I'm over it!!!

Went wheeling this last weekend. Kept having MC2100 carb issues with stalling, hard starts and vapor lock...all of which I attribute to heat since the issues popped up once the engine was at full temp. The one that pi$$es me off most is the vapor lock issue. I've wrapped the gas lines in that heat restricting tubing from the carb all the way to the driver side door...I've installed a really nice 3 core aluminum radiator, put in a 180*F thermostat, have a new clutch on the fan, have a fan shroud...engine pegs 192*F, which I think is normal...but yet I STILL get vapor lock. How the heck did Jeep ever get these 360's to run without vapor lock issues?

It was noticeable on the trail for sure...sputtering after being at temp for awhile. Keep in mind, its the stock MC2100 carb with #48 jets...its STOCK for gosh sakes. Idle screws are set ~3 turns out, carb is very clean. I just don't have the $$$ to go fuel injected...but even a new Edelbrock manifold and new carb would put me in the $500-$800 level.

Traveling home was the worst. After a highway run at ~ 60MPH of a couple hours I would exit and the engine would just stutter. A few times it stalled, and on a restart would backfire (yes I know that my power valve is probably now shot).

I have another Jeep weekend coming up in two weeks, over labor day weekend. I hate to cancel out, but I'm seriously considering it if I can't resolve this issue by then.

 

48's seem a little small(running lean)but its your ride.
Do you have a all steel line fuel system?
Are you running a return line?This helps the fuel stay cool.
Have you checked the fuel pump pressure?
Have you considered raising your float level a little?

 

Per TSM...48 is right.
All steel near the engine...yes to the return line.
Newer pump...haven't checked pressure.
Carb float has been adjusted upward (i.e. more volume in the bowl), and is within spec.

This really is a stock setup. There has been no customization to the fuel delivery system.

I'll add...I also have stock spark plugs, Champion 12y, that are very new, gapped at 45 I believe.

I do have an MSD6 connected to a TFI coil and large cap distributor...obviously not stock.

 

some thoughts...

-Gas tank vent... check my build thread for some of the issues I was having..
-Return line as mentioned above
-gas filter?? is your tank new or?

I have a running 2100 on my CJ6 (not the one I built) If you want you can give that a try and see..

 

I had a similar problem in that when my 258 was hot after running, the gas would vaporize when the engine was shut off for about 15 min. I bought a phenolic carb insulator for the motorcraft 2100 that I use and have had no problems since. Found the insulator on ebay. This could help you situation as well. I had also installed the later water heated manifold about 2 yrs ago, so that didn't help the situation either. In any case, the insulator/spacer solved my problems/

 

I should blow out the return line to make sure it's actually clear.

The tank vents through the carbon canister, last I checked the lines were clear.

I do have the phenolic spacer. Its a newer tank. I dropped it just about a year ago to move the pickup line to the bottom of the tank, it was up too high. I also have changed the fuel filter by the carb very recently.

Keep in mind, the Jeep runs pretty well until its been up to temp for awhile. I can go to the store and some short around town trips starting and stopping and its all good. When it runs at temp for awhile...lets say at least an hour straight, thats when the problems start to come up. And they really get noticeable when the Jeep has been running a few hours, like on a slow crawl through the woods, or on the highway.

 

just a hunch...
if you have your stock ignition setup I would switch it over

I had a bad coil once and this was exactly how it acted..

 

I've been considering a new coil anyway since I'm running a stock Ford coil, so this might be the right time to do that. I don't have the original ignition though.

 

I had the exact same thought reading this... Weak coil perhaps getting hot... I've had that issue before as well... on a Ford no less.

 

My Dodge did the same..

 

If a replacement coil fixes it, I owe you guys a beer, or other favorite beverage.

 

I know all about vapor lock.. Had my share in my time, but I also had issues at work in the plant process.

The Jeep. Usually occurs in the fuel line towards the back closer to the fuel tank.. Really old timers would clip wooden clothes pins on the line to stop it.. The pins act as a heat sink and do not allow the fuel to get hot enough to boil.. Not very practical.. I had the same issue on very hot days while running both a 2100 and later TBI.. My solution finally was to install an in-tank fuel pump ala 90's Chevrolet truck. This raised the pressure in the entire fuel line and also raised the boiling point of the gas.. End of problem..

 

For those guys that suggested a new coil...it looks like I owe you a beer (or other favorite beverage). I replaced the Ford TFI coil with a new MSD TFI coil and my CJ performed awesome this last weekend. I did a highway run at about 65MPH for about 90 miles or so and didn't have the first problem when I pulled off the exit...no backfire, no fuel vapor lock type issues. I then took it offroad for trail rides over a two day period, it idled great and I had no stalling issues like the last trip.

I believe you guys are genius's...(quote me now before I delete this).

 

I have my MC2100 set at about 5 psi going in, and I adjusted the float DOWN to reduce fuel splashing off road. Runs like its fuel injected on the trail now. Used to cough flood and stall all the time prior.

I never drive highway, so high continuous RPM fuel starvation hasn't been an issue on my 304.

The pressure regulator seemed to help with vapor lock too.

I'd suggest something like this for you:
http://www.afterhoursautoparts.com/...gulator.aspx?gclid=CP-A2cXm58cCFVMXHwodktIIDg

That way you can reduce on the trail and crank it up on on the street.

 

Told you so!

there I said it