new fuel pump and rebuild carb it could be fuel related. I don’t want to overwhelm with a bunch of things I’d test so start with a few easy tests to see where the problem leads. Sent from my iPhone using Tapatalk Pro Carb was rebuilt by the previous owner only a few months ago, thinking maybe he messed up the timing as he was having this problem about 1000 miles ago or so. Will try that wd40 trick and get that belt fixed soon! Thanks for the tips Link to comment Share on other sites More sharing options...
quinn132 Posted February 26, 2021 Author Share Posted February 26, 2021 Read somewhere on another forum this is where the fuel pump ground is (rear drivers side tail light). It was nasty so I cleaned it up. Got under the car and cleaned all the connections I could find. Car starts right up and no high/low idle.. yet, haven’t taken it for a long drive yet. Seems to die more when it’s warm. Next step is cleaning the egr and iac valves and tuning the carb! Link to comment Share on other sites More sharing options...
zomeizter Posted February 27, 2021 Share Posted February 27, 2021 Your fuel pump is mechanical, no ground (or power feed) needed for it. There is no IAC valve that needs checking. Do check all vacuum lines are good and where they need to be... Link to comment Share on other sites More sharing options...
quinn132 Posted February 27, 2021 Author Share Posted February 27, 2021 2 minutes ago, zomeizter said: Your fuel pump is mechanical, no ground (or power feed) needed for it. There is no IAC valve that needs checking. Do check all vacuum lines are good and where they need to be... Oh good to know😅 is there a schematic of where the hoses go anywhere? The last person definitely took some hoses off and trashed what didn’t turn the car off as I can see where some are supposed to go but no hose... anyone have any pictures of what the engine is supposed to look like/ where hoses go? Link to comment Share on other sites More sharing options...
zomeizter Posted February 27, 2021 Share Posted February 27, 2021 There should be a vacuum hose routing diagram on the firewall in the engine compartment. If yours is gone, I'll take a picture of mine and post it later on, I have the same power train on my 'manche which should match yours... Link to comment Share on other sites More sharing options...
Pete M Posted February 27, 2021 Share Posted February 27, 2021 still good idea to clean all the grounds. :) that one will help keep your brake lights bright. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted February 27, 2021 Share Posted February 27, 2021 Yeah the original fuel pump is Mechanical on the driver side of the engine block. There’s a small stone type filter in the back of the factory carburetor I believe. There’s a mess the vacuum lines are only a handful that really matter.The timing is correct if it runs and drives. There is a module in the distributor that tells the ignition coil when to fire. But the distributor is the delivery mechanism. See what happens when it fails like this again. In a carbureted car pumping the gas actually helps spray gas stored in the carburetor bowl. Really makes me think it’s a fuel problem or even crud in the tank that settles in clogging the pick up tube/sock (the filter on the tube/sock is probably disintegrated by now. But it’s not worth running down problems that might not exist. Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
quinn132 Posted March 1, 2021 Author Share Posted March 1, 2021 On 2/26/2021 at 6:39 PM, zomeizter said: Your fuel pump is mechanical, no ground (or power feed) needed for it. There is no IAC valve that needs checking. Do check all vacuum lines are good and where they need to be... Whoops haha. Will check the vacuum lines today! Link to comment Share on other sites More sharing options...
quinn132 Posted March 1, 2021 Author Share Posted March 1, 2021 On 2/26/2021 at 8:40 PM, Green Mesa XJ said: Yeah the original fuel pump is Mechanical on the driver side of the engine block. There’s a small stone type filter in the back of the factory carburetor I believe. There’s a mess the vacuum lines are only a handful that really matter. The timing is correct if it runs and drives. There is a module in the distributor that tells the ignition coil when to fire. But the distributor is the delivery mechanism. See what happens when it fails like this again. In a carbureted car pumping the gas actually helps spray gas stored in the carburetor bowl. Really makes me think it’s a fuel problem or even crud in the tank that settles in clogging the pick up tube/sock (the filter on the tube/sock is probably disintegrated by now. But it’s not worth running down problems that might not exist. Sent from my iPhone using Tapatalk Pro Wouldn’t happen to know which vacuum lines are the only ones I need? I’ve got a mate coming over today that’s a lot better with carbureted engines as I’ve only ever worked on the in-line 6. A good cleaning of all the fuel lines and gas tank wouldn’t hurt right? Who knows what’s built up in there the last 30 years Link to comment Share on other sites More sharing options...
quinn132 Posted March 1, 2021 Author Share Posted March 1, 2021 On 2/26/2021 at 6:57 PM, Pete M said: still good idea to clean all the grounds. :) that one will help keep your brake lights bright. Haha very true, appreciate the positivity :) Link to comment Share on other sites More sharing options...
quinn132 Posted March 2, 2021 Author Share Posted March 2, 2021 Set the idle a little high on the carburetor, kinda helps but it still dies once the engine is warm when you decelerate quick and won’t start up when it’s warm.. starts when cold though. I think the choke may be getting stuck/old carb parts are just worn down. Anyone know any edelbrock bolt ons or any other carbs that would work better on this engine? I’m thinking I should trash the whole thing as I’m getting fuel and spark.. tips? Link to comment Share on other sites More sharing options...
Pete M Posted March 3, 2021 Share Posted March 3, 2021 if you're really ambitious, the fuel injection from a Camaro 3.4L is possible but it means stripping the block down to the block and heads, and honestly I would go the step further and trashing the entire block for a 3.4L block too. links to that swap are in the link in my signature. Link to comment Share on other sites More sharing options...
quinn132 Posted March 4, 2021 Author Share Posted March 4, 2021 On 3/2/2021 at 7:30 PM, Pete M said: if you're really ambitious, the fuel injection from a Camaro 3.4L is possible but it means stripping the block down to the block and heads, and honestly I would go the step further and trashing the entire block for a 3.4L block too. links to that swap are in the link in my signature. I'm a little ambitious, is it a project that can be tackled in a week for someone whos never swapped an engine? I need something to get me to and from work (30 minute drives tops) I need to take the cheapest route atm but if an engine and fuel injection out of a junk yard can be swapped for the same price as a carburetor I'm game, sounds like its inevitable with these engines eventually anyways. Link to comment Share on other sites More sharing options...
Pete M Posted March 4, 2021 Share Posted March 4, 2021 the cheapest would be fixing the carb you've got. might just need a new choke or even just a cleaning. an engine swap will always be a big deal because of the "devil you know" vs "devil you don't know" conundrum. unless you bought a running Camaro/Firebird/S-10 so you knew ahead of time that the parts are good-to-go. that would give you a bug leg up vs a junkyard swap. Link to comment Share on other sites More sharing options...
quinn132 Posted March 4, 2021 Author Share Posted March 4, 2021 42 minutes ago, Pete M said: the cheapest would be fixing the carb you've got. might just need a new choke or even just a cleaning. an engine swap will always be a big deal because of the "devil you know" vs "devil you don't know" conundrum. unless you bought a running Camaro/Firebird/S-10 so you knew ahead of time that the parts are good-to-go. that would give you a bug leg up vs a junkyard swap. I do have a running 4x4 4.0l sitting in a 2000 cherokee in my drive way atm... don't need the car anymore because it got side swiped pretty bad. How hard would that swap be/ is it even worth it with 180,000 on the engine? I've read a couple threads on it but seems to me they aren't very detailed or just skim over the swap. I heard about needing to adjust the firewall with a hammer lol Link to comment Share on other sites More sharing options...
quinn132 Posted March 4, 2021 Author Share Posted March 4, 2021 Also, I realized yesterday the electric choke is not plugged in. Maybe this is causing the choke to stay shut? can't figure out which wire is supposed to hook up to it, is there a simple way to wire a new connection to the choke? Link to comment Share on other sites More sharing options...
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