Frustrating Acceleration Problem

eaglevets said:

Well, we put a new carb in it and it runs good. Except, now it is slow to start. The starter turns for a good 60 second plus, before there is fire in the hole. Thoughts?

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When you say new, do you mean it was overhauled or was it NOS? If you put an NOS carb on it that maybe your problem. The accelerator pump in the carb might have dried out and have a hole in it or it shrunk from improper storage. Another thing to look at is the choke. It will give you starting issues if its not adjusted correctly.

We used a rebuilt carb. We've put in new plugs and Monday will replace the spark plug cables, distributor cap and rotor. Running out of options. So weird in that the issue involves getting the engine to fire from a cold start. Once we get it rolling and the engine warmed up, it starts up every time. On a cold start today I worked the starter, accelerator and choke for two minutes, and while the starter churned and churned, the engine never fired once.

You have certainly been through in pursuing this problem. My M151A2 has been cantankerous at times in a similar way. I found that no fuel was going in through carb (engine would run w/starter fluid spray only) . Blew some compressed air into intake side of metal fuel filter at carb and it seemed to dislodge a stuck needle valve. It then started as it always has when warm. Hope this helps.

Mine is hard to start at times also. It has a brand new drivetrain, electronic ignition, carb, etc. I think I need to fiddle with the timing a bit because when it's warm it fires up on the first turn over. One thing we learned is to be very easy on the accelerator when starting. M151s have a tendency to flood VERY easy. I have the best results by holding the accelerator to the floor until it fires, then work the choke and throttle to get it smooth. Also, we bored out the main jet to .055 to fix the stock lean problem that necessitated the choke to be out for the vehicle to run correctly.

Go through the valves and make sure they're all set correctly. Even in the new engine we had to set them because a few were out of whack. It was a REAL bear to start. Once that was straight it was good to go.

SITREP please.
Thanks, Pvt. Hotdog

Pvt Hotdog, The MUTT is with the club members in Columbia, SC for triage. We'll see what kind of insight they have, hopefully this week. It is now beyond my capabilities!

In the 70s and 80s the 151 jeeps were famous for issues with the fuel filter at the carb.
we would end up on the side of the road. The first thing we would do is take a welding rod or a piece of wire and knock the guts out of the filter. Typically that would get us back to the motor pool where we would replace the filter.
Good luck and please keep us posted.
BTW. I am in the Columbia area if I can help.
Thanks, Pvt. Hotdog

Thanks! You may be getting a call!!

So, we're back on the road, thanks to the good folks in the Columbia Chapter. Some serious tweaking and rebuilding the rebuilt carburetor! Yes, there seem to be problems with carb rebuilds on the market. As you can see...the kids at the car show are enjoying the MUTT..

Mr. eaglevet
Thanks for the update.
Those guys at the MVCSC are good guys.
Thanks, Pvt. Robert