power loss on '98 Force 50hp

[Irish Rob]

Last week I began having this problem, I can't gain any speed even with WOT. I replaced spark plugs, fuel impeller, and the water/fuel separator to no avail. Then with the cowling off to see what was happening the motor was able to get on plane and acts normal. Put the cowling back on and the engine slows back down significantly and can't plane. Carb need air, right? No lose wires noticed, no obstruction to carb., Cowling not touching anything. I talked to a mechanic over the phone and he mentioned a possible exhaust leak might be filling inside the cowling prevent air intake to the carb. But how do I diagnose this? I see plenty of exhaust coming from the lower unit and none really from the little opening in the cowling. I'm mystified. Please help. Thanks.

[eurolarva]

You might want to start with doing a decarb. See frequently asked questions. Motor seems too new to be doing gasket replacements. That motor also has a recirculation system that may not be working. Decarb would be the cheap easy first step. I prefer Seafoam Deep Creep. Use the whole can in one treatment. Are you mixing your gas 50 to 1?

[roscoe]

I would bet on the exhaust leak.Dish soap and water works good.Start engine and pour the solution around the base of the powerhead. If it starts bubbling, you found an exhaust leak.There was a post on here a few months ago where the exhaust gaskets on a late model Force had gone to heck.

[eurolarva]

http://www.iboats.com/cgi-bin/ubb/ul...=005689#000001

[Irish Rob]

Thanks, I'll try the dish soap trick first, if I don't get any bubbles (I pray I don't), I do a decarb.

[Irish Rob]

Didn't see any bubbles, so I did the decarb with Seafoam Deep Creek. A lot of white smoke/exhaust coming from the prop but none coming from the powerhead area or general area. If I had a exhaust leak preventing planing on WOT, wouldn't I see enough exhaust fumes coming from powerhead area make it obvious it is an exhaust leak? What do you guys think? My next step is to test run again on open water and see if I can plane. Any info would be appreciated. Thanks again.Irish Rob

[eurolarva]

After the decarb you might want to get a new set of plugs. Decarb tends to foul plugs pretty bad. Maybe the problem is not exhaust gas inside the cowling. On my chrysler there are two holes in the front just below the cowling and a couple more on the port side. If you force has these make sure they are not blocked. Lack of air could be the problem. Good luck on the test run.

[Docdoc]

Rob:Just curious, have you run a compression test on this motor lately? If so, what were the results?

[bnk999]

If you had an exhaust leak I'd expect to see that white smoke coming out of it-

[Irish Rob]

Well the test run went good. I was able to get on plane almost immediately. Don't know if the decarb was the trick, but I really didn't do anything else. Thanks for the info you guys, y'all saved me a lot of heartache. Also, I just changed spark plugs before the decarb and didn't use the Seafoam in the spark plugs. Should I change just in case? I'm still a little pessimistic, I'll do a few more test runs before I think I'm out of the woods.

[Irish Rob]

I haven't done a compression test, but I'd like to know the numbers. How do I do one? Thanks guys.

[Docdoc]

Purchase a compression guage at most any auto parts store or Sears (about $25-$35). Put on the muffs, start motor and run at idle until warm. Shut off the motor, remove both plugs and ground them to the power head. Rig jumper wire across neutral interlock switch. Place throttle in WOT postion. Screw compression gauge into cylinder #1. Crank engine about 4-5 complete revolutions until max compression reading is obtained. Write down the number. Screw compression guage into #2 cylinder and crank 4-5 revolutions. Write down the number. Compression should be at least 110 psi and no more than 10% difference between cylinders.

[eurolarva]

When you decarb a bunch of carbon may foul your plugs. That is why it is recommended that you replace them. If motor is running good it would not hurt to carry a spare set in your tackle box with a plug wrench.