M931 Fuel Line & Filter Replacement Results

[D6c]

Thanks for the advice helping me fix the fuel prime problem I was having on my M931. I had to prime the fuel pump each time I started it and it would lose prime within 10 minutes after it was shut off.

I replaced all the rubber fuel lines, (6) short hoses on tank selector valve plus supply & return lines for fuel pump.
It seems to be pretty difficult to find anyone that can make up fuel lines with crimped on fittings unless you use bulky hydraulic fittings. Some of the tank valve lines had already been replaced with push-lock fittings so I decided to go that route with all the lines. The best part is you don't have to know exactly how long each line is....just cut hose to match the old lines and push the fittings in and it's done. If the line ever gets bad again the fittings can be reused.

While it was apart I disassembled the tank valve, cleaned it with scotch brite, and replaced the o-rings. (#111 o-ring for shaft & #124 o-ring for cap)

The hose & fittings I got from http://www.discounthydraulichose.com/ They've got just about every fitting imaginable at good prices and were at my door in less than two days.
If anyone is interested I can come up with a list of the fittings that are required.

The water drain valve on the fuel filter can was plugged so I took it apart and cleaned it up. The Napa #3401 filter listed in Parts Reference spreadsheet on this site is indeed the correct filter. I comes with the cover seal and and o-ring for the center bolt that fit perfectly.

After putting everything back together I filled the fuel filter by removing the schrader valve on the top of the filter and pressurized the tank with air until fuel flowed out of the top of the filter can. I used a flat plate with a small hole over the filler neck of the fuel tank and pressurized it using the rubber tipped air blow-off from the shop air.
Once the fuel filter is full it's quick to bleed the rest of the lines with the hand priming pump.

When I first got the truck I replaced the o-rings in the hand priming pump but don't know the exact size because I just dug around in a box of misc. o-rings I had until I found ones that would work.

The result is, now the truck starts right up without priming, even after sitting overnight. The best part is it now idles much smoother. It was no doubt getting air in the system and causing the rough idle.

Thanks again for the help.

 

[taylordc15]

If anyone is interested I can come up with a list of the fittings that are required.

My truck is doing the same thing yours was, I would very much like a list of the required fittings so I can get my hoses replaced

 

[D6c]

I've had a couple of requests for a list of parts I got from http://www.discounthydraulichose.com to repair the fuel lines so I thought I'd post the part numbers from my invoice.

This is probably not a complete list of fittings to do your truck because there were at least a couple of push-lock hoses already on the truck and I reused those fittings. At least it should give you a good place to start. I know it took me a while to figure out what fitting combinations and hose was going to work. So far it's working much better. Unless it sits for a long time I don't have to bleed it with the hand priming pump any more and it idles much better.....previously if it sat for just a few minutes I would have to re-bleed the fuel lines.

10' of : 3/8" Black PUSH-LOCK Hose
10' of : 1/2" Black PUSH-LOCK Hose
2 of : 272-0606C | 3/8" PUSH-LOCK x 3/8" NPTF Male Pipe
1 of : 272-0808C | 1/2" PUSH-LOCK x 1/2" NPTF Male Pipe
1 of : 284-0610C | 3/8" PUSH-LOCK x 3/8" SAE 45° Female Swivel
1 of : 287-0814C | 1/2" PUSH-LOCK x 5/8" Dual Seat Female Swivel

 

[dan2002dd]

Thanks to the above post for getting me started in the right direction for replacing the hoses on my fuel selector on my M939. For anyone wanting to just put everything back like it is and only replace the rubber lines and you don't already have the push lock ends, here is a list of the fittings you need:

3 - 272-0606C 3/8" PUSH-LOCK x 3/8" NPTF Male Pipe
3 - 292-0610C 3/8" PUSH-LOCK x 3/8" Inverted Flare Female
3 - 272-0806C 1/2" PUSH-LOCK x 3/8" NPTF Male Pipe
3 - 272-0808C 1/2" PUSH-LOCK x 1/2" NPTF Male Pipe

and of course the hose listed above. I will try to post a pic of the finished product.

 

[dan2002dd]

Pics

 

[bchristensen]

I haven't had any luck finding the push-lock fitting that goes to the fuel injector. I replaced all the lines for an M929A1 on the tank selector just fine but trying to replace the fuel line from the fuel filter to the fuel injector has left me purchasing a bunch of fittings that don't work. The Male connection from the fuel injector appears to be a 7/8" Male SAE 45 degree flare. discounthydraulichose provided all the fittings for everything else but I can't seem to find this needed connection anywhere. I have 3/8" hose. Does anyone know where I might find this?

The original post has a picture of the fitting (second image). That's the fitting I need.

Brian

 

[simp5782]

I haven't had any luck finding the push-lock fitting that goes to the fuel injector. I replaced all the lines for an M929A1 on the tank selector just fine but trying to replace the fuel line from the fuel filter to the fuel injector has left me purchasing a bunch of fittings that don't work. The Male connection from the fuel injector appears to be a 7/8" Male SAE 45 degree flare. discounthydraulichose provided all the fittings for everything else but I can't seem to find this needed connection anywhere. I have 3/8" hose. Does anyone know where I might find this?

The original post has a picture of the fitting (second image). That's the fitting I need.

Brian

Post a picture of what your setup is. Such as your pump inlet for fuel and your filter setup

 

[MyothersanM1]

When I first got the truck I replaced the o-rings in the hand priming pump but don't know the exact size because I just dug around in a box of misc. o-rings I had until I found ones that would work.

The primer pump o-rings are Brasscraft SC0562 or 3/8" I.D. x 1/2" O.D. x 1/16" wall

I eliminated the selector valve and pull fuel to the left tank from the right using a frame mounted transfer pump.
I also replaced all the fuel lines with AN fittings and braided nylon/steel hose.

 

[bchristensen]

I like what you did on the fuel tanks. I left those connections alone because they are all hard lines on mine. I replaced all the soft lines to the tank selector switch. The fuel line from the fuel filter to the fuel pump is about 40" long. It's a soft line. I have a connector that fits the fuel filter side but the push-lock connector that fits the fuel pump is nowhere to be found. I've purchased 5 different connectors thinking they might work but none of them do.

It measures out to be around a 7/8" SAE 45 degree flange Female connector that I need. It needs to be a swivel to allow for connection without twisting. The original poster's 2nd picture is exactly what I need.

	This is the connection to the Fuel Pump. I cannot find a single push-lock fitting for this. I cut off the old fuel tube thinking that surely one of the fittings I had would work. I'm using 1/2" fuel tube and the female fitting for this roughly measures out to about 7/8" ID.
	This is the Fuel Filter connection. I have a push-lock fitting for this. Not an issue.

The fuel selector switch came out great and is ready to go. I can buy a complete fuel tube but I'd like to re-route using the push-lock fittings and new 1/2" push-lock tubing I have.

Thank you!

Brian

 

[simp5782]

I like what you did on the fuel tanks. I left those connections alone because they are all hard lines on mine. I replaced all the soft lines to the tank selector switch. The fuel line from the fuel filter to the fuel pump is about 40" long. It's a soft line. I have a connector that fits the fuel filter side but the push-lock connector that fits the fuel pump is nowhere to be found. I've purchased 5 different connectors thinking they might work but none of them do.

It measures out to be around a 7/8" SAE 45 degree flange Female connector that I need. It needs to be a swivel to allow for connection without twisting. The original poster's 2nd picture is exactly what I need.

View attachment 868520	This is the connection to the Fuel Pump. I cannot find a single push-lock fitting for this. I cut off the old fuel tube thinking that surely one of the fittings I had would work. I'm using 1/2" fuel tube and the female fitting for this roughly measures out to about 7/8" ID.
View attachment 868522	This is the Fuel Filter connection. I have a push-lock fitting for this. Not an issue.

The fuel selector switch came out great and is ready to go. I can buy a complete fuel tube but I'd like to re-route using the push-lock fittings and new 1/2" push-lock tubing I have.

Thank you!

Brian

That is a Boss fitting. You need a 1/2" sae to pipe to get to your push lock style fitting.

 

[MyothersanM1]

View attachment 868520

This is the connection to the Fuel Pump. I cannot find a single push-lock fitting for this. I cut off the old fuel tube thinking that surely one of the fittings I had would work. I'm using 1/2" fuel tube and the female fitting for this roughly measures out to about 7/8" ID.

Is this the push-lock fitting you are looking for...


I believe it is a 37/45 degree dual seat.

 

[bchristensen]

Is this the push-lock fitting you are looking for...
View attachment 868536View attachment 868537View attachment 868538View attachment 868539

I believe it is a 37/45 degree dual seat.

That looks like exactly it. Why I can't find a ruler with 7/8" mark but it appears "28" on this ruler is 7/8" so I would say it's exactly what you have in your hands. The fuel line is 1/2" ID so that piece in your hand is exactly what I'm looking for. Any idea where I might find that connector? I couldn't see it on DiscountHydraulichose.com. The biggest one they have is 3/4".

This is a picture of the original with the crimped hose that I cut off.

 

[MyothersanM1]

That looks like exactly it. Why I can't find a ruler with 7/8" mark but it appears "28" on this ruler is 7/8" so I would say it's exactly what you have in your hands. The fuel line is 1/2" ID so that piece in your hand is exactly what I'm looking for. Any idea where I might find that connector? I couldn't see it on DiscountHydraulichose.com. The biggest one they have is 3/4".

This is a picture of the original with the crimped hose that I cut off.

It's actually 5/8" OD tube which is a 7/8"-14 thread. And, yes, for 1/2" ID hose. It swivels until tightened.
Discount Hydraulic Hose or McMaster-Carr
Also, if you'd like, I will offer mine to you "pay-it-forward". It is surplus to me, but it is good used serviceable.
If so, PM me with your info.

 

[bchristensen]

It's actually 5/8" OD tube which is a 7/8"-14 thread. And, yes, for 1/2" ID hose. It swivels until tightened.
Discount Hydraulic Hose or McMaster-Carr
Also, if you'd like, I will offer mine to you "pay-it-forward". It is surplus to me, but it is good used serviceable.
If so, PM me with your info.

Thank you for the links! Ordered. I had some other items to get as well but I really appreciate the offer. Only a couple minor adjustments left and its ready to be put to work excavating a pond in the mountains.

Thanks again!

Brian

 

[MyothersanM1]

Thank you for the links! Ordered. I had some other items to get as well but I really appreciate the offer. Only a couple minor adjustments left and its ready to be put to work excavating a pond in the mountains.

Thanks again!

Brian

Glad to be of some assistance.

 

[kungfu dave]

I am having issues similar to the original post and have done most of the line replacements to stop the air leaks. However, I also have a crack in my return line. I was unable to get a solid answer on fixing the line so I ordered a replacement one. What I got was a flexible line with brass fittings. Before I destroy the old line by cutting it out, have any of you tried these after market lines? I searched the forum for return line posts but there were no matches so I thought I would drop it into this one. Thanks.