motor problems

[tomO]

I have a 94 mercury on my boat, I took it out this morning and ran it up the river and about 20 minutes in it died, started right back up and ran about 5 seconds and died again repeated this a couple more times and let it set. About 45 minutes or so later started it up on the second pull ran about a minute and died again repeat for the next 4 hours till I got back to the boat ramp on my trolling motor. Good news is we caught a few nice Walleye and sauger. Any one have a clue to what may be the problem? thx in advance.

[DRIFTER_016]

First of all, does the primer bulb in the hose go soft when it stalls?

Does it remain running if you pump the bulb when it starts to stall?

Is the vent on the tank open? Clogged?

[Luke V.]

Sounds like a fuel issue

Maybe a dirty filter

How old is your tank? Have you ever cleaned the sand/dirt out of the bottom?

 

Could also be the engine loosing prime as drifter pointed out

[Kerry]

Do the easy stuff first.Ethanol in gas will cause a lot of little problems with the fuel system especially if it has been sitting over the winter.I would check the fuel filter first or replace if it has been a while,then check the fuel line for clogs at the fittings.If the line is older it could be degrading.Is there a primer bulb on the line?If it is getting hard it might not allow a full prime or full flow after.

Drain the carb bowls and purge the rest of the lines on the motor of what gas is in there and use fresh premium for a tank of gas.

Kerry

[tomO]

The gas is fresh and I got a new tank and hose last fall. The bulb on the hose never did get hard last fall but ran fine.This is my second outing ran well the 1st time, I'll check the fuel lines and such tomorrow . thx

[Fisherman]

What does a primer bulb do? Primer bulbs siphon gas from the tank to the motor and prevent it running back when the motor is not running. The primer bulb has 2 rubber flap valves in it, it doesn't have to stay hard to keep the engine running. Motors have a fuel pump that keeps the gas coming once it's running. The only reason there's a primer bulb is that most if not all tanks are below the carb level of the motor, it's just an assist to the motor fuel pump. If tanks were at carb level or above, such as gravity flow then a primer wouldn't be needed.

You may have crud floating around in the main jet clogging the system, a sticky float or even bad plugs that won't fire while hot.

[Gnote]

Also a good idea to check the small fuel hose under the cowling running to the carb. If its loose hard or cracked it may be losing pressure.

I changed one last season.

[Big Cliff]

Sure sounds like a fuel problem, check the fuel filter before you go making it all complicated. When was the last time you replaced it?

[grt1]

i had a similar problem and the marina said it was a dirty carb. once it was cleaned by them it ran fine.

[DRIFTER_016]

What does a primer bulb do? Primer bulbs siphon gas from the tank to the motor and prevent it running back when the motor is not running. The primer bulb has 2 rubber flap valves in it, it doesn't have to stay hard to keep the engine running. Motors have a fuel pump that keeps the gas coming once it's running. The only reason there's a primer bulb is that most if not all tanks are below the carb level of the motor, it's just an assist to the motor fuel pump. If tanks were at carb level or above, such as gravity flow then a primer wouldn't be needed.

You may have crud floating around in the main jet clogging the system, a sticky float or even bad plugs that won't fire while hot.

 

Yes exactly.

If pumping the bulb keeps the engine running when it's trying to quit it tells you there is most likely a fuel pump issue.

It's just one diagnostic tool to help figure out what is causing the stalling problem.

[didoban]

seem like water in fuel or water in the carb. Drain your carb and prime with fresh fuel.

[Sinker]

Since nobody has said it yet........seafoam!

 

My bet is the carbs sat empty all winter, some varnish formed and is blocking fuel flow. Seafoam will clear it up.

 

S.

[tomO]

Ok I checked the fuel filter it was spotless a little bit of fine stuff in the sediment bowl couldn't see any fuel leaking from any of the lines. Fuel filter was replaced 2 years ago Cliff and I tried the bulb trick Drifter but to no avail,but when it dies it just quits ,doesn't spit and sputter.I poured a couple of gallons of gas out of the tank into a bucket and put some in glass jar to check for water but saw none I assume the water would seperate and be on the bottom. I'm not sure how to tear into a carb so off to the shop I guess.Also the bulb will get hard at times then soften up. thx again all.

[tomO]

Sinker I put stabil in the gas every time I fill up and I never run the motor out of gas at the end of the season, don't know if thats bad or good but never had any problems before.

[fishnsled]

Maybe your new fuel line. I had one years ago that I had bought brand new and the bulb would not stay hard. Went out and bought another fuel line and problem was solved. One of the clamps was not tight enough allowing air to leak in but not enough to allow fuel to leak out. If you have a buddy with the same fuel line, maybe borrow it and see what happens.

[mr blizzard]

Tom O.

As mentioned earlier check the vent on the tank, make sure it is open, if it is shut or vibrates shut your motor will shut down, happened to us on Lake Muskoka 17 years ago, another boater came by we checked , opened it up and were good to go, also as mentioned check under the gas cap for debris. Seafoam does a great job, its sure proven itself up here.

 

Hope it is a cheap fix for u let us know. Also check the connection where the fuel line meets the motor.

[Sinker]

I'd still run the seafoam before taking it to a shop. They are just going to charge you to do what the seafoam will do.

 

S.

[ecmilley]

does it run with the choke slightly on?

does it always run for 15-20 minutes cold then start to act up as it gets warm?

may be fuel related but don' rule out igniton issues on mercs changed lots of coils, stators/ignition triggers on them get a spark tester make sure you have adequate spark and then recheck it when it's hot,

[DRIFTER_016]

If it just shuts off and doesn't sputter it sounds ignition related.

Could be a CDI unit that is acting up when it gets hot thus the dying after 15 or 20 minutes.

Could also be a coil or stator assembly doing the same thing.

[Sinker]

Ya, I was thinking coil as well. Seemss more plausible. I've seen them quit when they get hot lots of times, and then run fine when cold.

 

S.

[tomO]

Electrical was my 1st thought also I'll take it in on monday and I'll let you guys know what they find.

[Old Man]

With the info you've provided, I'd bet on it being a coil issue.

[fishrking]

I'm going to echo the statement above: Mercs are notorius coil killers - I've replaced two in five years in mine.

 

jf

[ecmilley]

lots of coils, go figure they fail in cold storage, wonder how many problems I"ll see when the marina opens this year

[DRIFTER_016]

Don't trash the Mercs 'cause believe it or not some of them actually work.

Mine is a '91 and the only issue I've had with it in all that time is a failed oil level sensor in the oil tank.

 

Had to do a bunch of work on my old 1960's Johnson though when I owned it.

Coils an gasgets mostly.

Edited April 12, 2013 by DRIFTER_016