Stalls after highway run

So I'm on a short trip right now. Took the freeway, speeds up to 65 for a little over an hour. Got off my exit and when I came to a stop the Jeep died. It was really hard to restart too, like it was starved for fuel. Even after a restart it stumnled quite a bit. Found a Chik Fil A and pulled in for a rest. I haven't had this issue before. What could cause it? Float too low in the bowl?

Engine temp was running at 210. About par for highway speeds and warm ambient. I recently replaced the fuel filter and applied a heat tubing around the fuel lines. Around town it drives and idles fine.

 

Fuel or spark. Kinda sounds like fuel starvation.

If it's fuel, maybe you have a plugged sock in the fuel tank? Or the fuel pump is getting weak? Or there is a leak in the fuel lines on top of the tank, and you are sucking a little air with the fuel? The fuel pump has a pressure spec in the FSM, and you can test the volume of delivery by directing the fuel pump outlet into a jar and cranking the engine (careful of fire hazard).

 

Can't be sure without a photo or two, but it sounds like the fuel in the line was boiling and probably flooded the carb when you dropped to an idle.

 

I had a problem with that sock in the tank coming off because the fuel inlet line didn't go to the bottom of the tank. MTS 15 gal tank and sender. I dropped the tank, extended the inlet with stainless fuel line and then installed an inline filter right out of the sender on top of the tank.

 

I'm thinking fuel boiling off since it seems to be fine around town and feels like it has good power. Since I swapped back out to a mechanical fan it runs a bit hotter. It runs about 10 degrees cooler when NOT on the highway.

 

210 is maybe high. I avoid pushing my engine too much. I stay at 180.
I had an old car when young, I adapted my speed to the temperature!

When too hot, many problems can arrive. Dilatation of metal. Plugs ... depends of the conditions of the engine and equipement.

 

I also think it sounds like vapor locking to me too. I dont think 210 is too hot but I would not want it to be any hotter. Did you start to loose power going down the highway before it died on you when you stopped. What was the ambient tempoutside? Mine will start to vapor lock and loose power when it is driven in temps above 95-100 degrees.

 

if it is vapor lock that can be cured with a return line from the pumpso fuel is always moving not stacked up in the lines .... what motor do you have and does it have a return line?

 

I have a return line. I opened up the idle circuit to be more rich and it seems to help. But it still stumbles a bit when accelerating from a stop once at running temp.

 

Vacuum leak? Suggests that it's running too lean off-idle now. Too lean can also make the engine run hotter than it should. Have you checked around the carb base gasket? The 360's plastic insulator with a thick cardboard gasket is known to be troublesome. Iron manifold and 21xx?

 

I was plagued by vapor lock issues for a while. If you suspect vapor lock, then the next time it dies, pull the fuel line at the carb and crank it over. You are looking to see if fuel is actually making it to the carb.. My vapor lock was occurring in the fuel line back by the tank and muffler.. What I found with vapor lock was that the engine would not restart until things cooled off. I even changed a fuel pump that was good because of vapor lock in the line..

 

I checked for carb based leaks last week. I was prepping for this trip and was checking it out. Sprayed carb cleaner and didn't hear anything change. It is the iron manifold and MC2100. All vacuum lines look good and tight. Seems to be passable for now. Idle screws are backed out about 4 turns. I'll have to work on it when I get home again.

It's around 90* here today. Morning trail ride went well, but it was still cool outside.

 

90°?? That's when mine was the worst..

 

Just got home after 2 hours on the highway at about 60MPH. Still had bad stumble after exiting. Increasing richness at idle did help, but it's still very noticeable. I think its just getting too darned hot. My electric fans kept the Jeep at or below 200*, but the mechanical, with shroud, nails it at 210*.

Now I'm in a quandary, do I go back to electric, do I buy an aftermarket radiator for the 360, do I buy a high flow water pump? Or do I do some combination of the above. I know the electric would only cost $50 at most, but then my alternator works over time since the fan never shuts off once its hot...but the big money comes in the radiator and pump. Some days I just have to ask why I do it.

 

What's the radiator's history?

Have you flushed the radiator and block?

 

The engine and associated parts have about 6,500 miles on them. I had the OEM style (for 304) radiator professionally cleaned and rodded at a radiator builder before installation. I've always kept coolant ~50:50 to de-mineralized water and its very clean, no dirt or other additives. The water pump is a FLAPS stock item.

I have not flushed anything since it was installed. It seems that its running hot only since my swap back to the mechanical fan.

If its a radiator capacity issue I was thinking about the Champion 4 row...but if I don't have to spend the money I'd rather not.

 

If this were a 60-over 401, this would make sense ... but a 360 shouldn't overheat any more than a 304. Indeed, I'd think the fan would be irrelevant all the time you are moving at more than a running pace.

If you were here, I'd swap radiators for a few days and we'd see what happens. I'm running a RockAuto replacement radiator in the CJ-6 and it seems fine. http://www.rockauto.com/catalog/moreinfo.php?pk=63696&cc=1309597

 

I can appreciate that Tim. I was thinking that maybe the larger displacement of the engine may require a larger radiator to dissipate the heat. I'm grasping at straws I guess...because I'm frustrated with dealing with this issue. I was okay with allowing it to run at 210*, but now that I know it also results in vapor lock, I need to fix it, but I want to do it right without throwing money at it.

 

JMO - it should run near the set point. If it runs above that, you have no extra cooling capacity. The load is then controlling the temperature, not the thermostat.

Mmm. Seems like the physics says the larger displacement would not require more cooling until it is worked proportionally harder than a 304 would. I know that when Brian Chuchua put crate 401s into new CJ-5s he just put them in - they did not need any heroic extra cooling or such. The factory radiator was fine. And it's fishy that your temperature would get much higher with the mechanical fan - when did the electric fan run, on the highway? So under hot conditions driving down the highway the fan was on? I think that's not normal. Not a lot of experience with electric fans, but in my VW, the electric fan only comes on when you are stuck in traffic or when you drive around in warm weather then shut the engine off.

I'm sure you've addressed the usual subjects - too lean, retarded timing, lean and retarded timing, thermal clutch broken, etc. Then if it's not cooling capacity, it has to be something weird like excessive core shift in the block. How much overbore? Or a defective water pump with the wrong impeller or the impeller on backwards. I'm trying to think of goofy things that could cause this ...