Electric fuel pump.

[maxumiain]

Hi Folks,

Has anyone any experience of electric fuel pumps? In 2010 I privately purchased a 1996 Maxum 1900SR. ( Eyes wide shut. Buy in haste repent in leisure).
There were some cosmetic problems that I eventually got sorted. Have had no problems with the engine so far. There is an electric fuel pump instead of a standard pump. To my horror recently I have discovered that the pump is connected to the ignition sw and when the ignition is switched on the pump runs whether the engine is started or not. I have checked out possible solutions on the net. If I connect the pump via the starter supply on starting and then the oil pressure sw when running. I presumably have to use 2 no. relays for same. I'm not sure if a regular pump can be fitted or not. My question is (eventualy) Is an electric fuel pump harder on fuel than a regular pump as it pumps the same amount of fuel at 1200 rpm as 5000rpm. My engine is a 4.3 v6 Mercruiser. Thats all I know about the engine as my mechanicial knowledge would be fairly limited. Not sure how carb works etc.

Thanks in advance for any replies.

Iain

 

[Don S]

Re: Electric fuel pump.

Here is a picture to show you how the electric fuel pumps are wired in on Mercruiser carbed engines.

My question is (eventualy) Is an electric fuel pump harder on fuel than a regular pump as it pumps the same amount of fuel at 1200 rpm as 5000rpm.

No, all the fuel pump does is keep the carb full. The carb along with tuneup and engine condition determines fuel mileage.

The reason electric fuel pumps are used on the newer engines is the fact that when the engines were automotive, they went to electric and the mechanical boss on the block was not machined for a fuel pump, and no lobe on the cam for the pump if there was.
The automotive version was EFI and requires higher pressures, thus an electric pump. But marine engines continued using carbs and needed a safe electrical fuel pump that didn't pump if the engine wasn't running.

 

[Bondo]

Re: Electric fuel pump.

Ayuh,.... Welcome Aboard,....

I think yer motor should Need an electric pump, as the block isn't machined for a mechanical by 1996....
But yer Right, the wirin' is in need of Fixin'...

To rewire yer, no relays are needed...
From the starter to the pump's (+), 'n then the ignition to the Op switch, to the pump's (+).....
Ya should have the wires in the harness,...

 

[ENSIGN]

Re: Electric fuel pump.

Look on the port side of the engine above the oil filter. There is a oil pressure saftey switch for the fuel pump thats either shorted or some moron has jumped the wires together ,i've seen it done more than once.