[tobaccogrower]

first, id like to start by saying thanks for this great site! i wish i knew about it 4 years ago when i bought my Z302!

i bought my Z302 in key largo, florida in 2004. i've always been a outboard man so this is my first I/O!
we bought the boat because we were sick of coming down to the keys and not being able to boat. we always come down february to march. its winter time so there is always alot of wind and it was hard on my 21 foot baja hammer(with a evinrude 250 V8 outboard)! we finally had enough and found our Z302.
we picked up the boat for what i thought was a fair price:$29,900 with a brand new aluminum magic tilt dual axel trailer(junk, never buy magic tilts)

the boat ran very well and only had 84 hours on it. it had been neglected by the previous owner. a little blood, sweat and beer we cleaned it up real nice!
we have ran the boat 4 seasons. 3 of them were in key largo. some of the best boating anywhere!


ok, no the problems!
my first problem is a surging idle. the Z302 has a mercruiser 502mpi powerplant with a bravo 3 outdrive. i belive there are 28pitch props on it.
when i come off plaine the engine will idle high. usally around 1200 in gear. if i slip it in netural it will lope from 1500 down to 800 back and fourth until i goose the throttle a couple times then it will settle down. i've taken the throttle cable off and checked the idle and it's the same deal. i thought it might be a misadjusted cable.

second problem is the motor will stall when going from forward to reverse or vise versa. somtimes even going from netural to forward or reverse. almost seems like alot of strain is put on the motor when going into and out of gear. this makes it almost impossible to dock the boat. backing in a slip is impossible. also, the boat will move in gear at idle at 6mph, forwatd or reverse! this makes it very hard to dock!

third, the boat lists to the starboard side when under power. i've added trim tabs to fix the problem. without them the boat runs to the starboard side unless i have passangers all on port side.

there are more problems but i figure this will be a good start. i'm going to bite the bullett and have a mechanic look at it and try to figure somthing out. bravo3's are supposed to be some of the best drives for dockside manners and i have just the opposite!

great site and look forward to your replies!

[ShabahZ280]

Welcome to the board, and thanks for your compliments, that's exactly why we created this forum, to help each other out. And you'll never find a more loyal and helpful group of people anywhere!

Let's see if I can offer you some help, and I'm sure the other members will chime in.

1. Do you know when the last tune-up was made on the motor? ie plugs, distributor, etc. This could be one of the first things to check, especially if the previous owner neglected the rest of the boat, I'm sure routine maintenance got neglected too. One thing to remember, I'm not sure what year your Z302 is, but even if it was an 01, that's 8 years old now, it's bound to have a few quirks. Start with cleaning the throttle body (behind the flame arrestor/air intake) with some air intake cleaner and some paper towels, then run some fuel injector cleaner or seafoam through the system, then see where you are. If the problem persists, do a tuneup, plugs, distributor and rotor button, then replace your fuel/water seperator filter and then see if there's any improvement. If you've still got issues, I'd check with a Mercruiser Certified mechanic, and ask them to perform a diagnostic check on it. The MPI engines have a number sensors that could fail and cause these issues.

2. That sounds like a shifter cable problem. I'm not 100% certain on that, but it seems to me I've read about people with similar issues and it turned out to be something wrong with the shifter cable. What kind of shifter do you have? The standard one lever shifting, or the Kiekhaefer controls, with two levers (one for throttle, and one for the transmission)?

3. You say the boat lists while under power. What about at rest at the dock? If it does it while not under power, I'd say you have a weight balance issue, that can be solved by moving any accessories, etc to the port side. However if it does it under power only, and regardless of the weight load, I'd have the drive alignment checked. You've done the right thing by adding trim tabs and I never understood why they weren't standard on Mariah's over 24ft. Anything larger, with a few passengers onboard, really needs some leveling ability. Which did you add, Bennett Hydraulics, or Lenco Electrics?

Overall, I'd say all your problems could be fixed by a Mercruiser Service Facility, if your budget is fairly flexible. As for your other issues with the boat, post them here, and we'll help you get them sorted out! The Z302 is a fantastic boat, and you don't need these type of problems with it! It really just sounds like the previous owner neglected the maintenance on it. We'll help you get squared away, and back to enjoying your Mariah the way it should be, stress free!

[tobaccogrower]

thanks for the quick reply!

i have never done plugs cap rotor. maybe it's time....

when i got down here i filled the tank(90gallons). i added a gallon of seafoam with that fillup.

the boat sits level while at dock. only lists under power. i didnt know i could have the drive aligned. sounds like that could be the problem. i added lenco's 2 seasons ago. the didnt work when i got down here though. i think the actuters are shot. i disconnected then from the control box and hooked them directly to a hot and ground(lenco told me to try this) and nothing happned!


i have the keikeffer controls. i was thinking cable also. had the same problem on my baja. cable fixed it. have you ever taken apart keikeffer controls? i wouldnt recommend trying it! took me about 4 hours to reassamble. ball bearings everywhere!

i have limited tools down here on vacation. i'll look for a cheap set of torx drivers and try to remove the throttle body. as far as doing plugs and rotor that will have to wait till i get home to connecticut!

[z275st]

Hi, tobaccogrower
My buddy has that same boat. I think you got a great deal at $29,900 in 2004 no matter what year it is! You stated you have list problems to starboard. Since you have problems with your tabs are you sure the port tab comes all the way up! I just added Bennett tabs last year and the slightest deflection of a tab will roll the boat to the opposite side.
I think if you get the idle RPM's down and steady it will help with docking, although with 28P prop you still move faster at idle. I have noticed this driving my friends boat as opposed to mine. If you raise the lower unit at idle it helps to reduce speed.
I totally agree with ShabahZ250, get a good mechanic to go over things. Sure it will cost extra but you and your boat are worth it, especially when you boat on the ocean! I would love to boat in the Keys! Happy boating.

[tobaccogrower]

the boat always listed, even before the trim tabs. what pitch props does your buddy have on his boat? i'm wondering if the previous owner changed mine...also ask him what his top speed is at wot. my max is about 54mph trimmed with 3 people in the boat.


this boat is awsome! we took it 7 miles out to molasses reef in john pennacamp state park skuba diving last week. boat roating report said 1-2 foot seas inside the reef and inshore waters moderate chop. well, we had 6-8foot waves at the reef and the mariah handled them with ease. this was when my trim tabs were set(had them adjusted for the listing last time i used the boat last season and forgot to put them up when i loaded it. they havnt worked since i've been in the keys so i manually retracted them)

my goal today is to find a mechanic down here to take a look at it. maybe it's somthing as simple as a vacume leak(i hope!)

[indykoch]

Engine stalling is most likely the shift interrupt switch. It retards the engine ignition for a split second to help the transmission engage/disengage. They're difficult to get "just right" for the average DIY. The cables could also be adding to your problems - maybe they've "stretched" slightly over the years.

[z275st]

His is a 2000 with the 502 also. he runs 28P's most of the time and topped out at 58mph. Then 2yrs ago he had a speed shop to "balance" the engine and add a Whipple Supercharger ($8,000) to increase to 500HP. To his disappointment it only gained 2-mph (60mph) top end. The shop said he would need to switch to a bravo1 drive to gain more speed.

I can only think of two more things that may cause your list problem.
1- A prop blade could be bent to have greater pitch than the others causing it to torque the boat to the side.
2- If a heavy boat has set to far back and the bunks don't fully support the transom it can cause the hull to hook causing unequal lift to one side of the boat.
Good luck!

Sounds like some great boating down there!