1987 mercury 115 bogs after full throttle

[waterguy123]

I have a 1987 mercury 115 inline 6 I just replaced all the seals on from lost rpm hard start and a back fire problem. It now runs and idles fine. But bogs after maybe 10 seconds at full throttle and dies unless I let off

 

[Chris1956]

If she gets to full throttle and then dies suspect a fuel delivery issue. Have someone pump the primer bulb while accelerating and see if that fixes it. If so, rebuild the fuel pump, clean the fuel filters.

If the primer bulb collapses, the fuel tank vent is likely clogged.

 

[Arronh]

Depending on what you find with the primer bulb test, you could also try to choke the engine as a separate test to see if there's a carb issue.

 

[jimmbo]

Is it bogging as it is accelerating, or after it hits top Rpm?

 

[waterguy123]

Ok thanks I have a new fuel pump and lines ordered. It hits full rpm but not for long.

 

[jimmbo]

Asa previously mentioned, like a fuel Starvation issue. Pull the Fuel Pickup out of the tank and inspect for contamination of the Strainer on the end of it. I used to find a Jelly like substance on the screens in my tanks.

 

[waterguy123]

I checked to make sure the vent wasn’t clogged.
The only issue with checking the pick up in the gas tank is it’s welded in an aluminum tank but Ill try to shot some air in the line and see what happens thanks.

 

[waterguy123]

I’ll also try the choke idea thanks for the help

 

[QBhoy]

Apart from all of the above…mark sure you aren’t just running on residual battery power alone. Meaning she’s not charging or giving an output of her own back. That would mean that high demand from the ignition would eventually make the motor die, if she was just running on what’s in the battery. Put a meter across her and see if she’s giving out her own charge.

 

[Chris1956]

A 1987 IL6 motor will have ADI ignition. The battery is not used to generate spark. If you had an ignition issue, the motor would not start at all.

 

[racerone]

Agreed----The battery is used to crank the motor over.-----The spinning flywheel generates the spark.---The battery has nothing to do with making spark for the plugs !!

 

[markhodges78]

Did you do anything with the carburetor's? if so is it possible the floats are set incorrectly ?

 

[racerone]

Friends have one these wonderful motors.----Found the check valves in the fuel pump were hanging up .----Possibly due to age / E10 fuel.----New diaphragm / check valves and like new again.---Cheap easy fix as the small brown bottles did the trick.

 

[QBhoy]

Agreed----The battery is used to crank the motor over.-----The spinning flywheel generates the spark.---The battery has nothing to do with making spark for the plugs !!

So if the stator and rectifier was not producing, it wouldn’t start at all ?

 

[racerone]

The stator has 2 sets of windings.----One to charge the battery via the rectifier.----One set feeds the switch box / capacitor to fire sparkplugs.------These motors can be started with a dead battery.----You spin the flywheel with a rope and you get spark.----Just like a lawnmower or chainsaw !!----No battery required.

 

[QBhoy]

The stator has 2 sets of windings.----One to charge the battery via the rectifier.----One set feeds the switch box / capacitor to fire sparkplugs.------These motors can be started with a dead battery.----You spin the flywheel with a rope and you get spark.----Just like a lawnmower or chainsaw !!----No battery required.

Amazing. Did not know that about them at all. Is that the 2+2 machine ? Just realised it likely is. Witchcraft

 

[racerone]

That motor in post #1 is the old proven inline 6 cylinder !----The 2+2 was a 4 cylinder machine.

 

[QBhoy]

That motor in post #1 is the old proven inline 6 cylinder !----The 2+2 was a 4 cylinder machine.

Not the first time I’ve not read or picked up crucial information from previous posts. Often guilty of that ! I should really start using a bigger device than my phone from now on. Apologies

 

[waterguy123]

I ended up replacing all the fuel lines the plastic liner had collapsed in side it runs better then ever. Starts better then my truck

 

[jimmbo]

A lot of Fuel Lines did that, a particular 3rd Party Gray was Famous for that. However even Quicksilver Lines are now Gray, so all bets are off. The Hoses inside the Cowling would likely withstand the Assault that Alcohol does to them, being an 87