M38 starting issues

jerry72 · Post by **jerry72** » Wed Jan 18, 2012 12:01 pm

Have to crank the engine when cold for awhile to start it. This started happening after reinstalling rebuilt fuel pump from then and now. Used to start well before the repair, now it takes awhile of cranking to start it. I've tried priming the fuel pump with the handle, still does not start right away. Tried with choke and without no difference. Before it would start cold without choke, what could be the cause?

Jerry

53a1 · Post by **53a1** » Wed Jan 18, 2012 3:24 pm

I have the same problem using a stock rebuilt pump. I had no problem with other carberators. I noticed I have to give it full choke and a couple squirts and it helps but very cold blooded. When it's warm it starts up easily.

Post by **wesk** » Wed Jan 18, 2012 6:25 pm

If the carb bowl is full of gas then the starting will be the same with or without the rebuilt fuel pump. Look elsewhere for the problem. The carb bowl has enough fuel in it to start and run for about 3 to 5 minutes under both hot and cold conditions.

Proper starting for the YS637S and YS950S carbs which have vacuum operated accelerator pumps is:

1-Leave the gas pedal alone.
2-Apply full choke.
3-If it doesn't start in 1 or 2 seconds (0ne thousand one, one thousand two etc) then depress pedal all the way to the floor and if there's gas in the bowl and spark at the plugs it will start.

To better troubleshoot a no start issue you think is fuel supply wait the normal amount of time that you normally let the jeep sit when she gives you grief. Then instead of trying to start it bone cold remove the air horn of the carb and observe exactly how much fuel is actually remaining in the bowl. If the bowl is near empty find out why. If it is low or about half empty check float setting. If all in the bowl is just fine and full then inspect the accelerator pump diaphragm. Make sure you have the spring between the diaphragm and the housing cover and that the correct spring is in there.

If you have the dash mounted direct primer pump does the jeep start OK using it?

jerry72 · Post by **jerry72** » Thu Jan 19, 2012 11:43 am

Removed air horn and bowl was almost emptied. removed carb and sent to army jeep parts for exchange. It was time for a rebuilt anyway. Tired of carb. problems with this one. Hopefully new one will work well. Thanks for your advice guys.

Jerry

jerry72 · Post by **jerry72** » Thu Jan 26, 2012 12:10 pm

Received rebuilt carb. from army jeep parts. Runs great, just had to adjust idle. Now i dont have to crank the engine for an eternity to start it !

Jerry

jerry72 · Post by **jerry72** » Sat Feb 11, 2012 6:37 am

Engine started to turn off when hot. started to hard crank again. Checked ignition coil and sure enough it was leaking oil. Ordered new coil, points, condenser, rotor from Debellas.
once installed the engine should run like new (hopefully)

Could I use motor oil to lubricate the felt on the shaft, counter weights?

Jerry

Post by **wesk** » Sat Feb 11, 2012 11:36 am

You could use motor oil so long as you use a 30 or heavier straight weight oil.

jerry72 · Post by **jerry72** » Sat Feb 11, 2012 1:07 pm

Could I use grease?
Once again thank you for your expertise Wes.

Jerry

Post by **wesk** » Sat Feb 11, 2012 2:48 pm

Have you read the lube chart? GAA grease on the cam and several drops of PL preservative oil on the pivots and governor plates.

GAA = any quality #2 chassis lube
PL = LPS-3 or good ole fashion 3-in-1 sewing machine oil.

jerry72 · Post by **jerry72** » Wed Feb 15, 2012 11:18 am

Used grease for the shaft and 3 in one for the felt. Gaped points .020, new rotor, condensor, points. Starts just fine now. Thank you Jesus

On to the next problem

Jerry