M38A1 -- Idle's OK, Stalls on Acceleration

Hi,

I have a '53 M38A1 with what seems like a very "diagnosable" issue. The engine was rebuilt about 3 years ago and has a the correct carb. I leave it in MA during the winter, so it sits for about 8 months at a time before being driven again during the summer.

On to the symptoms:

The car was running fine until about two weeks ago when it began to stall out when you step on the gas. It starts and idles well, but as soon as I step on the gas, it revs a little bit then dies until I let up on the gas again.

I'm not sure if the engine is flooding or starving (is there an easy way to tell)? Any idea what would cause this?

-Steve

Reply to
steve.newhouse
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When that happens to my Jeep, I need to change the fuel filter.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Reply to
Mike Romain

Like Mike said, it could be a fuel filter, especially considering how much the vehicle sits. You might also want to check and make sure that the accelerator pump is functioning properly. When you open the throttle, you should see a good stream of fuel coming out of the accelerator pump nozzle.

Chris

Reply to
c

Hi Steve, A weak coil and/or spark plugs will act the same way, and will not fire under more compression, as happens went you open the throttle. Which often happens with the change over to twelve volts, the resistor is forgoten. Choke the carburetor with your hand will tell instantly if it a carburetor problem. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com

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Reply to
L.W. (Bill) Hughes III

Reply to
RSMuddog via CarKB.com

I agree with Chris & Muddog that it sounds like an accelerator pump problem. Sitting that long without running could cause the rubber seals to dry up. Changing the fuel filter would also be a wise idea because old gasoline will develope into a "laquer". If you let it sit very long, I would reccomend using "Stabil" (gas stabilizer) to help prevent tha laquer build up

Good luck, Darrell

Reply to
d

Well, I always figured the 'accelerator' pump was so named because it gives an 'extra' shot of gas for 'acceleration'....

It isn't needed for running.....

If it is bad, the engine will stumble or bog on 'acceleration', it won't up and die until you let off the gas....

Just on the ones 'I' have seen anyway....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Reply to
Mike Romain

Hey your carb may also be clogged. You may want to spray some carb cleaner in it. To see what happens. My brother has a 61 falcon and it would do about the same thing as you are saying sprayed some carn cleaner in it seem to run after ( now it has about 5 fuel leaks by the engine and one on top of one of the HOT exhaust manifold so can not be driven).

you all have fun off roading

Reply to
Jamie Mello

Even a plugged up air filter will kill top end.

Mike

Jamie Mello wrote:

Reply to
Mike Romain

To test to see if that is the problem the air filter just remove the air filter and see if that fixes the stalling. If it does just replace the air filter. But be sure to put air filter back in after. As I am sure you know the air filter keeps a lot of junk out of the engine.

99 wrangler TJ 2.5 lift 31 inch Good year MTR tires and a ton of lights Warn M8000 winch and more toys to come.
Reply to
Jamie Mello

Thank you so much guys- very very helpful and made sense even to non- mechanic like myself. I will work through each of these suggestions when I get some time and let you know how it goes.

Reply to
steve.newhouse

Hope it's something cheap and easy, Good Luck!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Reply to
Mike Romain

Yea let us know how it goes.And like mike said I hope it is something cheap and easy.

99 wrangler TJ 2.5 lift 31 inch Good year MTR tires and a ton of lights Warn M8000 winch and more toys to come.

Some people have an addiction to drink... Some people have an addiction to drugs.... I just have an addiction to Jeeps and their accessories....

Reply to
Jamie Mello

If I can put in my two cents worth, the problem may be related to the fuel. Ethanol is mandated now, generally 10%, and alcohol will tear up the rubber in older fuel systems. Some older mechanical fuel pumps use rubber bellows and valves and they will deteriorate, as will the rubber bellows in the older accelerator pumps. Connect a fuel pressure gauge in the line at the carb, should be at least 6PSI. If it is, then change the filter in the carb, if there is one. Alcohol in the fuel can knock a lot of crud loose and plug it. I had exactly the same problem in my '61 CJ5 with an Olds V6. The filter in the carb plugged up and stopped me dead. I rebuilt the carb with alcohol-tolerant parts. I replaced the stock fuel pump with a Carter and added a Facet electric pump near the fuel tank. No problems since.

Reply to
Bill Lahr

As an update (disclosure: I am extremely new to auto mechanics): Removing the air filter did not fix the problem unfortunately, so now I'm checking if it's the fuel filter.

I removed the fuel pickup plate from the gas tank (had to remove the driver seat) so that I could check the fuel filter element. It was pretty dirty, not terrible though. I have ordered the correct replacement and am waiting for it to show up.

While I had the pickup plate removed, I though I'd check out the tank condition with a flashlight... It was gross in there. The gasket that seals the pickup to the tank had essentially disintegrated and pieces of it were floating in the gas along with other junk. I removed and cleaned the tank and will replace the gasket and filter when they arrive (soon). I'll also be sure to add some Stabil when I fill it up again. I'll update again once the filter is replaced.

Here's a picture of the of what an M38A1 pickup plate with filter attached looks like:

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-Steve

Reply to
steve.newhouse

How did you clean that tank? It will probably need more than just a rinse. Instead of Stabil, you might run a bit of Seafoam in there to clean up any varnish in the lines, etc.

tw

Reply to
twaldron

That is the main pickup screen, not the fuel filter.

You have a fuel filter either on top of the pump or in the carb depending on what engine you have. I think the 151 has the filter in the carb and may also have the one on the pump.

Some Jeeps have one in the line just before the carb too.

The one in the pump is supposed to be cleaned regularly.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - G> As an update (disclosure: I am extremely new to auto mechanics):
Reply to
Mike Romain

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