New Member, New M 817 Owner

[Manzyman]

I just joined this site and Just purchased a 1971 M 817. I am excited to use this on my farm and just have fun driving it. It start up great hardly a turn and a half and it fires. But when you try to drive or just hold the throttle down it idles up for maybe 30 seconds and then slowly idles back down to just above low idle. In gear it barley crawls up a hill or level, if the hill is too steep it won't climb at all. If you give it 30 seconds it will idle up again then right back down. I am going to change fuel filters, fuel hose and maybe drain the tank as I believe its a lack of fuel. The hand primer pump also doesn't seem to work. It also has a brake issue. When you first press the brakes the pedal goes to the floor. If you pump it 10 times or so it builds up brake pressure and toward the end you can begin to hear the air discharge from the airpack. If you don't use them immediately the go away again. The winch drum is empty also, is 280 ft of 5/8 cable right for a 20000 lb Garwood winch with level wind? I am pumped to get this truck running normal and drive it around. I would appreciate any thoughts or advice.

 

[dmetalmiki]

Welcome to the site and the hobby.
Yep, Change the filters.
Check the in tank pump is running properly as these trucks (The 5 tons) won't run without the in tank pump.
Paint it GREEN,..bleed the brakes..carry out a full service after reading up on the T.M.s.
try to attend local events.

 

[DeMilitarized]

Your fuel problem is most likely filters but could be a bad fuel pump on the engine. Happened to our m915 and it made almost no power but with a rebuild it was roaring. Check your fuel fittings are tight and your rubber lines have no apparent cracks or breaks anywhere as air in the fuel is a major nono for diesels.

 

[Mullaney]

I just joined this site and Just purchased a 1971 M 817. I am excited to use this on my farm and just have fun driving it. It start up great hardly a turn and a half and it fires. But when you try to drive or just hold the throttle down it idles up for maybe 30 seconds and then slowly idles back down to just above low idle. In gear it barley crawls up a hill or level, if the hill is too steep it won't climb at all. If you give it 30 seconds it will idle up again then right back down. I am going to change fuel filters, fuel hose and maybe drain the tank as I believe its a lack of fuel. The hand primer pump also doesn't seem to work. It also has a brake issue. When you first press the brakes the pedal goes to the floor. If you pump it 10 times or so it builds up brake pressure and toward the end you can begin to hear the air discharge from the airpack. If you don't use them immediately the go away again. The winch drum is empty also, is 280 ft of 5/8 cable right for a 20000 lb Garwood winch with level wind? I am pumped to get this truck running normal and drive it around. I would appreciate any thoughts or advice.View attachment 843167View attachment 843168View attachment 843169

.
Interesting paint job on it. I guess we could call it Green Incognito - or the Grape Escape.

Like the other guys said, fuel filters seem like the place to start. Welcome to the Steel Soldiers organization. Make use of the books. They will tell you how to swap the fuel filters the right way. Part numbers are here too if you don't have a number on the installed filter.

 

[98G]

Your fuel problem is most likely filters but could be a bad fuel pump on the engine. Happened to our m915 and it made almost no power but with a rebuild it was roaring. Check your fuel fittings are tight and your rubber lines have no apparent cracks or breaks anywhere as air in the fuel is a major nono for diesels.

And at the point you haven't found any obvious problems to correct and you feel the need to start throwing parts at it.... start with the rubber fuel lines.

The rubber lines can appear to be brand new with no problems whatsoever and still suck air.

 

[Manzyman]

Thank you all for your help, this machine has been switched over to a spin on type fuel filter, and it seems quite small for the engines size. I will get pictures when I am back up working on it, but would it possibly be to small also as well as plugged or bad fuel lines?

 

[MyothersanM1]

I second any opinions on fuel lines. These NHC's DO NOT like air in their fuel lines. I replaced all mine with Fragola Series 2000 AN fittings and their black nylon race hose.
Also, make sure you check the fuel primer tubing and the o-rings in the fuel primer itself. Classic place to unknowingly suck air.

 

[SCM35A2]

Welcome to the site, good looking truck.

 

[Ajax MD]

Welcome to the site and the hobby.
Yep, Change the filters.
Check the in tank pump is running properly as these trucks (The 5 tons) won't run without the in tank pump.
Paint it GREEN,..bleed the brakes..carry out a full service after reading up on the T.M.s.
try to attend local events.

I think you're referring to the earlier series of 5-tons. The 809 series do not have an in-tank fuel pump.

 

[tobyS]

I was having fuel problems too (929). Not only changed fuel filter but the fuel filter can gasket and o-ring on top of bolt. Seems to have solved a long problem of losing prime. Fingers crossed.

I loved my 817 and it looks like someone made yours a work truck with sides and cover. Good find....hope you got a deal.

Behr ultra in 383 green can be brushed and rolled. A bit of Flo-trol makes it flow out.

 

[Manzyman]

Yes they added side walls and a taller tailgate to the dump bed, but in the process they cut off the old tailgate and latches and now I only have a swing gate.
I was under the impression that mine did not have a lift pump in the tank as a 1971. I am attaching pictures of the fuel filter, I found a replacement that is bigger and fits on the same housing and it has a water drain, I am going to try that. I also plan to replace all the fuel lines. My right tank is wired off and a previous owner painted do not use so I will have to look into that. What are all the small steel lines, maybe vacuum lines going into the tank, is that for the fuel gauge and primer?

 

[Mullaney]

Yes they added side walls and a taller tailgate to the dump bed, but in the process they cut off the old tailgate and latches and now I only have a swing gate.
I was under the impression that mine did not have a lift pump in the tank as a 1971. I am attaching pictures of the fuel filter, I found a replacement that is bigger and fits on the same housing and it has a water drain, I am going to try that. I also plan to replace all the fuel lines. My right tank is wired off and a previous owner painted do not use so I will have to look into that. What are all the small steel lines, maybe vacuum lines going into the tank, is that for the fuel gauge and primer?

.
I'm sure you already know it, but those rubber hoses sure look "tired".

 

[US6x4]

A truck with dual tanks has a fuel selector valve under the cab which is known to spring multiple air leaks. I believe there is a "sticky" thread on rebuilding that valve.

*edited: incorrectly stated the valve was behind the dash.

 

[Manzyman]

A truck with dual tanks has a fuel selector valve behind the dash above the steering column which is known to spring multiple air leaks. I believe there is a "sticky" thread on rebuilding that valve.

Am I correct that the selector on the dash is for the fuel gauge, and the one on the floor to the left of the drivers seat is for the tanks?

 

[98G]

Am I correct that the selector on the dash is for the fuel gauge, and the one on the floor to the left of the drivers seat is for the tanks?

You are correct.

The dash switch controls where the fuel gauge looks. Th floor valve to the left of the driver seat on the floor controls where the fuel comes from.

I'm not familiar with the valve "us6x4" mentions.

 

[US6x4]

I'm not familiar with the valve "us6x4" mentions.

I rechecked the TM which I was picturing from memory and it looks like I'm dishing out some fake news. I was thinking the sheet metal layer in the diagram was "dash" but indeed it says "cab floor". I'll edit my earlier post.

 

[Mullaney]

I rechecked the TM which I was picturing from memory and it looks like I'm dishing out some fake news. I was thinking the sheet metal layer in the diagram was "dash" but indeed it says "cab floor". I'll edit my earlier post.
View attachment 843791

.
I happened to be searching for the type of fuel lines to use on the 5-Ton fuel tank selector valve.

While on that quest, I discovered the fuel tank selector valve rebuild thread and thought it might be worth sharing here. The original post was written by AMGeneral on October 4th 2011. Same valve or very similar is used on the M39, M800 as well as the 939 series trucks.

5 ton fuel tank selector valve cleaning/rebuild

Well,After searching the threads and getting questions from other members,I decided to cover the cleaning /rebuild of the fuel tank selector valve used on the M39,M800 and possibly M900 series 5 tons. First off,this valve is a common air leak in the fuel system on the 800 series trucks with...

www.steelsoldiers.com

 

[INFChief]

I just joined this site and Just purchased a 1971 M 817. I am excited to use this on my farm and just have fun driving it. It start up great hardly a turn and a half and it fires. But when you try to drive or just hold the throttle down it idles up for maybe 30 seconds and then slowly idles back down to just above low idle. In gear it barley crawls up a hill or level, if the hill is too steep it won't climb at all. If you give it 30 seconds it will idle up again then right back down. I am going to change fuel filters, fuel hose and maybe drain the tank as I believe its a lack of fuel. The hand primer pump also doesn't seem to work. It also has a brake issue. When you first press the brakes the pedal goes to the floor. If you pump it 10 times or so it builds up brake pressure and toward the end you can begin to hear the air discharge from the airpack. If you don't use them immediately the go away again. The winch drum is empty also, is 280 ft of 5/8 cable right for a 20000 lb Garwood winch with level wind? I am pumped to get this truck running normal and drive it around. I would appreciate any thoughts or advice.View attachment 843167View attachment 843168View attachment 843169

Welcome. Nice truck! Start by checking fuel pump operation.

 

[INFChief]

I just joined this site and Just purchased a 1971 M 817. I am excited to use this on my farm and just have fun driving it. It start up great hardly a turn and a half and it fires. But when you try to drive or just hold the throttle down it idles up for maybe 30 seconds and then slowly idles back down to just above low idle. In gear it barley crawls up a hill or level, if the hill is too steep it won't climb at all. If you give it 30 seconds it will idle up again then right back down. I am going to change fuel filters, fuel hose and maybe drain the tank as I believe its a lack of fuel. The hand primer pump also doesn't seem to work. It also has a brake issue. When you first press the brakes the pedal goes to the floor. If you pump it 10 times or so it builds up brake pressure and toward the end you can begin to hear the air discharge from the airpack. If you don't use them immediately the go away again. The winch drum is empty also, is 280 ft of 5/8 cable right for a 20000 lb Garwood winch with level wind? I am pumped to get this truck running normal and drive it around. I would appreciate any thoughts or advice.View attachment 843167View attachment 843168View attachment 843169

https://tfsweb.tamu.edu/uploadedFiles/FRP/New_-_Local_Capacity_Building/TFS_Assistance_Programs/TM-9-2320-260-10%20Operators%20Manual%20for%20M800%20series%205%20Ton.pdf

 

[INFChief]

I just joined this site and Just purchased a 1971 M 817. I am excited to use this on my farm and just have fun driving it. It start up great hardly a turn and a half and it fires. But when you try to drive or just hold the throttle down it idles up for maybe 30 seconds and then slowly idles back down to just above low idle. In gear it barley crawls up a hill or level, if the hill is too steep it won't climb at all. If you give it 30 seconds it will idle up again then right back down. I am going to change fuel filters, fuel hose and maybe drain the tank as I believe its a lack of fuel. The hand primer pump also doesn't seem to work. It also has a brake issue. When you first press the brakes the pedal goes to the floor. If you pump it 10 times or so it builds up brake pressure and toward the end you can begin to hear the air discharge from the airpack. If you don't use them immediately the go away again. The winch drum is empty also, is 280 ft of 5/8 cable right for a 20000 lb Garwood winch with level wind? I am pumped to get this truck running normal and drive it around. I would appreciate any thoughts or advice.View attachment 843167View attachment 843168View attachment 843169

https://www.ccsurplus.com/PDF/Manuals/5-ton-unit-maintenance.pdf