Need Help

**The Marine Doctor** · 03-23-2009, 04:34 PM

Originally Posted by kinglx1

I have a 87 Mercury 115 it starts and idles great but if you run it at full throttle for about 20 minutes it will start sputtering and cutting out, has anyone had this problem before or have any ideal whats wrong with it. Thanks for any info

You have to provide more info than what you listed.

Does it restart right away?
Does the starter just click?

Fuel pump would die within 30 seconds at full throttle if its bad.

Primer bulb would collapse if there was a restriction in the tank.

Is it pumping water?
Have you checked it for gear oil?

The Marine Doctor

**Donald Stonecipher** · 03-23-2009, 10:46 PM

Speaking from experience as a sears lawn mower technician, sounds just like the vent in the fuel tank is plugged as mentioned before me.
Just like mower starts and idles fine, drive around yard for about 20 minutes and the sputtering starts and dies. Usually its just dust from mowing that is plugging a very fine hole in the gas tank cap.
Hope its just as simple as this for your sake.

**kinglx1** · 03-24-2009, 05:00 PM

Originally Posted by Donald Stonecipher

Speaking from experience as a sears lawn mower technician, sounds just like the vent in the fuel tank is plugged as mentioned before me.
Just like mower starts and idles fine, drive around yard for about 20 minutes and the sputtering starts and dies. Usually its just dust from mowing that is plugging a very fine hole in the gas tank cap.
Hope its just as simple as this for your sake.

I took the vent line off and checked it , it is not stopped up and didnt seem like it had been sucking together anywhere in the line . I took the line from the inside of the tank out also and it wasnt stopped up either.

**kinglx1** · 03-24-2009, 05:04 PM

Originally Posted by The Marine Doctor

You have to provide more info than what you listed.

Does it restart right away?
Does the starter just click?

Fuel pump would die within 30 seconds at full throttle if its bad.

Primer bulb would collapse if there was a restriction in the tank.

Is it pumping water?
Have you checked it for gear oil?

The Marine Doctor

It doesnt kill the engine if i let up off the throttle, primer bulb doesnt collaspe,it is pumping water but i have not checked the gear oil, how would that make it sputter and cut out

**The Marine Doctor** · 03-24-2009, 05:18 PM

The letting up on the throttle is what I need to know to fill me in on whether the gear case would be a problem or not.

Seizing gear case...if it just died and would not restart.

When the fuel pump was rebuilt...did the check valves get changed?

Have you squeezed the primer bulb when it happens.

Any water in the fuel tank?

TMD

**kinglx1** · 03-25-2009, 02:09 PM

Originally Posted by The Marine Doctor

The letting up on the throttle is what I need to know to fill me in on whether the gear case would be a problem or not.

Seizing gear case...if it just died and would not restart.

When the fuel pump was rebuilt...did the check valves get changed?

Have you squeezed the primer bulb when it happens.

Any water in the fuel tank?

TMD

if let off the throttle it will still idle just fine,as far as the check valves go i really dont know i had a guy to do that for me last year, i havent tried sqeezing the primer bulb at the time it starts sputtering , i dont know if there is any water in the tank it is a built in plastic tank

**Barnacle Bill** · 03-25-2009, 04:56 PM

The check valves MD referred to can cause that problem. Mercury has a TSB out on it saying ethanol causes the edges to curl up and they don't seal properly. (and it does) I have replaced a couple of them and it did fix the problem. The kits from Merc include the new style check valves.

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