Which side of the filter/separator should the primer bulb go ?

telecast · 01 June 2021, 11:26

Hi guys could anyone tell me where the primer bulb should go in the system ?

After doing some reading on here I decided to fit a racor filter then thought I might as well fit new fuel line and primer. Then can’t decide if the bulb should be before or after the filter ( or even if it matters)

Cheers

TimB · 01 June 2021, 11:48

Mine is before fuel filter

charliee · 01 June 2021, 12:26

Mine is after the filter, between the filter and the engine.

beamishken · 01 June 2021, 12:27

Id fit it after you can build more pressure than vacuum & therefore more chance of forcing crud into the engine

TimB · 01 June 2021, 12:35

That doesn't make sense, surely crud in fuel tank will get filtered in the filter, that is what it's there for I would have thought.

charliee · 01 June 2021, 12:45

The fuel pump in the engine will "suck" fuel into the filter and a pump on the tank side will "push" fuel into the filter - I think filters are designed for sucking.

beamishken · 01 June 2021, 15:14

Quote:

Originally Posted by TimB

That doesn't make sense, surely crud in fuel tank will get filtered in the filter, that is what it's there for I would have thought.

Yes the filter will stop crud but when it starts to become contaminated the temptation is to squeeze the bulb harder & potentially force smaller particles through the filter. Also fitting the primer on the engine side will give you an indication of the filter becoming clogged because the bulb will tend to collapse as the vacuum increases.
Its not a big issue either way but my preference is after the filter for the reasons above. Neither will be an issue if the filter is well maintained and tank reasonably clean

jeffstevens763@g · 01 June 2021, 16:16

Before bulbs push more than pull plus the sediments drop out to the bottom of the bowl the bulb pushes fuel from the top not the bottom of the bowl

GuyC · 01 June 2021, 16:56

The normal way is for the filter to be installed on the vacuum side of the 'pump' i.e. the priming bulb should be between the engine and the filter.

Whilst it probably doesn't matter for a priming bulb, it may be possible to squeeze the bulb to such an extent that the pressure exceeds the limit of what the filter can cope with if it is on the pressure side.

jeffstevens763@g · 01 June 2021, 18:26

Looked into this it appears either side is ok although before is better for filling the filter with fuel if it has to be drained especially at sea or you run out of fuel. when I fitted mine i couldn’t fill the fuel leads and filter with the bulb engine side not enough vacuum with a big air space if the engine had fuel I could have run it to draw fuel so I guess that’s why some say engine side as you don’t need to prime if the engine is full of fuel.

telecast · 02 June 2021, 09:15

Ok thanks guys - as we have no real consensus and I don’t want to fit two bulbs. My initial instinct was to put it after the filter - but my worry was about getting the filter filled if it’s run empty.

So I am leaning slightly towards before the filter - will go and have a think

Thanks for all your reply’s

SimonCh · 02 June 2021, 12:08

Quote:

Originally Posted by telecast

Ok thanks guys - as we have no real consensus and I don’t want to fit two bulbs. My initial instinct was to put it after the filter - but my worry was about getting the filter filled if it’s run empty.

So I am leaning slightly towards before the filter - will go and have a think

Thanks for all your reply’s

Just to throw in my two pennies worth... I'd have as little stuff "downstream" of the filter as possible. If the bulb was to start depositing debris, the filter would catch it... not that thats a likely occurrence, just seems sensible to me.

telecast · 02 June 2021, 13:39

Quote:

Originally Posted by SimonCh

Just to throw in my two pennies worth... I'd have as little stuff "downstream" of the filter as possible. If the bulb was to start depositing debris, the filter would catch it... not that thats a likely occurrence, just seems sensible to me.

Thanks - that’s an angle I had not considered.

TimB · 02 June 2021, 13:44

Very good point. As last season I replaced my fuel lines and primer bulb as the primer bulb was getting sticky to touch on the outside and I suspect inside was worse. I think the fuel line was the original one.

Miss Guided · 03 June 2021, 05:37

This is a really interesting thread. If you really want a "belt & braces", fit two, one either side of the racor, BUT my preference is for after...

MG
x

GuyC · 03 June 2021, 07:08

Quote:

Originally Posted by Miss Guided

This is a really interesting thread.

You probably need to read it then.

Pikey Dave · 03 June 2021, 10:56

My logic is that bulbs are designed to push not pull. So I place them as close to the tank as possible, in my case, inside the console as close to the tank as possible. Bulbs also work best when vertical with the arrow pointing upwards. So my setup is :-tank-bulb-filter-engine.

neil.mccrirrick · 03 June 2021, 12:50

I’m with that you can exert considerable pressure by hand pushing the fuel. The pull is the bulb, nowt you can do to help that along so make that the clearest shortest stretch