carb problem
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
carb problem
Hoping someone can shed some light on my problem. Recently bought an older 440 crawler and the guy I bought it from said it has had a carb problem for years - namely it will only run with any kind of power if you keep it on at least 1/2 choke. Since I'm a retired auto mechanic with a lot of carb experience I thought this would be an easy fix. After all, how hard can it be to set up a simple carb as this. Well, it has me stumped. I've taken this thing apart and cleaned/inspected it at least a half dozen times. Tried to back out the power needle until it is just about ready to fall out but I can't seem to get enough fuel under load. It will idle just fine with no choke, but if you advance the throttle much past 1/4 throttle it will die unless you give it some choke. I'm to the point of ordering a rebuilt carb but I thought that if anyone here with more experience with these carbs can shed some light on why this thing is acting this way, maybe I could still fix the one I have.
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- 440 crawler
- Posts: 223
- Joined: Sun Oct 27, 2013 8:41 am
- Location: Saint John, NB, Canada
Re: carb problem
Certainly sounds like a fuel flow problem. You have probably covered this but the first thing I would check is the flow through the fuel line. Your problem is a typical symptom of a plugged filter or partially obstructed fuel line. I'm not familiar with the 440 but if it has gravity feed make sure it doesn't have an aftermarket in-line filter. These filters will play havoc with a gravity flow system as there is not enough pressure to provide enough volume of fuel. Good luck!
have 40c 4 roller crawler, 1927 Ford T Touring car, 1931 Ford A Roadster, 1951 Standard Vanguard Saloon. Never a dull moment!
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
Thanks, but I've checked that. Even pulled the fuel inlet elbow off of the carb to check the strainer - clean as a whistle. No additional filter in line. It's definetly something in the carb ( I think ). Open to other suggestions.
Re: carb problem
I risk be over-simple, but is the air cleaner clear of obstructions? I know you said it was running, but it was unclear to me if the air cleaner was "hooked up". Is the governor functioning properly?
I have much more experience with Waterloo two-cylinder carbs. We actually use small drill bits about 4-5" long to hand drill out fuel-air passages. Are there super small passages that could be blocked?
Best regards, Bruce
I have much more experience with Waterloo two-cylinder carbs. We actually use small drill bits about 4-5" long to hand drill out fuel-air passages. Are there super small passages that could be blocked?
Best regards, Bruce
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
Air cleaner is hooked up, clean and functioning properly. I've taken apart the carb several times and blew out every passage in it. Thanks for the replies but so far everything mentioned has been checked or done.
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
And the governor is working as it should.
- gregjo1948
- 350 crawler
- Posts: 1000
- Joined: Mon Aug 30, 2010 5:58 am
- Location: Newark Valley,NY,USA
Re: carb problem
A plugged air filter would do the same thing as chocking it. Have you checked the compression? Low compression is also low vacuum. You need vacuum to draw the air/fuel mixture up through the carb and manifold to get into the cylinders. Perhaps, if it has low vacuum, by chocking, it's forcing inflowing air to be pulled with more force and drawing the air/fuel mixture into the cylinders. Basing this idea on an air hose or water hose being reduced down in diameter and seeing the pressure results. Vacuum works the same except instead of pushing it's pulling.
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
Have not checked compression. I don't think that is the problem because it idles so well. If the compression was low I would think the idle would not be as good as it is. I will check it just to be sure.
Re: carb problem
If the fuel and carb system are up to spec as you have discussed, I would start to troubleshoot the ignition. It has been my experience that many a problem blamed on the carb were actually ignition system problems, condenser, points, etc..
I think the compression test is a great idea, also.
I agree with the air cleaner blockage causing a fuel rich situation. But when focused on a problem that doesn't seem to be getting better with your intervention it is time to step back and take a wider POV.
Best regards, Bruce
I think the compression test is a great idea, also.
I agree with the air cleaner blockage causing a fuel rich situation. But when focused on a problem that doesn't seem to be getting better with your intervention it is time to step back and take a wider POV.
Best regards, Bruce
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
I was wondering about an ignition problem. I have cleaned and set the points, but do you think a coil going south could cause these symptoms? It has new plugs.
Re: carb problem
I have had condensers do weird stuff as well. My JD 630 had a lean issue with throttle, lots of troubleshooting later, I changed the condenser with an NOS (USA made) one. No more issues. Maybe it can store a charge at slow idle but no faster ??
Re: carb problem
Have you completely disassembled the carb? Removed main nozzle, all the jets, etc? Something is plugged it seems like.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
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- 420 crawler
- Posts: 26
- Joined: Sun Oct 21, 2018 9:57 am
- Location: Northern Minnesota
Re: carb problem
Yes, I have completely disassembled it several times. That is what I'm thinking, something is plugged somewhere but I just can't see it or find it.
Re: carb problem
? To Lavoy. Do the Dubuque carbs have passages that can be stubborn and need cleaned with a drill bit(by hand) like the Waterloo carbs can be known. Bruce
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- 1010 crawler
- Posts: 258
- Joined: Wed Sep 11, 2013 3:34 pm
- Location: Shiner, texas
Re: carb problem
Run it up to where it runs poorly (while reasonably cool) and hose down the entire intake with WD40 (everything above carburetor), looking for an intake leak bigger than you would have with throttle shaft wear alone.
Early 40C w/Yakima toolbar and homebuilt ripper: 350 w/6-way
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