mechanical vs electric fuel pump?

[greg578]

I have the aq125a 4cyl volvo. I finally got the boat out this past weekend and when I was heading out the intake to the fuel pump kept getting pressurized, we kept relieving the pressure and it would run a little bit longer, well long story short we got towed in. I have been told to replace the mech fuel pump with an electric one and to get it from an auto store. I am curious to everyone's opinions and suggestions on which fuel pump and pressure and flow and all of that I should get to replace mine. Anyone who has done the swap mech to elect, feedback would be great, Thanks

 

[Buttanic]

Re: mechanical vs electric fuel pump?

Do not understand what you mean by by the intake to the fuel pump getting pressurized and how were you relieving the pressure. Auto electric pump is a big no no.It is not designed or certified for marine use.<br />Could you possibly mean the pump would quit pumping and you were removing the gas filler cap to relieve the pressure. If that is the case your gas tank vent hose may be plugged or linked shut. If that is not it perhaps the gas filter in the carburator is your problem.<br />Buttanic

 

[snapperbait]

Re: mechanical vs electric fuel pump?

A marine rated electric fuel pump (not auto), wired in with the correct oil pressure cut off switch, is the only way to fly, IMO.... Pump should be able to supply around 35 gallons per hour and you'll need no more than 3 to 4 psi..<br /><br />On to the problem at hand...

Do not understand what you mean by the intake to the fuel pump getting pressurized and how were you relieving the pressure.

Yeah????

 

[greg578]

Re: mechanical vs electric fuel pump?

ok on the hose between the intake on the fuel pump and the fuel filter/wtr seperator was getting pressurized somehow, we relieved the pressure by taking the hose off and reconecting it, resulting in about another 2 minutes of use from the engine before we had to do it again because it pressurized itself again

 

[ASI Imperial]

Re: mechanical vs electric fuel pump?

Is your water seperator cloged or rusted? Have read that this can happen to the inside of the filter if not changed often.

 

[Buttanic]

Re: mechanical vs electric fuel pump?

Is the hose near a heat source that might be causing vapor lock in the hose.<br /><br />Buttanic

 

[greg578]

Re: mechanical vs electric fuel pump?

it's a brand new filter. I know all the hoses are not clogged cause we blew through them all. The intake hose runs along the engine but I don't believe it is too close about 4-7" away. I would guess that the pressure was building to about 10-25psi on the intake of the pump.

 

[greg578]

Re: mechanical vs electric fuel pump?

The outlet(hard pipe) of the pump does run closer to the engine than the rubber hose inlet, I'm just trying to find out if anyone has had this happen or have any more suggestions as why it would be doing that. I am getting the impression that swapping to an electric one would be best, but I am looking for a little more imput to the topic.

 

[Destin]

Re: mechanical vs electric fuel pump?

This is a guess, but if the inlet check valves in the fuel pump were leaking then the anti-syphon valve on the tank would hold pressure in the line between the tank and the pump. I would just replace the standard mechanical pump. They are reliable and usually last for years. A new pump is less than half the cost of an electric marine fuel pump and safety cutoff switch, not to mention fabricating mounting brackets, tapping into the oil line, wiring to the pump and safety switch, and fabricating new fuel lines. I had to do that when I installed a new Vortec engine in my boat (no provision for mechanical pump). After 5 years and 1200 hours, I am on my second pump (Carter 4389 marine pump). I wish I could have used a standard mechanical pump.

 

[greg578]

Re: mechanical vs electric fuel pump?

Thanks Destin, I was going to break open the fuel pump today to check the internals to ensure everything is in order. I was just gonna buy a new one but at $73 I'll do a little more investigating. I understand that swapping to electric is a bit more than running a new fuel line, and not something I want to get into right now

 

[delta breeze]

Re: mechanical vs electric fuel pump?

Greg Have you previously installed the water seperator??Is the plumbing correct?One fuel tank or two.Portable tanks or floor mounted??Just curios about the set up?? Good luck Delta Breeze

 

[greg578]

Re: mechanical vs electric fuel pump?

bought the boat with seperator already installed, put brand new filter in. one 40 gal bilge mounted tank. plumbing is correct and not blocked.