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1977 Johnson 55hp Fuel Supply Problem

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petstud3

New member
I have a 1977 Johnson 55hp outboard (55EL77D) that fights to start and run at lower RPM's while on the lake. When it gets going at high RPM it runs like brand new. It refuses to start after it is warmed up and dies when I put it into gear. It idles rough and also slowly cruises rough. This is the 3rd fuel pump I have put on this motor. The fuel pump put out a continuous 3 psi no matter the engine speed the other day when I got the primer bulb to a firm position. I took it out on the lake and everything just went to heck. It didn't want to start and when it did every time I would put it into gear it would die. I would prime it until the bulb seemed firm, start it and then die. When I did get it running it wanted to die but would take off when I choked it for a quick second. I had to use the thumb wheel on the throttle cable to increase the RPM's to a minimum of 2400 then slam it into gear, choke it and then pray. I rebuilt the carbs last year which included soaking both of them. The jets are set so no adjusting them. Cylinder compression is 150 psi on both. Plugs have a nice tan look so no fouling or flooding. I have shortened the fuel hose so the bulb is as close as possible to the tanks. The tanks are Attwood 6 gallon poly. Maximum spark gap is about 1/2 inch and strong. I'm about 2 seconds from going against USCG recommendations and put an electric fuel pump on it. Any help would be appreciated.
 
The factory fuel pumps are ultra reliable and easy to test and repair !-----Doubt you need an electric pump.------What did you soak the carburetors in ??-----
 
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Flywheel key checked ?-----Take starter apart for inspection and ohm check on armature.---Perhaps new brushes.----Load test battery ( even if new ) and check battery cables.
 
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My 1977 85 hp had trouble starting warm. Turned out to be the auto 1/2 choke. It would 1/2 choke motor even when warm due to bad temp switch. This would end up flooding out and fowling plugs. There was a TSB from factory on how to disable the auto choke. Fixed mine right up. You can check if yours has auto choke by taking cover off motor and turn key to first position to right while looking back at motor. You should see and hear choke lever move. Then after warming up motor with muffs or in tank, see if choke still engages when warm. If so it’s an easy fix, just swapping a wire. I can find the link and post how to do it if you find that’s the problem.
 
Trapper----The 76 model 85HP appears to be the last year that they used " thermo-electric choke "-----What is your model #----So I doubt that the 77 model 55 HP had that feature as it was last shown on the 74 model 50 HP.
 
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the TSB said to put purple/yellow wire with solid purple on power strip if I remember right. It made it so only the toggle switch would operate choke. I know my remote is older than the motor because of toggle choke instead of key push but pretty sure motor is a 77. Choke would move to 1/2 when I would key it before the fix.
 
Trapper your model # indicates a 1977 model.----Perhaps powerhead was older.-----Book does not show thermo-electric choke for 77 model.-----Or perhaps only the early 77 models had that feature.------And I am quite familiar with the 1970's motors !
 
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