85 CJ7 258 idles then dies w/ video posted

[moranda]

This is my first post on Jeep CJ Forums so if I have done something incorrect I am sorry ahead of time.

The motor in my jeep will cold start and idle for about a minute or two and then just dies out. I can restart it and have it idle again for another minute or two and then just dies out again. I have checked the fuel filter it is clean. I think it is getting spark. I want to assume that its the carb somehow. Carb has not been on the jeep that long the jets and idling tubes are clean. Any help will be greatly appreciated. The link to the video of the motor idling and dying is below.

85 jeep cj 7 motor idling and then dies - YouTube

 

[Torxhead]

Checking fuel pump pressure is a good start. If you have no knowledge of when it was last replaced, now might be a good start or just by checking fuel flow. There could be a clog in the needle & seat too. A bad coil might also be a culprit. Basic start for this situation is to determine if it is an electrical or a fuel problem.

 

[moranda]

Thanks torxhead, I have been looking at the team rush upgrade and plan on doing this. Should I go ahead and do the team rush upgrade and get a blaster 2f coil while i am at it? The thing I am worried about messing up is the timing because I have never set it and the distributor is not facing the right direction to do the timing correctly.

 

[Torxhead]

I don't think that the Blaster coil will not give you any performance upgrade other than what any other new coil will give you. It will get away from the oem plug in style coil connection though. The Team Rush Upgrade will help smooth out the ignition though. Sounds like it is time to learn how to adjust a distributor also.

 

[Old Dog]

In the vid. it looks to me like you have the top outlet for the fuel filter going to the carb, I believe the bottom outlet should be the carb.
I'm not a big I6 guy so someone correct me if I'm wrong.

 

[Dolamite]

In the vid. it looks to me like you have the top outlet for the fuel filter going to the carb, I believe the bottom outlet should be the carb.
I'm not a big I6 guy so someone correct me if I'm wrong.

My AMC 258 i6 / 4.2l is set up with the bottom port of the fuel filter going to the carb.

 

[Posi]

Yes, the smaller 1/4" return line needs to be on top or you may have problems with vapor lock. It looks like he may have the lines correct but the filter needs to be rotate so the return line is on the top.

The egr isn't functioning as well.

 

[moranda]

Posi is right the lines were connected up correctly it just needed to be rotated. So while I was working on it I twisted that into the right position. I tinkered with it for a few minutes today to cold to really work on it for long periods of time. I got it start up run and idle as its dying I can gas it and it does shoot gas into the carb. It was idling pretty good toady. I would rev up the motor and hold it at some higher rpm probably around 2K. You could see that it was not very responsive to the throttle increase and did not want to climb in rpms. As it would sit there at a higher rpm it would would start to die again so I would drop it back to idle and it would idle. I would rev it up again and hold and it would start to die. I probably did this about 4 or 5 times. Eventually it did completely die and it would not restart. Thanks for all of your help so far I did not know that about the filter and it causing vapor lock. Also when the jeep was running and driving the EGR was not connected.

 

[Jimbos76cj]

Do you still have the computer hooked up to it? If you you need to take care of the vacuum leaks first. Or nutter it. Id also disconnect the fuel line and hook a short section of fuel line from your pump to a gas can of clean fuel and see if it will run like that. You may have debris in your tank and as it gets sucked up to your intake sock it begins to clog it until it can't flow enough fuel to keep it running.

 

[Posi]

You could see that it was not very responsive to the throttle increase and did not want to climb in rpms. As it would sit there at a higher rpm it would would start to die again so I would drop it back to idle and it would idle. I would rev it up again and hold and it would start to die. I probably did this about 4 or 5 times.

Check the float level:
When it cuts out, and before trying to start again I would check the carb bowl for fuel, float level, and debris. I understand you shot some fuel in the carb when it was dieing but I would double check the bowl to rule out as an issue.
If the bowl is clean, float is at spec level, good fuel pressure then you can focus on the electrical side.

 

[BlackOmega]

I don't think that the Blaster coil will not give you any performance upgrade other than what any other new coil will give you. It will get away from the oem plug in style coil connection though. The Team Rush Upgrade will help smooth out the ignition though. Sounds like it is time to learn how to adjust a distributor also.

Without a matching ignition module, something like an MSD 6AL, a coil wont make much difference unless the old coil was bad.
With that said, an MSD ignition module makes a huge difference. It'll smooth out the idle and it'll run better throughout the RPM range.

My AMC 258 i6 / 4.2l is set up with the bottom port of the fuel filter going to the carb.

Looking at the pic in your post, I was wondering if the top port of the PCV valve has a plug in it. If it doesn't, it's supposed to. If it's not plugged up then you very well may have a very large vacuum leak which will cause it to die and not want to run properly.

Posi is right the lines were connected up correctly it just needed to be rotated. So while I was working on it I twisted that into the right position. I tinkered with it for a few minutes today to cold to really work on it for long periods of time. I got it start up run and idle as its dying I can gas it and it does shoot gas into the carb. It was idling pretty good toady. I would rev up the motor and hold it at some higher rpm probably around 2K. You could see that it was not very responsive to the throttle increase and did not want to climb in rpms. As it would sit there at a higher rpm it would would start to die again so I would drop it back to idle and it would idle. I would rev it up again and hold and it would start to die. I probably did this about 4 or 5 times. Eventually it did completely die and it would not restart. Thanks for all of your help so far I did not know that about the filter and it causing vapor lock. Also when the jeep was running and driving the EGR was not connected.

Well this could be a few things. Timing could be way off. Vacuum leak, or cylinders that aren't firing.

When was the last time you checked your plugs? Especially the gap. If the electrodes are rounded and the gap is way out of spec (.035" IIRC) then they need to be replaced. Check ignition wire condition; if there is any chafing, they need to be replaced as well.

You could also do an ohm test on the coil to see if it's within spec. However, more often than not, the manual will only give you the ohm spec for a cold coil. So not much help really when it's hot.

Do you still have the computer hooked up to it? If you you need to take care of the vacuum leaks first. Or nutter it. Id also disconnect the fuel line and hook a short section of fuel line from your pump to a gas can of clean fuel and see if it will run like that. You may have debris in your tank and as it gets sucked up to your intake sock it begins to clog it until it can't flow enough fuel to keep it running.

It does sound like it has some vacuum leaks to me too.

 

[moranda]

Yeah looks like I got a lot of work ahead of me. Thanks for all the input I plan on trying to work on it these week and I will keep yall updated on what I find out.

 

[moranda]

So I got out to the Jeep today and took the spark plugs out to see what they looked like and as you can see in the picture it wasn't very good. I don't know what the gap spacing is on them I need to pick up a tool when I am at the parts store. So they are carbon fouled very bad and these plugs have only been in the jeep for about 3-5k miles. Would have done some more work on it to try and figure out what is wrong but the rain had other plans. Also the plugs are bosch platinum. I have read that a lot of guys run copper plugs and and did not know that when installing these hence why I used them.

 

[Torxhead]

From what I understand those Bosch Platinum take more juice to spark than the Motorcraft ignition has to offer, so switching back to maybe a set of Autolites might be a better bet. When you convert to the Team Rush, you can open up the gap to about .040. As I recall the stock Motorcraft takes about an .028 to .032 spark plug gap.

 

[moranda]

Today I replaced the carbon fouled spark plugs with some new copper ones and gaped them to .035. I checked my fuel flow by disconnecting the fuel filter and running the fuel line from the pump into an empty bottle. I did this once while cranking it for thirty seconds and i did it again while the jeep was at low idle (The jeep was able to low idle for 30 sec with the fuel that was left in the bowl and the fuel filter line). I found out that cranking it pumps about 20ish oz and idling it was pumping 32 oz per 30 sec. Does this sound like to high of a fuel flow? I don't have a pressure regulator and would this be a fix for high fuel flow? Also I found a sensor that had a wire pulled off. Don't know what this sensor does. I don't really think it is the cause of my troubles i'm adding it just in case.

 

[Torxhead]

There is a test in the factory service manual that covers that same test by cranking for 30 seconds and filling a small container. Right off hand it seems that you are getting enough fuel to the carb. That loose plug that you have hanging loose-what colors are they? it should be listed just what it is on a wiring diagram for your vehicle.

 

[mtnwhlr]

If you are talking about the round sensor on the side of the intake next to the return line it would not cause you problem. The wire on mine is broken off also.

 

[moranda]

I have a sneaking suspicion that the trouble is in the carb. My question is do i go ahead and do a nutter bypass while I am taking it apart or do I wait until I am able to get the jeep running to do it?

 

[mtnwhlr]

I think you want to get running alright before you start changing things.

 

[moranda]

So today I took the whole carb off and took it apart cleaned it up real good replaced all the gaskets. I even replaced the steel line from the filter to the needle and seat. Cranked it over and it fired up. It idled like it normally does then it died. So I am guessing that my problem has to be in the electrical????? Does anybody know whats going on with this jeep?