1996 Force 120 won't start. Ran fine all week

[JordyOutboard]

So I took my boat down to the bay and ran it for the first time in saltwater in years. I had Frank (RIP) replace a piston at the end of last season and it has been running great ever since. I had it out for 4 days this past week. On the last day it stalled once and the. Started up and got me to my destination. A few hours later I started it and then it stalled a few minutes later. I wasn't able to start it back up. I removed the spark plugs while out on the water and they were wet and very dirty. Like almost a muck on them. Very strange.

I wiped them clean with a rag and put them all back in. I was then able to get the boat started and rode it about 2 miles to the ramp and got it back on the trailer. At first it was moving at 1/4 throttle even with the throttle at full position (2000 rpm?). Eventually it clearer itself out and climbed to 5k rpm at which I then slowed to about 4-4500 rpm to get home.

So a few days later when I got the bot back home to my garage I took all plugs out and cleaned them good. I also had the battery tested and ended up replacing it. The engine still cranks slow and isn't starting.

I'm running out of ideas here. All plugs have spark. Anyone have any ideas where I can start next?

Thanks

 

[SkiDad]

Maybe torn fuel pump diaphragm?

 

[jerryjerry05]

Muck?? Could be water??
Do a compression test.
Check filter for water.
You have a water sep filter?
Install one and take it for a ride.
Then check the filter for water.

It sounded like you had a slug of water go through the system??

 

[JordyOutboard]

Maybe torn fuel pump diaphragm?

Thanks, Ill look into this

 

[JordyOutboard]

Muck?? Could be water??
Do a compression test.
Check filter for water.
You have a water sep filter?
Install one and take it for a ride.
Then check the filter for water.

It sounded like you had a slug of water go through the system??

I did a compression test and all cylinders came up at 60 psi. This isn't normal as they were all around 120 after i had the piston replaced.

Could it be that the cylinders are dry and the compression is now lower?

 

[Nordin]

Are you using the same gauge as showed 120 PSI?
Sounds your gauge not shows right. Try another gauge before doing anything else.

 

[jerryjerry05]

.
​Get a second comp tester.(Nordin)
Remove all the plugs and then do the comp test.
Then spray WD 40 in the holes and do another test.
Post the #s.

Dry cylinder?? If your mixing the oil/ gas right there should be oil in the cyl

ANY moisture on the plugs.
Look for TINY, TINY drops on the edges.

Test the overheat buzzer and see if it works?

 

[JordyOutboard]

Thanks guys. I am gonna get a new compression tester and squirt some WD40 in the cylinders to get the most accurate reading.

If the numbers all come back low and within 10% of each other, i will assume the head gasket blew. Ill check for any moisture as instructed above as well.

I appreciate everyones help!

 

[jerryjerry05]

Do the test before and after adding WD

 

[JordyOutboard]

Alright so I removed the spark plugs after pulling the first one and seeing rust on the plug bottom. I took the rest of them out and moving down towards the bottom of the engine the spark plugs gradually get better.

I tried to do a compression test but the engine was barely turning over. It's like it was being restricted. I also have a brand new battery in it.

Next I pulled the head and the Pistons look like water got in there. I used WD-40 to clean them and make everything lubticated again. The top cylinder that had the rusty plug had some a abrasive areas of the wall that I could feel to the touch. It wasn't Terrible but there was a difference between the feel of the bottom cylinder.

So with my low compression numbers along with the water in the cylinders indicate I just need to replace the head gasket or is there other things I should be inspecting?

Thanks again for the help. I'm a noob with these engines

 

[JordyOutboard]

I have pictures that I can post when I get home. I'm getting an error on my cell phone

 

[jerryjerry05]

Gotta make sure the head gasket was the problem.
Water comes from 4 ​places. Head gasket, exhaust chest, cracked block, cracked head.
Check the exhaust chest screws and make sure they are tight.
If waters only in the top cylinder? then it's probably a head gasket.

Before the gaskets installed. Maybe a bit of steel wool and clean up the rusty cylinder.
Use a magnet to get the wool that sluffs off.
Carb cleaner in the hole and WD after the cleaning.

 

[JordyOutboard]

Gotta make sure the head gasket was the problem.
Water comes from 4 ​places. Head gasket, exhaust chest, cracked block, cracked head.
Check the exhaust chest screws and make sure they are tight.
If waters only in the top cylinder? then it's probably a head gasket.

Before the gaskets installed. Maybe a bit of steel wool and clean up the rusty cylinder.
Use a magnet to get the wool that sluffs off.
Carb cleaner in the hole and WD after the cleaning.

Will do!

Gonna order the gasket now. Should i use some sort of RTV sealant as well? Both sides of the gasket?

Ill probably replace the spark plugs as well.

Thanks again for hanging in there with me!!

 

[JordyOutboard]

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[JordyOutboard]

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[jerryjerry05]

No sealer needed unless the mating surfaces are bad??
​Try the gasket first and do a compression test.
Before starting and then again after it's ran for 15min.
The gasket is covered in a sealer that melts and fills in the cracks.

I've only used sealer on 2 motors that had bad corrosion.
Both were Yamaha smaller motors 40 and 60hp.

 

[JordyOutboard]

Gasket just came in the mail this weekend and i just got new spark plugs

Does anyone think i should replace the head bolts? Or at least put some washers on before i reinstall? I hear they may have stretched which may explain the two head gaskets in such a short period of time.

Thanks

 

[jerryjerry05]

You only have 20# of load on the bolts
​I doubt they stretched at all.
The older style came with washer, not lock washer.
The newer doesn't seem to need them.

I don't think it would hurt if you installed them.

If you went through 2 head gaskets. I'd check the mating surfaces and make sure the gaskets are fitting right?

You have a straight edge?
A piece if glass is pretty flat.
Check the block for any gaps.

 

[Derrick Fronckowiak]

Jerryjerry05...good point. If the head or block are warped or otherwise not true you could be replacing head gaskets all day. That goes for four-strokes too. Do these motors get that hot to the point of warpage?

 

[jerryjerry05]

Yes.
​They can get so hot you can crack a cylinder wall.
Or separate the cylinder liner from the block