Outboard runs then stalls...

[oliversdad]

I have an '81 Evinrude 4.5.Hadn't been run in years.A month back I changed the old impeller then tried it in a test tank.She started right up and ran real nice.But it couldn't be that easy.As soon as I launched the boat 2 weeks ago.Engine starts ,runs for maybe 5 or so seconds then dies.Checked screen filter on fuel pump,replaced clamps on fuel line.The odd thing I notice is when pumping the gas bulb it never gets hard.Could there be a bad check valve there that might cause the motor to die?Any Ideas are appreciated.

 

[jdratlif]

If it is carbureted like I think it is, you should probably start with cleaning your carburetor. If the carburetor is gunked up and causing the internal parts to stick, this will cause both issues you are having. I had a similar problem with my 9.8hp Merc that was solved with carburetor work.

 

[Winkfish]

If your bulb does not get hard, you have either a faulty bulb or, just as likely, a leak in your fuel line. When you rev up or put it under load, the engine's not getting enough fuel, which could be your problem.

And cleaning the carbs is never a bad idea. You might try running Sea Foam through it before spending a lot of money or time on a manual clean out or rebuild. Put a pint in 3 gallons of fuel. Run the motor for 15 minutes, then let it stand for 15 minutes. Repeat that cycle 8-10 times. That will clean out any carbon buildup in your motor and should help immensely. Then use Sea Foam in a maintenance dose when you add fuel.

 

[Stu Jackson]

Easy to check if the hose assembly, including the bulb and the hose is working properly. Also check that the kill switch circuit, if you have one, is OK. I had service work done on my 9.9 that corrected a glitch in the kill switch circuit that did the same thing as you described.

 

[Bill Roosa]

ditto Jdratlif's comments. Pay particular attention to the air inlet air ports. those little holes that come before the butterfly valve. the have brass inserts (screw in) with a TINY hole in it. It does not take much of a bug at all to plug it up.
Also, if the bulb is not developing pressure that would surly mean the float vavle is not closing. This would result in flooding, do you smell gas? or does it act like it is flooded?

Kuddos to you for making the observation about the bulb. We are going to have to keep our eye on you as one of those elite mechanical persons that pays attention to what is going on around them.

 

[oliversdad]

Thanks to all above who have posted with much needed advise.I took a chance and replaced the primer bulb but to no avail.Same problem...Argh!So I took the motor home,pulled the carb and it was clean but found the float was stiff.Like the little hinge pin was a bit bloated not letting float move smoothly up and down.The pin is made of what looks like a nylon type of plastic.Wondering if modern fuel had an affect on it.Luckily,dealer nearby had a rebuild kit in stock.In the new kit I can see a new pin made of metal.It and the carb now sit on my bench with me just looking through the plastic of the bag too afraid to attempt what must be a simple enough project.Will the new float need adjustment or will it just work as is?I haven't any experience with a carb rebuild.Thanks,Barry

 

[oliversdad]

O.K. Worked up the nerve and gave the rebuild a go.I hope to test her out tomorrow.

 

[jdratlif]

Normally those floats will have a tang that adjusts the height of the float in the bowl. Did the rebuild kit not have a little piece of paper that shows a cross section of the float and the dimensions of height? I would do some searching online for the correct float level for your carb. Normally the float level is dependent on the model of carb you have, not the engine model. I would look for some markings on the carb that might indicate its model number. For instance, my carb is a B1B Tilloston and has B1B marked on it.

 

[oliversdad]

Normally those floats will have a tang that adjusts the height of the float in the bowl. Did the rebuild kit not have a little piece of paper that shows a cross section of the float and the dimensions of height? I would do some searching online for the correct float level for your carb. Normally the float level is dependent on the model of carb you have, not the engine model. I would look for some markings on the carb that might indicate its model number. For instance, my carb is a B1B Tilloston and has B1B marked on it.

Thanks for this.Unfortunately no helpful diagram with kit.I set it just above level when holding carb level upside down.But I will look for a model no. of this carb and see what info turns up just to be sure.I'd prefer to go through this drill one time as the boat sits on a mooring and mounting engine from the dingy is a pain!Also will install inline fuel filter...I noticed filter on the end of the pickup tube in tank had a tear.

 

[Winkfish]

I hope you didn't go through all the carb trouble to find out it was a faulty pick-up tube all along!!! Rule 1: Do the cheap and easy stuff first. ;-)

 

[oliversdad]

I hope you didn't go through all the carb trouble to find out it was a faulty pick-up tube all along!!! Rule 1: Do the cheap and easy stuff first. ;-)

Thanks,no it was stuck float and the rebuild cured that.I was hoping for cheap and easy but carb rebuild wasn't as difficult as I thought.Got her back up and running. even went out for a test ride and she's running well. For now...