Bypass mechanical lift pump

[NetMagi]

I have an old IR Lightsource ex-light tower with a D905 in it. When I got it, the mechanical lift pump was bypassed (12V electric fuel pump pushing fuel up to the inj. pump instead). The mechanical pump is still installed in the block, with nothing connected to it, and open fittings. Motor runs fine, and I love the convenience of the electric pump for priming when changing filters, etc.

I also have a brand new D1005 with a Mecc Alte head on it that I'll be semi-permanently installing for backup-power use. It also has a mechanical fuel pump, but I plan on using an electric lift pump instead of the mechanical on it as well, for the same convenience factor with priming, etc.

Here's the question:

What is the PROPER way to bypass the mechanical lift pump:?

1) just bypass it, leave it installed in the block, don't cap the fittings on either side

2) just bypass it, leave it installed in the block, but cap the fittings somehow

3) leave it connected, and put the electric pump ahead of it

4) remove it altogether and cap the hole in the block

It looks like the mechanical pumps are driven by a cam that raises and lowers a plunger in the pump, so I guess my fear in just disconnecting is that it's still moving, but there's no fuel in there to lubricate the parts.

Problematic over time, or no?

-Rich H.

 

[Daren Todd]

If your worried about any leakage later on from the mechanical fuel pump, just loop a hose from one side to the other of the fuel pump. And just clamp it off. Shouldn't be any issues just leaving it bolted to the block and just cutting the fuel lines going to it.

Seen some folks leave it inline with the electric fuel pump, pumping through the mechanic fuel pump. Only issue I could see doing that, is if an internal seal went out. Then it would pump fuel into the engine block.

 

[D2Cat]

I'm not familiar with your specific situation. When pumps connected to the engine are replaced with electric fuel pump, simply remove the mech. pump and cover hole with a plate with a gasket behind it.

Then there are no chances of fuel/oil contamination. You then need to be sure your battery is in good order for fuel supply.

On some engines the fuel tank is higher then the engine and gravity become the fuel pump. The system may also have a fuel pump, but the fuel will flow through the pump even when not working. Pump is required for fuel supply when engine (on machine) is in an inclined position where gravity won't help.

 

[ShaunRH]

D2Cat has my opinion as well, remove and cover. I'd use the cover as a nice mounting spot for the electric pump.

What he said is also true: no electric power, no motor. Often on the new tractors you don't get much of a choice, but I love the fact that diesels don't need a single wire to run when they are fully mechanical. My D-17 didn't HAVE an electrical system for the last 20 years, I barely bolted up an alternator to it last year.

So I get what you're saying, but I personally would stick with the mechanical pump if it were a tractor. For an electrical device like a generator, electric pump is fine.