Geo Tracker Kubota Diesel Engine Swap

[bandit86]

I want a kubota in my land rover

[flying_gage]

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[DieselDrewski]

Last night, I finished putting together the dash (still a lumber of loose ends there, literally and figuratively), filled the crankcase with oil, and the radiator with antifreeze. I put a temporary fuel container under the hood, did my best to purge the lines, and tried firing it up. I couldn't get it to catch (definitely air in the fuel system still) so I'm going to complete the fuel system build before I try again. I plan on using the fuel pump in the tank as-is, but I found some low pressure switches on the Mendelson's website, so I bought a couple, along with some other odds and ends. I hope the connections for the switches are a standard type; there isn't much info on the page. From experience, I know that trying to wire the pump from one switch is likely to cause a lot of cycling within a narrow range, so I designed this circuit:

The pump will run until the high pressure is reached, but not turn on again until it drops below the low pressure.

[Diesel_Dave]

Do lift pumps typically cycle on an off? I thought they just stayed on all the time.

What type of high pressure (injection) pump is on the Kubota?

[DieselDrewski]

Originally Posted by Diesel_Dave

Do lift pumps typically cycle on an off? I thought they just stayed on all the time.

What type of high pressure (injection) pump is on the Kubota?

Just to be sure we're on the same page, the electric pump is the one in the fuel tank that provided pressure for the original gasoline EFI. The Kubota has a mechanical feed pump going into a Bosch K-type mini injector pump.

I think the electric pump would have normally run all the time, but also would have a pressure regulator with return line to minimize pump load.

I may discover that no pump is required.

[Diesel_Dave]

I'm confused then, why can't you just use the electric pump as-is? It'll keep the feed pump suplied, right?

[DieselDrewski]

Originally Posted by Diesel_Dave

I'm confused then, why can't you just use the electric pump as-is? It'll keep the feed pump suplied, right?

With no relief (such as the regulator that is no longer there, shunting to a return line) I don't know what sort of pressure would develop, considering the electric pump would essentially be blocked all the time. (heck, some pumps use less power when they are blocked, but even so, the heat can build up more)
I really should do some more experiments before I spend too much time on this... see what kind of pressure the pump develops, current use blocked and unblocked, and whether the engine needs the electric pump at all.

[Diesel_Dave]

Maybe you could steal the regulator off the old engine (assuming it's still available). Or get a cheap one off ebay. Nothing against your circuit, but I'm thinking the regulator valve will give you less trouble. Just my opinion.

[DieselDrewski]

I worked on purging all the gasoline from the tank last night, using first the in-tank electric pump, then resorting to a manual piston transfer pump to get the dregs out. Then I flushed 3 times with diesel. Today, I'll put in diesel for fuel and plump the engine. From the way I was able to draw through the un-energized electric pump, I think the mechanical feed pump on the engine should be sufficient. I might wire in a momentary switch to the pump to make bleeding the system easy.

[Diesel_Dave]

If you can get away with the mechanical feed pump that would be ideal.