1989 Force 85 hp power loss at wot.

[CaptainMcDonald]

Hi i'm a lost on trying to get started on fixing the issue with my boat. I have a 1989 Force outboard 85hp that has a power loss at wot. It starts every time with no issues and runs smooth until i try and give it full throttle. At wot i am sitting at only 3400 rpms for some reason and it will surge between 3400 and 4000 the whole time in the water at wot. But when i take it out of the water and hook up the water muffs it runs like a champ it will run up to 6000 rpms with ease. I have replaced the spark plugs and cleaned out the distributor wire caps that hook up to the plugs. I haven't done a compression test yet. Should that be my next step or is there other things to do also? Any help would be appreciated Thanks.

 

[jjr1975]

Re: 1989 Force 85 hp power loss at wot.

I have the same boat (L-Drive) with the same problem. Runs fine in neutral at high RPM but in gear, it bogs down when you give it gas. Also, if you give it gas while in gear and then raise the lower unit slowly, the RPMS do climb.

Anyone???

 

[Frank Acampora]

Re: 1989 Force 85 hp power loss at wot.

If it has a distributor it is NOT an 89. It is earlier, like 78.

Anyway, simply put, you are running out of gas. Out of the water and with no load on the prop, it will rev to well over 6000 RPM using very little fuel. Revving an engine in neutral does nothing and tells you nothing. Even an engine with one cylinder not firing will rev up in neutral.

So, If you have not done so in the past, replace the fuel pump diaphragm and gasket. Remove all three carbs and clean them, then reset the float levels. Check the entire fuel system for partial clogs from tank to carbs. Finally, for safety, put a cheap plastic inline filter between the fuel pump and carbs.

By all means, do a compression check. It will tell you the general health of the engine. Look for numbers up around 145 (factory new) but age and gauge variations may give you numbers as low as 120. The key think is uniformity between cylinders--no more than 5-10 PSI difference.

 

[jerryjerry05]

Re: 1989 Force 85 hp power loss at wot.

Like Frank says your running out of gas or the fuel system is clogging(vent line) or possibly sucking air under load.
Check all hoses for soft,weak.
Ethanol is de-laminating the inside of the hoses and can make them collapse.
The original gas line connectors have a rubber seal.It goes bad and allows air in.