Correct fuel line piping?

This is a bit lengthy, if anyone knows where to find a service manuel on the fuel system and can direct me to it, that'd be great. I just aquired a 1967 Kaiser Jeep M51A2 Dump Truck, multi-fuel turbo. I was told to leave the transfer fuel pump switch on when driving. This didn't sound right so I started looking at the system. Apparently the vehicle uses the left tank to operate, the right tank is an auxillary tank and simply transfers fuel to the left tank. There are three fuel filters, one on the frame in the left wheel well and two on the left side of the engine. When I traced the fuel lines, the right tank line goes to a transfer pump located on the rear of the battery box, this might not be the original, and continues to the left tank. The left tank has two lines coming out, one on the in-tank fuel pump which goes to the frame filter than on to the front of the injector pump. The second line appears to have been added, a fitting welded to the top of the tank in the front frame side corner of the tank. This line appears newer, no paint, and runs directly to the inlet of the on-engine filters. There are two additional lines to the on-engine filters that appear to be coming from the injector pump. The outlet of the on-engine filters go to the rear of the injector pump. I removed the in-tank pump from the left tank and found it all gummed up with old fuel. The motor works, but was not pumping fuel. I have cleaned this and is now working. But I am a little baffled as to what is the proper fuel line configuration, and how the engine even ran. The right tank line does just transfer fuel, as I can see it dump into the left tank when the transfer pump is on, and there is a float shut off on its line in the left tank.

the system needs a return line. the line that you said looks like a new fitting may be the return.

Thanks for the reply DaveP. I was thinking there sould be a return line, but was confused as to why it would come off the inlet of the fuel filter. I'm not too savy on the diesel injection and am learning.

I have the same truck. The passenger side tank feeds the drivers side with the intank pump. The primary fuel filter is the same as the secondary and final. The pump located on the battery box is probably an after market to feed the engine since the in tank pump was not suppling the fuel.

Won't the injector pump act as a pump to suck fuel from the tank? I'm thinking it might be doing this even thought the in-tank pump was not working. I've attached some photos of the configuration. I'm not sure how the 'T' fitting works on the on-engine filters as it is right off the inlet to the filters. Perhaps it does not connect to the filter and is simply the return line to the tank ??

desertfox said:

I have the same truck. The passenger side tank feeds the drivers side with the intank pump. The primary fuel filter is the same as the secondary and final. The pump located on the battery box is probably an after market to feed the engine since the in tank pump was not suppling the fuel.

Click to expand...

For some reason i lost this thread.
the pump on the batt box is not an add on. it is used to transfer fuel from the right tank to the left tank.
the right tank is used for storage only. I have no idea why they were designed this way.

Thanks, I did find some info on the fuel filters on the engine and it is a return line coming off the inlet. There is an internal pressure valve that allows the excess fuel to return to the tank. Have everything cleaned up and working properly now.