Fuel Pump - Which End is Up?

[Windborne]

I purchased a replacement fuel pump for what appears to be the original on my 1988 Universal M25. If it is not the original (I don't know their life expectancy) it's certainly many years old.

The original is the barrel/cylinder type and the replacement by Facet is identical in size and shape. However, the installation instructions for the Facet suggest my current fuel pump is installed upside down.

The pump is mounted vertically. The instructions with the Facet say the inflow should be at the bottom and the outflow at the top. This also means the removable cap to replace the internal filter is on the bottom making changing the filter messy at best.

My old pump is mounted vertically but with the inflow and cap at the top and the outflow at the bottom. This has apparently served the boat well for very many years.

I image gravity and potential airlocks come into play. Does it really matter which end is up? I would like to install the new pump with the cap on top. Thank you,

Len Keller
Madeira Beach, FL
(on Florida's left coast)

 

[pogo2]

fuel pump

I have the same pump on my 1987 Universal M18, and the pump is installed with the filter on the top. It makes checking the filter and cleaning it so much easier. I have seen it installed with the filter cap end down, this was a boat show and after I pointed out the advantages to it being the other way, the salesman agreed with me. I've had it this way for the last 11 years I've owned the boat and its never failed me yet.
Al Duquette
Mast Confusion N30
Tonawanda, NY

 

[Chris Patterson]

You can hang an electric fuel pump from a tree limb suspended by its power wires and it will pump. The pump is too dumb to know how it's oriented..

 

[Windborne]

Thank you for the replies. I did find this on the Facet-Purolator website http://www.facet-purolator.com/faq.php I'm quoting it exactly so the typos are theirs.

"The fuel pump should be mounted with the outlet above the inlet. This will help with eliminate vapor lock issues. Never located the pump so the outlet is below the inlet. Horizontal mounting will not effect fuel delievery performance."

I don't know what causes vapor locks, how often they occur, what the symptoms are or how they clear up. More questions. I suspect there may be some CYA going on at Facet-Purolator. -- Len

 

[Roger Long]

I don't know what causes vapor locks,...

Gasoline. Not a problem with diesel fuel although you might have some initial priming problems when the line is full of air.