1987 Yamaha 6 hp dinghy motor won't start

[nightsky]

I have 1987 Yamaha 6 hp dinghy motor that won't start. Any suggestions for trouble shooting?

[Insails]

could be the spark plug....or the gas.
if the motor has set up awhile you may need to add a fuel stableizer.
try changing the plug and using freash gas

[cardiacpaul]

engines are not the stuff of nuclear power plants or the female psyche.

the "gas" engine needs a very few things to run.

1) air
2) fuel (the right amount, at the right time)
3) spark (at the right time)

alrighty then, you've got a 2 stroke, easy peezy.
(check to make sure you have fuel, and its connected and "on". dumber things have keep me at the dock, it ain't personal.)


you need to check two things, no matter what the order.

A) Are you getting fuel thru the carb?
B) are you getting spark?

these can most times be accomplished by taking out a spark plug.

Is the plug a bit "moist", not wet? Or, is it dry.
If its dry, fuel isn't going "thru" the carb., find out why. Check fuel supply, lines, filter.
Tap the side of the carb with a plastic handle of a screwdriver. Don't beat it to death, just tap it. Give it another try. If you have fuel to the inlet of the carb, it may need to be rebuilt.

If its wet, then assume fuel is getting thru, maybe far too much. dry the plug(s) off, or replace them. Check the "choke" on the carb, make sure its not sticking.

If its moist, (lightyly damp) then fuel is getting thru, on to plan B.

Spark. With the plug(s) out of the engine, connect one to the wire and ground it. The "grounding" can be having a clip from the metal base of the plug to the block, or if you've got a kid, have him hang on to it. and pull the cord. If the kid jumps, (Its not gonna kill him, it builds character... I wouldn't try this with the wife, she'll beat you till she gets tired) then you got spark. If you see a nice blue arc between the electrodes, you got spark.

If not, find out why. (make sure all electrical connections are tight, replace the plugs with new, or known good ones)

Look at the plugs. Is the business end, grey, brown, white, or black, is there any crud on the end? that may be a clue as well.


Thats a good start, there are a bazillion possibilities below these options, let us know whats what, and we'll take a stab at it.

As a side note, my neighbor is the regional manager of the pharmacies at a very large chain.
One day his lawnmower wouldn't start, he pulled on it for a good half an hour. Then he comes out of his garage, and beats the paint off of the thing wiht a shovel & drags it out to the curb. He said he's leaving it there as a warning to all of the other lawnmowers on the street.
I bent over, turned on the gas, pulled it 3 times. It runs fine. Poor besterd can't even look at me.

[carl762]

Good story and good advice.

Also, get yourself a manual for your motor. I'm learning tons about my Evinrude.

[gershel]

I have the same vintage Yamaha 8hp. Whenever I've had a similar problem, I removed the carb, very easy on that engine, disassambled it, and blew carb cleaner thru every hole I could find. It worked every time. I can do that job in 30min, you should be able to do it in 1 hour or less if it's your 1st time. Very simple solution on a very simple engine.
Marc

[MarkCK]

If its a two stoke ethanol in the gas might be gummning things up. After you have gotten it running again using previous listed instructions use the "blue" Stabil every time you mix your gas. Otherwise the problem become recurring.

[carl762]

Keep the carb cleaner off rubber parts as much as you can. Use Sta-Bil and definitely try and use non-ethanol gas. I've sworn off using regular gas, treating it and trusting the same.

Sta-Bil works for keeping water at bay for a bit.

Clean your fuel pump's screen, change the filter (if one exists) and be sure the vent line is clean.

[Pub911]

starter fluid.

Have someone spray it in the throat of the carb without using the choke while you pull the starting cable. If that doesn't make it run - even if temporarily - then it's probably a spark problem, so change the plug(s) and verify the deadman switch is working.

It starter fluid DOES make it run temporarily, it's likely fuel related. VERY VERY IMPORTANT: Don't keep running it on starter fluid. There's no oil in it and it will eventually cause major issues as a result. But as a diagnostic tool to determine the big IF/Then/Else, it's great.

If it's fuel-related, 86 the fuel you have and start fresh. Follow the advice above on filters and such. The most likely fuel-ralated issues are those that stem from water in the gas, then eventually elsewhere. Do the easy/cheap first, I like to say. E.g. gas, filters, etc.

Good luck.

[St Anna]

With all due respect. It is old and beyond its use by date. Fix one problem and it will not be reliable.

If it a spare, then fix it, but if it is for the dinghy, then a dinghy outboard is needed to be reliable so ditch it and buy a new one!!! A bit harsh, but just my view.

[nightsky]

The motor started up the next time I went out. Thank-you for your suggestions.
Possibly what happened: While I was towing a dinghy that had conked out with my dinghy in the Hudson (which has quite a strong current- he was on his way to the GW bridge), the towee got snagged by some guys fishing along the walkway. We stopped to untangle him, and in the excitement my motor died. On the ensuing startup I attempted to start the engine with the choke pulled out (not the correct procedure for a hot engine). He actually wound up getting his engine started and towed me back.