kalli

Hi all,

I have the following setup:
tank->fuel filter->Fuel pump->pressure gauge->carb

i have installed the fuel pump as low as i could and I got 7 psi pressure behind the pump.

Now I'm getting only 2-3 psi there and when that happens the fuel filter is half empty
Sometimes it fills up, the pressure goes up and then down again ...

is there a way to get constant pressure there (keep my filter full?)
it seems it's only the gravity that brings the petrol to filter, there seems to be no 'suction' at all from the pump.

Anyone experienced this before ? is there a way of maybve bleeding it?

Kalli

jamieNerikas66stang

i had this problem and the same set up,...i was told to move the filter to AFTER the pump and before the carb,..and fixed my problem,..you want to filter the gas before entering the carb,....

kalli

thanks for the idea, I had that in mind as well, but I actually wanted to filter what's going into the pump as well (extend pump life) ;-)

but i'll definetly give it a try if there are no other ideas

Gary H

Most companies say to use two filters. The one before the pump isnt as fine as the one before the carb so it has les restriction. 100 micron before the pump and 10 micron before the carb.

http://www.aeromotiveinc.com/d_syste...emdisplay=carb

kalli

ahhhh .... you mean my filter is too restrictive and that causes me the problems?
that would explain my problem and jamies solution.
will move the filter and see if that solves the issue.

The filter i bought is of such low quality and price that it doesn't even give micron ratings .... anyway i'll let you know if i get constant pressure back this way

urban_cowboy

Kalli, check out Aeromotive's suggestions on fuel system design. I have considered moving over to their stuff and suggestions myself.

http://www.aeromotiveinc.com/d_syste...emdisplay=carb

kalli

i'm about to go insane here. i bought this piece of crap:
http://store.summitracing.com/partde...rt=SUM-G3136-1

just to find out it doesn't suck, only pump. this thing needs to be mounted directly at the tank and _well_ below it so you might even be able to drive up a hill

tank is half full. when i leave her off for half hour I get 5psi pressure then in idle it slowly drips down to nil and then the engine dies. just broke down in front of house (lucky me). but as soon as the fuel pressure goes up a bit its running again.

heck I can't even adjust the carb when the fuel pressure changes constantly. no way to adjust floats

annoyed I'll be looking in a local parts store for any electric 6psi suction pump ..

they should have said that this thing is utterly useless for any application unless you have the tank on top of your roof

Gary H

Most electric pumps are supposed to be mounted lower than the tank and as close to it as possible. Move the filter and see what happens... BTW, you do have a vented gas cap right? Or the tank has a vent? Otherwise you'll create a vacumn in the tank and the pumps not going to work good.

fakesnakes

Kalli,

I agree, remove the filter and try it that way. If the sock on your pick up is still in good shape, it is good enough as a prefilter before the pump.

The better option is to always look for an electric pump with a gerotor v. vane. The gerotor will create suction and stay primed at all times. This one and the Mallory 140 are my favorites:

http://store.summitracing.com/partde...5&autoview=sku

Of course they are more expensive! I use two of the 140's on my GT40 (one for each tank) and they lift the fuel about 14" and still deliver constant pressure.

kalli

i guess it's my fault for not thinking it through. manual says that that pump needs to be mounted near tank as it doesn't suck.
i tried without filtr and there's a bit of an improvment, but sooner or later pressure collapses slowly again. if disconnected it from the fender and had it dangling near ground and it's again a bit better but nowhere near constant and steady.

I'll check locally first, i guess I'll find a good suction pump. if not i'll go for the malloryto match my future ignition system ;-)
thanks for the advise, I like going with pre-tested things :-]