Lift pump

[billyfish]

I guess by the very name a lift pump gets the fuel to the main pump but how high can it pull the fuel up. My Volvo penta d1-30 is about a foot above the tank which is about a foot deep so its already going uphill 2 feet. I'm moving the primary filter another 6 inches or so higher. Will it make any difference?

 

[Boater Sam]

Unlikely to be a problem.

 

[coopec]

"The maximum theoretical suction height of the water, at sea level, is about 10.33 meters. in practice we consider the NPSH of the pump and the pressure losses due to fluid flow" "The practical maximum suction height is located around 7 meters at ambient temperature." (Mecaflux)

When I've put down x2 water wells I've made sure the suction pump was within 20ft (to be on the safe side) of the surface of the water.

When I've siphoned fuel out of the car petrol tank for the lawn mower using a bit of plastic tube typically I would suck up 2-3ft of fuel. (Apparently that is a dangerous practice for health - not recommended)

 

[ChromeDome]

The installation manual doesn't state anything, but there is a drawing showing the tank below the engine level

https://www.lundskov.eu/bavaria/manualer/Volvo/volvo_penta_installation_manual.pdf

Since engines are installed near the bottom the tank presumably can't be so much lower that it could pose a problem. Once the hose/pipe is filled the actual lift is only the net distance from the diesel level to the lift pump.

 

[coopec]

The installation manual doesn't state anything, but there is a drawing showing the tank below the engine level

https://www.lundskov.eu/bavaria/manualer/Volvo/volvo_penta_installation_manual.pdf

Since engines are installed near the bottom the tank presumably can't be so much lower that it could pose a problem. Once the hose/pipe is filled the actual lift is only the net distance from the diesel level to the lift pump.

Outboard motors have no trouble sucking up fuel from the fuel tank which is on the floor of the boat.

 

[ChromeDome]

Outboard motors have no trouble sucking up fuel from the fuel tank which is on the floor of the boat.

That's true, but lift pumps can be different. Common rail or MPI engines def. have more powerful pumps.

If the OP is experiencing problems, an extra pump near the tank will help. D1-30 consumes up to 6.8 liters per hour, so even the cheapest (less than a tenner) in-line universal pumps can deliver several times more than required. Also helpful if someday he needs to bleed the system.

 

[coopec]

That's true, but lift pumps can be different. Common rail or MPI engines def. have more powerful pumps.

If the OP is experiencing problems, an extra pump near the tank will help. D1-30 consumes up to 6.8 liters per hour, so even the cheapest (less than a tenner) in-line universal pumps can deliver several times more than required. Also helpful if someday he needs to bleed the system.

I thought Billyfish had a mechanical D130 pump like this. But
"These pumps are either mechanically driven off an eccentric on the camshaft, or driven electrically. The diaphragm is pulled down by the action of the lever arm"

(The mechanical lift pump on my Perkins 4.109 has no trouble sucking up fuel from either tank, through the filter. Both fuel tanks would be at the level of the sump)

 

[billyfish]

Thanks all that's what I figured. The addition of cheap in line pump to help bleeding is food for thought

 

[Stemar]

If the OP is experiencing problems, an extra pump near the tank will help. D1-30 consumes up to 6.8 liters per hour, so even the cheapest (less than a tenner) in-line universal pumps can deliver several times more than required. Also helpful if someday he needs to bleed the system.

Good point. I've always figured that either the filter needs to be below the level of the fuel in the tank or you need an in line lift pump before the filter to push it through when bleeding the system.

 

[BobnLesley]

... cheap in line pump to help bleeding is food for thought

Alternatively fit a bulb type outboard primer pump in the fuel line for bleeding; cheap simple and no electric needed.

 

[billyfish]

Yep , especially as I'm adding a y piece and another filter. This grotty fuel situation isn't going to get any better.

 

[billyfish]

How about a simple in line bulb pump

 

[Stemar]

Actually, that's what I fitted to Jazzcat - I had a senior moment and couldn't remember what I had. My fuel line comes out of the top of the tank and the filters are uphill from there, so I've no idea how previous changes of filters were done, but I could imagine copious amounts of blue air being involved.

 

[ChromeDome]

A bulb pump is fine for the bleeding, if an extra supply is needed for running the engine, the in-line 12v pump is the option to go for

 

[Stemar]

if an extra supply is needed for running the engine, the in-line 12v pump is the option to go for

I think my first call would be to my friendly local car breaker for one of these at a sensible price. It'd probably be cheaper to get a pump and a spare from them than to buy new, especially if the "Marine Quality, Sir" tax is involved