Out board motor problem

[ThunderBolt]

I was wondering if there are any mechanics out there that could possible give me some ideas as to what is wrong with my boat motor?
A couple days ago I had it on the lake and it ran beautiful, today I took it out and there was no power. At 5000rpm it goes about 40 mph, today at 5000rpm it went about 20to 25mph. I thought it might be the fuel that I just put in it today, however one mechanic said it couldn't be the fuel because I managed to get 5000rpm out of it. It is a 100hp Merc and when it travels below X amount of rpm only two cylinder function. When it reaches a certain amount of rpms the other two cylinders kick in, however it did not seem to me that they were kicking in at all. I thought maybe it was the spark plugs so I changed them but that did not make a difference. Does anyone have any ideas?:angry3:

[harrydude]

more info please

what year , model numbers of motor?

were are you located??

[ThunderBolt]

more info please

what year , model numbers of motor?

were are you located??

It is a 1996 100 hp Merc outboard motor and I think this is the Model number 400-8715-C4.
If this is not I will have to go to the boat and look for it, I am giving the info I have on my insurance policy here at home. I am in Camrose.
Thanks!

[bagwan]

I had a 115 merc that had two power packs that supply power (spark) to the plugs. One conked out and it still ran on 3 cyl. Mechs advised to change them in tandem because the second one would fail but I opted for one and it was still working two years later. They're not cheap.

[juno]

Sounds like a power pack issue as was mentioned. They are built this way so you have two cylinders to bring you home if there is a problem like this. Not a hard problem to fix if you are a little handy.:)

[deanmc]

RPM should translate directly to speed unless your prop is slipping. Maybe power pack troubles make the tach wonky as well?

[ThunderBolt]

RPM should translate directly to speed unless your prop is slipping. Maybe power pack troubles make the tach wonky as well?

Check the prop, its OK

[ThunderBolt]

RPM should translate directly to speed unless your prop is slipping. Maybe power pack troubles make the tach wonky as well?

Maybe the rpms were out of wack because the motor sure didn't seem like it was working hard when it was at 5000rpms.

[harrydude]

loook here

http://www.crowleymarine.com/mercury-outboard/360.cfm

[harrydude]

loooks lkie there is 4 coils there

[ThunderBolt]

So what I get out of everybodies replies is that it can be a power pack problem or coils? I will check into these possiblities.
Thanks!!

[-JR-]

Few questions: does it start normal ,does it sound normal at idle and at higher rpm,does it sound like its missing ,Is your prop damaged,etc.
As a machanic I first would be checking for spark at each cylinder.
Do you know how to do that ?

[ThunderBolt]

Few questions: does it start normal ,does it sound normal at idle and at higher rpm,does it sound like its missing ,Is your prop damaged,etc.
As a machanic I first would be checking for spark at each cylinder.
Do you know how to do that ?
To your questions; yes it starts normal, sounds like normal idle but the rpms read higher, and at higher rpms sounds like they don't jiv with the tack. The engine doesn't seem to be working hard at all and yet the rpms are up higher than normal. No its not missing and the prop is not damaged. I took it off and everything looks good! Yes I will check for a spark in the plugs. Thanks!

[ThunderBolt]

Hey guys when I took the coil cover off I pushed on all the connectors in there and when I started to motor it sounded like the revs of the motor were in sink with what the tack was showing. I could tell it was sounding the way it should at higher rpms. I checked all the spark plugs for spark and they were good. I knew the prop was good because I had checked it yesterday. So when I got her going on the lake.......she ran like a top. Thanks you gentlemen!!! All your advise lead me to the answer.:sHa_shakeshout:

[harrydude]

so i was a bad conection at the coil.........

good thats all it was...........

another thing I recomend is to dielectric grease all your wire conection plugs....

and was there any white chaulky stuff in the conections???

[ThunderBolt]

so i was a bad conection at the coil.........

good thats all it was...........

another thing I recomend is to dielectric grease all your wire conection plugs....

and was there any white chaulky stuff in the conections???
First of all "dieletris grease" is that what they call it? If so I am thinking you have to get it at a boat shop or can you get it anywhere else? There was no white chaulky stuff? It was clean!!:sHa_shakeshout:

[ThunderBolt]

so i was a bad conection at the coil.........

good thats all it was...........

another thing I recomend is to dielectric grease all your wire conection plugs....

and was there any white chaulky stuff in the conections???

harrydude, just out of curiousiy what does that mean if there is a "white chaulky" substance?:Lightning:

[deanmc]

First of all "dieletris grease" is that what they call it? If so I am thinking you have to get it at a boat shop or can you get it anywhere else? There was no white chaulky stuff? It was clean!!:sHa_shakeshout:

Grease - Dielectric Silicone
Napa or Canadian tire or almost any auto parts store.
http://www.napacanada.com/en/PartsAccessories/PartsSearch/SearchByKeyword.aspx#Detail

[harrydude]

the white chaulky stuff is just corosion........you need to clean that with contact cleaner

[ThunderBolt]

Thanks guys!!