Force 85 lost power at WOT.

[Blackcatecho]

Hi guys, I'm new to boating and recently purchased a 1988 Bayliner Capri with a Force 85 motor. I had replaced the spark plugs and replaced the gear oil as a preventative measure, but otherwise the boat looked to be well cared for. We had it out all of labor day weekend without issue, until Monday. We had turned around to head back to the marina with about a quarter tank of gas left. While at WOT the engine started to surge, then surge less, then just cruised at about 10mph (throttle still at WOT position). We continued this way for about 20-30 min (I stopped a few times to look around an scratch my head). Prop looked good, no odd vibration, just quieter and slow like as if I throttled down. We eventually ran out of fuel after having to cruise back at such a slow pace and were towed in. Could this have been due to low fuel? Could we have cruised for 20-30 min on low fuel with engine running smootly (albeit slowly) the whole way back? I checked the fuel line and filter, both looked good. The I pulled the plugs and they looked a little oily and dark, but not ridiculous. The bottom plug looked a little more oily on the bottom half of the plug. I feel like I should take it to the marina to get looked over (as to not get stranded with our little one again), but wanted to find out if there was anything obvious that I am overlooking or if this is just how the engine acts approaching low fuel. Thanks in advance for any advice.

 

[Frank Acampora]

No, that is not how low fuel affects the engine. They should run strong until fuel level gets low enough to suck air. Before taking it to a marina where you will be charged outrageous prices and probably need to wait weeks, buy or borrow a compression testing gauge and check compression on all three cylinders.

 

[Blackcatecho]

Thanks Frank. I didn't think so, but this is my first outboard. I'll check the compression and go from there.

 

[batman99]

Yes. check engine PSI. All cylinders should be within 10% range (from lowest to highest) and above 100 PSI. Higher than 110 the better. While checking PSI, do check for all plugs for good spark as well. To do this, remove all plugs, ground each plug and do a visual check. Never do spark test in open air (without grounding the plug) because is hurts its ignition system. Hope this helps.

 

[Blackcatecho]

Turns out compression was 130psi on all three cylinders. I blew compressed air through the fuel lines, checked the fuel filter (clean) and spark was there. Against my wallet's wishes, I did want to get out on the water this weekend and next, so I ended up taking it to the marina since I wasn't going to have time this week to figure out what the issue was much less fix it. They found that two plugs were getting lower voltage than they should and the third was significantly low. Had this been the off season, I would have used the repair manual and tinkered more, but hopefully I'll enjoy the boat a few more times. Has anyone here swapped out a stator on these motors? The part itself seemed to be the expense in this repair.

 

[Blackcatecho]

Incidentally, what do you guys suggest to be best way to secure the motor while trailering the boat? Roads here in IL aren't always great to say the least. I would like to keep strain off of the transom and hydraulics if possible. I don't think I can use a typical transom saver with the Escort trailer I have since it doesn't have a rear cross bream. Thanks again for your advice.