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1955 Evinrude Fleetwin 7.5HP

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Gillbilly72

New member
Hello all...I recently purchased a 1955 Evinrude Fleetwin 7.5HP #7518 and original Evinrude 4 gallon dual hose tank. I rebuilt the carb and entire ignition system, replaced the gas and oil and barrel tested it. It started right up but ran rough so still frustrated, I took it to the lake to test it out and dial it in a bit more.
I started it at the lake and the motor ran flawlessly for a bit like it had just came off the showroom floor but I noticed that I hadn't hooked up the fuel line at the motor and it was simply running on fuel in the glass carb fuel bow so I shut it off and hooked up the fuel line. Primed the tank and started it again. It would start up, idle and run at low speed but not as well and would not accelerate up to higher speeds even with the throttle handle cranked to fast . I attempted to find the correct settings on the carb adjustments to smooth it out but had no success.

My question is- Could there be an issue with the tank, the hoses or the quick connector at the motor that would cause it to run "rich" or rough while being hooked up to the tank? There doesn't appear to be any leaks at the tank and holds pressure because when I release the pressure there is a long hiss when the cap is turned. The hoses are decent with clamps and the connector works other than fuel that seeps out of the tip of male connector at the motor after being disconnected. It seems like it's getting to much fuel even with both carb needle adjustments lightly seated. Or is it the opposite and drawing air from somewhere? Thanks.
 
(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

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Fuel Cap closed tightly??? Backwash filter element in carb cleaner...O-rings at connector in good shape???? Soap the tank and hoses to check for leaks.
 
I made sure the tank cap was tight and cleaned and soaked the fuel filter element in carb cleaner and blew it out with compressed air when I rebuilt it. I have not replaced the o rings in the connector or soaped the tank yet but that is my next step in the elimination process. Probably will replace the hoses as well while I'm at it. It ran great without being connected to the tank so I figured that area would be the culprit.
Should I have added any additional gasket sealant to the new carb gasket other than the new gasket material when reinstalling the rebuilt carb? Everything's snugged down well but I thought about that as well..
Also both the low speed and high speed adjustments on the carb do not allow the recommended back turn after being lightly seated. I only get 3/4 back turn on the low speed and about 1 back turn on the high speed. Packing nuts probably too tight because they look to have plenty of thread on each one for adjustment. thanks
 
If the packing nuts are that tight,I would be careful as it would be hard to tell when they are lightly seated.Loosen those pups and seat the needles then snug the packing nuts a touch.You should be able to unscrew those all the way out of the carb body if you wanted to.Expensive parts.No sealant on the gasket.
 
The stops on the knobs prevent them from rotating more than one turn. Simple. Defeat them until you get it adjusted, then put the knobs on in mid-scale.
 
The packing lock nuts should be just tight enough to keep them from moving dues to engine vibration... BUT... loose enough so that you can turn them when needed.

The tabs on the back of those knobs.... you can remove those tabs so that you can rotate them, install, and remove the needle valves without needing to remove the knob every revolution if you like. I think those tabs were put there for the benefit of dimwits and senile little old ladies from Pasadena whose main purpose in life is to turn knobs. :)

Did adjusting those needle valves as I suggested in post reply #2 help you any?
 
Thanks for the help guys! I will leak check the fuel system and adjust the low and high speed adjustments on the old gal and see how she runs.
 
Check to ensure that your fuel bowl /filter is not the slightest bit loose. Sometimes after first run on rebuild they will need retightened. The yokes will vibrate slightly loose during rough idles. You may see a small amount of fuel mix laying under the powerhead. Otherwise these guys have already given the best advice.
 
Well guys I finally had a chance to run the motor on the lake. I adjusted the needles per recommendations and it idles fine but when I go to accelerate I have to turn the high speed adjustment almost all the way in and then the motor begins to ramp up to speed and then kicks the motor out of drive once the rpm's increase. I primed the tank then soaped everything down...tank,hoses, fittings, everything and found no leaks. It looks like I found the correct high speed settings but now I'm worried that the drive gear may have some worn teeth once motor ramps up to speed due it popping out of
gear. Could it just be a shift rod adjustment or does it sound more like a clutch dog/drive gear problem? I've read you can flip flop the reverse and forward gears if the drive gear teeth are worn down.
 
I had a problem similar to this after replacing impeller. The shift rod wasn't seated properly just had to adjust and it was fine.
 
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