1970 mercury 650 fuel pump 1 or 2 ?

chrismercury · #1 April 2nd, 2003, 11:26 AM

Does anyone know if a 1970 mercury 650 4 cyl

outboard needs 1 or 2 fuel pumps? I bought this motor with only an upper fuel pump, it runs to the upper carb then from there to the lower carb

is this how it's suposed to be. Or do I have to put the lower fuel pump on, and run it to the lower carb???

thanks for any help

mellowyellow · #2 April 2nd, 2003, 11:36 AM

welcome aboard,

pretty sure they came from merc with 2 pumps.

can tell you my inline 6cyl '70 1150 has 3.

mounted on right side of block from behind.

have heard of folks adding an extra electric

pump to them... the factory pump works off of

internal pressure. maybe this is what yur seeing?

good luck,

M.Y.

chrismercury · #3 April 2nd, 2003, 11:53 AM

thanks for the info

mellowyellow · #4 April 2nd, 2003, 01:15 PM

you'd be surprised how many of these old girls are

still running... click on "search" link above and

there's hours of reading about them on specific

questions. if'n you don't already have a service

manual, get one! they are great motors but they

require good maint. there's a link below for

manuals, or at local library for free perhaps?

thirsty motors, so start with fuel starvation.

good luck!

M.Y.

Gold Bear · #5 April 7th, 2003, 02:49 PM

chrismercury

Not trying to start any trouble here... I used to have a 1972 50 horse and I'm sure it had only one fuel pump.

Also, my 1971 115 horse has two fuel pumps. There is a "boss" on the side of the block for a third, but it has only two pumps.

Are you having any problems with the way the eingine is running?

Good Luck,

Gold Bear

chrismercury · #6 April 7th, 2003, 04:38 PM

I only heard it run for a second when I bought it. I tried to start it but it just turned but wouldn't start or even try to.not sure what a "boss" is, but there is a place under the upper fuel pump that looks like you could put a fuel pump just like the upper one.

Gold Bear · #7 April 8th, 2003, 09:29 AM

chrismercury

That is a "boss". I believe my old 50 horse was the same way - one fuel pump and an extra "boss".

If you find she is not getting fuel, it is simple to change the fuel pump diaphram.

Check for fuel, spark, timing, and compression. You may have to re-build the carbs etc.

Do a search for trouble shooting on this board and I'm sure you can get the old girl running.

Good Luck,

Gold Bear

chrismercury · #8 April 8th, 2003, 02:54 PM

Thanks, I already bought a kit to rebuild the fuel pump,I'll get the carb kits and do it all at the same time.

Thanks for the help