Hot stalling issue

[ducktapeguy]

Running a Howell EFI on a stock 258 and I'm having an issue with the engine stalling when hot. It only happens on long uphill grades during hot weather. First, the engine will lose power, even when shifting to 1st gear. Then it will begin to cut out then finally stall. After cooling down for about 15-20 minutes it will eventually start, and run fine until it gets really hot again. I replaced the ignition coil thinking it was going bad, but that wasn't the issue. I then replaced the CTS sensor and it seemed to work for a day travelling hundreds of miles, but the problem just appeared again while climbing a steep grade.

I've contacted howell, but hoping someone else might have some input into this.

Forgot to mention during this the engine temp doesn't change, or at least the gauge doesn't.
I felt the fuel pump and it's not getting hot, so I don't think it's vapor lock
During the initial troubleshooting I measured the CTS sensor while hot and it was reading out of spec. Should be 200-250ohms, and when it stalled I took a reading and it was down to 170ohms. So I thought the sensor was bad and replaced it. After it stalled with the new sensor I didn't have time to take the reading I was in a some what bad spot and wanted to move the scrambler.

 

[CJ8Rockcrawler]

You've already addressed the primary items I can think of. The only other thing is the vacuum line or fuel line routing with the Howell Kit as it does sound like a vapor lock issue.

 

[ducktapeguy]

I’ll try and check for vapor lock next time it happens. One of the first things I did was feel the fuel pump and filter to see if they were hot, but they were just warm. I don’t know that can definitively rule out vapor lock though. The steel lines from the tank do run on the exhaust side so it may be picking up heat. I wouldn’t mind if it’s just vapor lock then I know I’m not doing permanent damage, I’m more worried that my engine is actually overheating without me knowing it, I know stockgauges aren’t all that great, but it should at least tell me if the engine is getting hotter than normal. So far it acts in a typical fashion, starts out cold and slowly creeps up as the engine warms up.

My fuel pump and filter are located next to the transmission under the skid where Howell recommended. I forgot to mention I have a torqueflite 999 and put a trans temp sensor in the rear servo port which does go up in temperature when this happens, so that could be a possibility. I thought that the trans cooler might be dumping too much heat in the engine bay and causing another issue.

Which vacuum line are you talking about? It’s been a year since I installed it so I’ll have to go back and review the manual.

 

[HighSierra CJ]

I agree with Ducktapeguy. I had an issue with my Mopar Fuel Injection vapor locking. Same situation that it sounds like you’re dealing with (Vapor locking). I ended up using a heat gun to check the temperature of my fuel pump/fuel lines, once I vapor locked. Turns out that my fuel pump was getting really hot. As a result, it was turning the fuel to vapor. I ended up installing a in tank fuel pump in from Novac and the problem went away. In your case with the Howell Fuel Injection, you use a lower pressure fuel pump. I’m not sure you can find a low pressure fuel pump that goes in the tank. If it were me, I would relocate your current fuel pump somewhere along the frame rail where it can get some airflow.

Edit: I forgot to mention that I rerouted my fuel lines to the passenger side of the jeep, away from the exhaust, as they were getting hot as well

 

[ducktapeguy]

I also forgot to mention that when this happens, there's a strong fuel odor, like the car's running rich. i don't know if maybe the howell is somehow trying to compensate for low fuel pressure by opening the injectors more? Not quite sure. Other than that it has all the same symptoms of vapor lock.

I already have some shielding on the exhaust around the muffler and catalytic converter. What worries me is the return line to the tank runs down the left side frame rail just inches from the exhaust. Even though I have some heat shield between them it's still enough to get the return line pretty hot. That might be one of the causes. I will probably re-route all the fuel lines down the right side just to be safe, unfortunately it'll have to wait a while.

 

[CJ8Rockcrawler]

Here's the link to the Howell instructions. I've attached a screenshot of the vacuum line diagram. Based on what you're saying about smelling fuel, I wonder if it is an issue with the charcoal canister hoses. I'd also check if your fuel tank is getting pressurized or pulling vacuum (remove the cap when you stall) and pull the air cleaner and look inside the throttle body to see if you're flooding out when stalling.

Model-JP1-EFI-Kit-for-JEEP-258-CID-4.2-6-Cylinder.pdf https://share.google/2nw2e6hKhxUFf46i2

 

[FLCJ8]

Does the problem relate to the amount of fuel in the tank?

Just a few thoughts...
if the fuel return line is transferring heat to the tank a low fuel level could cause the temp to rise sooner.
if the return line is clogged or restricted the tank could have a vacuum (as suggested above) and cause loss of fuel to engine. The higher the fuel level the quicker the vacuum in the tank would occur.

Had a similar issue with my friends 8, his return line was obstructed and created a vacuum in tank. You could hear the air enter the tank when the cap was released, also if the cap was left loose the problem went away for the most part, other issues arose from lack of fuel return.