1996 Mercury 115 ELPTO

[pinrun]

My 1996 Mercury 115 ELPTO will start in the morning and after lunch but when I'm fishing and try to start in the evening it may start but immediately stop. Then when trying to start it will wheeze and backfire. I'm aware that this engine isn't made for idling. the top 2 cylinders are operating when idling and the other 2 kick in about 1800 RPMS. After being towed within 1 hour it will start and run like a top...a bit rough but it always idles a bit rough. I had a 100 hour tuneup last october and took it in last week because it wouldn't start. It has 150 compression on each cylinder. When they pulled the 6 month old plugs the top plugs were black, number 3 was fouled and number 4 looked new. Any help would be greatly appreciated. I'm sure someone has experienced this problem before. Thanks

 

[tds566]

Re: 1996 Mercury 115 ELPTO

My 1996 Mercury 115 ELPTO will start in the morning and after lunch but when I'm fishing and try to start in the evening it may start but immediately stop. Then when trying to start it will wheeze and backfire. I'm aware that this engine isn't made for idling. the top 2 cylinders are operating when idling and the other 2 kick in about 1800 RPMS. After being towed within 1 hour it will start and run like a top...a bit rough but it always idles a bit rough. I had a 100 hour tuneup last october and took it in last week because it wouldn't start. It has 150 compression on each cylinder. When they pulled the 6 month old plugs the top plugs were black, number 3 was fouled and number 4 looked new. Any help would be greatly appreciated. I'm sure someone has experienced this problem before. Thanks

Never heard a a outboard that only fires on two cylinders at low speed

 

[racerone]

Re: 1996 Mercury 115 ELPTO

Mercury has made these for quite a long time.----The inline 4 only runs on the top 2 cylinders at idle.---This is because the bottom 2 do not get enuff fuel to fire consistently.--The bottom 2 only get a little bit of fuel for lubrication and cooling.---Spark is still there just no fuel.-------So on this motor you should check for spark that will jump a gap of 7/16" on all 4 cylinders.--Also check the bleed circuit hoses and check valves.------Have you tried adjusting the low speed needles on the top 2 carburetors ?----No adjustment for that on the bottom 2 carburetors.

 

[1FASTLASER]

Re: 1996 Mercury 115 ELPTO

These are referred to as the 2+2 motors and can be a headache. Great motors when right but they do require the right touch. IMHO what you seem to be experiencing is a fuel delivery problem. If you can check spark when the motor gives you a problem. As stated it should jump a 7/16 gap. If that checks out visually inspect ALL fuel lines AND tank vent and primer bulb.

 

[racerone]

Re: 1996 Mercury 115 ELPTO

If #4 looks new then there is no fuel there, or no spark to that plug or a bad sparkplug.

 

[CharlieB]

Re: 1996 Mercury 115 ELPTO

Merc has built the 2 + 2 for a goodly number of years, once dialed in most owners are not even aware that they only idle on 2 and the transistion to running on all 4 can be so seemless as not even noticeable.

All adjustments, carb sync, timing, idle mixture on the top 2, and accelerator pump, all must be done to the LETTER as spelled out in the factory service manaul. Do not waste your time with an aftermarket manual, they skip too many details, and it is the details that make this motor shine.

After sitting and cooling for an hour you MUST use the fast idle lever to start and warm the motor before going into gear.

This is the exact motor, year, model, that I had on my Pro Craft, I wish I had never sold it. But the new owner was delighted with it.

 

[Fun Times]

Re: 1996 Mercury 115 ELPTO

Quick note guys, At this time there's really no need to go into great detail to help the original poster as looking at his last online activity here on iboats was back on March 6th, 2011 01:58 PM.

racerone, welcome to iboats, Thanks for coming over to iboats to help out here as well, Your sharing knowledge of outboard engines is truly appreciated. For future reference here on iboats, Please keep an eye on the date of the original posters last post as typically iboats likes to consider old threads like this one an archive even if there was no helpful reply back then. On engine technical forum topics, iboats likes to consider any thread older than 90 days an archive and should only be reopened by the original poster. We like to encourage new members here to start a new thread of their own and if needed, they could reference a link to the thread that brought up the question they may have due to it to see if we can help them out in any way possible. Thanks again.

Iboats Moderation team!

 

[CharlieB]

Re: 1996 Mercury 115 ELPTO

I thought there was a red bar across any post older than 90 days since last post.

I definitely missed the date on the first.

As a Mod is there anyway that you can re-mark this thread as old?