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-   -   Fuel pump (suction) (https://www.offshoreonly.com/forums/general-q/366936-fuel-pump-suction.html)

Rookie 06-17-2020 10:29 PM


Originally Posted by riverrunner242 (Post 4744078)
yes correct

The valve you removed is there to eliminate the issues you are having. Why did you remove it? Once primed the Mallory pump will lift fuel to an extent.

riverrunner242 06-20-2020 11:11 AM


Originally Posted by Rookie (Post 4744091)
The valve you removed is there to eliminate the issues you are having. Why did you remove it? Once primed the Mallory pump will lift fuel to an extent.

It was removed before I got the boat your saying I should install one?

AllDodge 06-20-2020 02:20 PM

While I would admit that the antisiphon valve would help the issue, but this would only help on restarts. Once the pump has fuel it should be able to keep pumping, unless the lift (height) is to great for its design. Vane pumps should be at least level with top of the tank and having a dip in the line can help

The antisiphon valve is a USCG safety regulation so if the fuel line breaks or leaks, it will not siphon all the fuel out of the tank.

Can you make a bracket to mount the pump on which allows it to be placed lower. The bracket will allow it to be removed/installed with screws higher, but the bracket lets it be lowered.

Similar to installing a bilge pump under the motor and using an aluminum plate to place it low, but the screws into the stringers beside the motor for easier access

SB 06-21-2020 06:44 AM

Throwing another curve, wouldn’t be terribly uncommon for fuel pickup in tank to have a crack in it and not pick up fuel when the level gets to that height.

riverrunner242 06-21-2020 11:51 AM


Originally Posted by SB (Post 4744486)
Throwing another curve, wouldn’t be terribly uncommon for fuel pickup in tank to have a crack in it and not pick up fuel when the level gets to that height.

yeah I checked that it's good I'm thinkin I'll have to try running the line down below the tank

IHTFP 06-21-2020 03:49 PM

Is a low pressure block mounted diaphragm pump running into a high pressure electric fuel injection pump an option? I am thinking about doing this as I don't want to mount my electric pump so low that a flooded bilge could submerge it.

riverrunner242 06-21-2020 04:36 PM


Originally Posted by IHTFP (Post 4744534)
Is a low pressure block mounted diaphragm pump running into a high pressure electric fuel injection pump an option? I am thinking about doing this as I don't want to mount my electric pump so low that a flooded bilge could submerge it.

that was my concern

AllDodge 06-21-2020 04:41 PM

Doesn't need to be below the oil pan just even or bit below the top of the tank.

The cool fuel module is mid way of the oil pan (behind motor mount), so about even with the starter. Even if there was a leak large enough and the pump was lower then the pan, marine pumps are water proof

Post some pics of what your working with, this way there could be some real discussion of the issue(s)

SB 06-21-2020 08:36 PM


Originally Posted by riverrunner242 (Post 4744524)
yeah I checked that it's good I'm thinkin I'll have to try running the line down below the tank

I had to do what Rookie did (see his drawing above) when I used a aero motive pump many years ago. They said I didn’t need go, but I did. The fuel left in the loop and thus the pump, made it work correctly.

Rookie 06-21-2020 08:39 PM

What Mallory pump are you running? I run Mallory 140's. I just went and looked at my Scarab and the pumps are mounted even with the top of the fuel tank. My loop does go down to about halfway down the tank.


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