Posted: Thu Apr 21, 2022 3:42 pm Post subject: M38 was easy to start, now hard?
Our family has had 2 M38's, a 1951 and a 1952, continuously since 1965. We have had the '52 since 1975 when the '51 rusted out. all authentic running gear, 24v system.
For all their other foibles, neither was ever a hard start, even after sitting an extended period. Two pedal pumps, 1/2 to full choke and it would catch after 1-3 seconds of cranking. Last year, the '52 became hard to start: endless cranking, ether, even with pumps, full choke etc. Also became hard to restart even warm. once running it runs fine and strong.
I suspected a bad fuel pump and took to my 30+ year mechanic (for other vehicles, this was his first shot at this one) . No, he says, the pump is fine. He rebuilds points, carb (i got him the kit from Kaiser), adjusts timing, replaces the PCV, and it runs ok, but is still a devil to start and restart. "They are like that" he says, yet i have 55 years experience going the other way. "Leave the PCV valve off" he says, well it ran great before with it on and with it off, that opening is a "road draft" oil exit....
Joined: Oct 02, 2014 Posts: 1904 Location: South Carolina, Dorchester County
Posted: Thu Apr 21, 2022 5:07 pm Post subject:
Hi Ramapo (? name ?),
Need to know what carburetor is on it.
The original M38 carb is a YS-637S and it's vacuum operated.
"Pumping the gas pedal" to start the motor does nothing with these carbs (doesn't inject gas to the intake). Closing the choke uses vacuum to pull gas to the bowl and on from there.
There's many possibles with what you describe.
Do you have copies of the M38 manuals that can aid a lot in troubleshooting?
They're free for download in this forum.
They help tremendously to avoid communication confusion when troubleshooting and provide logical steps to follow.
They also give specs (for things like fuel pump pressure) so you can test what you have is working properly or not.
There's a tremendous amount of knowledge in this forum, but likely need more details to help.
I'm not the expert. They should chime in shortly.....
Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Ramapo, I took the liberty of viewing your three drop box links and copied the correct URL for each of the three photos and reposted that URL inside the [img][/img] brackets so folks don't have to search the internet for your photos. One of the boards on this web site is for Photo questions. If you use that board you will find detailed instructions for how to use photos here.
Now back to your topic: That is a WWII Willys MA/MB and Ford GPW jeep carb. It does not have vacuum operated accelerator pump or metering rod. It is listed in the TM 9-1826A which is a free PDF download right here on our web site's downloads page so you can determine how to troubleshoot and repair your WO carb. Proper operating pressures and adjustment data will be there and also in the old WWII jeep TM 9-803. I will assume you already changed that carb fuel inlet filter just to be sure it wasn't starting to plug up? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I would also check the carb fuel bowl vent to insure it is not plugged up. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
The saga of this M38 and not starting is long but comes out well. Apologies for the delay, but it did not come back from the mechanic (John Santos, Milllis MA - did great job) until November 2022 and I have been waiting for good weather to run test it.
Recall that the problems were endless cranking to start, whether hot or cold, then very poor running, huge backfires (literally exploded the muffler). Would never idle down below about 1100 w/o stall. Rebuilding Carter WO = NG, replacing fuel pump 2x = NG. New coil, points etc all NG. Towed back to my house twice in 2022 and went to Santos on a flatbed for tow #3.
New Carter WO from Kaiser Willy's = only partial fix. New points, plugs wires and coil again = only partial fix.
Then he found "It". "It" was an aftermarket jury rigged fuel filter/ sock on the end of the pickup line inside the fuel tank, created by some mechanic in the last 70 years. The sock clogged over time, the line cracked over time, again inside the tank. Result: some fuel got through when the engine was merely cranking but the the car would immediately suck air once the engine was actually running. the heavy choke countered that, some.
so a long battle and some $ sacrificed but i found a determined and capable fellow who fixed it.
on we go.
now I have a spare "recently rebuilt" (by the prior mechnic) W/O if someone is looking
Glad you resolved the issue. Enjoy the jeep again! Just for the heck of it what is your actual first name or nick name? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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