1980 50HP evinrudeE

First i would like to say hi to all I am new to the forum and seeking some help any would be appriciated.

I have a 1980 50 HP evinrude E on my bowfishing boat I took it out this weekend duckhunting and it ran great to my duck hole about 3 miles up river.
when it was time to leave i fired the boat up and headed out well i got the boat up on plane and it fell flat on its nose like it was shut off. I started back up and ran for about a min or so and died again. it would fire up on fast idle then die. it went on like this for a few then it fired up and ran for about 3 or 4 min then it acted like it ran out of gas ( full tank of 50.1 mix ) it then would not start. I got it home and it started up then died. I had a similar problem last summer when it would run at 3/4 throttle great then it would start lugging down i would back the throttle off and it would run good, then i would take it back up to 3/4 and it would run for a while then start lugging down

does anyone have any suggestions?

thanks

Re: 1980 50HP evinrudeE

Sounds like fuel starvation to me, bowfisher.

Is the fuel tank vent open and not restricted?
Is there a pinch or restriction in the fuel lines?
Is there an air leak in the fuel supply system?
Is the fuel pump putting out a strong stream?

Re: 1980 50HP evinrude

Re: 1980 50HP evinrude

Does the primer bulb pump up firm? Try pumping the bulb and see if she goes. Fuel pump may be on the way out as suggested...Possible bad check valve in the bulb will restrict flow too...

Re: 1980 50HP evinrudeE

is the bulb collasping( going flat) when running.

Re: 1980 50HP evinrudeE

When was the last time the carbs were disassembled, cleaned and rebuilt? If it has the original style (black) rubber gaskets, they can deteriorate if you have fuel with any alcohol in it. Your float needles may also have rubber tips on them that can deteriorate and stick. New rebuild kits have alcohol resistant rubber parts (more of an orange color). If the carbs are somewhat recently rebuilt then it's possible they are just gummed up a bit and need cleaning...
- Scott

Re: 1980 50HP evinrudeE

Squeeze the fuel primer bulb to see if there might be a item laying in the bottom portion of it. If so, that would be the inner portion of the outlet valve leading to the engine's fuel pump.

That valve has been know to come apart as mentioned above, then as the engine runs that inner portion of the valve would be drawn back into its outer sleeve BUT it would be drawn into that sleeve BACKWARDS. This effecively converts the outlet valve into a shut off valve.

If you're using a built in tank, another type fuel restriction could exist as follows.

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vaccum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

What is the compression reading of each numbered cylinder?

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... Does it?

Let us know what you find.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

Re: 1980 50HP evinrudeE

wow thanks for all the help im working on it right now never thought of it sucking air on the primer bulb. it pumps up firm but not real hard.. I will get back to you tonight.

Re: 1980 50HP evinrudeE

The portion of my reply above about the warning horn pertains to the V6 and V8 engines only. Don't let that mislead you.

Re: 1980 50HP evinrudeE

lol yea i figured that out but im off to the water to run the boat ill keep ya posted

Re: 1980 50HP evinrudeE

Ran Great I found out that the gas tank was leaking (sucking air / and yea water ) a boat will not run when you have 9 gal of gas and 1 gal of water in the mix.
cleaned the carbs and the fuel filter and housing. I think the problem is solved.

Thank you everone for the help