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Old 15-10-2009, 04:22   #1
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Unable to Lift Fuel Using Standard Generator Lift Pump

My tank is low down and when under half full, my generator cannot lift the fuel.
Some generator manufacturers state that you can put an electric pump in line to lift the fuel in this situation.

I have done this and it works fine and has done for 2 years.

Now I have been told that if the manual pump gets a hole in the seal then I will pump diesel into the sump and then I run the risk of having the dangerous situation of diesel runaway or whatever its called when it cant be stopped as it is fueling itself from the sump.

Has anyone experience of this as when I have read the instructions on this, it seems that the electric pump is normally placed before the mechanical lift pump and it is not specified that it must only be after the mechanical pump.
Thanks John
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Old 15-10-2009, 05:39   #2
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MOST mechanical pumps if getting a hole in the diaphrame will bleed to the outside and would be obvious in your catch tray.The electric should only run when the engine is running.
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Old 15-10-2009, 05:54   #3
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I have used an electric feeder pump to help when fuel is low or when bleeding the system. It sounds like you need a header tank, maybe fed by electric or manual pump. This will eliminate the problem and you only need 10 L or so which will give you a few hours of motoring before it needs refilling.
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Old 15-10-2009, 06:15   #4
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Echoing Rusky,
My boat has a 7 gal day tank which feeds by gravity to the engine. I fill it every 3 to 4 hours when motoring. I also have a small lift pump in-line between teh day tank and the engine, but this is only for bleeding the air form the lines after changing the fuel filters (very handy and quick).

My regular lift pump, which is closer to the fuel tanks, only runs when I am filling the day tank. I had a leak in one of the fuel lines a couple of weeks ago, but because of my system, I saw it immediately and repaired it, only losing about a cup of fuel. If I had a system which constantly pumped, I probably would have been completely unaware of the situation - and it could have been a 100 gallon fuel spill.
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Old 15-10-2009, 06:34   #5
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Echoing Rusky,
My boat has a 7 gal day tank which feeds by gravity to the engine. I fill it every 3 to 4 hours when motoring. I also have a small lift pump in-line between teh day tank and the engine, but this is only for bleeding the air form the lines after changing the fuel filters (very handy and quick).

My regular lift pump, which is closer to the fuel tanks, only runs when I am filling the day tank. I had a leak in one of the fuel lines a couple of weeks ago, but because of my system, I saw it immediately and repaired it, only losing about a cup of fuel. If I had a system which constantly pumped, I probably would have been completely unaware of the situation - and it could have been a 100 gallon fuel spill.
Thanks for the replys..
The day tank is the ideal solution but i dont have one yet because of time constraints and wont have for a few more years as it needs to be custom built to fit. I am trying to get time sailing rather than time fixing and changing as I have spent too much time in fix and change mode and not sailing mode.
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Old 15-10-2009, 07:47   #6
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Hi John, check the lift pump condition, working presure lb, no leaks, a lift pump in good working condition is able to suck the diesel from the bottom of the tanks, the electric pump run before the manual lift pump, i have one electric pump in my system but just to help bleeding air and refill the racor fuel filter after a filter change, Regards.
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Old 15-10-2009, 08:39   #7
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I have seen squeeze bulbs like on an outboard on several boats, mine included. Once the fuel reaches the pump it will continue to feed unless there is a leak in the system between the bulb and pump. This would appear to be a cheap and user friendly way around the expense and possible problems of an electric pump. It works well on my boat as the little Yanmar lift pump is in an almost impossible place(behind the belts) to access with my fingers............m
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Old 15-10-2009, 10:07   #8
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by pass the manual pump entirely?
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Old 15-10-2009, 11:21   #9
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Quote:
Originally Posted by swabbmob View Post
Echoing Rusky,
My boat has a 7 gal day tank which feeds by gravity to the engine. I fill it every 3 to 4 hours when motoring. I also have a small lift pump in-line between teh day tank and the engine, but this is only for bleeding the air form the lines after changing the fuel filters (very handy and quick).

My regular lift pump, which is closer to the fuel tanks, only runs when I am filling the day tank. I had a leak in one of the fuel lines a couple of weeks ago, but because of my system, I saw it immediately and repaired it, only losing about a cup of fuel. If I had a system which constantly pumped, I probably would have been completely unaware of the situation - and it could have been a 100 gallon fuel spill.
What kind of electric pump do you use? I am interested in installing a day tank as well. Did you put a racor on the feed into the day tank?
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Old 15-10-2009, 13:50   #10
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Hey Cheechako,

No don't by pass the pump just use the squeeze bulb to lift the fuel to the pump and to help stop it flowing back into the tank if there is a small leak in the system. A manuel pump will almost never be able to suck fuel from a tank if there is even a slight leak in the system but a few gentle pumps puts fuel to the pump which can help them (usually) stay ahead of the slight system leak. My old Yanmar had a very slight leak, a few drops, collected in a pan, but if I left the boat for a week the fuel would flow back to the tank making an air lock. Squeezing the bulb until hard while cranking the starter would get things right again. Since the rebuild I don't have to do this but I've left the bulb in place just in case. It also makes bleeding the system after fuel filter changes much easier to...........m
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Old 15-10-2009, 14:23   #11
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Originally Posted by neilpride View Post
Hi John, check the lift pump condition, working presure lb, no leaks, a lift pump in good working condition is able to suck the diesel from the bottom of the tanks, the electric pump run before the manual lift pump, i have one electric pump in my system but just to help bleeding air and refill the racor fuel filter after a filter change, Regards.

The previous owner installed an electric pump before the lift pump on the Yanmar in my boat with the fuel tank in the keel. This was put in because the installation manual from Yanmar said if the rise was above the specified height you needed one.

John
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Old 15-10-2009, 16:36   #12
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To answer questions asked. 1. Yes it is possible for fuel in some types of pumps to fill sump with diesel however some pumps have bleed holes in the body casting allowing fuel to escape to atmoshere ,if electric pump has large flow capacity over flow can spill to sump. #2 Yes electric fuel pumps are placed prior to lift pump. #3 Yes crankcase fuel dillution will cause bearing failure, pressure fueling [run away] and possible crankcase explosion. Very rarely replace a diarphram only when gross fuel system neglect is evident ie, dirt,water etc.If fuel system is kept in good condition 5,000hrs or 10 years service is quite easly achieved before replacement.
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