Priming bulb before or after filter?

[doggypaddle]

Originally Posted by Dirk Diggler

Who really cares. It isn't really going to make much difference where it is. And it only really matters if you have inbuilt tanks. A portable 20 litre or so tank doesn't really need a filter, hence the reason why the motor comes with a fuel tank and fuel line that doesn't have provision for a filter.

I only fit spin on water seperators to outboards (60+ hp) as per the manufacturers instructions. And then only if the boat has integral tanks. At one time we were informed by Barrus not to fit anything to OPTI's, as they had their own filter on the powerhead, this has now been revised to a mercury style spin on and a bulkhead fitting.

When asked by the customer for something in excess of that, I fit a Racor, as they seem to be the only ones that are approved for petrol, most of the separ type filters seem to be for derv only.

I am going to fit a crossland 522 on mine, again a diesel filter but aparently OK with petrol, time will tell mainly as a water trap as the gray barrus tanks are a bit pants at keeping petrol in and water out
the filter in the powerhead is shockingly coarse!

[Bigmuz7]

Originally Posted by Dirk Diggler

I fit a Racor, as they seem to be the only ones that are approved for petrol, most of the separ type filters seem to be for derv only.

Oh no .. here we go again

I have to say I have had boats rigged both ways by dealers, but I think doggy had some fair points about the bulb pressure being greater on the output and therefor before filter was best, also to show any leaks in the arrangement, so that when running normally under vacuum you could be sure you werent going to draw air into the system, which I didnt even know was a problem with modern injection engines, although it is an absolute nightmare with diesel stuff, you could hunt for ages just looking for the smallest ingress but worse than that .. if you are taking a lot of water/spray over the stern, some water could get sucked into the fuel system if your system wasnt air tight

[doggypaddle]

Originally Posted by Bigmuz7

Oh no .. here we go again

I have to say I have had boats rigged both ways by dealers, but I think doggy had some fair points about the bulb pressure being greater on the output and therefor before filter was best, also to show any leaks in the arrangement, so that when running normally under vacuum you could be sure you werent going to draw air into the system, which I didnt even know was a problem with modern injection engines, although it is an absolute nightmare with diesel stuff, you could hunt for ages just looking for the smallest ingress but worse than that .. if you are taking a lot of water/spray over the stern, some water could get sucked into the fuel system if your system wasnt air tight

dont know about modern petrol outboards and the effect of airated fuel, but i guess it cant be a good thing!
air in a diesel?? if i had a put a tenner by for every day i had wasted looking for air leaks in diesels i would have enough to buy a new RIB now and an inboard diesel at that!

[Bigmuz7]

Originally Posted by doggypaddle

if i had a put a tenner by for every day i had wasted looking for air leaks in diesels i would have enough to buy a new RIB now and an inboard diesel at that!

Tell me about it the best one I had recently was a filter that wasnt bonded properly together in the middle. All the hoses are black,.. you cant see nothing, and ofcourse the filter is tucked away somewhere but when I found it the world was right again

Bit like the middle 'un below

[doggypaddle]

Those disposable filters are discusterous and maggotaceous things

[JSP]

Originally Posted by doggypaddle

Those disposable filters are discusterous and maggotaceous things

Margowhat?

[gaelforce]

Great aul' thread this.

My flow was tank - bulb - separator - engine.
The bulb did get polluted and failed. Which it possibly wouldn't have done if it was downstream of the separator/filter. That said, I was able to keep priming to get me home.

After reading this I will go against jwalker's advice for the first time in my life and change the running order to tank - separator - bulb - engine.

I will leave a bit of slack near the tank to allow me bypass filter at sea if needs be.

And I will use stainless jubilee clips and have the bulb low but vertical.

[Hightower]

I'm in the process of changing my filters during a service. I have replaced the console mounted racor with glass bowl.with the primer after the filter I can't successfully prime using the primer. I idled the outboard and primed and drew a little fuel in to the filter but I can't fill it up. The problem is that the bulb doesn't like pumping air.

I've never had this problem before so perhaps the primer is passed it's best. Going to mount it before filter and see how it goes.

[jyasaki]

Most sources say to pre-fill the filter before installing. May or may not help with your problem.

On the other hand, isn't priming what a priming bulb is supposed to do?

jky

[Hightower]

I eventually got there in the end. I didn't change primer position as the fuel pipe and fittings I had available to me prevented the move. I ended up using my portable tank and back filling the filter to prime it.

With regard the position of the primer bulb. I would recommend mounting it after the filter as the time before this change, which was the first time it was changed since the fuel tank was made there was lots of gunk that could have got caught if pulled though the bulb. This time around there was a piece of fibreglass sitting on top of the filter.

[jyasaki]

A buddy of mine had a bunch of fuel flow problems (diagnosed by a repair facility as low pressure fuel filter, then a high pressure fuel filter.)

After many iterations of supposed repair, he found that the fuel line was some sort of cloth-reinforced rubber with a plastic lining, and that plastic lining was falling apart and clogging everything up.

He changed out the fuel line (and added a canister filter) and everything has been OK since. New fuel line does not have the plastic lining.

His boat is a 15.5' Zodiac Rib with a Merc 60EFI.

jky

[Pikey Dave]

Originally Posted by jyasaki

he found that the fuel line was some sort of cloth-reinforced rubber with a plastic lining, and that plastic lining was falling apart and clogging everything up.

He changed out the fuel line (and added a canister filter) and everything has been OK since. New fuel line does not have the plastic lining.

jky

That sounds like ethanol degredation of the fuel line.

[jyasaki]

Originally Posted by Pikey Dave

That sounds like ethanol degredation of the fuel line.

Could be. Though it would have hard to prove with a 7 year old boat.

Personally, I was surprised by the lined fuel hose. I'd never seen that before.

jky