Onan external fuel pump?

[camperdave]

I was doing a little maintenance getting ready for a trip, and was servicing the Onan 4k generator. fresh oil, new air filter and plug.
I bought a new fuel pump and fuel filter too (as it's 15 years old on the original fuel pump) but didn't install it. I figure if it does go out while on the trip, at least I'll have it with me and can do it then.

Got me thinking... Couldn't I install the new pump external to the whole generator box? It looks to be just a 1/4" rubber fuel line into the filter/pump, and another 1/4" rubber line to the carb. Seems like it would not only be easier to mount a new pump external (kind of a pain getting to the stock pump), but probably be better for the pump (cooler outside of the generator box). Anyone done this? Any reason not to do this?

[KMLsquared]

Absolutely , put it where ever you want as long as you can get power to it from the gen control board. I agree that it’s mounted on the gen to keep it simple. Pumps are much happier pushing fuel than sucking it. Good on you for thinking about it and coming up with a better way!

[camperdave]

STBRetired wrote:
Can you pump fuel through the pump when it is off (failed old pump scenario)? Will that cause excess pressure drop or restrict the flow rate? How will you get the 12V to power the pump? Needs to be fed by the control board inside the Onan.

No. I'd just bypass it. Literally just remove the rubber fuel hose from the front of the existing filter, and plug it into the new remote filter. Run a new rubber line from the pump output to the carb. Use the existing two wires for running the fuel pump.

Seems simple in my mind...

[STBRetired]

Can you pump fuel through the pump when it is off (failed old pump scenario)? Will that cause excess pressure drop or restrict the flow rate? How will you get the 12V to power the pump? Needs to be fed by the control board inside the Onan.

[camperdave]

The fuel pump is a known failure point so it's getting changed out as preventive maintenance.

I feel like the pump is where it is because of manufacturability. The enemy of the fuel pump is heat, so it's logical to me to move the pump out of the engine box.

[Chum_lee]

"Any reason not to do this?"

Hummmmmmmmmmmmm. A few questions. Why would you want to modify the proven design of a fuel system that has been working fine for +20 years? Why would you change out a pump that is currently working fine? (I'm not saying the fuel pumps are without issue and don't wear out)

Do you have a specific reason? Any specific problem you are having? I'm not saying there aren't good reasons to make changes, just that I would like to know your specific reasons.

Do you understand that making changes could possibly complicate the system and REDUCE the reliability rather than IMPROVE it?

When I was I kid, my friend "thought" he needed an additional fuel filter on his car. So he installed one not realizing that the plastic filter he selected and mounted was too close to the manifold heat control crossover. His filter lasted a few days before it melted spilling pressurized fuel in the engine compartment setting his car on fire. 100% his fault! Come to think of it, my friend is now dead because of another silly mistake he made which I won't go into here.

Chum lee

[enblethen]

Each end of the pump and the filter use flare style connections. I would not use any barb fittings on the fuel pump output.
I would reinstall as came from Onan!

[camperdave]

Onan Microquiet 4000, model number 4KYFA26100K. Pump is Onan 149-2311-02. I don't have the filter number handy but it's 1/4" hose barb on the inlet.

[enblethen]

Which Onan 4K?
What is model # of filter and pump? Are they from Onan?
Rubber lines are common on gensets that do not normally have filters.
My Onan genset uses steel lines with flared fittings.