? for the engine guys

[vinnimon]

What I have is a 140 mercruiser inboard 3 ltr engine(mechanical) 1974 0r 76 era.

Now what I was thinking of doing is adding an elctric fuel pump in line with the mechanical pump. Reason being is, it has a filter housing attached to the pump, and its easier to hook up the new one in line with it.

Will it effect the fuel delivery in any way to the carb? Build up too much pressure?

The other thing I can do is cut off the lever on the original pump, that way there arent any issues. But I prefer not to do that.

Thanks in advance

V

 

 

[irishfield]

Run into this quite often with airplanes Vince... and in many cases when guys plumb their back up electric in series with the mechanical it can work as a two stage pump.. the electric gives the first 5 psi and then the mechanical increases it beyond the acceptable pressure for the carb float needle and they flood. Another issue is you really have no redundancy as if the mechanical pump blows a diaphram.. all the electric is going to do is spray fuel faster thru it and out the vent hole. I prefer a parallel dual fuel pump set up, but it requires check valves to make if function properly and safely.

 

Still not sure I understand why you're doing this? The filter is built into the electric pump??.. why not just install a filter if that's what you're really after?

Edited April 30, 2011 by irishfield

[DRIFTER_016]

If you want an electric fuel pump just purchase a cover plate and new gasket to block off the mechanical fuel pump opening. If you are just looking for a filter just purchase one of These and plumb it inline. The added bonus is it's also a water separator.

[Bernie]

I seen a car one time that someone added an electric fuel pump to.

The engine backfired and stalled due to a stuck open needle valve in the carb.

Because the fuel pump was wired to ignition on the pump continued to run and the engine took fire.

The lady panicked and left the ignition on.

They wrote off the car.

 

Make sure any electric fuel pump shuts off if the engine isn't running.

The best way is to wire it to an oil pressure switch. But the pump still needs to operate when cranking so a relay hooked into the crank circuit is the best option.

 

I'd just leave it alone and leave it the way it should be originally. They worked well enough.

[vinnimon]

Thank you kindly guys, being a marine aplication, I needed to ask. Car wise, out with the old and in with the new.

Anyhow i will keep the pump as a back up, just in case.