Fuel pressure
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=142482
Printed Date: 19 Aug 2025 at 2:33pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Fuel pressure
Posted By: Dozer
Subject: Fuel pressure
Date Posted: 15 Sep 2017 at 7:32am
| The fuel pressure gauge on my HD6G was 5 psi but is now registering zero. Full throttle RPM is now lower. I have not changed the fuel filters in 4 years but that in not many operating hours. The OEM restriction in the return line may have been removed by a previous owner but the machine runs as it should. My question: Does this mean that my fuel pump is going bad or should I just adjust the governor to add the lost RPM? |
Replies:
Posted By: CAL(KS)
Date Posted: 15 Sep 2017 at 8:17am
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Id have to double check to be sure but Im pretty confident both my dozers run in the 30 psi range. I would sure be looking into it especially if you have a psb pump as no one fixes them! ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: rustydollar
Date Posted: 15 Sep 2017 at 8:28am
There should be two filters a primary and secondary change them both. With todays modern diesel blends I would also install a water separator  . |
Dozer wrote:Posted By: Coke-in-MN
Date Posted: 15 Sep 2017 at 8:40am
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if you have any bio-diesel fuel in use - it has a tendency to loosen every old contaminant in system and put back into fuel change the filters before getting real excited about what else is wrong . ------------- Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel. |
Posted By: doctorcorey
Date Posted: 15 Sep 2017 at 11:33am
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Filters are cheap, this injector pump isn't . Substitute a known good gauge for the stocker, verify if it's a instrumentation problem, change the filters. Lack of usage is hard on filters and fuel tanks. At the very least change the secondary filter. Good time to blow out the line from the tank, too. ------------- Semper Fi USMC 1958 HD6G, 1959 MF 203 loader, 1960 Case 420B Backhoe, MF 65 Tractor/Loader Diesel |
Posted By: DMiller
Date Posted: 15 Sep 2017 at 11:52am
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Seeing what I did as to my filters this last week I will be changing more often than a low pressure indication. Sludge city! I may even invest in a newer style more easily replaced and inspected. |
Posted By: DMiller
Date Posted: 15 Sep 2017 at 12:02pm
| I have been considering making a spin on adaptor head to replace my canister oil filter as well. Is always a mess to get off and replace a spin on may be a tad easier as well more available. |
Posted By: doctorcorey
Date Posted: 15 Sep 2017 at 1:01pm
Dennis, I had the same thing; I changed the filters and the sec. looked like the bottom of a basement sump. Rusty sludge everywhere. I was a bit ashamed as being a professional mechanic I took it for granted since I had 'just' changed them 4 years ago. Less than 100 hrs. on machine since. Once a year for me from now on, and full tank year round for the condensation. When my pump got sticky, I traced back through the fuel system and it got uglier as I went ------------- Semper Fi USMC 1958 HD6G, 1959 MF 203 loader, 1960 Case 420B Backhoe, MF 65 Tractor/Loader Diesel |
Posted By: Ray54
Date Posted: 15 Sep 2017 at 3:28pm
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Just one of those things ALWAYS ALWAYS change the filters before spending more money.Unless you have money to burn,but then just send that to me and I can lighten your load. Dmiller the heads to add spin on filters where cheap to in the old days,so are you going to make them just cause you can?????????? Or the fact that most of them came with the Ford threads holding you back from buying one.
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Posted By: DMiller
Date Posted: 15 Sep 2017 at 3:32pm
| Cannot be had anymore, the conversion kit for my old 7000 series no longer exists according to Wix and Baldwin. |
Posted By: DMiller
Date Posted: 15 Sep 2017 at 3:54pm
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A question to the guys that might know, will the Detroit spin on adaptor install as the Allis adaptor did? Can still get the canister conversion for 8/6v-71 DD engines, OB1303 Baldwin or K3390 Fram? Would use a PH3690 Short Fram or B105 short Baldwin. |
Posted By: Ray54
Date Posted: 16 Sep 2017 at 12:02pm
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Just a idea I had as walked past my transfer tank with pump and filter. The filter suppliers make the heads to put a filter as you transfer fuel,which are generally 3/4 or 1 inch pipe treads which is way bigger than needed. But if you can find room. It also helps to have a helpful person at the store you buy filters from.They make so many sizes of filter as well different degrees of filtering that will fit the same base. But with the average counter person your out of luck if you cannot give make and model that is in the computer. So I wish you luck in how ever you proceed.
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Posted By: injpumpEd
Date Posted: 17 Sep 2017 at 9:59am
Questions like drive me crazy as a fuel injection pump mechanic! So, you take the time and trouble to get the pump rebuilt, then put it back on and same issue. "Oh man, pump guy must not have fixed my problem!" or "Man, those pump shops are just not fixing the problems anymore!" I have heard it all before. I cannot stress it enough, MAKE SURE YOUR FUEL SUPPLY AND RETURN CIRCUITS ARE PERFECT! And change your filters while you're taking the filter bases apart to clean everything up. If the engine starts and runs, the injection pump is probably fine. Don't go messing with settings to compensate for poor fuel flow. Today's fuel likes to grow algae, and form all kinds of goop the plugs filter bases, and lines. The PSB should have a restriction fitting on the return side, so no matter how much fuel you provide it, it will never build pressure without the controlled restriction fitting. ------------- 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: doctorcorey
Date Posted: 19 Sep 2017 at 8:50am
 ------------- Semper Fi USMC 1958 HD6G, 1959 MF 203 loader, 1960 Case 420B Backhoe, MF 65 Tractor/Loader Diesel |
Posted By: injpumpEd
Date Posted: 19 Sep 2017 at 12:51pm
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well, my post wasn't intended to ridicule, but to point out how often people overlook the very obvious basic things. Does the pump have some wear? Probably. Would I just throw an old used pump on my stand? Not under most circumstances. I wouldn't expect an engine shop to dyno an engine that is running poorly, and using oil, in need of a rebuild, but yet putting an old pump on the stand is not a lot different. You are right, it is not rocket science, even an idiot like me can do it lol! ------------- 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! |