No power in 150HP Force

[JohnBayliner]

Hello,I have a 1991 150HP Force wich starts good and runs good, but most of the time it has no power.Sometimes is runs great and has a lot of power, but most of the time it hasn't.It seems to run on 3 or 4 cylinders and sometimes it runs on all 5 cylinders.I've changed the sparkplugs but this didn't help.Can anyone help me with this problem.I come from the Netherlands and use my boat only in sweet water.Thanx,John.

[roscoe]

Hello John, welcome to the board.Lets start with the basics.Check the compression.Check for spark on each cylinder.Chech to ensure fuel is reaching all cylinders.Also check all wiring for loose connections or wear.I suspect that part of the ignition system is failing. Hopefully it is something inexpensive, like a coil or a sparkplug wire. (a repair manual will have an extensive instructions to test the ignition) order manual here

[JohnBayliner]

Hello Roscoe,Thanx for your reply, i'll check all of your suggestions when it stops raining here.I just can't understand why it's running bad one time and running good at the other time.I think it can't be the compression, that will cause the problem to be the same allway's

[JohnBayliner]

Originally posted by roscoe: Hello John, welcome to the board.Lets start with the basics.Check the compression.Check for spark on each cylinder.Chech to ensure fuel is reaching all cylinders.Also check all wiring for loose connections or wear.I suspect that part of the ignition system is failing. Hopefully it is something inexpensive, like a coil or a sparkplug wire. (a repair manual will have an extensive instructions to test the ignition) order manual here

[JohnBayliner]

Hello Roscoe,I just checked the compression and found out that i have no compression on the 4th cylinder.What do you advise me to do??

[fixin]

Double check that's not good!if you have 0 compression something probable broke

[JohnBayliner]

I've checked it by hand and on the 4th cylinder i could rotate the flywheel very easy.On the other cylinders i had resistance while rotating the flywheel.I don't have a compression-meter so i did it this way.

[fixin]

try taking a straw and puting in plug hole and turning flywheel by hand and see if you can feel the piston moving

[JohnBayliner]

I can see the piston moving and the surface looks ok but that is all i can see.I think it's either the gasket or a hole in the piston. But is it a difficult job to repair it?

[fixin]

The gasket is easy,everything else is a compleet tear down,did the plug look wet?

[JohnBayliner]

Yes, the plug looks wet and there is also a crack in the insulation of the plugs cap.

[JohnBayliner]

Can I use this engine for this summer, or do I do much more damage to it when I use it in this condition?

[fixin]

I'd say its probably the gasket,you might want to check local auto parts stores,some will let borrow or rent a compresion gage,its up to you to procead with pulling the head off and looking,24 bolts 225in.lbs torque when replacing starting in the center and working your way out alternating top bottom.

[JohnBayliner]

Thankx,I work at a GM dealer, and they will have the right tool for this job, so i'll ask them for it.I hope it is the gasket, because of the cost.Do you know where i can buy a new gasket?

[fixin]

I'd wait and see if you get some more post,everyone is probably out for the holiday,I'm getting ready to leave myself,but will check around for you and get back to you tonight,have a safe one.

[eurolarva]

It looks like the head gasket is Mercury part number 27-F694529-1. I hope you have a merc dealer over there. If not I will try and find you a link however I got to think most places here do not ship to the Netherlands.good luck

[JohnBayliner]

Thank you all for the help, i'll go and take the engine apart and see what's the problem.If anyone knows where to buy the parts, please let me know.Thanx again.John.

[eurolarva]

You can try here. merury/force partsBefore buying parts though you may want to narrow down what is wrong. You could have a coil that is bad, A carb not working a distributer or bad compresssion. Do the compression test first then go from there. YOu really need a manual as a guide.

[JohnBayliner]

I've checked the compression and found out that i've no compression at the 4th cylinder.I've checked this manualy, but found out that the 4th cylinder has almost no resistance when I rotate the flywheel.

[fixin]

hey John;I made it back,did you find anything?I hope your waiting to do a mec.comp test.I didn't realize you were in the Netherlands I have know idea who ships there.eurolave is definetly the one to talk to(can't thank enough for all the help gave me)anything I can do to help I will

[eurolarva]

Here is a picture of the gasket. It is about 55 us dollars. Maybe you can contact them and see if they ship overseas. I would think you have a merc dealer somewhere over there. gasket

[JohnBayliner]

Hello everyone,Today i got the time to take the head off.I found out that one piston is burned so i have to replace it. Can anyone give me some help on how to do this job?And where can i buy ths piston?

[eurolarva]

Here is a link to the breakdown and parts for the piston. You can copy the part numbers down and try and find them over there somewhere. They are actual Mercury part numbers. Good luck crank piston

[DJ]

johnbaylor,Just replacing the piston is not the cure. You are fixing the symptom and not the cause.One of two things caused the piston meltdown.1. Carbon buildup stuck a ring. (not unusual for a Force-regular decarbs are a must)2. A carburetor jet is clogged and leaned out that cylinder.