phebus

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

GOODT

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

phebus

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?

GOODT

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 ??????

phebus

No, he is using the Mercury handheld scan tool.

GOODT

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

GOODT

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

phebus

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

BryanTuvell

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

GOODT

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