Engine dies after running fine.

[DPCD1941]

So I will try and keep this short and to the point. It has been very frustrating to say the least. 
Background: 230ci have had it for 10 years and taken it on +3 hr drives.

Current: In July I was about an 90 mins into a drive and I started losing power. If I pulled the choke all the way out I could kind of keep it running but with low power. Limped it to my destination. In the process I noticed the carburetor was getting very hot and boiling the fuel. After some reading online I came to a conclusion it may be due to ethanol and summer temps. Wrapped the entire fuel line with manifold tape and headed for home at the end of the weekend. Made it about 30 mins and it started again. Removed the Thermostat on the side of the freeway to see if that would get me home. No luck and it was never running hotter than usual. After more research I came to the conclusion my Distributor advance was shot and causing early ignition into the exhaust manifold causing the excessive heat and cooking the radiator. Bought a remanufactured distributor and went for a 20 mile drive in November everything worked great. Also attended a very long Parade in November with no problems but I trailered it to the Event in Oregon. So the only driving was about a half hour in the parade. 
This weekend I went for a drive and after about 2 miles the engine lost power. I was able to keep the engine running with the choke on but not create enough power to move. Flat towed it home and now it sits. 
 

The Question: what else could be causing the excessive heat that is boiling the gas? I have had this vehicle for ten years and this engine for about five. It has made a 240 mile trip every August with no problems in the heat. Please help!!

*rebuilt distributor IAY-4102

*did not reuse old points and condenser
*Have not put the Thermostat back in *was at 110° when it lost power
*Military truck with stock 12v System 

 

 

 

[Sniper]

Did you check the exhaust flapper valve and make sure it was free and working?

 

 

 

 

[Los_Control]

Can be many things .... My first thoughts is fuel delivery.

Closing the choke is shutting off air which enriches the fuel.

Possible a failing fuel pump can deliver enough fuel to run fine at idle, fill the float bowl .... But going down the road it just cant keep up.

Might take a couple miles to drain the float bowl. Then with the small amount of fuel being delivered ..... closing off the air/choke it runs but without enough fuel to give normal power....

 

Another possibility would be a plugged pickup tube in the tank .... some obstruction in the fuel line .... plugged filter?

 

Could be electrical also .... does the coil get hot when this happens? .... Should be warm, too hot to touch I would replace it.  <--- first thing I would check

 

Just a couple ideas to get you going.

[DPCD1941]

1 hour ago, Sniper said:

Did you check the exhaust flapper valve and make sure it was free and working?

 

 

 

 

I don’t believe it has ever worked for the last ten years. It is on my list of things to replace. The question is why would it be a problem now in summer and winter. It was 33 degrees when it happened Saturday and about 80 in July. Worth looking into though. 

[DPCD1941]

42 minutes ago, Los_Control said:

Can be many things .... My first thoughts is fuel delivery.

Closing the choke is shutting off air which enriches the fuel.

Possible a failing fuel pump can deliver enough fuel to run fine at idle, fill the float bowl .... But going down the road it just cant keep up.

Might take a couple miles to drain the float bowl. Then with the small amount of fuel being delivered ..... closing off the air/choke it runs but without enough fuel to give normal power....

 

Another possibility would be a plugged pickup tube in the tank .... some obstruction in the fuel line .... plugged filter?

 

Could be electrical also .... does the coil get hot when this happens? .... Should be warm, too hot to touch I would replace it.  <--- first thing I would check

 

Just a couple ideas to get you going.

Not sure about the coil but the fuel bowl was full when it happened. Also the manifold and carb are very hot. The unfortunate part of this whole process is I have to drive it until I’m stranded to test these things.

[oldodge41]

Is it possible something is plugging the exhaust? Maybe in the pipe or muffler?

Edited December 5, 2022 by oldodge41

[keithb7]

 

By chance do you own tools for further troubleshooting? Multimeter. Vacuum & Fuel pressure gauge. Timing light. Dwell meter. Laser thermometer.  Compression tester. 

 

When you pull the choke out you are cutting down the engine’s air intake. The engine still sucks hard so it is still drawing plenty of fuel. Creating a rich air/fuel mixture ratio. Sounds like when you do this you are able to nurse it along, a little bit at least.  Might be a clue if it is running lean. Not enough fuel for some reason.  Lean running engines generally do run hot. 
 

Not saying that’s it but worth looking into. When was your carb last cleaned? A partially plugged main jet and leaky sandwich gaskets could create a lean mixture. 
 

I like the “plugged exhaust or exhaust thermal valve stuck” idea. When the engine is dead cold the counterweight on my Mopar is sitting up, vertical. When its hot the counterweight rolls forward toward the rad.  If yours is not moving, wire it to the fully forward “when hot” position. Meaning it won’t be able to direct any hot air up to the base of the carb and intake manifold. 
 

Too tight valve clearances. Could that be happening?

 

A vacuum/pressure gauge may be enlightening. Its well worth buying. It can tell you a lot. Fuel pump condition too. 
 

How about turn engine piston #1 to TDC. After TDC turn it until its on the exhaust stroke.  About piston halfway back up, with spark plug out, have someone blow compressed air into the cylinder. Put your ear near the exhaust tip.  Good air flow out the pipe?

 

Hopefully you shouldn’t have to drive far-away to replicate the problem. By running the various tests with all the tools I mentioned, something “should” turn up. Right in your driveway at home. 

 

Edited December 6, 2022 by keithb7

[DPCD1941]

28 minutes ago, keithb7 said:

 

By chance do you own tools for further troubleshooting? Multimeter. Vacuum & Fuel pressure gauge. Timing light. Dwell meter. Laser thermometer.  Compression tester. 

 

When you pull the choke out you are cutting down the engine’s air intake. The engine still sucks hard so it is still drawing plenty of fuel. Creating a rich air/fuel mixture ratio. Sounds like when you do this you are able to nurse it along, a little bit at least.  Might be a clue if it is running lean. Not enough fuel for some reason.  Lean running engines generally do run hot. 
 

Not saying that’s it but worth looking into. When was your carb last cleaned? A partially plugged main jet and leaky sandwich gaskets could create a lean mixture. 
 

I like the “plugged exhaust or exhaust thermal valve stuck” idea. When the engine is dead cold the counterweight on my Mopar is sitting up, vertical. When its hot the counterweight rolls forward toward the rad.  If yours is not moving, wire it to the fully forward “when hot” position. Meaning it won’t be able to direct any hot air up to the base of the carb and intake manifold. 
 

Too tight valve clearances. Could that be happening?

 

A vacuum/pressure gauge may be enlightening. Its well worth buying. It can tell you a lot. Fuel pump condition too. 
 

How about turn engine piston #1 to TDC. After TDC turn it until its on the exhaust stroke.  About piston halfway back up, with spark plug out, have someone blow compressed air into the cylinder. Put your ear near the exhaust tip.  Good air flow out the pipe?

 

Hopefully you shouldn’t have to drive far-away to replicate the problem. By running the various tests with all the tools I mentioned, something “should” turn up. Right in your driveway at home. 

 

I have most of those. My theory was that as the fuel boiled off it was too lean to run and full choke cut out enough air to keep it running. I pulled the carb today and disassembled it tomorrow I’ll order a gasket kit and the new heat flapper and rod. At this point I’m just going to overhaul all of that. Mechanical fuel pump is fairly new but I’ll look into a pressure test on it. Not quite sure how to plumb that up but I’m sure google will help. When I have the intake/exhaust off I’ll check valve clearance. Is it a long shot to assume the carb is dirty and the truck is running lean leading to excessive heat that then heat soaked the carburetor and compounds the problem?

[Dan Hiebert]

That is indeed a good assumption given the symptoms.  I lean towards a fuel issue diagnosis, either the carburetor itself or delivery.  That's what I'd work on first, anyway. 

[Young Ed]

10 hours ago, DPCD1941 said:

I have most of those. My theory was that as the fuel boiled off it was too lean to run and full choke cut out enough air to keep it running. I pulled the carb today and disassembled it tomorrow I’ll order a gasket kit and the new heat flapper and rod. At this point I’m just going to overhaul all of that. Mechanical fuel pump is fairly new but I’ll look into a pressure test on it. Not quite sure how to plumb that up but I’m sure google will help. When I have the intake/exhaust off I’ll check valve clearance. Is it a long shot to assume the carb is dirty and the truck is running lean leading to excessive heat that then heat soaked the carburetor and compounds the problem?

The shop manual should have the specs. You should get 4.5lbs at the carb. There is also a volume check 15 strokes of the pump should net you 5-6ounces of fuel. 

 

 

[Doug&Deb]

An electric pump close to the tank would be a good investment also. It helps with starting after the vehicle sits for extended periods and helps with fuel boiling after a short shutdown. This isn’t a substitute for correcting your problem but it would get you home if needed.

[MarcDeSoto]

I'm not saying this is your problem, but back in the 80s, I worked on the famous Star of India ship's carpenter's 47 Chrysler business coupe.  It was running poorly.  I did a compression check and found it had a burnt valve, I rebuilt the carburetor and replaced the fuel pump.  It still ran poorly.  He took it to a pro mechanic and they found out the fuel line had a little rust hole on the top where you couldn't see it that caused the fuel pump to suck air.  They replaced the fuel line and solved the problem.