'75 70hp fuel pump ???

tnstreamy

Seaman Apprentice
Joined
Aug 23, 2010
Messages
39
70esl75b I'm in need of a schematic for the fuel pump in order to reassemble, have kit and upon disassemble i saw how the plungers work but a small o ring is in question. The diaphragm piece was worn but no holes. Also when removing from engine i left inlet with screen intact, however there wasn't a circular spoke gasket there but this kit has two needed? This is on a 24' pontoon.
the motor starts cold with choke and idle lever up, after warm starts with or without choke sometimes, then idles ok, however putting throttle to half or higher it gets hurky jerky, if i back off to a third it cruises fine. sit for a spell, then start and go she throttles up WOT for 45sec to a minute or so then fades to up/down, up/down like throttle on off until you back off and at one third cruises, will go all day on a third.
I have replaced fuel line, and tanks, ball stays firm. Motor ran good last year, i winterized carbs. has good compression, and i set timing this year advanced 24 degrees suppose to be 27 by the flywheel, but this seems to be what she likes.
thank you all in advance.
 

David Young

Chief Petty Officer
Joined
Jul 12, 2015
Messages
485
Johnson Motor?
265690_11_0.gif
 

tnstreamy

Seaman Apprentice
Joined
Aug 23, 2010
Messages
39
Thanks David I'm in need of the exploded view of the fuel pump itself there is three layers of internal gaskets and plunges etc.
 

interalian

Commander
Joined
Jul 23, 2009
Messages
2,105
It's easy enough to take apart and carefully note how it fits together. There are springs and plungers inside, so loosen/remove the screws while holding it together, then gradually release the tension (not a lot of tension either). Lay it out on a clean towel in order. Put the replacement parts in order above, then move the hard parts in line. Make sure you don't unseat the valve discs, and be sure they're closing properly (look through with light behind). Re-assemble.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
Might check here: http://www.boatinfo.no/lib/library.html I haven't looked for your pump assembly, but should be worth a try. I believe it's a NLA pump.

If you found the diaphragm wasn't perfect, really should just replace it if you have a kit with a diaphragm that fits. It should be flat and flexible. If the old one is stiff, it's not going to do the job.
 

tnstreamy

Seaman Apprentice
Joined
Aug 23, 2010
Messages
39
thanks to you all. I did take it apart and as you said carefully note how it fits together, which is normal procedure, but as it goes I got interrupted and didn't see where the O-ring came from. It fits around the threaded nut piece just right ? thanks for the link will check.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,575
If the intake cover has 2 o-rings the pump is a newer replacement.----What does a compression test show on this motor?
 

tnstreamy

Seaman Apprentice
Joined
Aug 23, 2010
Messages
39
when i bought it two springs ago 110,110,109. will do another this week. is there a good exploded view of pump itself? besides purchasing a manual?
 
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