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hi all - any reason *not* to use a generic inline fuel filter, in place of the OEM Yamaha? at least for the purposes of testing? I have a fuel flow issue and want to eliminate obvious stuff first - but there's no Yamaha dealer near me (and it's the 4th) - thanks!
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Any filter is better than no filter at all during testing
just an opinion -
If you're thinking automotive/Autozone type filters then maybe go for a bit larger clear plastic unit so fuel flow will be maximum and you can do a visual inspection for water/debris....Comment
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exactly, will doComment
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replaced fuel strainer w/ brand new OEM - made no difference - motor still dies slowly from fuel starvation
moving on, next suspect is the fuel pump
I have partially disassembled it, but cannot find a rebuild kit online
A) anyone know if it is possible to buy a rebuild kit for this 22yo pump?
B) if not, is there any thing else that *might* be the culprit in a fuel supply issue before I plunk down $80 for a new pump?
vacuum issue? debris in the lines? crud in the carb?
motor starts instantly and purrs
but it slowly starts running slower, and then dies
anywhere from a few seconds to a few minutes
(the timeframe *may* have to do with how aggressively I've primed w/ the bulb)
I can keep the motor running by pumping the bulb
thanks for any thoughtsComment
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The primer bulb is just a hand operated fuel pump, so if you can keep the motor running by pumping the bulb, then it could well point to a failing fuel pump...A new pump for my C90 Yamaha is about $50, 2 bolts to replace it...Not a bad idea to replace these pumps every 5 or 10 years....or hopefully Before it fails...Comment
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There is no fuel pump "kit". Just buy what you need.
1993 T9.9ELHR Yamaha Outboard FUEL SYSTEM Diagram and Parts
As noted, pump the primer ball to do what the fuel pump is supposed to be doing. If the motor runs fine when pumping the ball, but not when pumping the ball, you might suspect the fuel pump has gone south. After 22 years it might have.Comment
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have rebuilt tons of auto diesels, but outboards are new to me
of course diaphragm is suspect, but not sure how to finish disassembling fuel pump
don't want to break anything critical
anyone know a good generic DIY on this?
thanksComment
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could be sucking air from a bad connection or like said bad pump.
Did you make sure tank was vented?
I did not see a kit either so will have to buy the parts needed individually or the whole pump
Diaphragm , check valves, and gaskets
not much to mess upComment
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have disassembled the fuel pump, and nothing obviously wrong - the diaphragm seems to be intact, although I'm sure it couldn't hurt to replace
everything else seems to be simple springs/pistons, which all seem functionalComment
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meanwhile, tracing back through fuel supply, looking for potential air leaks or blocks:
- both clip attachments that connect motor > bulb hose > tank are iffy and hard to engage - they pop off if I don't get them on exactly tight - so that's a big question mark
- the fuel cap on tank may or may not have some kind of vent - I always assumed there was, can't imagine you're supposed to boat around with the fuel cap half off...
- and last but not least, the sender unit/fuel level window on top of the fuel tank has a crack and leaks when I fill the tank - maybe I'm sucking air or losing pressure there?
pics attachedComment
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Test fuel pump by un-bolting it from motor but leaving hoses hooked up...then pump the primer bulb....no gas should come out of the round port/hole on back of pump...if it does then the diaphragm is ripped....real easy check!....Comment
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great tip, thanks for that!
(but wouldn't that mean that fuel was getting into the motor lube/sump area? i.e. not ideal design)Last edited by Rolf@YOP; 07-09-2015, 05:31 PM.Comment
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Robert was thinking about his 2 stroke motor not your 4 strokeOriginally posted by Rolf@YOP View PostComment
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