Sounds like a suction side air leak... filter seals/gaskets? suction side bleed screw?

 

bad filter? or filter gasket/seals would be the first thing to check/replace

 

Possibly an air leak in the downstream side of the fuel delivery system, bad seal in the filters or connections. Maybe the tank is not venting properly, try running with the filler cap off or loose. Maybe debris being sucked up against the feed pipe screen, if there is one.

If you pressurize the system from the tank outlet downstream by using a squeeze bulb from an outboard or an electric pump, fuel may leak out at any bad connection of filter mating surface.

You could also try a separate gravity fed tank, bypassing the permanent tank.

Paul T

 

Possibly an air leak in the downstream side of the fuel delivery system, bad seal in the filters or connections. Maybe the tank is not venting properly, try running with the filler cap off or loose. Maybe debris being sucked up against the feed pipe screen, if there is one.

If you pressurize the system from the tank outlet downstream by using a squeeze bulb from an outboard or an electric pump, fuel may leak out at any bad connection of filter mating surface.

You could also try a separate gravity fed tank, bypassing the permanent tank.

Paul T

Like that bolded bit......

 

Yeah.. slow vent starves feed... stoppage allows tank to equalize, OK for a while and starts over again...

 

Hey John I know it has been a while since this post I have a similar issue what was it? How did you fix it?

 

This can also be a problem of a bacterial infection (pseudomonas aerugoinosa) that colonizes as 'strings'. What happens is that such 'strings' when formed on the sharp ends of fuel system 'fittings' or the inlet to the tank dip tube, begin to block the fuel flow volume ... and the engine loses rpm which in turn releases/relieves the pressure by the action of the mechanical fuel lift pump ... or the compression of the 'strings' relax after the engine is shut down.

Rx.: If you're not already 'dosing' your tank with a 'bacteriostat' attempt a 'shock' treatment of Biobor to kill the Ps.Aeruginosa and then see what happens.

Alternative Rx: if the tank is dirty and shedding a fantastic load of fungal debris to the (Racor, etc.) filters, such can also be caused by the extreme pressure/vacuum developed in the fuel delivery system during a blockage that in turn 'extrudes' (unloads) 'through' the filters, re-leaves the obstruction on an intermittent basis, etc. If your Racor filters are 'black-ish' this may be the cause. If so, a Biobor 'shock' application AND a thorough cleaning-out of the tank walls, etc. is probably warranted; ...... and also, do expect to soon to clean out the now 'coke' plugged water injection elbow, prior to your water lift muffler.

 

I'll take a bubble of water or sludge washing around the bottom of the tank for 2 dollars Alex.

 

Rich H, question is there a way to see if the bacteria is present, is it visible? The Racor was not black in any way when I recently changed it, there was sediment and some water as well. I have just ordered new filters and this Sunday I plan to investigate everything that was posted.

THANKS GUYS FOR ALL THE RECOMMENDATIONS!!

I will keep you posted and take pictures so I can post and hopefully find the root cause and provide a corrective action that others can use...

Please feel free to comment if you have any other ideas...