1992 mariner 115 hp question

i cant seem to figure out why it wont start i have great compression great spark and fuel. i tried priming it in the sparkplug holes as it has been in storage for at least 8 years. i primed it and nothing not even a pop. i went on to the local marina and was told that at an idle it only runs on 2 cylinders. i couldnt believe it but could this possibly be true???? i am stumped any help is greatly appreciated. thanks

Re: 1992 mariner 115 hp question

I'm not much help but I do know I have a mariner 115 hp I just had in the shop and they also said it ran on two cylinders at idle.

Re: 1992 mariner 115 hp question

i cant understand why they would do this though? what was wrong with yours mine has a bad record of having ignition components being replaced. but it should run but i cant figure it out.
thanks

Re: 1992 mariner 115 hp question

I don't know. I would assume it would be to save gas, as mine drinks gas like no other.

Here's my issue.

http://forums.iboats.com/showthread.php?t=537440

Re: 1992 mariner 115 hp question

ok thanks it was my uncles boat and now i am trying to get it to run with no knowledge of it what so ever. he passed away so i dont know what he had done to it and if it was running good or just barely running when it was put away
thanks

Re: 1992 mariner 115 hp question

The 100's and the 115's were designed to be the big motors that could troll all day. Hence, they are setup to run on two cylinders up to around 1700 RPM and then the other two cylinders kick in. The way they work is that the fuel to air ratio on the non-firing cylinders is adequate to provide lubrication but not combustion. The have an accelerator pump and mechanical injectors on cylinders 3 and 4 that provide the extra fuel needed for combustion. The system actually works very well but they do bog a little on the bottom end out of the hole. Once the accelerator pump kicks in it feels like a turbo comes on.

They are not hard engines to work on but they do have rather weak lower units and have been known to warp the exhaust diverters and cause a weird miss fire problem at mid to wot.

If you're sure you have spark and fuel but not even a pop then my first suspicion would be a problem with compression. A simple inexpensive compression guage can be used to check that, you don't need anything fancy. Compression should be around 135 and fairly even in all cylinders. 110 or less and it should be rebuilt but will still run. At 100 or less it shouldn't start but I've seen a couple that did but ran pretty bad.

Re: 1992 mariner 115 hp question

What do you call 'great spark'?

Spark must be able to arc across a 7/16 inch gap, any less makes it difficult to start.

Cranking speed can be an issue, a minimum 300 RPM is necessary for the stator to generate sufficient voltage for the ignition system to create an acceptable spark.

Spaying pre-mixed fuel into ALL the carbs should cause all cyls to fire, the lower two will fire until they use up your added fuel.