1996 4.3XL Problems

[lancer78]

I have a 1996 Larson speedboat with a 4.3 XL Mercruiser engine. Whenever the boat is in drive, it shudders and the RPMs will not go above 1200 and the boat shakes moderately. However, in neutral, the engine can rev up to maximum and the boat doesn't shake at all. There are no good mercury technicians nearby, so I came here looking for help.

 

[searay3]

Re: 1996 4.3XL Problems

Check the obvious first. Condition of drive oil, bent prop/propshaft. There should be no 'wiggle' in the shaft as you turn it, it should turn true. If ok, pull the drive and inspect bellows/ujoints/gimble etc. Revving the engine with no load really doesn't tell you much. If all looks good post back, but I think you will find something there.

 

[Chris1956]

Re: 1996 4.3XL Problems

Lancer, It sounds like a bent/damaged prop. Try a known good one to see if the damage is something more sinister. It could also be bad u-joints, but they would need to be pretty bad!

 

[Gary H NC]

Re: 1996 4.3XL Problems

Hard to say without a load on the engine..Has it ever overheated?