7020 loss of power
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=46244
Printed Date: 05 Sep 2025 at 9:56am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 7020 loss of power
Posted By: cowkicker
Subject: 7020 loss of power
Date Posted: 25 Feb 2012 at 8:27pm
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Neighbor has a 7020 that has has lost it's power. It revs slowly,has lots of gray/white smoke, and seems to have a flutter or slight miss when the throttle is wide open. The injectors checked okay, seems to have plenty of fuel getting the pump when loosening the line and hand priming, turbo feels okay, and there are no air restrictions. Thinking maybe it was the pump, I put a pump off of a 7040 on it that I know was good several years ago when I parted out a tractor. Still the same thing , no power, slow to rev, gray/white smoke. I did crack the lines at each injector and it would cause a definite miss at each cylinder at idle. Anybody with suggestions what to look for next?
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Replies:
Posted By: Orange Blood
Date Posted: 25 Feb 2012 at 8:38pm
My first thought was pump or timing, hard to believe two pumps make it act the same. Since you checked good fuel delivery, and the turbo won't affect RPMs much under no load, what fuel is in it? Filters? What does it do, if you prime it while running? Could it have gotten some gas in the diesel, I am sure you are aware white grey smoke is typically unburnen fuel, suggesting spray pattern or pump problems. I am at a loss, hopefully you will get some better ideas from others.
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Still in use:
HD7 WC C CA WD 2-WD45 WD45LP WD45D D14 3-D17 D17LP 2-D19D D19LP 190XTD 190XTLP 720 D21 220 7020 7030 7040 7045 3-7060
Projects: 3-U UC 2-G 2-B 2-C CA 7-WC RC WDLP WF D14 D21 210 7045 N7
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Posted By: cowkicker
Date Posted: 26 Feb 2012 at 3:59pm
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Any thoughts? Think it would be worth trying another pump?
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Posted By: Orange Blood
Date Posted: 26 Feb 2012 at 5:24pm
Well If you have one laying around, then yes, but I don't know if I could bring myself to spend the money on mine to have the pump reworked just yet, since it exhibited the same exact symptoms as before even with a different pump. Yes it was a used pump, but from what I read you know that pump, how did it run on the tractor it was on, when it was removed? Yes pumps can die in storage if they are weak already, but I would find it hard to believe the exact same symptoms were displayed. It's possible, it really does sound like fuel delivery, especially the "won't rev part" Even an engine that is out of time a few degrees retarded will still rev properly, I have never found one too advanced to know what happens, but I would imagine it could handle a few degrees, as long as it wasn't under load.
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Still in use:
HD7 WC C CA WD 2-WD45 WD45LP WD45D D14 3-D17 D17LP 2-D19D D19LP 190XTD 190XTLP 720 D21 220 7020 7030 7040 7045 3-7060
Projects: 3-U UC 2-G 2-B 2-C CA 7-WC RC WDLP WF D14 D21 210 7045 N7
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Posted By: Russ SCPA
Date Posted: 26 Feb 2012 at 5:26pm
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Replaced the fuel filters? My 7020 will act the same with a bad filter, also might you have a warm weather fuel blend?
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Posted By: injpumpEd
Date Posted: 26 Feb 2012 at 7:46pm
put a pressure guage in the intake manifold (intercooler) to make sure it's building boost. Could be a blown intake gasket, or a plug has fallen out somewhere allowing all charge pressure to escape. Seen it several times on 301's!
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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: mark vaughn
Date Posted: 26 Feb 2012 at 9:45pm
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I had a 7045 Allis do and acted the very same way one time. Took the pump off to have it checked out , diesel shop rebuilt the pump , put it back on the tractor after checking the fuel filter and it ran the very same way. The tractor had a JD glass fuel filter on it so replaced it and tractor ran the same. Took the line off the exit end of the filter and it looked like enough fuel running out. So took filter back off and took the mounting block off. Took the fittings out of the block and could see dirt and crud built up in the interence fuel port. Cleaned the ports out, installed back onto tractor and it ran like a new one.
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Posted By: MACK
Date Posted: 27 Feb 2012 at 7:40am
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Put a vacum gauge between pump and filter with a clear plastic line. Check for air in fuel and vacum draw at full rpm.
If it is one with electric fuel pump it should show pressure.
If it has electric fuel pump also check for vacum between pump and tank.
Make sure front damper has not sliped causing timing marks to be wrong. MACK
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