496HO stalling
 

O.K. I've done a search, but I can't find anything that matches the problem I am having.
My 496HO will sometimes stall when you are going out of gear and into neutral. It runs great otherwise, but seems to do this at the worst time, when you are around docks or other boats.
It has been to the dealer a total of 9 times now, and would never throw a code, it would just die like you turned off the key, and would be very hard to get restarted.
So far, the dealer has replaced the TPS, the IAC, and just recently the throttle body. He also swapped out the PCM, and the problem still persists.
Yesterday, it finally started sounding the warning buzzer, and I took it back again to be scanned. The codes it was throwing were for the crank sensor, the cam sensor, and low voltage. He stated if the cam sensor, or the crank sensor were bad, it wouldn't run as good as it does (runs great at throttle, just has the problem stalling coming out of gear)
He said he doesn't know where to go next with it, and I told him I didn't care, just fix it. If he has to put a new crank and cam sensor in to find out if they are the problem, just do it. He said he doesn't know the reason for the low voltage code.
Again, this problem has been going on for a long time now, and it never through codes before, so were stumped.

SUGGESTIONS?,
thanks

Re: 496HO stalling
 

where are you located??????

its hard to diag a problem of this nature with out seeing the spx read out or to do a on water test while recording the data when it occurs

as your mech said I to doubt it a cam or crank sensor it sounds more like a short in the system or a bad ground

best thing to do is find someone very familiar with the 496 a lot of techs around still arent very familiar with them just because they went to a couple of classes doesnt mean they know the motors

if you let us know what area you are in I my be able to recomend someone if not Im sure someone here can,
there are a lot of great techs here from all over

Re: 496HO stalling
 

I'm out in Lake Havasu, AZ. It's a warranty issue, and there is a lot of shops out here, but not many that are Merc certified. The mechanic that is working on it comes highly reccomended, and I beleive he is giving it his all, it just has him stumped.
The wierd thing is that it does it going from gear, into neutral. I could see a problem if you put a load on the motor, but this happens when you take the load off. It is an early 496HO, and has no type of interrupt on the shift mechanism.
I have checked the grounds where they bolt on the back of the block, and they are clean and tight, and I have unplugged and replugged every plug on the motor I could see, but nothing has solved the problem.
I'm wondering if I need a whole new harness to solve the problem?

Re: 496HO stalling
 

ive had two that I had to replace the harness, so I wouldnt rule that out,

Is he using a laptop to check it out ?????

ie the dealer SPX program ??????

Re: 496HO stalling
 

No, he is using the Mercury handheld scan tool.

Re: 496HO stalling
 

he'll never find the problem using that.

find a shop that knows that mtr if he's still using the ddt ( the hand held unit) then they havn't worked on many 496s with diag problems

the 496 is a very complicated engine and the pcm 555 is the most advanced computer merc has ever put out the ddt is 20 years old and can not do many of the funtions needed in order to properly diagnose the 496


no offense but he may be very good with the older mercs but the smart crafts need the spx or the rinda program if not hes wasting your valuable boating time

ive been working on the 496s for over 5 years and till I got the laptop programs it was like pissing in the wind all you do is bang your head against the wall so if he doesnt have it by now it means he doesnt work on them that much

Re: 496HO stalling
 

if you want give me a call and Ill explain the issues why

Re: 496HO stalling
 

I don't know if there is a shop in Havasu that uses a lap top for diag. That is just Havasu, even though it is a boating mecca, it is very old school.
I will check around.

Thanks

Re: 496HO stalling
 

Just a thought, swap motor harnesses, then see if it is a repeat on the good motor.
Bryan

Re: 496HO stalling
 

great idea but you are talking several hours per motor to swap and it can turn into a can of worms

here is the wiring diagram sorry so small but had to fit it in

Re: 496HO stalling
 

if not have him get his merc rep out there they carry the spx with them but a lot of times the techs pride gets in the way and they waste alot of time before they call him but push the issue if not he will be wasting your valuble time


oh by the way Im as old school as they get, I still have people bringing me omc stringer drives to build, my wife says I wake up in my sleep yelling that Thought I was done building them 15 yrs ago

Re: 496HO stalling
 

with the exception of John ( pwbt 33 ) at offshore performance I like to think that I have more time working on the 496s then anyone around here and I wouldnt even think about trying to diag you problem with out the spx or rinda

it would be a waste of your time and mine


if nothing else call merc customer support and tell them, then ask if they can send out the rep that is the fastest way to get it done,

youll be suprised how fast it gets fixed

Re: 496HO stalling
 

I called Merc customer support, and asked what could be done to get my boat fixed. After all, is has been in the shop nine times now for the same problem.
Their response was that they were approving everything the dealer was requesting, so they were doing their part.
Maybe I need to call back and request that a Merc service tech visit the dealership.
Any idea how long something like that might take? I'm have no idea how regional they are, and where they would have to come from. If the dealer can't fix it, I would think that is my only option no matter how long it took. My problem is that Havasu is a vacation destination, so everyday I haven't been able to use the boat, is a wasted day of vacation while I'm still having to pay the hotel bills etc.
What a pain in the a**. Why couldn't it have been something simple........

Re: 496HO stalling
 

insist that the rep come out tell them they dont have the spx ( they dont know if you dont tell them) and that you paid all this money for the product and warr and now its costing you your boating season because this shop wont spend the money for the right equipment.....


watch how fast it gets done

I no longer work for a merc dealer...... have my own small shop...... but I have both rihnda program and merc spx program


I dont play when it comes to taking care of my customers,
I belive in what Lee Iaccoa used to say..... to be the best

Re: 496HO stalling
 

Joe has a point that the right guy with the right equipment may be able to find the problem quickly. But the answer may not be stored in the ECM, and sometimes recording this type of failure is not possible because you lose communication with the ECM when it loses power (if that is what is happening).

I think I would start by monitoring voltage at the output of the Main Power Relay. Have you checked to see if there is any problem with the shifter mechanism itself hitting or pulling at ignition or lanyard switch wiring?

Dave

Re: 496HO stalling
 

Well, the dealer may have found the problem. Off the back of the motor, by the bell housing, are several unused wire looms that would be used if my boat had the smartcraft system. As it turns out, one of the sets of wires had gotten wedged in the steering system, and had bared the wires, causing an intermittent short.
Hopefully, that was the cause of my problems. The dealer tied up all the wires so they can no longer get pinched in the steering, and he says the problem is cured.
My fingers are crossed.
Thanks for all the helpfull advice, and I will post my findings.

Re: 496HO stalling
 

that could do it best of luck, the spx more then likely would of shown it as it can read all of the smart craft values

Re: 496HO stalling
 

I removed the additional harness that wasn't being used. I was tired of it hanging back there. It just unplugs, and then I put a piece of plastic over the end.

Re: 496HO stalling
 

I checked it out a little better myself. The wires that had bben pinched/rubbed, exposing bare wire were: a set of three wires that enter into the drive gimbal, and a set of two wires that enter the drive gimbal. All five wires had exposed wire. I re-taped all wires, and encased them in split loom.
I am going out today, and I hope my problems are gone.

Re: 496HO stalling
 

Boat runs great!! Thanks for all the replys from everyone :D