M38 - Hard Starting When Cold

[M606BR]

Hello everyone!

It has been hard to start my M38 lately when cold. I need to crank it at least three times until it starts. I always follow the instructions from the manual: pull out throttle control 1" and pull choke control all the way out.

This morning, before cranking the engine, I removed the air horn of the carburetor in order to check how much fuel was in the bowl. The amount of fuel in the bowl measured between 1/2" to 3/4" from the bottom. I put some extra fuel into the bowl and cranked it, but once again I needed to crank it many times to start the engine.

Everytime when the engine is hot, it starts immediately. The only issue is the hard starting when cold. The engine always works fine after warm up.

Any guess on where to start troubleshooting it?

Thanks.
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Luiz Felipe Santos
1952 M38
1965 M606

[skyjeep50]

According to TM9-8014 Operation and Organizational Maintenance, Pg. 33 when starting the engine cold the choke is pulled completely out but the hand throttle is not touched. For the choking mechanism to work properly the throttle must not be opened. That may be part of your problem - leave the hand throttle closed and foot off the accelerator pedal until the jeep starts. The hand throttle can be used to keep revs up after starting to help warm the engine but you can use your foot as well. You also mention having to "crank it at least 3 times" until it starts. Although a well-tuned engine should pop right off the reality is that with these older engines we often have to crank a little longer - the manual says up to 30 seconds - before the engine springs to life. If you are having to crank it for 3 - 30 sec trys, it might be time to check out a few things - carb settings, fuel delivery, spark, timing, compression, etc. - to see where the problem might be.
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1951 M38