Fuel Lift Pump Backup

demonboy

demonboy

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When we were stuck in an anchorage in the middle of Eritrea, about an hour before we were forcibly moved on by gun-totting military types, I changed a fuel filter. Great timing. The problem was my fuel lift pump was ineffective... I must have been pumping for about ten minutes and could not return fuel from the new filter to the engine, despite filling the filter with fuel. It was only when someone lent me a large oil-remover type pump that had an adaptor on it that I was able to get any kind of pressure to suck the fuel up.

I just wondered what back-ups people use. I was thinking of putting something in-line in my fuel pipe, but I don't know what the technical name for such a device would be. I'm planning on an big order from West Marine so I'm hoping I can find something in their catalogue. I do know of one liveaboard who used an outboard fuel pump permanently attached to the bottom of his fuel tank which he swore by.
 
Ive got a small header tank which is filled via a hand pump from the dieso tank. Its installed above the lift pump. Open a valve & let gravity take its course.
 
I like Sandyman's solution. Previous boats had the tank above the engine and I didn't realise how difficult things could be until I got this boat.
My primary filter has two unused unions, so perhaps a pipe vertically up from one to a small 'daytank' with suitable valves fitted , would do the job.
Even better if it could be slightly pressurised to speed things up!
 
An electric pump is always a good idea. I bought one off ebay as the driver for a fuel polishing system ( pump, separator / filter and return to tank. ) with the addition of a tap and tee piece it becomes a nice way to flush the engine fuel system of any air bubbles and also to back up the mechanical lift pump.
 
demonboy said:
When we were stuck in an anchorage in the middle of Eritrea, about an hour before we were forcibly moved on by gun-totting military types, I changed a fuel filter. Great timing. The problem was my fuel lift pump was ineffective... I must have been pumping for about ten minutes and could not return fuel from the new filter to the engine, despite filling the filter with fuel. It was only when someone lent me a large oil-remover type pump that had an adaptor on it that I was able to get any kind of pressure to suck the fuel up.

I just wondered what back-ups people use. I was thinking of putting something in-line in my fuel pipe, but I don't know what the technical name for such a device would be. I'm planning on an big order from West Marine so I'm hoping I can find something in their catalogue. I do know of one liveaboard who used an outboard fuel pump permanently attached to the bottom of his fuel tank which he swore by.
Click to expand...
I have used a squeezy bulb off a peugeot 406 (early) on my previous and now have a CAV type filter housing with a thumb button on top for easy priming.
Stu
 
demonboy said:
The problem was my fuel lift pump was ineffective... I must have been pumping for about ten minutes and could not return fuel from the new filter to the engine, despite filling the filter with fuel.
Click to expand...

What nobody's pointed out so far is that you don't need a back-up! Your fuel pump is cam-driven. If the engine stops with the cam in such a position that it's operating the pump, then twiddling the little lever won't achieve anything. The easy solution is just to rotate the engine sufficiently to get the cam off the pump, then the lever will work fine. You'll feel the difference in resistance on the lever. I use a spanner on the crankshaft pulley if I need to do it to bleed my filters.
 
You can use a grenade type pump the same type as used on the dingy from the fuel tank.I have used this system for the last 10 years. You must fit the grenade type before any filters as close as you can.Do not use the primer pump from the engine just use the devise to bleed the system out. What i normally do when i renew my filters is clamp the fuel pipe after the filters before removing the filters. I renew my filter then bleed my filters by using the grenade when i am satified that there is no air left in the system i just remove the clamp just give it half a dozen pumps and start up the engine . If any problems just keep pumping with the primer and the engine should start.When the engine has started you might find the revs start to drop that is because it has a few air bubbles in the system just keep puming the grenade with the engine running. After about a minute you should have no problems.If you have any problems email me.
 
pvb said:
What nobody's pointed out so far is that you don't need a back-up! Your fuel pump is cam-driven. If the engine stops with the cam in such a position that it's operating the pump, then twiddling the little lever won't achieve anything. The easy solution is just to rotate the engine sufficiently to get the cam off the pump, then the lever will work fine. You'll feel the difference in resistance on the lever. I use a spanner on the crankshaft pulley if I need to do it to bleed my filters.
Click to expand...

Quite correct PVB, however, depending on the position of your tank to the lift pump you can often spend what seems like ages bent double pumping and pumping a small lever up & down up & down waiting for it to start pumping & getting seemingly nowhere. With a small header tank on a tee connection & valve in the fuel line it sure makes things easier.
 
There is a good argument for mounting the filter below the normal level of the tank so that it will flow to the bleed screw in the filter head. If the engine side is valved shut, then after allowing the filter to vent, just re-open the cock and you're away.

Rob.
 
First one, Nick.

I did not know that about the lift pump. I couldn't be sure if it was in the wrong position but I definitely spent 5 minutes (did I say 10?) continuously pumping with no joy. Header tank seems like the best solution but surely the easiest is to attach the outboard pump I was referring to (see Nick's first link) inline by the fuel tank.

The thing I was lent, btw, was one of these.
 
Last edited:
demonboy said:
First one, Nick.

I did not know that about the lift pump. I couldn't be sure if it was in the wrong position but I definitely spent 5 minutes (did I say 10?) continuously pumping with no joy. Header tank seems like the best solution but surely the easiest is to attach the outboard pump I was referring to (see Nick's first link) inline by the fuel tank.

The thing I was lent, btw, was one of these.
Click to expand...

Yes, agree, last time I changed the fuel filter got fed up with pumping and ended up sucking it through, an operation I will not repeat.
 
I have two Ford Mermaid diesels. The port engine kept stopping on a roughly hourly basis.
New lift pump did similar. It appears that the cam inside the engine was floating and not always making contact with the lift pump lever.
Solution simple: bought a £35 generic lift pump, which is wired into the port ignition switch.
Advantage is that fuel filter changes on the port engine are a doddle, no more pumping the manual lift pump lever for 10 minutes to get the air out.

I have for sale a brand new lift pump for the Mermaid diesel. Almost completely unused!
 
Outboard fuel type squeezy bulb, as recommended on here when this question came up some time ago.
Very quick one handed operation whilst simultaneously opening and closing the various bleed points.
Apparently though they do go hard with age.:eek:
 
pvb said:
What nobody's pointed out so far is that you don't need a back-up! Your fuel pump is cam-driven. If the engine stops with the cam in such a position that it's operating the pump, then twiddling the little lever won't achieve anything. The easy solution is just to rotate the engine sufficiently to get the cam off the pump, then the lever will work fine. You'll feel the difference in resistance on the lever. I use a spanner on the crankshaft pulley if I need to do it to bleed my filters.
Click to expand...

+1
 
On my wish list is to have a day tank above the engine. Ideally this would be fed from the engine lift pump and gravity down to the ninjector pump, but unfortunately the injector pump needs about 5 bar pressure, which equates to a 16ft head for diesel. Could put it up the mast.
So I would need another lift pump, electric I suppose, not a popular idea for me. The day tank would be constantly fed with filtered fuel, and constantly draining back to the main tank. It would have a filler cap for emergency top up, and a sump and drain off. Its the subsidiary pump puts me off. Perhaps it could have an alarm for low fuel in the header tank, but all these bits and pieces are tempting Murphy. Every action has an equal and opposite malfunction.

Some older French boats had a semi rotary pump in the engine room to fill the day tank, which needed attention every few hours, thus forcing you to go down and check round.
 
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