7040 fuel pump problem
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=108470
Printed Date: 11 Sep 2025 at 9:10am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 7040 fuel pump problem
Posted By: critter
Subject: 7040 fuel pump problem
Date Posted: 03 Jul 2015 at 6:26pm
Last week our 7040 (about 6800 Hrs) wouldn't idle below 1000 rpm it would just stall, ever since we have had it the rpms would bounce around when running under 1000 rpm. Now the throttle seems sluggish slow to rev up and slow to slow down, after setting for about a week I fired it up and it wouldn't rev above 1000 no mater where the throttle was, shut it off and restarted it and the throttle worked although sluggish. It is the roosa master pump
I already changed the fuel filter and that made no change.
Seems to me something is getting stuck or sticky in the pump is there anything I can check in the pump or is it time for a rebuild?
Will it hurt anything to keep running it like this?
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Replies:
Posted By: injpumpEd
Date Posted: 03 Jul 2015 at 9:45pm
could be some issues inside, but first, make sure it isn't sucking air in the supply side of the fuel system.
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Posted By: Auntwayne
Date Posted: 03 Jul 2015 at 10:43pm
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You need to start at the beginning of the fuel system , the tank . Not in the middle .
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Posted By: JPG AUSTRALIA
Date Posted: 04 Jul 2015 at 12:29am
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ed is the most knowledgable person on pumps here,but I would get someone to watch the fuel pump while you move the throttle, I remember years ago my7060 behaved like that and was slow to rev up and come back and it was the throttle /deacelarator linkage needing a lube. Throttle lever wasn't moving the fuel arm properly.The other thing about the idle is make sure the stop lever on the other side of the pump is getting opened properly by the stop button, sounds like its half closed.HTH
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Posted By: Adam Stratton
Date Posted: 04 Jul 2015 at 8:35am
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One of the friction discs on the throttle of our 7580 broke the other day. If you held the foot feed down, you could raise the rpms, but the lever didnt do anything. I would probably run a pretty stout mix of whatever fuel treatment/snake oil you prefer, and see if that helped before you took off the pump, but you might be headed that direction.
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Posted By: critter
Date Posted: 05 Jul 2015 at 6:22pm
Thanks for the replies, the cable and linkage do fully move on the throttle and the shut off, I don't feel any soft spots on the fuel hose so I am pretty sure it's not sucking shut.
Started the tractor yesterday when it fired up it reved to 1500 then down to 1000 and you cant speed it up or slow it down. I think its time for a pump rebuild.
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Posted By: injpumpEd
Date Posted: 06 Jul 2015 at 7:25am
it sounds like the metering valve is sticking. Probably all gooped up with old fuel.
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Posted By: SteveM C/IL
Date Posted: 06 Jul 2015 at 8:53am
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Been setting with biodiesel?
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Posted By: critter
Date Posted: 06 Jul 2015 at 11:13am
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It sat for 2 years but I have put 300-400 hours on it since, don't know if the previous owners used biodiesel or not but we don't.
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Posted By: injpumpEd
Date Posted: 06 Jul 2015 at 11:34am
If it had sat, then it is gummed up causing problems. You're actually lucky it even ran at all. I've seen so many times with today's fuel, and tractors sitting for a year or two, not good!
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Posted By: Lonn
Date Posted: 06 Jul 2015 at 1:48pm
My combine sat from may 2012 to August 2012 and it gummed up bad enough to ruin the pump. Biofuel really blows.
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