Farm Equipment - AC-7040 - No throttle response

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AC-7040 - No throttle response

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=208813
Printed Date: 06 Nov 2025 at 9:42pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: AC-7040 - No throttle response

Posted By: dualquads
Subject: AC-7040 - No throttle response
Date Posted: 06 Nov 2025 at 8:24am

Needing some advice.. Think I may have an injection pump problem? Tractor will start and idle at ~1000 rpm. Constant or extremely slow throttle, might get 1300 rpm sometimes. Engine sounds normal firing all 6 but no power, lifting the wings on a bat-wing mower will lug or stop the engine. I have replaced the fuel filter, rebuilt the primer and blown out the fuel line back to the tank. The throttle moves the pump linkage fore and aft to the stops on the pump. Tractor sat in shed without being started for almost 5 months this spring/summer due to my medical issues, was running fine before.

Thank you for any insight!

Replies:

Posted By: injpumpEd
Date Posted: 06 Nov 2025 at 8:35am

Metering valve in pump is probably sticking. Take top cover off and timing window off side to drain fuel down, and spray brakleen around the metering valve. If it's sticking, it will not respond to any loads. It may be due for proper servicing if it's really nasty inside. When they get gummed up, they can have the transfer pump regulating piston also stick, causing the pressure to spike and it results in a seized head and rotor assembly. Then becomes a very expensive repair lol!

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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!

Posted By: Clay
Date Posted: 06 Nov 2025 at 9:35pm

Not saying this will work in your injector pump but I dumped some ATF into my John Deere 4050 fuel tank. This seemed to help free things up. Tractor runs perfectly again.

Worked well with my 1983 F-250 with 6.9 diesel.