Carb Flooding

cknight · Post by **cknight** » Sat Jun 09, 2007 6:48 pm

Some of you may have tried to help be back in March. My M38 is in the restoration process but I did have it running last fall and it ran great. After sitting all winter I tried to start it this spring and all it would do was fill the manifold with gas. After rebuilding the carb with a kit from midwest it did not help the problem. After several weeks, I got it to start but it ran poorly and only for a short time before it died. I gave up.

The restoration has progressed alot in the last two weeks. I would say it about 80-85% complete. I tried to start it today and guess what. It did not start and the manifold was again full of gas. I have an idea to try to see what is gong on with this carb. I am going to rig up a flexable hose and have my son crank the engine while I am holding carb it in my hand. I will than be able to see if its dumping fuel down the throat non stop.

Any other ideas?

OKCM38CDN · Post by **OKCM38CDN** » Sat Jun 09, 2007 7:09 pm

Have you checked the float adjustment... it should be 1/4"... also maybe som grit ot other got tin the carb keeping the float open...

Just a thought...

Hope this helps...

cknight · Post by **cknight** » Sat Jun 09, 2007 8:18 pm

Float is 1/4". I used a pencil. I inverted to top of the carb and adjusted the float so that the pencil (1/4") would slide under the float just touching the pencil with the float resting on the spring in the float valve.

I have had this thing apart at least twenty times, its clean

cmpman · Post by **cmpman** » Sun Jun 10, 2007 6:31 am

It is a bit of a longshot, but could you have a porous casting? I had a brand new M38A1 carb one time, that would unexplainably flood. It turned out there was a leak in the casting of the upper plate so the fuel was able to bpass the float.

With all the trouble you are having with this carb, I am surprised you have not picked up another one. I would not want to miss a summer of driving over something as minor as a carb.

cknight · Post by **cknight** » Sun Jun 10, 2007 9:58 am

If I cannot get this resolved by the national convention, I plan on getting one there if not before. The problem is, I drove the jeep for two years before starting the resoration, and even had it running nice after the engine rebuild. Than I let the carb sit full of gas for a year and it has been all downhill from there. Two rebuild kits from Midwest, cleaning, cleaning, cleaning, and still a maniford full of gas.

Post by **wesk** » Sun Jun 10, 2007 1:42 pm

find any F134 carb to test with. You will really be bummed if it turns out not to be a carb issue at all.

cknight · Post by **cknight** » Sun Jun 10, 2007 8:02 pm

When this happened back in March, I started questioning the integrity of the coil. Seems I would have fire and than not have fire. Well the problem has started again.

Before I tried to start it a few days ago, the first thing I did was check for fire and had it. I just checked again have have none. Coil is warm but not hot. Have 24.4 volts going in and .4 going out. Now, I am nothing more than a shad tree mec. I don't think it will create spark on .4 volts. I am going to let it cool down and see if the voltage increases.

As for the coil heating up, it rases a question. I understand the vent lines keep the coil cool and I do have the vent lines to the coil installed but I do not have the line open to the wipers as I have not windsheld on at this time. Should I plug this off or is it ok for now?

usma41 · Post by **usma41** » Mon Jun 11, 2007 2:13 am

Wes, I had the same problem and found that there are two type's of carbs for the m38. As I said before IF YOU HAVE THE WRONG GASKET KIT, THEN IT WILL DUMP FUEL INTO THE MANIFOLD! One has a larger throat opening on it. I wish I can explain this better but all I can say is Been there done that.

cknight · Post by **cknight** » Mon Jun 11, 2007 7:42 am

I assume you are talking about the gasket between the carb and manifold.

I drove the jeep for a year before I had the engine rebuilt. It than ran well after the engine rebuild. After sitting all winter it would not run. I have rebuilt the carb twice with kits from Midwest. The original and both rebuild kits have the exact same gaskets.

I took the top part of the carb off and connected a four foot flexable fuel line to it and had my son crank the engine. I could than operate the float with by moving it up and down to see it it was a float issue. I did discover a small amount of fuel was passing with the float pushed up. I have corrected this problem ( I think ) but now have lost fire. I think I have a coil problem. I have fire and than loose fire. I am ordering a coil today and will see if this fixes the problem. I will report back after I install a new coil.

Post by **wesk** » Mon Jun 11, 2007 8:58 am

There is only one carb model for the M38. The larger throat you are referring too is the M38A1's carb. M38 uses the small bore YS637S and the A1 uses the large bore YS950S. If you buy the new kits from Midwest or AJP they have all the parts and gaskets for both carbs in them so you must be carefull which parts you use.

OKCM38CDN · Post by **OKCM38CDN** » Mon Jun 11, 2007 5:17 pm

When purchasing a coil ask for the US model do not accept one of the reproduction ones from China... I got one and it blew up the first hour...

Buy one of the ones for the M-151... last forever... Cost more but saves lots of headaches...

Hope this helps...

cknight · Post by **cknight** » Tue Jun 12, 2007 6:28 am

I already ordered one from Midwest. I hope John sends me a good one.