2001 Maxum 2900 SCR 7.4L STOPPED PLANING OUT!

[NautiGal]

Boat/purchase history: 2001 Maxum 2900 SCR 7.4L MPI 454 w/Bravo 3. Found the boat online through local dealer this past January and loved everything about it so went to take a look. She was immaculate and has every bell & whistle you could ask for! 300 hours on engine & 1500 on Westerbeke generator (older couple bought her from same dealer 8 yrs prior and used her primarily to cove out on wknds. Selling her so they could travel to see grandkids more). Always freshwater kept. Opened the engine compartment & immediately noticed thick black liquid in bottom of it…not water with a film over it. Broker tried to tell me that was normal – I knew better & said so. Still very interested in boat so proceeded to set up survey/sea trial. Morning of survey they have her up on a trailer to check hull, lower unit, etc. Broker says to try & stop my surveyor if possible because he had some problems getting her up to speed – idle was fine but bogging under power. Surveyor already on way so he did the out of water check which was all good. We also pulled quite a few zebra mussels off lower unit. Local dealer shop determined the fluid in engine compartment was gear lube from broken seal in lower unit (confirmed what surveyor suspected) so owner agreed to repair that, replace faulty thermostat, and replace spark plugs, etc(basically a mini tune-up). Went for sea trial following wknd. Surveyor was out of town for 2-3 wks so took my marina mechanic who is also married to old friend of mine. She planed out/sea trialed beautifully! We ran her for half hour with no problems whatsoever. He noticed slight starter drag while starting and perhaps small leak in riser but nothing that would be a deal breaker. Pulled trigger following week(mid-Feb) then had to wait a month to have her transported to my lake/slip (beam too wide for us to legally tow without permit). My mechanic met us upon arrival at ramp so he could inspect lower unit, bellows, bottom job, etc. since he didn’t get to see during sea trial – all looked good. Noticed center lights of transport guy’s trailer were busted – he said my broker pulled the boat up a little too far on trailer that morning & lower unit broke the light cover but everything looked/worked fine. We launched, she started right up, ran well, planed off and I managed to back her into my slip on second try! =)

When problems began: Weather went south so couldn’t run her for a few weekends but when I was able to she planed out & ran fine - although I had a heck of a time getting her started and she died under idle a few times. We assumed due to starter drag, half tank of old gas & lack of use so mechanic suggested I add a bottle of Techron Fuel Cleaner (said he’s had better luck with Techron than SeaFoam) and RUN HER! He said running her is the best thing I can do for her since we really have no idea how long she sat or how long that gas had been in her. Fast forward a few more weeks to late April/early May and the starting/dying problems are resolved, she has new gas and things are improving BUT then one day she wouldn’t plane out. Could only get 3900 rpms and 10 mph out of her – UGH! Had passengers get in cabin which made her plane. Mechanic takes her for a spin, notices a rhythmic miss and thinks bad spark plug/cylinder creating power loss. Opens her up to diagnose which plug and says it didn’t look like the spark plugs had recently been changed like they were supposed to have been by dealer so he slaps a whole new set in. Still won’t plane 95% of time! The only two times she planed after this were after I slept on the hook - she didn’t plane on the way to sleep cove but she did plane out when I was driving her back to marina the next morning. Go figure?! Now he’s thinking maybe dirty fuel injectors so we add Techron Injector Cleaner and keep running her (he says I’m not hurting anything else by running her). Tried new plug wires with no luck. She won’t even plane when I’m solo now OR when I put people in cabin bow. Last test run he was been able to get her up to about 4100 rpm using some little tricks he knows but still not planing and he says she should plane around 3500 - 3800. Oh yea, we shut it down to jump in water to cool off and when he went to start her the dang ignition switch broke so now that has to be replaced. UGH!!! I asked if we need to do a compression test - he says no because she’s idling smooth, all gauges reading fine, etc. He is running out of options to check in ignition system. Now he’s wondering if it’s prop or lower unit related instead of/in addition to fuel injectors. Really hate to spend a few thousand on new injectors only to find out that’s NOT the problem! Btw, trim tabs and trim are working fine. Any suggestions as to what it might be or what tests he can do to diagnose it? At my wit’s end!