Replace mechanical fuel pump with electric

[robert644]

Hello,

I have a 90 Merc, '78 vintage, and it's a nice looking motor, only fresh water use, but it's sat a long time and many of it's parts need replacing. All the electrical wiring insulation is crumbling away.

Upon taking apart the fuel pump, I found the hoses stiff as iron pipe and that they had springs inside the hoses, which were badly rusted. I think these may be the 'pulse lines'?

Instead of messing with these ancient (and expensive) parts, can I just mount an electric fuel pump in there? Reliability of electric fuel pumps seems to be not very highly regarded, but there are marine versions, and considering the age of the motor may end up being the most reliable part of the unit.

Are there any problems with plugging these 'pulse line' fittings?

Thanks,

Sincerely, Robert.

 

[coolguy147]

Re: Replace mechanical fuel pump with electric

no electric fuel pump

 

[tx1961whaler]

Re: Replace mechanical fuel pump with electric

Not a good idea. There is no way to automatically shut it off if the engine dies. That's a pretty bad safety hazard,

 

[Chris1956]

Re: Replace mechanical fuel pump with electric

Robert, Rebuild kits for the fuel pump are quite inexpensive. Replace the pulse lines with standard fuel line. New engine wiring harnesses are available from many places. Look around for a good deal.

 

[Woodnaut]

Re: Replace mechanical fuel pump with electric

Rob, I had a 70 HP 1977 model Merc. I had the same problem with all of the hoses and insulation on the wiring - hardening and then breaking or splitting. I replaced as many parts as possible with factory items. From a reliability standpoint, I really like the genuine factory stuff. BUT, I did run into a few "NLA" items at the parts counter. (No Longer Available). As I recall, the fuel pump assembly might have been one of them. I was able to get a few factory parts, however, and between the old stuff and the new stuff I was able to make a go of it. Again, I really favor replacing/rebuilding to factory specs. Once I completed all the replacement that old engine ran great.

 

[Silvertip]

Re: Replace mechanical fuel pump with electric

Modern EFI engines run electric fuel pumps but the ECM on those engines knows when the engine is running. When it is not the pump is turned off. Your engine does not have that capability. If the engine stalled, the pump keeps running and if the carbs had marginal inlet needles and seats or could not handle the pressure of the electric pump the engine would fill with fuel in a very short time (well before you realize it happened). This can cause a hydraulic lock or a horrible explosion. Likewise, any fuel leak presents a fire hazard. Since fire on a boat means everyone likely goes overboard to escape, there is a pretty good chance you didn't stop to turn off the ignition so the pump continues to feed the blaze until the boat sinks, blows up completely, or electrical power is cut. This is simply a very bad idea.

 

[Frank Acampora]

Re: Replace mechanical fuel pump with electric

I bought one but did not hook it up because it needed to be within 1 foot of the bottom of the tank. Thus it could not be mounted inside the engine and I did not want it under my splashwell. Otherwise I would have installed it with a relay.