Cat 950 Fuel System

[crusier_32]

I have an Cat 950 loader 81j series that had developed a hard starting problem. This has been an issue for me in the past and it has always been fuel lines leaking air. 30+ year old fuel lines tend to be on the brittle side. It was due for a service anyhow yesterday so I ran it into the shop. I poked around and wiggled a few different things, before calling it a day.

This morning I went back in and started it to allow it to warm up before I dropped the oil on it. It started probably easier then it has been, but the fuel pressure never came up like it usually does. After more some time and more less putting it to the floor it finally kind of made it into the green. I stepped out of the cab and the thing was pumping gallons of fuel on to the floor.

I shut it down and found the leak. It was one of the lines that I had wiggled last night. I assume I must have broke it off when I was messing around. But the trouble is I for the life of me can not find the other end of this thing. I will attach a picture of where it came from, with an arrow point to it (the line was not on when the picture was taken). I remember from last night though that the line in question ran from the pump straight down and came out somewhere around the crank case vent behind the alternator.

I had the idea that this maybe was some sort of vent with a pressure valve on it. I can look up into the hole where it was threaded with a mirror and I am not completely sure that it was not cut for a ball type check valve. When I took the line off I don't remember any spring or ball falling out. Though it would not be the first time that I have missed something like that, and lost the ball and spring. I stuck a bolt in the hose with a hose clamp on it, and started the machine up. Which it did easily and seemed to run well for quite awhile but it eventually ran out of fuel. Which leads me to believe that this line must go some where and I am just not seeing it.

I am hoping to find someone that may know a thing or two about these old loaders, or possibly someone with a service manual. If not I am going to have to run up and check out the dealers manual or buy my own. The dealer is about an hour and a half away, so I am hoping someone here has some ideas.

This is my first post here, and I realize it is a long one. Any help would be much appreciated.

http://imgur.com/VSZUu7y

Will

 

[Bob/Ont]

Check the bleed valve you open when you get air out of a new filter. Sounds like you might have opened it when wiggeling stuff. That would cause low fuel pressure.
Later Bob

 

[crusier_32]

Yea I am sure that the bleed screw is closed. I am heading out today to poke around some more.

Thanks

 

[zlssefi]

Is it a return line going to the tank possibly? if that was a fuel pressure line the engine wouldnt run at all i wouldnt think.

 

[crusier_32]

I don't think so I covered this thing from one end to the other looking for the other half and have not found it. It either broke and is missing a significant length of fuel line or it does something different. I plugged of the line with a bolt and hose clamp and it seems to run fine after I primed it up so?

 

[Bob/Ont]

If it's leaking above the arrow in your pic, that's the fuel transfer pump. It has a weep hole to let any fuel that leaks from the pump drain before getting into the engine oil.
Think you need a new gear pump.
Later Bob

 

[crusier_32]

That is making a little more sense now. I had the transfer pump off it, it did not look bad other then some slight wear on the gear. How would one tell if it is bad?

It is worth noting that the line I am talking about is not on the transfer pump though, it is on the main housing.

Will

 

[Bob/Ont]

That is making a little more sense now. I had the transfer pump off it, it did not look bad other then some slight wear on the gear. How would one tell if it is bad?

It is worth noting that the line I am talking about is not on the transfer pump though, it is on the main housing.

Will

Will, I think the bleed hole from the transfer pump goes back through the mounting flange and into the drive housing. Take it off again and check that out. The fuel comes in through the steel sediment bowel up throug the drive housing, into and out of the pump back through the drive housing and up to the filter. If you see a small hole on the mounting surface blow air into it and see if it's the one leaking. If it doesn't go out the mounting surface it might go out the bore the pump sit's in.
Later Bob

 

[crusier_32]

It is starting to make an awful lot of sense now. I think I will just call the dealer tomorrow and order a transfer pump. I will update this after the new pump is in.

Thanks for the advise.

Will

 

[crusier_32]

Well I called cat and it was $670 for a new pump plus another $50 next day air freight. Or $48 dollars to replace all the seals, which they had on stock. So that is what I did, when I got into it the first seal coming out of it more less did not exist, there was only a tiny shred of it left to even know that it existed in the first place. Put it back together and it runs like a charm.

Thanks again for the help.
Will

 

[Bob/Ont]

Well I called cat and it was $670 for a new pump plus another $50 next day air freight. Or $48 dollars to replace all the seals, which they had on stock. So that is what I did, when I got into it the first seal coming out of it more less did not exist, there was only a tiny shred of it left to even know that it existed in the first place. Put it back together and it runs like a charm.

Thanks again for the help.
Will

Well done Will.
Later Bob