Merc 3.0L I/O - it's get-up and go has got up and went!

[chrisg]

I have a 2-year old Bayliner with a Mercursor 3.0L 4 banger. <br /><br />I made the error of letting the local marina 'tune up' the motor. ( at 2-years old, it really did not need it)<br /><br />It was hard to start and would backfire untill warmed up.<br /><br />So I got a timming light, and with a help of a friend, checked the timing. It was at 11 deg. ( not sure which way), so he adjusted the rotor to about 6 degrees, which slowed the engine down( at idle) He then adjusted the idle screw untill it was reading 6-700 rpm on the tach. <br /><br />Now the engine starts better, but sometime back fires and dies when I 'floor it', even when it has warmed up. <br /><br />The thing still does not have the punch it use to. When I'm pulling a tube with 3 kids, I can advance the trottle from 1/2 to full, with no change in speed, the boat will not get up on plane!(this was true before we adjusted the timing). It maxes out at 3200 rpm. and its top speed now it 30 MPH!<br /><br />The problem I have is that I could take it back to the dealer, but there is no water around there, and the real problem does not appear until you pull something. I hate to haul it out there, and get it back, just to find it still has the same issues.<br /><br />I was thinking of taking the cover off the engine, and keep adjusting the timing while pulling someone on skies. <br /><br />Is there more to this then getting the timing right, or is there some carb adjustments to be made?<br /><br />I'm going to go up tonight and put some of that sea foam? in the tank to clean the carb, and also replace the park plugs to see if that helps. Again, its only 2 years old.

 

[Haut Medoc]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

Are you sure the wires are right? 1-3-4-2 cw. J

 

[chrisg]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

I will check that, but would it not start if the wires were wrong? It does not run rough.

 

[Alumarine]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

Are you sure your friend set the timing and adjusted the carb correctly?<br />If not, that could still be your problem.

 

[cosander]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

maybe a spark plug wire not snapped in all the way?

 

[craze1cars]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

There's a procedure for adjusting that timing. Not sure about your 2 year old model, but for example my 1992 required unplugging some of the electronic controls, and putting a jumper wire between two connections, etc to make sure electronic timing advance was disabled so base timing could be set. Then you remove the jumper wire and check the function of the electronic timing advance. Then idle mixture needs to be set, as well as idle speed, which can often only be adjusted by disconnecting and adjusting shift/accellerator cables, etc. I'm being very vague here with exact procedures because it takes about 4 or 5 pages to explain from my mercruiser manual. You just need to realize that this is not as simple as simply hooking up a timing light and turning the distributor cap and thinking that it's done. If any timing or carb adjustment is off by just a little bit, the 3.0 will run VERY poorly.<br /><br />If your friend, or the marina, didn't follow the exact and proper procedure when they messed with your timing, I'm absolutely certain that your base timing is probably WAY off and this would most certainly cause a lack of power, backfiring, and strong potential for engine damage from detonation. I think you got lucky and it sounds like your friend retarded the timing instead of advancing it. Retarded timing will cause the sluggish handling you're describing. Advancing the timing may blow holes in your pistons and crack your heads. So don't let your friend mess with it anymore unless he has a Merc manual in-hand. And if someone turned some screws on your carb somewhere in all this, you no longer have a baseline to work from to even get the timing set right at this point because the mixtures and idle speeds are all off.<br /><br />If you don't have the Merc owner's manual to guide you through the proper steps of a tune-up, then take it to a marina and have them return the whole thing back to factory specs in the systematic order that Mercruiser spells out. SeaFoam and sparkplugs will do nothing for you until a basic tuneup is properly done. I'd do this soon, you honestly have the potential to do internal engine damage if you continue driving the boat with these adjustments as far off as it sounds like they are.

 

[Wotknot]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

Before your friend did the timing, did he put it in base mode? If not, then the timing's still gonna be off.

 

[chrisg]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

Thanks all, <br /><br />Sounds like mercs are not simple. (Now I can understand the cost of the tune-up!).<br /><br />Lessons learned:<br /><br />1) NEVER let local boys at a marina touch your engine<br />2) Take Mercs back to dealer<br /><br /><br />So, If I haul it back to the dealer, will he be able to put it back without having a lake to run it in?<br /><br />I know that originally, the engine would run on after turning the key off, which is what is it now doing again.<br /><br />Guess I'll have to live with the run on.

 

[vipzach]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

The 3.0 motors are really picky about being dead on when it comes to their timing. The dealership should be able to set the timing with the boat hooked up to muffs. I don't think it is just a merc thing.<br />As far as the run on, if it continues when you get it back, try switching to a higher grade gas, running the blower more, or letting it idle for a couple minutes before you turn it off. Good Luck!

 

[craze1cars]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

You don't need a lake to tune it, most marinas or dealers do it on land with cooling water hooked up or with the use of some type of test tank. <br /><br />Also, there's generally nothing wrong with most local marina mechanics, if they follow Merc's procedures. The 3.0 is an old-tech motor that has been around a long, LONG, time. I'd think any marina, or person (I did my own, in my driveway, and I've never worked at a marina. Just took a couple hours of reading the manual and systematically following the steps in order), could do a respectable tuneup on a 3.0 if they just read and follow the listed procedures and use the right tools, not sure why yours went wrong. You haven't mentioned whether or not you complained to the "local boys" about this. Maybe they just did something simple wrong that they would correct for you for free? Or maybe they'd re-tune it again for free since you paid them once already and they obviously did something wrong. Unless they've completely destroyed your faith in other ways, it might be worthwhile to let them try one more time...everyone makes mistakes. Either way, this shouldn't be a difficult problem to correct for anyone who knows the procedures for doing a 3.0 tuneup.

 

[chrisg]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

Thanks guys, I adjusted the thing one more time - found that the rotor and cap has rust on them! Once they were cleaned, the thing worked fine!<br /><br />Now I have full power, RPM in the correct range, top speed 45MPH, It pulls skiers out of the water like before. All is good!<br /><br />I most likely will take it in for a good tune-up at the end of the seson when it is put to bed!<br /><br />Now to find others so I can ski!

 

[Don S]

Re: Merc 3.0L I/O - it's get-up and go has got up and went!

It's best to do your tuneup in the spring while getting it ready for the new season.<br />When the engine is winterized, the fogging oil ends up sitting on the spark plugs all winter. This isn't good for spark plugs.