Is an external fuel pump necessary?

[CSY Man]

. 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.

Good point.
If that happened I would bypass the lift pump, although I did not plan ahead for that scenario.
My lift pump failed earlier and mixed diesel in the lube oil.
Found it on the survey, 6% diesel in the oil.

[Nicholson58]

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'?

I have several of this manufacturer's pumps in different places in my fuel system, FACET. Here is the short list of their products including the rated lift height (120 inches max). Best to make sure its a stock item before you plan.

Catalog Part Finder Index | Motor Components, LLC | Facet Purolator

[Nicholson58]

Originally Posted by CSY Man

Good point.
If that happened I would bypass the lift pump, although I did not plan ahead for that scenario.
My lift pump failed earlier and mixed diesel in the lube oil.
Found it on the survey, 6% diesel in the oil.

Ouch! I think you dodged a bullet. I thought ours may have been bad so I bought a whole spare pump and a rebuild kit. Pretty easy to change. Some have replaced/abandoned the engine mounted mechanical pump for an electric as otherwise noted in this thread. My gen set has only an electric lift pump. Certainly lots of options - at least as many as there are participants here. Sort of like a best anchor thread.

[hpeer]

Walbro pumps are rated to 48" lift only.

The Facet-Purolator dura lift pump looks like a good choice for deep tanks.

I've been using a diesel Whale diagram pump to fill my day tanks. That seems to work well and has a good flow volume.

I did tear one up, stripped the gears, sucking through a 2 micron filter. I've now switched to 10.

[GrahamHO]

Originally Posted by CSY Man

Good point.
If that happened I would bypass the lift pump, although I did not plan ahead for that scenario.
My lift pump failed earlier and mixed diesel in the lube oil.
Found it on the survey, 6% diesel in the oil.

You would need to have the necessary fittings ready to bypass. My mechanical pump has a flex hose on the input and a steel pipe up to the engine filter which is not so easy in a hurry.
Perhaps best to use an electric pump all the time and blank off the mechanical opening with a plate. Keep the mechanical pump you already have as a spare in a locker with a couple of appropriate hoses so you can do a quick change if necessary.
The mechanical pump should have no trouble drawing fuel through the electric pump ⛽ even if thats not operating. It could be checked out prior. If you can blow through the electric pump the fuel will flow.

[Canibul]

Looks like it might make sense to replace the mechanical lift pump with an electric rather than add it in series. I was wondering about this, thinking that putting the electric pump nearest the tank would pressurize the entire suction side of the fuel system. Any previous air leaks would become pressurized diesel leaks. That would include the lift pump diaphram.

One of my old Yanmars has an infuriating air leak I have been unable to find. The fuel lines have been replaced twice. Now I'm wondering if it's in the lift pump. That's the only thing that hasn't been changed on it.

[Canibul]

Originally Posted by GrahamHO

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.

These little 35's sip half a gallon an hour each. Not sure about the alternator question. Haven't thought about that one, but does the alternator output go up to the helm, through the key switch, and then back down to the batts? That doesn't sound like my setup. I think the gauges and warning buzzer are on the switch. Engine runs fine with it off.

If I replace the lift pump entirely with a plate, then I'd just run the electric all the time and carry two spares. Two because we have two engines and I've already experienced the loss of all dc wired systems on board in a lightning strike once.

[onestepcsy37]

I installed an electric fuel pump between the tank and the Racor to make it easy to bleed my Perkins 4 108. Pump wasnt cheap, 120 bucks. I dont use it for normal engine running, the manual pump runs fine and pulls fuel right through the non running electric pump.

But I discovered an extra benefit. You can polish your fuel when the engine isnt running by just running the electric pump. It routes back to the tank at the overfow port all by itself. I can run the 50 gal tank through the Racor a couple of times in maybe two hours.

I considered the squeeze bulb approach but had no cofidence in the quality of the ones I looked at.

[GrahamHO]

Originally Posted by Canibul

These little 35's sip half a gallon an hour each. Not sure about the alternator question. Haven't thought about that one, but does the alternator output go up to the helm, through the key switch, and then back down to the batts? That doesn't sound like my setup. I think the gauges and warning buzzer are on the switch. Engine runs fine with it off.

If I replace the lift pump entirely with a plate, then I'd just run the electric all the time and carry two spares. Two because we have two engines and I've already experienced the loss of all dc wired systems on board in a lightning strike once.

You might need to carry 4 spares in case you are hit twice again! However you have sails. Joshua Slocum sailed through the the Straits of Magellan and around the world without a motor. The spare you need is likely to be the one you are not carrying.

I think you are right about the switch. Probably has no effect on the alternator; just the warnings. I was thinking that after I wrote.

Easier to swap over identical electric pumps than to change to a mechanical spare, apart from the cost of buying extra electric pumps if you already have good mechanical pumps you are not using.

On an Italian motor I once had, the mechanical lift pump failed due to wear in its rocker arm pivot. It was actuated by a short push rod from the camshaft. The wear in the pivot was greater than the movement of the push rod. Of course I first experienced the failure when motoring through a narrow passage between reefs to avoid a cruise ship in the main channel. Unrolling the jib kept us going.
The motor would stop when the tank was down below 1/2.

Because the tank top was a little higher than injection pump it would happily gravity feed on a full to half full tank until I could obtain a replacement. But electric would have been better.

[Alika]

I had a certified diesel mechanic install a squeeze bulb on my fuel line of my Yanmar only to have a strict boat surveyor order me to remove it as "squeeze bulbs are not fire rated" and have no business being in an engine room. They are a fire hazard. Of course when I took it up with the mechanic, it all got very huffy. But I did remove the squeeze bulb and never had a need for it since.

[GrahamHO]

Originally Posted by Don Craigmyle

I had a certified diesel mechanic install a squeeze bulb on my fuel line of my Yanmar only to have a strict boat surveyor order me to remove it as "squeeze bulbs are not fire rated" and have no business being in an engine room. They are a fire hazard. Of course when I took it up with the mechanic, it all got very huffy. But I did remove the squeeze bulb and never had a need for it since.

I suppose they are a fire hazard with outboard motors too?
Did all your other fuel lines and filters etc pass?

[GordMay]

Greetings and welcome aboard the CF, Don C.

[Compass790]

Thanks for posting the link about squeeze bulbs. Didnt have luck with first attempt as I hadn't plumbed as pictured but this guy talks sense. Instantly saw the advantage of the squeeze bulbs over the tiny lever on the side of the mechanical fuel pump. Thanks paul

[Canibul]

I commonly use the 'blow into the tank' vs. suck on the hose method when siphoning fuel. Made me wonder about the idea of applying positive air pressure to the vent line in a conventional tank. Seems a little air pump up top would solve a lot of issues. Also would help find any leaks in the system.

Early yet, still on first cup of coffee and watching a sunrise.

[GrahamHO]

Originally Posted by Don Craigmyle

I had a certified diesel mechanic install a squeeze bulb on my fuel line of my Yanmar only to have a strict boat surveyor order me to remove it as "squeeze bulbs are not fire rated" and have no business being in an engine room. They are a fire hazard. Of course when I took it up with the mechanic, it all got very huffy. But I did remove the squeeze bulb and never had a need for it since.

I was thinking that because you needed a "certified diesel mechanic" to do a simple installation of a squeeze bulb, that you probably need the mechanic to do filter changes for you too. That is not a criticism as you don't need to be able to do all that yourself. But it might explain why you "never had a need for it since".
Possibly it's also why the mechanic got "very huffy" as it would help him when he does your filter changes.

If they are a "fire hazard" with diesel they must be an even bigger fire hazard with gasoline for an outboard. And they are primarily designed for outboards.

Now I'm no expert on that but I would be interested to hear of any fires caused by squeeze bulbs. You could perhaps ask your "strict boat surveyor" about any documented evidence, or whether it's just what he thinks.