5.0 MPI Mercruiser Sluggish after Tune-Up

AJBeastro

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Jun 23, 2010
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3
I recently had a tune-up and bad IAC valve replaced by a local Glastron dealer on my 2005 SeaRay 200 Select with a 5.0 MPI engine. After getting the boat back on the water it seems very sluggish out of the hole and it wasn't like that before I brought it in even with the bad valve. Altogether, the IAC valve, rotor cap, fuel filter, oil filter, and spark plugs were replaced, as were all the fluids, and the timing belt was adjusted. The dealer tried to charge me an additional 15% over what was quoted and because they didn't order the parts needed for the tune-up when the boat was dropped off it set the repair back an additional 2 weeks. All of that caused quite a falling out between us so now I am afraid that the work was done wrong (either on purpose or not) and now I won't get any help from them. What I'm wondering is if it is normal for sluggishness to happen as a sort of new break-in period since there are many new ignition parts installed. I've only briefly driven the boat so far but I don't recall having this issue when it was brand new so I'm a bit worried that something wasn't done right with the repair and tune-up. Any help or suggestions would be appreciated.
 

indy440

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Jul 15, 2009
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400
Re: 5.0 MPI Mercruiser Sluggish after Tune-Up

adjusted the timing belt? How does one do that on an engine without one?

Check to see if its running on all 8 cylinders, and make sure none of the wires are mixed up or crossed. That would be my first guess for it being sluggish.

They could have also thrown the timing off if the distributer bolt isn't tight. Put a timing light on it and check that.

Or if they already checked the timing then maybe they forgot to remove the jumpers and left it in timing mode? This wont let the ignition advance.
 

Bondo

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Apr 17, 2002
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70,458
Re: 5.0 MPI Mercruiser Sluggish after Tune-Up

What I'm wondering is if it is normal for sluggishness to happen as a sort of new break-in period since there are many new ignition parts installed.

Nope,... It should be at it's Peak Performance...
 

AJBeastro

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Jun 23, 2010
Messages
3
Re: 5.0 MPI Mercruiser Sluggish after Tune-Up

I took a look at it last night and found out that there was no spark on wires 3 and 7 coming off the rotor cap. I replaced the "new" one with the one that was replaced and everything works great! Most of the corrosion on the old setup was on the rotor itself so I'm hoping that having the combination of the two will continue to work for a long time. Thanks for everyone who gave me some suggestions. I'm glad it's working now with minimal work done on my end but I can't believe that the mechanic didn't catch this. You could feel a slight shutter since two cylinders weren't firing not to mention that the exhaust didn't smell right with all that gas that wasn't burnt.
 

6meter

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May 15, 2010
Messages
525
Re: 5.0 MPI Mercruiser Sluggish after Tune-Up

I'd go back and have them explain the "new" bad cap. More than likely it was an after market cap, cheaper, or used. I'd also would like an expaination on how they "adjusted" your timing belt. A 5.0 has two gears and a timing CHAIN, which there is no adjustment to it. Seems like you should have a refund coming
 

AJBeastro

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Jun 23, 2010
Messages
3
Re: 5.0 MPI Mercruiser Sluggish after Tune-Up

Adjusting the timing belt might have been a term I misinterpreted, maybe they said that they were just going to inspect the belt and adjust any tension pulleys. As far as the bad rotor and cap go, yeah, I should go back and make a stink about it but I probably won't. I had already made them discount the repair for about what it was worth since they a) didn't bother to order it until the first day they had time to work on it a week and a half after it was dropped off, and b) didn't bother to tell me that it was on backorder until two days after I was told for the first time that they even had to order it. Basically, they said this was something they do for all tune-ups but it seems like they didn't have the foresight to order it in time and to make sure I was aware of that fact. The part definitely looks like new but everything works now using the old cap and the new rotor so I'm probably just going to wash my hands of it and never look back. I'm in Minnesota and there are plenty of other places I can give my business to, including two more places just across the street from this one.
 
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