Fuel filters - before or after

[Warren Casey]

I'm having some problem with my atomic 4. It will not run very long. The problem seems to be fuel. When I bought the boat (May 2004) I put in a new fuel tank, fuel lines, and new Racor filter. I replumbed the line and put the filter before the pump, suction side, as most say is best. I kept the old electric fuel pump which along with the hard pipe to the carb.

So today, I bought a new fuel pump and want to redue the whole system.

MY QUESTION IS: Can I put the new fuel pump before the filter? This could help with any air leaks around the filter (if the're any) and simplify the plumbing. Any suggestion would be great! Does anyone have a link to a page of fuel system layout?

 

[Davis Modlin]

The problem with putting the pump before the filter is that the pump will get all of the junk that comes out of the tank, And you risk damaging the pump.

Davis
E-29
#226
Holy Guacamole

 

[admirals barge]

fuel pump

warren

i agree the fitler has to go before the pump. have you tested the pump ? you can connect some tubing to the output of the pump and energize the pump and let it pump into an appropriate container and see how much gas is flowing into the container. another thought is that it could be the float sticking in the carb. just my 2 cents

greg

74 e35 II # 325

 

[Art Mullinax]

"Hot fuel pump"

Several years ago I had a similar problem with my A4. The mechanical fuel pump went out and I couldn't find a repair kit. I purchased an electric pump that was suppose to be a replacement for the mechanical pump. It came with the oil pressure sw. and a metal blank for the old pump location on the block. I installed it according to the directions. After a few minutes running it would shut off then start again after a few minutes. The pump was designed to pump more fuel than the A4 needed and was deadheading. This caused it to get hot and stop pumping. I ended up going to the local NAPA dealer and buying a smaller displacement pump. I'm not sure if its marine approved but it hasn't skipped a beat yet. Check your pump and see if its getting too hot. You may need a bypass regulator to send the extra fuel back to the tank or a smaller displacement fuel pump?
Art,
71 E29 #53

 

[jmoses]

A-4 fuel problems

Warren,

Have you inspected your Zeinith carb? Even with the best of filters, new tank and hoses, the carb can still plug up. You don't mention anything about the carb itself and if you have cleaned it lately. It sounds like everything else (except the fuel pump and carb) have been addressed.

I've had a similar problem with scrupulously clean fuel tank and system; the carb bowl had a few grains of crud in it which plugged up the jets which resulted in the A-4 stumbling and idle like crap.

An easy way to test the fuel pump is to pump the little arm (looks like an "A")which protrudes off the pump. You can pump it a few times and it should stiffen up. If not, then possibly the fuel pump diaphgram is busted.

Cleaning the carb takes about 45 minutes and is easy.

I suggest you carrouse the Moyer Marine web site and if not already in hand, order his A-4 repair and troubleshooting bible. It is excellent and offers many suggestions and maintenance tips. He also has all the parts for an A-4 at reasonable prices. Don Moyer is the owner's name and he is incredibly helpful.

http://www.moyermarine.com/

As for filters, be sure to read if it is of "Pressure type", "Vaccuum Type", or both. Also, be sure it is for gasoline service and doesn't have a clear see thru bowl. Although tempting, it will not pass a survey or USCG regs.

If technically inclined, you can always install a vaccuum gauge at the input side of the fuel filter and see what vacuum it's pulling. Many times the fuel line is so small and/or long that any plugging of the filter will cause a rise in vaccuum above engine specs and cause fuel starvation. Also, check the micron rating of the filter and make sure it's not too small (<2 micron). 5 - 10 micron is plenty.

Hope that helps,

John M.