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1981 90hp fuel related issue

8

81_chapparral_194

Member
ok I have a 1981 evinrude 90 hp e90tlcm after running a couple hours with no noticeable problems the BIG ugly monster shows his head. it will start bogging down as if starving for gas, I went back to pump the primer bulb and it was soft so I squeezed it and when I squeezed it it didn't fill back up but stayed flat. after removing the gas cap (under deck tank) thinking I had a clogged vent it made no difference. bulb still flat, so I kept messing with the bulb squeezing and shaking until finally the engine died. it seemed that as soon as it died the bulb filled back up. (coincidence????) so I primed the carbs back up and fired it back up. just loaded on trailer as to not get stranded on the lake. I had this same problem a couple weeks ago so I changed fuel lines from tank all the way to the carbs, including under the cowling too, EVERY fuel line., but this didn't fix it. ok to give some insight I know its not a vent issue, nor an anti siphon valve because it doesn't have an anti siphon valve. and I removed the cap while starving for fuel. I replaced fuel line but NOT bulb as the bulb seemed fine. any suggestions appreciated. also the tank shouldn't have any trash clogging the pick up tube as I just put the tank in the boat, (running on very first tank of gas in new tank) and checked to make sure there was no trash in the new tank. I was even careful to not let the foil seal from oil jug get into the tank.
 
forgive me for sounding dumb. but how can the bulb go bad? I mean its a rubber ball that just sucks gas to the carb bowls until the fuel pump picks up. right???
I was told by an old salt that the bulb is only bad if it gets cracks or holes in it,..im assuming this is wrong then? again just trying to understand how this works.
 
the bulb has got to be OEM the one at wally world will fail ans let fuel flow back toward tank..check ebay for original Johnson part they are around $55
 
avantifishski said:
the bulb has got to be OEM the one at wally world will fail ans let fuel flow back toward tank..check ebay for original Johnson part they are around $55
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ok so is this whats happening with mine?? or just a good guess? I don't mind replacing the bulb as its 2+ years old. and its an attwood bulb. or could it be a fuel pump problem? I have a fishing trip next weekend and need it fixed by then.
 
faztbullet said:
The aftermarket bulbs usually only have one internal check valve where OEM has 2....
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ok thanks. but are you suggesting this is my problem or just informing me that oem bulbs are better than aftermarket? I realize ANY OEM part is better quality than aftemarket as I have over 5 years parts experience working in automotive dealer parts dept. also one thing I noticed also when unplugging the quick connector that connects the line to the engine that several drops of fuel dripped from the connector on the engine side connector. is this normal? would this be related to my issue?
 
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ok found my problem on my own after replacing fuel lines and bulb. there was a screen/filter inside of my pick up tube going down into the tank that no one seemed to know about, even the repair shop. it was clogged up.
 
joereeves said:
Fuel primer bulb goes flat = Fuel restriction.
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yes I am aware of that even before I posted the thread, I was trying to get pointed in the right direction as to where though. I originally pulled the pick up tube and inspected it but saw no issues. not knowing there was a screen just beneath the elbow inside the stand pipe. and apparently no one else did either because no one mentioned checking that, so I wanted to post what I found incase anyone else had this problem they would know there was a screen in there.
 
81_chapparral_194 said:
yes I am aware of that even before I posted the thread, I was trying to get pointed in the right direction as to where though. I originally pulled the pick up tube and inspected it but saw no issues. not knowing there was a screen just beneath the elbow inside the stand pipe. and apparently no one else did either because no one mentioned checking that, so I wanted to post what I found incase anyone else had this problem they would know there was a screen in there.
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Glad to hear that you found the problem and that it was a small (non expensive) one. The screen you speak of... if that is the screen just beyond the elbow that exists at the extreme lower portion of the supply tube within the tank... that is such a common component which is probably why it wasn't mentioned. The usual item that sticks and causes a fuel restriction is the "anti siphon" valve, a fitting located right where the fuel hose normally clamps on.

The weirdest fuel restriction I ever ran into was a Marine Police boat, direct out from the factory... a intermittent fuel restriction whereas the rig might run a couple weeks perfectly, then not at all... and of course when I would check it, there would be no restriction. However, I finally took up a portion of the deck so as to gain access to the built in tank access plate. Within the tank I found a huge clear plastic bag such as what might provide protection for and cover a good size helm seat. Something one does not forget.
 
yes my anti siphon valve was replaced with a regular barbed nipple or never had one (im 2nd owner) this screen was at the top of the pickup tube that slid down into the tube where the tube threads into the 90* elbow that the anti siphon valve screws into. I was leaning towards something being in my tank but was being doubtful as this is a new tank however I used my old pick up tube assembly,
 
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