3.0 L will not get up on plane

[Coork Johnson]

OMC 3.0 L will not go above 2200 RPM, new plugs, new plug wires, new fuel filter, disconnected fuel line and fuel spurts high (no fuel pressure gage available). With out load engine revs normally.. Fuel is from late last year, but stabilizer was added.

 

[Walt T]

Re: 3.0 L will not get up on plane

Do a compression check, and be sure the hull is clean and the boat isnt water logged. If it has points, be sure theyre okay. I assume it once ran fine with the prop that's on there. If all else checks out be sure the exhaust shutter isnt stuck shut.

 

[Coork Johnson]

Re: 3.0 L will not get up on plane

Pulled plugs wires one at a time. Engine ran rough when all except # 4 is pulled. Engine runs the same when plug wire # 4 is on or off. Checked for spark on # 4 and has what appears to be a good spark. I will not have compression tester until Monday. Any Interim ideas? Could timing off cause this?

 

[Franki]

Re: 3.0 L will not get up on plane

If cyl 4 isn't firing, then it isn't likely to be a timing issue..<br /><br />did you check the actual plug on that cyl?<br />if not, change it for another cyl and try again. see if the problem moves to the other cylinder.. I have seen that happen.<br /><br />Check the compression on that cylinder, pull the plug, and stick your finger in the plug hole while its turning over.. if it has a hole in the piston of something else that would cause total lack of function, there will be practically no compression at all.. if it blows past your finger hard, then its probably got enough to at least fire..<br />pull another plug out and use that to compare between the two for compression..<br /><br />its not terribly accurate, but it will tell you if there is a big difference between the two..<br /><br />rgds<br /><br />Frank

 

[Coork Johnson]

Re: 3.0 L will not get up on plane

Pulled plugs on #1 and # 4 and placed thumb over hole. I could not keep my thumb over the hole on cylinder in # 1, cylinder # 4, I could keep thumb over hole if I used all of my weight, (and I weigh over 200 lbs. and have been called a gorilla by my wife. BTW she normally posts on this site not me, she is churching today. I check earlier posts and noticed that she did not mention that we installed new manifolds last week. Prior to installing manifolds acceleration was erratic on several occasions (identical to current problem, but would clear up on it own, we thought that it was bad gas and once we burned out all of the winter storage gas problem would go away)). We found crack on bottom of manifold (small water leak) while troubleshooting, and that was why we replaced manifolds.

 

[hu g rections]

Re: 3.0 L will not get up on plane

did u change points & dist. cap? make sure the points are adj. properly. also replace dist. cap. it may have a hairline crack that u can't see. pull the cap & check condition of distributor. any rust build up on the rotor? moisture?

 

[screenbuzz]

Re: 3.0 L will not get up on plane

i'm not an expert but had a similar problem once with my boat not wanting to get on plane and rpms ran low .it happened right after having lower unit rebuilt. come to find out chokes were not fully opening at full throttle. thay were only opening up about a 1/4 of the way. adjusted throttle linkages, fixed problem boat then planed, rpms ran 5500/6000.

 

[Coork Johnson]

Re: 3.0 L will not get up on plane

I have found reference to a leak down check in my Clymer manual, but no procedure for it. How do you perform? Also where to attach hose for vacuum gauge check to compare compression test results?