Farm Equipment - CAV injector pump on AC 170

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CAV injector pump on AC 170

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=34887
Printed Date: 23 Aug 2025 at 12:25am
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Topic: CAV injector pump on AC 170

Posted By: Gary J
Subject: CAV injector pump on AC 170
Date Posted: 02 Aug 2011 at 10:19am

Hope someone can help me out here. I have a 1973 AC 170, was running at 1800 rpm when it died sounding like lack of fuel. Replaced fuel filters, bled lines and it would start for about 3 seconds and die. Bleed, start, 3 seconds, die, etc. Now I can not even get that, there are no air leaks that I can find. I was told the CAV injector pump return line is at the end near the timing cover, this is the only line where I get fuel! I get nothing from the line on the other end. Does not seem to have enough fuel at the injectors maybe, not sure. Any ideas? I was thinking the injector pump is bad, but if the fuel is routed wrong?
Any help is greatly appreciated and thanks.
Gary J

Replies:

Posted By: DSeries4
Date Posted: 02 Aug 2011 at 10:23am

The mechanical fuel pump (primer pump), may have died. That happened on my 175 some years ago. Got going quick with a new one. No problems since then.

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'49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '63 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080

Posted By: Gary J
Date Posted: 02 Aug 2011 at 11:18am

Forgot to mention, it has an electric fuel pump. There is fuel to the one line closest to the timing cover at the injector pump.

Thanks,

Gary J

Posted By: farmtoybuilder
Date Posted: 02 Aug 2011 at 11:57am

The line at front of pump is inlet Supply line! rear is return. If electric pump is working -supply of fuel to pump and you have fuel spraying out bleeders and your not getting any smoke or fuel to injectors. Something broke inside inj. pump! I can't remember the part that breaks, but it happens on them.

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5 different TT-10's,5 TT-18's Terra Tigers,B-10,2 B-207's,B-110,2 B-112's,HB-112,B-210,B-212,HB212,2 Scamp's & Homilite T-10. Still hunting NICE HB-112 & anything Terra Tiger & Trailers for them.

Posted By: injpumpEd
Date Posted: 02 Aug 2011 at 12:34pm

farmtoybuilder wrote:

the line near the mounting flange(front) is the RETURN! Inlet is at the rear, near injection lines. DPA pumps do not suffer from broken flex ring issues, you are thinking of Roosa pumps. Make sure your supply is good, as well as the return line not restricted.

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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: farmtoybuilder
Date Posted: 02 Aug 2011 at 1:29pm

We had a brand new tractor with Cav pump was running and it just quit like you shut it off. They found something broke inside the pump? It's been to many years to remember.

Ed is correct , Rear is inlet! I should have looked at book and not the tractor! As ours front line is going back into filter thats marked with out arrow? So I firuged it was inlet. and its been that way since new?

Posted By: den/southern illinoi
Date Posted: 02 Aug 2011 at 2:08pm

I have a NOS injection pump for a 170 and/or 175, Part # is 255997. Asking $500.00 which includes the shipping. Den

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Own 4 wheel 20, 2-5015, 5020 and associated equipment and 2 electric forklifts.

Posted By: Gary J
Date Posted: 02 Aug 2011 at 5:09pm

Thanks for the help, I switched the lines coming from the filter and it started and ran. Next question would be why! What would change in the filter housing to make the fuel come from the opposite port? Is this a temporary fix and should the filter housing be changed?

Thanks,

Gary J

Posted By: Gary J
Date Posted: 05 Aug 2011 at 10:06am

Update for future reference. It was in the filter housing. It would only run for about 2 minutes with the lines switched. So cleaning, swapping out if that does not work, the filter housing. Better that then the injector pump! Thanks for the information.

GJ