Is an external fuel pump necessary?

[hpeer]

I bought one of them but it would not lift fuel 24". Install manual says to place at bottom of fuel tank level.

Anyone got a suggestion for a run dry pump that will lift 6'?

[GrahamHO]

Originally Posted by Nicholson58

I think the squeeze bulb is a bit dodgy. If you keep this, I would make sure there is at least one new spare aboard.

We have chosen to install a fuel refiner that circulates about 10X the engine fuel rate through a 1 micron dirt & water removing polishing system. The pump runs when tie engine is running. The loop includes the RACOR filters so their effectiveness is also enhanced. I added small versions of this also on each crank-case (engine & generator). On the fuel system, the lift pumps of the engines take super-clean fuel only form the polished source. Over the road truckers use these to protect their fuel system and to eliminate regular oil changes. Oil changes are stretched to well over 100,000 miles. Often, fleet operators install these on their entire fleet. True even in federal and military fleets. Three sources are Pacific Coast, Petro-savers and Franz. I have Franz filters.

Squeeze bulbs are not dodgy, but rather they are optional and useful. You don't need to carry a spare bulb only a length of spare fuel line and some clips, which I routinely have on board in case any fuel line needs replacing unexpectedly.

I can't understand how polishing the fuel to make it "super clean" can "stretch out lube oil changes to 100,000 miles". Diesel fuel is either clean or not clean and is a separate system to the lubricating oil.

If trucks do big milages between oil changes it is mainly because they are always running and never get cold, and also they have efficient lube oil filters, which might be changed before the oil is changed.

[CSY Man]

I installed an electric fuel pump on my 4-108 between the filters.
Worked great, easy bleeding the engine and acted as a go-home pump if the lift pump failed.
The pump was some heavy duty diesel truck pump. Worked great and would want another on my next boat.
It was expensive at $160, but for the safety and piece of mind it was priceless.

[GrahamHO]

Originally Posted by hpeer

I bought one of them but it would not lift fuel 24". Install manual says to place at bottom of fuel tank level.

Anyone got a suggestion for a run dry pump that will lift 6'?

It is fundamentally better for any liquid pump to be "pushing" up rather than "sucking" up. In other words in practice it's best to have the pump mounted level with the tank bottom if possible.

Also it shouldn't run dry unless the tank runs dry which is when the engine will stop and the beeper will sound and you then turn off the key to stop the noise and the electric pump will stop too. ( assuming it's wired to the start key switch accessories connection)

You could also have an additional engine accessible switch and turn the key on and the beeper to off if you want to bleed the system.

[CSY Man]

.

Also it shouldn't run dry unless the tank runs dry which is when the engine will stop and the beeper will sound and you then turn off the key to stop the noise and the electric pump will stop too. ( assuming it's wired to the start key switch accessories connection)

Can only speak for my self, but my electric diesel pump was "on demand" only
And wired over the 12 volt panel with a switch and a proper label.
No reason to make it run 24/7 if everything is working normally.
That being said, the pump was "certified" to run dry, as if I had left it on and never shut it down at dock or anchorage arrival.
It was loud enough to hear, but next time I will wire in a big red light.

[S/V Alchemy]

Originally Posted by HopCar

The fellow who wrote the following is a well respected diesel expert. He uses a bypass system that doesn't have the fuel continuously flowing through the squeeze bulb. I think the reason he uses a bypass for priming is that there are no squeeze bulbs big enough for the size engines he plays with.
Squeeze Bulb Priming on Diesel Powered Boats
If your fuel hoses are 3/8 or smaller you can probably get away with just putting the bulb inline.
I'm thinking of putting a bypass system with electric pump on my boat.

Same here. I already have the pieces, including a Walbro FRA-1 inline pump and several marine-rated three-way valves and barbs.

[GrahamHO]

Originally Posted by CSY Man

Can only speak for my self, but my electric diesel pump was "on demand" only
And wired over the 12 volt panel with a switch and a proper label.
No reason to make it run 24/7 if everything is working normally.
That being said, the pump was "certified" to run dry, as if I had left it on and never shut it down at dock or anchorage arrival.
It was loud enough to hear, but next time I will wire in a big red light.

Reminds me of the time after a having great sail, the cabin floor was full of water. A hose had come off the pressurised fresh water system and pumped one water tank dry. I fixed the problem connection and keep meaning to install a big red light.

[reed1v]

Diesel systems consume only a small fraction of the diesel that is being pumped to the engine. The rest return flow to the tank. Sometimes there is an air block in the system and the hand bulb probably is to quickly push the air block out of the way. Finally, the diesel fuel flow system is under rather intense pressure so if you are going to add any flexible parts to the system, be sure the materials are rated for system's psi.

[CSY Man]

. Reminds me of the time after a having great sail, the cabin floor was full of water. A hose had come off the pressurised fresh water system and pumped one water tank dry. I fixed the problem connection and keep meaning to install a big red light.

Been there, that:
We were in Rose Island next to Nassau at the beginning of a Bahamas cruise.
Gone to bed after taking a deck shower.
All is good.
Next morning wifey said "Aye, the water tank is empty"
I was still in the bunk dealing with a late Rum haze and said no Honey, not possible, we left Fort Lauderdale 3 days ago with 157 gallons.
She asked to double-check.
Sure enough, the big tank was empty.
After last nights deck shower we had left the hose and shower handle in the cockpit and the handle got jammed on the coaming, surely and quietly spraying all the water overboard.
We did not even hear the pump, brand new highly efficient and quiet pump it was.
Pulled anchor and motored into some Marina in Nassau for a re-fill.
I thought they were going to rape us with $1 per gallon or something, but no big deal, the Bahamians charged us $8 to fill up with city water.
Great deal and we continued to the Exumas, water was good.

[Huey2]

hpeer, I was having problems with my new Kubota replacement diesel. I talked to the engineer that designed a 12 volt Walbro pump that lifts the diesel fuel 4' on an 18' run and it solved all my problems. The Kubota people said the small mechanical pump on the engine would handle it........but it didn't. I connected the Walbro pump wiring to my starter switch & haven't had a problem since..

[jmschmidt]

I'm not surprised, it's not supposed to lift 24". That's way it says that in the directions and that's why I said place the pump near to the fuel tank and as low as possible. In the airplane business we have an expression. "RTFM" which stands for Read the blanking Manual. It's amazing who well things work out when you do that.

[Huey2]

I was stating just the opposite. The Walbro pump does lift the fuel 4' with an 18' run. The Kubota pump was the one that didn't work. None of the auto fuel pumps would work. There isn't any room to install a fuel pump on my 28' Fisher catamaran by the fuel tank. The Walbro engineer said the pump would easily lift the fuel 4' or more with no check valve.........& it does.

[Canibul]

I have been thinking of adding an electric pump for some time. I see that the size pump needed is relative to the HP of the engine. The Walbro people say that it works out to 10HP per gph. So my 35 HP Yanmar HM3-35 needs a 3.5 gph flow, but I'm not clear on what a three cylinder diesel needs for pressure at 3.5 gph. Anyone know?
I've been looking at a marine pump on Amazon, plan to wire it to starter switch. I can turn it on or off while diesel is running with the key. My tank outlets are a couple of feet higher than the Yanmar lift pump and run through Racor 500 filters. It would gravity feed at the inlet of the lift pump.

[GrahamHO]

Originally Posted by CSY Man

I installed an electric fuel pump on my 4-108 between the filters.
Worked great, easy bleeding the engine and acted as a go-home pump if the lift pump failed.
The pump was some heavy duty diesel truck pump. Worked great and would want another on my next boat.
It was expensive at $160, but for the safety and piece of mind it was priceless.

My only thought about that is if the mechanical pump failed it would probably be the diaphragm that ruptures as the valves are so simple there's nothing much to go wrong with them. There's not much else in a mechanical pump. If the diaphragm of the mechanical pump fails ( in any mechanical pump I know ) your "go-home"electric pump would be pumping diesel into the lubricating oil through the leak in the mechanical pump diaphragm. Then the electric pump probably wouldn't run the motor anyway, due to the pressure loss that stopped the mechanical pump running the motor.

I can see some advantages with electric pumps and I was once quite good at overhauling English SU electric pumps and converting old cars to them. Their main advantage then was that they primed the old carburettors float bowls before cranking the engine. Of course modern cars have mainly electric pumps, because their pressure is part of their fuel injection systems.

I don't believe electric pumps are any more reliable than mechanical; maybe a little less, involving electricity.

[GrahamHO]

Originally Posted by Canibul

I have been thinking of adding an electric pump for some time. I see that the size pump needed is relative to the HP of the engine. The Walbro people say that it works out to 10HP per gph. So my 35 HP Yanmar HM3-35 needs a 3.5 gph flow, but I'm not clear on what a three cylinder diesel needs for pressure at 3.5 gph. Anyone know?
I've been looking at a marine pump on Amazon, plan to wire it to starter switch. I can turn it on or off while diesel is running with the key. My tank outlets are a couple of feet higher than the Yanmar lift pump and run through Racor 500 filters. It would gravity feed at the inlet of the lift pump.

I don't know what flow it would need but I would think it'll be possibly 2X the maximum consumption rate as fuel is returned to the tank through the return line and you need an extra margin above all that.

If you want to turn the pump off with the key while the motor is running you might risk damaging your alternator? ? I'm sure I'll be contradicted on that one. I know that applies to the main power switches.