Farm Equipment - 7040 erratic rpms?

Print Page | Close Window

7040 erratic rpms?

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=211673
Printed Date: 18 Sep 2026 at 8:14am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 7040 erratic rpms?

Posted By: nickia
Subject: 7040 erratic rpms?
Date Posted: 12 Jul 2026 at 9:39pm

I have a 7040. Mowing 3/4 throttle and all of a sudden my Rpms jump maybe 2/300 rpms for no reason. Eventually the rpms will work it's self down but when it acts up it's like engaging a turbo boost. I've changed my fuel filter once dirt black fluid came out. Running trk stop bio fuel blend. Would you try another filter change? Or do I need pump service work?

Replies:

Posted By: DrAllis
Date Posted: 12 Jul 2026 at 9:46pm

Sounds like dirty/bad fuel. Bio blend prob not good. Remove filter and blow back into the tank and try another filter.

Posted By: WF owner
Date Posted: 13 Jul 2026 at 5:34am

...or possibly a little air getting into the fuel system.

Posted By: injpumpEd
Date Posted: 13 Jul 2026 at 8:45am

Fuel restriction, or air leak on inlet side of fuel system. With running bio you may want to plan for a pump service in the off season, provided it makes it though the busy season.

-------------
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: SteveM C/IL
Date Posted: 13 Jul 2026 at 8:51am

My opinion only....if running hard and constant bio is ok for less cost but something that sets alot not so much. Some BTO's run bio during spring and fall but switch back to real fuel before fall work is done to have systems rid of bio. Cheaper isn't cheaper.