Fuel filter before Facet pump?

[Robster]

I'm aware that admitting to having a facet silver top pump in the back of my Xflow will cause a lot of sucking of teeth out there!! However, I have, I'm proud of it to date....however...I have recently put a plastic fuel filter between the tank and the pump and I am not sure if I am imagining it..but the car seems to have lost some of its urgency to hit the rev limiter..maybe the filter is restricting the flow at full chat?

 

I would appreciate any advise on this. Is there any point having a filter here, if so how can I ensure that the filter will flow enough fuel bearing in mind that were it is the pump has to suck the fuel through it.

 

Thanks

 

Robster

[stevefoster]

Silver tops seem to be either fine or they fail. I had one that was ok the rest not...

 

I had one of the big plastic filters fitted. It seemed fine. The force of the bend in the hose

bent it so I replaced it with a metal / glass one. That is fine too.

Does the filter have the same bore size as the fuel pipe?

 

If your floats are going dry you will get leaning out and then misfiring. Not good.

 

As a rough guide, on track I use about 0.75lts to 1lt per minute as an average. This is from the race distance and the amount of fuel I have to chuck in.

It will be higher under max acceleration periods of course.

 

You could measure the flow rate / minute with and without the filter and compare.

 

 

 

/Steve

 

My racing pics, 7 DIY, race prep. Updated often here

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Edited by - stevefoster on 24 Nov 2002 18:51:45

[Graham Perry]

Its a fact of life that most pumps prefer to push than suck, so trying to suck through a filter may be causing it to struggle whereas blowing it through may be easier. Personally I would have the filter between the pump and the Carbs. The Pump has its own internal filter, as well, although its not as effective as a proper filter king or similar product , so you have done the right thing by fitting one. I have my filter after the pump and not before it and it works fine.

 

I might be worth having the fuel pressure at the carbs checked. From what I recall it should be about 4-5 psi at the carbs. Check the archives for the exact pressure. Any competant engine builder will have a fuel pressure guage and it is a five minute job to check while you wait.

[Blatman]

I'm with Steve on the pre-filter selection. I have used both plastic and metal/glass filters, and both have worked fine.

Fuel pressure should be only around 2.5 to 3psi IME, though. Currently, 2.5psi supplies my 220-230bhp atmo Cossie on 48SP's with no trouble whatsoever, through 5/16th's fuel hose, a pre pump filter and a filter king in the engine bay.

As Steve says, a look at the inner diameter of the filters' inlet and outlet would be the first thing to (double) check. Less than 5/16th's is probably too small.