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Car Forum / Jeep / August 2007M38A1 -- 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 > Hi, > [quoted text clipped - 14 lines] > > -Steve 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 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Hi, > [quoted text clipped - 14 lines] > > -Steve 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 in case you don't know, the accelerator pump is a little lever on the carburetor, usually on the top, with a linkage arm attached to it. The arm usually has multiple hole in it for adjustment purposes. I would change the filter, if that doesnt cure it, adjust the linkage so that it has a longer stroke, providing more fuel per stroke. If that works, you probably need a carb rebuild or can get by for awhile with that adjustment. There are rubber seals probably wearing out, causing less fuel to be delivered per stroke if that is the fix. What you are experiencing with your carb is a common problem, and is a off idle stumble.....very well known to mechanics. >> Hi, >> [quoted text clipped - 9 lines] > >Chris 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:LWHughes3rd@aol.com http://www.billhughes.com/ > Hi, > [quoted text clipped - 14 lines] > > -Steve  SignaturePosted via a free Usenet account from http://www.teranews.com 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 Even a plugged up air filter will kill top end. Mike > 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 [quoted text clipped - 4 lines] > > you all have fun off roading 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. > 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 [quoted text clipped - 4 lines] > lights > Warn M8000 winch and more toys to come. 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. >> 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 [quoted text clipped - 8 lines] > mechanic like myself. I will work through each of these suggestions > when I get some time and let you know how it goes. 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 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) 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.... 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. SignatureBill Lahr mr.bill@pcmagic.net > Yea let us know how it goes.And like mike said I hope it is something > cheap and easy. [quoted text clipped - 6 lines] > Some people have an addiction to drugs.... > I just have an addiction to Jeeps and their accessories.... 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: http://www.midwestmil.com/fuelpickupplate.jpg -Steve > As an update (disclosure: I am extremely new to auto mechanics): > Removing the air filter did not fix the problem unfortunately, so now [quoted text clipped - 19 lines] > > -Steve 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 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 - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > As an update (disclosure: I am extremely new to auto mechanics): > Removing the air filter did not fix the problem unfortunately, so now [quoted text clipped - 19 lines] > > -Steve >Hi, > [quoted text clipped - 14 lines] > >-Steve 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 >> Hi, >> [quoted text clipped - 24 lines] > Good luck, > Darrell 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 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) |
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