Starting problems m38a1

pockers · Post by **pockers** » Mon Oct 12, 2015 7:14 am

I know this is going to be a difficult question to answer for definite but I'm hoping answers will at least point me in the right direction

My jeep recently struggles to start
She turns over fine but just seems not to fire ( sometimes she gets there and then she runs just fine, others times she just turns over till the batteries flatten)
Batteries are only 1 year old,
I have checked the points and gap
Cleaned spark plugs and adjusted gaps
I have checked each HT lead and I get spark

Fuel seems to be getting through all ok

This usually occurs when she has been sitting for a few weeks
Any ideas??

4x4M38 · Post by **4x4M38** » Mon Oct 12, 2015 7:32 am

You need three things.
Spark, air, and fuel.

If you have spark, and air, my bet is fuel.
Especially after it happens after sitting for a while.

You say you have fuel but up to what point?

Remove the air horn and sprinkle a little gas in the carb, then
try and start. If it fires you definitely have a fuel issue.

The manuals have troubleshooting procedures but this is
what I've tried for a quick diagnosis.

pockers · Post by **pockers** » Mon Oct 12, 2015 9:52 am

Makes sense , I will give it a try today

pockers · Post by **pockers** » Mon Oct 12, 2015 3:07 pm

Ok - you were so right
Tried taking air hose off and squirting fuel straight into the carb
Hey presto she started!!!!
Once warm she ran ok

So as you suggested it now appears to be a fuel issue

The tank is v v v clean

Any ideas on the logical way of tracing through fuel system in order to find the problem?
I have a bottle of red x fuel system cleaner is that worth a try?

oilleaker1 · Post by **oilleaker1** » Mon Oct 12, 2015 5:24 pm

Remove the line at the carb and crank it while watching how much fuel is delivered. If it has good supply, you may want to kit the carburator. I assume your choke cabe is operating fine. Possible dirty carb and a quick cleaning might do the trick. John

Post by **wesk** » Mon Oct 12, 2015 6:14 pm

Before you try fixing something that is not broke I want to let you know that hard starting due to an empty fuel bowl has been a common problem since the 50's. The M38A1 came on line in 1952/53 with a fuel pump that had a built in hand pump lever so you could fill the carb bowl before your start attempt when she sat for a few weeks. The earlier solution was to provide an in dash mounted hand primer system for starting both in cold weather and after a long period of non-use.

If you drive it today. Start it tomorrow easily then let it sit for 2 weeks and it doesn't want to start then this is your problem.

It can be just the nature of the beast. But sometimes damage or worn parts can exacerbate the issue. Things like a cracked bowl, or cracked venturi area.

Here's the fuel pump with the built in hand priming lever.

Here's the earlier dash priming system.

Using either will solve your problem. But you should still inspect the carb for possible leaks thru cracked bowls and tired gaskets as well as checking fuel pump flow and pressure. Also insure the choke is closing all the way when you pull it. Hopefully you are following the proper starting technique in the operators handbook which directs you to always pull the choke full out when starting?

Don't overlook the item most overlooked when this problem comes up. The heat riser that adds or removes exhaust heat from the bottom of the intake on the M38. If it is stuck full heat on the intake gets so hot that when you shut her down the heat boils all the gas out of the carb bowl.