Electric Fuel pump Bypass Mechanical Pump

While thinking about installing the electric fuel pump I began to wonder what will happen if my mechanical pump fails and I run on the electric pump.

A problem I have seen with the mechanical rubber diaphram type pump (such as i have now) is that fuel will pass through the rubber diaphram when it ruptures (common mode of failure) and into the engine crankcase.

Of course the only time I saw such a failure was on a gas engine and mine are diesel.

So, with this concern in mind should I plumb my new electric pump with valves and lines to bypass the mechanical pump in the event it fails?

*

Or is this too much of a belt and suspenders solution to a problem that may not exist?

DavidM wrote:
Sounds like a lot of trouble for a very low probability failure. But why did you install an electric pump? A rubber squeeze bulb is a better solution for priming.

David

Click to expand...

An alternative to the squeeze bulb for priming, is to install one of the Racor filters equipped with the manual pump.

I agree with David, very low probablility of failure.* But you should probably have a backup manual fuel pump as a spare part.* My PO installed an electric fuel pump for priming and manual pump backup, but it has only been used for occasional priming during the past 4000 hours.* Cummins 210HP.

I brought the boat up from Seattle to Alaska a few years ago and plan to make the reverse trip soon back to Seattle.

A truely great trip.

As part of my planning I want to back up failure areas.

While I am aware that this is a low failure area it is still one that I have seen in high time trucks and the pump is the same.

Part of the problem is that the mechanical fuel pump can not be changed unless the exhaust manifold is removed. It makes a simple job into a major job. Not something that can be performed at sea.

It is all just a thought right now, thanks for the responses.

the elc pump is handy when changing filters and if you ever run the motor out of fuel on the ICW under a bridge in south florida.......or so I have heard

I use a simple electric fuel pump for priming and sometimes fuel transfer.

I could use it* if my fuel pump failed, but I would have to rig a bypass hose,

Could be done,* but hope never to have to.

JohnP

motion30 wrote:
the elc pump is handy* if you ever run the motor out of fuel on the ICW under a bridge in south florida.......or so I have heard

Click to expand...

*Also handy in the Harlem River

JohnP wrote:I use a simple electric fuel pump for priming and sometimes fuel transfer.

Click to expand...

*Very sanitary looking installation, nicely done.

The only thing I might do differently is to closely couple the pump*to the valves*with*tubing rather than hose. *

"Part of the problem is that the mechanical fuel pump can not be changed unless the exhaust manifold is removed. It makes a simple job into a major job. Not something that can be performed at sea."


A failed mechanical pump might allow fuel into the engine if pressurized.Or just flow out a failed diaphram into the engine space.

A mechanical pump by pass might make sense for offshore or the belt and suspenders folks.

Part of a fuel polishing system I designed / installed included an electric pump. It's configured for polishing, transferring from one tank to the other, and plumbed it in Parallel (not in series) with the lift pump to keep the engine running in case the lift pump failed. I did use the electric pump during an offshore lift pump failure. It got me through just fine. Sometimes I also use the pump to move the fuel if the boat has been sitting for a long time...prime / bleed injector pump etc.
Good luck!


-- Edited by botemon on Tuesday 26th of July 2011 03:41:21 PM

Nice idea