slow starting

[Richard42]

I have a 100 hp mariner 87 to 89. I was told it?s a fish and ski or something like that that it can troll and just run on 2 cylinders then kick the other 2 in when you gas it up. Well every time I first set off on the river it takes from 15 to 30 minutes before it feels like all 4 cylinders are running. 15 to 30 minutes of now power hard to get on plain max rpm 3000. feels like its flooding no power.
Then I hear the motor sound different gas it up and rocket time on my 16ft Lund 5000 rpm and as long as I don?t shut the motor down for more than 3 hours it?s a rocket. I can?t also find the serial # on the motor mounting bracket so I am really unsure of what I have for year.
Feels like something is sticking and the only way to make it get up and go is run it at about 2000rpm till you hear the engine sound better and see the tac go to 2200. Then gas it see if it goes.
Oh the plugs look really clean like its burning great the gap is like .030 not sure what the gap should be also.

 

[sschefer]

Re: slow starting

I have a 100 hp mariner 87 to 89. I was told it?s a fish and ski or something like that that it can troll and just run on 2 cylinders then kick the other 2 in when you gas it up. Well every time I first set off on the river it takes from 15 to 30 minutes before it feels like all 4 cylinders are running. 15 to 30 minutes of now power hard to get on plain max rpm 3000. feels like its flooding no power.
Then I hear the motor sound different gas it up and rocket time on my 16ft Lund 5000 rpm and as long as I don?t shut the motor down for more than 3 hours it?s a rocket. I can?t also find the serial # on the motor mounting bracket so I am really unsure of what I have for year.
Feels like something is sticking and the only way to make it get up and go is run it at about 2000rpm till you hear the engine sound better and see the tac go to 2200. Then gas it see if it goes.
Oh the plugs look really clean like its burning great the gap is like .030 not sure what the gap should be also.

Not trying to blow you off or anything but your problem is one that is difficult to troubleshoot. The problem is that these motors have a unique way of going from two to four cylinders. While it's not all that difficult to troubleshoot it is very difficult to do from a website.

The reason is because there are multiple paths to follow and if you go down the wrong path it can get very expensive. My heart felt concern is that we will get you in over your head when the path of least cost would be simply to take it to a certified Merc Mechanic with knowledge of the 2+2 inline 4 cylinder Merc engine.

 

[Richard42]

Re: slow starting

Well get me in over my head I was a machine technician worked on 10 million dollar machines I can fix anything. I have rebuilt everything on my 87 Lund or replaced. And yes I want and E-Tec But if I can get this motor cranking $7500 + saved. I always like to do my own work on cars, house, electrical, furnace, yard, and mowers. Money?s tight hurt my back so any help any direction. I just want some food for thought trouble shoot trouble shoot and fix maybe. How about this is there a way to bypass the 2 stage cuz I have and electric trolling motor I got working and a 8hp kicker that runs great. Really don?t need a 2 cylinder 100hp motor

 

[Dave1027]

Re: slow starting

How about this is there a way to bypass the 2 stage cuz

Nope. Instead of modifying, it would be a heck of a lot easier to get the motor working as the engineers designed it to. It's actually a fairly simple design. It has no idle fuel going to the bottom two cylinders.

When did the problem start?

Gap? I use gap-less plugs on mine and not a problem. Try replacing the spark plugs with 4 each NGK BUHW. I did try the gapped plugs once on a recommendation from a mechanic but went back to gap-less because they seemed to be more powerful.

After that the next thing you need to check is if you have spark to the bottom two cylinders. Use a timing light or spark tester.

We'll go from there.

 

[sschefer]

Re: slow starting

Well get me in over my head I was a machine technician worked on 10 million dollar machines I can fix anything. I have rebuilt everything on my 87 Lund or replaced. And yes I want and E-Tec But if I can get this motor cranking $7500 + saved. I always like to do my own work on cars, house, electrical, furnace, yard, and mowers. Money?s tight hurt my back so any help any direction. I just want some food for thought trouble shoot trouble shoot and fix maybe. How about this is there a way to bypass the 2 stage cuz I have and electric trolling motor I got working and a 8hp kicker that runs great. Really don?t need a 2 cylinder 100hp motor

First thing you need to do is to find a Merc Service Manual for the engine. It will help you to understand the theory behind the motor. Once you know how it works, you can start to trouble shoot it.

The manual will provide step by step procedures for isolating your problem.

The most common problem is that folks don't know about the two mechanical injectors that are in cylinders #3 and #4 behind the electrical plate and the 1/8" filter for them that is behind the oil tank.

The next thing that is easy to replace is the accellerator pump. It does fail and can cause symptoms like your seeing.

The carbs on this motor have sealed air mix screw. You'll find them on the top left of the carb and they should be sealed with a red filler material. Do not mess with these no matter how tempting.

Idle mixture is set on #1 and #2 only. The initial setting is 1-1/2 turns out from lightly seated. Do not turn these in and seat them hard or you will ruin the tip and need to replace them. If they are damaged it will affect your transiton from two to four cylinders.

The ignition circuit is the same as any other 4 cylinder inline. You can download the trouble shooting guide from www.cdielectronics.com

Conversion of these motors to all cylinders all the time has been tried with no known success. Once you get it running properly it will perform just as well as a full time motor.

I have owned one of these motors. I have rebuilt one of these motors. They can be difficult if you choose to wing it like I tried. Once the manual was in hand it all made sense and the motor ran beautifully.