3600 Fuel system modifications

LarryWA · Mar 7, 2015

I just bought a 1976 Ford 3600 diesel 3 cylinder. In looking it over I have seen a couple of modifications to the fuel system which I am considering removing and one that I do not know what it is. It appears to have an electronic fuel pump with an extra inline fuel filter. Why would someone put this on? I am thinking they were having problems with the intank fuel filter and decided to fix it with this. The handle for the fuel shutoff at the bottom of the tank is broken off, I already got a new part with filter to replace it.

The other modification is some kind of little cylinder with fuel in and fuel out lines on the diesel return line. Water trap? I have no idea what this is.

I have owned a Ford 7000 for several years and it does not have these extra parts in the fuel system. I would like some thoughts on whether to remove them when I replace the shutoff valve and regular fuel filter.

jwjsr · Mar 7, 2015

someone told me this:

"Unless you are splitting hairs to keep it original, what I have done on several old diesels is put an electric fuel pump in line right where the fuel comes out of the tank. This will put 4-6 psi pressure on the entire line going to the pump. It will help it start better by keeping the system primed and also help find other leaks since now fuel will come out instead of air going in. These are cheap on flebay $15-20 shipped"

Bern · Mar 8, 2015

That might be wise advice for machines with tanks below the engine, but is unnecessary when the fuel tank sits above the engine.

It is interesting to note that Ford recommended this as a fix to stop surging complaints on tractors with lower fuel tanks.

sunbeam · Mar 8, 2015

I had a 6600 had the injector pump rebuilt and the lifter pump was replaced. The new pump was bad you could manualy pump to bleed it but not when the tractor was running. The tractor would run fine when the tank was full and not so much when in the bottom half of the tank.

Sean in PA · Mar 8, 2015

On that little cylinder on the return line, is there an extra output that's not being used? If so it might be for the optional Therm-O-Start cold starting aid.

Bern · Mar 8, 2015

Your screen in the tank must have been partially plugged. Higher fuel level = higher head pressure.

LarryWA · Mar 8, 2015

Yes there is an extra line not being used and it appears to be leaking some also. I didn't know a Therm-O-Start option would work like that.

(quoted from post at 07:22:54 03/08/15) On that little cylinder on the return line, is there an extra output that's not being used? If so it might be for the optional Therm-O-Start cold starting aid.

LarryWA · Mar 8, 2015

Thanks for the input. I am not worried about it being original, it is for working. It runs pretty well, but extra parts seem like something else to go wrong. I am not going to change it since it works now.

Sean in PA · Mar 8, 2015

I didn't know a Therm-O-Start option would work like that.

The Therm-O-Start is a fitting that goes into the intake manifold. It has a fuel line and an electrical line going to it. The fuel line comes from that canister on the return line. The electric circuit comes from a special "heat" terminal on the key switch. When you have the key in the "heat" position it sends electricity to the fitting and there's an electrical heating element in there that heats up. When it heats up to a certain point there's a valve that opens from the heat and allows a little bit of fuel to dribble into the manifold and onto the hot element and catch fire. Then when you turn the key to the "start" position the flaming fuel gets sucked into the cylinders to add heat and allow for a quicker start. If you have the little canister but no third line going off of it, the original Therm-O-Start might have gone bad and a previous owner may have either removed it or just disconnected it.

sunbeam · Mar 8, 2015

Bern I replaced the lift pump and the problem went away.

3600 Fuel system modifications

LarryWA

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jwjsr

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Bern

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sunbeam

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Sean in PA

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Bern

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LarryWA

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LarryWA

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Sean in PA

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sunbeam

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