1985 85hp Force Request

[ForceHeadache]

Request - I bought a 1985 16' Bayliner Capri w/ a 1985 Force 85hp motor. Came with 2 6-gallon metal gas tanks (old). Ignition box was replaced a couple months before I bought it. Runs good some days, and terrible other days. Main problem is not wanting to start some days, but starts fine others. This weekend it ran fine on day 1, but on day 2 it kept stalling unless i started it in neutral w/ some gas, then jammed it back up and into forward gear. Plugs look a little rusty near insulaters - I pulled all 3 and they didn't look too bad, but not sure how bad, bad is.<br /><br />I am not a real gearhead, but do know some basic auto mechanics. Never touched an outboard motor before though.<br /><br />What should I do as a starting point to tune up this motor? I read through the owners manual, but couldn't really decide what should be done as a tune-up. I have also read some stuff about tachometers and buzzers for overheating, but have'nt seen either on my boat.

 

[12Footer]

Re: 1985 85hp Force Request

The first thing to check is thw compression. Rust on the insulators {inside surfaces) is bad news. Outside, in the elements,it's normal for the metal portion to rust quickly. But never should you have rust inside a cylinder. It is a sign of water injestion. Yes, it could be condensation from the fuel tanks,so check them next.<br />If they are clean, you may have a blown head gasket.<br />The Force engines (except for the 50HP and under) seem to share a weakness. The exaust port plates warp very easily durring an overheat event.<br />They will allow water to enter the combustion ports,and thus, into the cylinder.<br />But a compression test usually shows this up.<br />If you can hold a finger on the block by the head for three seconds,after two minutes of running, you are not overheating.<br />There will be a plug-type device in the block with one wire comming from it. This will be the temp sender.Short to motor frame to test.<br />The best indicator of water flow thru an engine is a pressure gauge.<br />But most of these Bayliners came with temp warning buzzer only. So anything more than that (IE,Temp or pressure gauge),is an improvement.<br />Most shops use a 120-140degree melt stick on the block to test for hot spots in the block (They only got ten fingers)

 

[jubjub]

Re: 1985 85hp Force Request

I have the same boat and engine. I recently purchased.<br />I ran good a few times out. I had plug foaling. Last time mine shut down at full throttle. After that I had the same symptoms and had to start and slam forward. The thing shut down anyway again. I had weak compression in 2nd cylinder and had begun tearing it apart. The lower two pistons show wear. My mechanic said it could be caused from lean fuel or mixture..Still exploring ... Definately do the compression test..Decarb the carbs...<br />We may have the same issue...<br />Good luck.