1979 6hp Evinrude problem

[jayandcarey]

Motor will run well for about 6-8 minutes then will only run slow for 20 seconds then will cut off. It will restart and only run slow for about a minute then runs normally again for about 6-8 minutes. It did this routine about 5 times last weekend. It was also smoking more than it should.

Brand new gas and oil 50:1mix
fuel filter is clean
just cleaned carb and put new carb kit it a few months ago, pulled it off tonight just to double check and it is pristine
not peeing well, just dribbling
water pump has not been changed in years

It seemed unlikely to be the water pump because I thought if it was overheating it wouldn't start running well after just a few minutes

thanks for your help,
jay

 

[Joe Reeves]

Re: 1979 6hp Evinrude problem

If pumping the fuel primer bulb (acting as a manual fuel pump) constantly doesn't help, I would suspect the engine is overheating as you suspected (Water pump).

 

[jay_merrill]

Re: 1979 6hp Evinrude problem

The question of whether it is getting adequate cooling should be easy to answer. If you are not getting good water flow from the port located on the backside of the exhaust housing, its time to start troubleshooting that system. Don't forget that your motor has a thermostat, so it may or may not be the water pump. One important factor though - your motor has a bypass circuit in the cooling system. You should get at least a little water flow at all times.

As a 1979 model, your motor also has a magneto CD type ignition, with a power pack. They have been known to develop problems that are heat related.

 

[raczekp1]

Re: 1979 6hp Evinrude problem

i wouldnt play with motor without proper cooling system.
check termostat-located on the top of head,
change water pump impeler.
both is preaty easy job, just do it
here are some good links
http://www.sschapterpsa.com/ramblings/OMC_6hp.htm
http://www.sschapterpsa.com/ramblings/OMC 6-8hp.htm

 

[F_R]

Re: 1979 6hp Evinrude problem

I think you have a cylinder cutting in and out. When that cylinder stops firing you get the low speed, when it fires again it runs normally. The unburned fuel going through when not running correctly would also make it smoke.

Could be a number of things, even just a spark plug. Or arcing out at one of the plug boots, or coil. Or water getting into a cylinder. Or a fuel pump diaphragm.

However, it also sounds like you are concerned about the water pump. Don't take chances with that. It only takes a minute to completely destroy you motor when you cook it.

Gotta ask: You aren't running it in a barrel are you? That'll do it too.

 

[kodibass]

Re: 1979 6hp Evinrude problem

Change the impeller/water pump first' then do a basic tune-up service on the engine, New plugs gaped 30*, check spark plug wires for wear cracks, nics, etc. check / replace all fuel lines, Get a new fuel to tank hose. F-R has you in the correct direction, If you have a vacuum tester check the fuel pump as well it should be 2 1/2 pounds min. keep us posted.

 

[jayandcarey]

Re: 1979 6hp Evinrude problem

I spoke to someone who said I need to check the compression before dropping any money on it. Is there any validity to that?

I plan to change the water pump, tank to engine fuel line, and spark plugs, and check all other fuel lines.

thanks for all the advice,
jay

 

[jasper60103]

Re: 1979 6hp Evinrude problem

I spoke to someone who said I need to check the compression before dropping any money on it. Is there any validity to that?

I plan to change the water pump, tank to engine fuel line, and spark plugs, and check all other fuel lines.

thanks for all the advice,
jay

That's good advice. You can borrow a compression tester free at some auto parts stores like Autozone or Oreilly. Else, there are not too expensive. Keep us posted.

 

[kodibass]

Re: 1979 6hp Evinrude problem

a motor that runs good for 6 to 8 min, most likely has good compression, but if you can get your hands on a tester then go for it, I'v seen stranger things! good luck