496ho mag help please!!!
 

Okay iv been working on the boat and trying to sort out the pleblem for a long time. Latest thing I'm trying to come up with is when you turn your key on it does the self check. Then start it and it acts as if you turn the key off and right back on and beenps one time. It's very random and happens quite often but I noticed Saturday if you shut the boat off then turn key back to run real fast, it won't self check and then you can fire it up and it runs like top until you shut it off and try to start back.

Do you have a warning horn hooked up ? If not the PCM does not see it or the other side of the coin is do you have a operating warning horn that goes off with the self check ???

I take it you have smartcraft craft gauges to see the system self checks ??? is this correct your app has smartcraft gauges ?

EC 555 and PCM 555 need to have a operating warning horn

you need to look for a fault of horn output while scanning. if you have that what is it showing ?

I do not have the smart craft gauges.
I just have the warning horn for low pressure and high temp and all that. It beeps on time when I turn the key on and everything just fine like it's always done. But once it's done that and then you start it, it will do it at random just like you turned the key off and right back on without dying, just makes the boat kind of lung forward.
But like I said once running if you turn key to off and then right as it dies take it turn it. Ack to run it won't self check or beep and the boat runs damn good. I'm not real sure how that self check oprerates or what would cause this. Thank you for the reply and for insite you may have to get to the bottom of it

Also not showing any failt codes whatsoever on entire engine

go back in history and look in there for what codes that may have faulted hours ago. The PCM persay controls the system checks / key battery voltage and horn output is also in the mix.

scan tool owners should know and perform this ? output tests - one with the scan tool has the ability to perform many pcm actuators and controls to see if they are correctly operating. The output tests, listing most of them are -- fuel injectors, IAC test, fuel pump relay, warning horn, tach output, ignition coils, plus a few more. The performed tests can determine a problem with what related parts and or related systems.

ALSO when performing the output tests it is called for to unplug the fuel pumps per instructions.

Check your kill switch, especially if you're in salt

I checked for stored faults and the boat doesn't shoq any. Also I ran the troubleshooting test and everything seemed to check out fineness on all test.
Thanks for your reply. I really wish I could get this thing figured out

Hard to find and fix problems like this without hands / eyes and ears on it. You need to take it to someone that works on 496's -- the problem is a lot shops hate 496's. Possible PCM issue or a ground issue and or even possible a 5 V issue.

anyone can throw out whatever - eventually that could be the fix but that could end up a lot parts changing. plus dollars and non use of the boat. .

I would be interested in the fix or possible figuring it out. but really this problem child does not need darts and dart board --- it needs to be looked at, tested and so forth..

Thank you for your reply and your help. It is very much appreciated. I wish you were closer cuz I would bring it to you in a heart beat. I also wish there was somewhere around me that worked on many 496s

if it was mine i would replace the ignition switch and the kill switch,i have seen ignition switches do weird things.many years ago i had a jet boat that i parked in a buddy,s garage,he called me and said the boat started by itself in the locked garage ,he pulled the coil wire and called me about it.i thought he was kidding but he was not.it ended up being the ignition key switch.

I put a new ignition switch in it already with no fix. Thank you for your reply though. I will check in to kill switch though. Thank you

My first thought is the power relay. You also could jump the ignition at the engine to rule out ignition or kill switch as a source.

But he has reported turn key for a fast start before horn output and the engine will run fine ALL DAY LONG is this correct for what I am saying.

A scan the MPR = main power relay should show up as fault or varying voltage. IMO someone with scanning indepth experience might be able to catch something.

he did mention changing the ign switch already in a past post.

IMO I think the horn output / PCM side is the problem.

BUP on the horn output/ pcm are you referring to the pcm itself or the wiring on that side or both. Also on the relays I have like three or four on top of the pcm and then there is one single one behind dash near ignition switch. Anybody know if that the mpr or if it's somthing different. I was under the impression that the mpr was on top of the engine

horn output / warning horn the PCM has a internal horn driver. As I asked from your statement saying this is the case with your engine - I am reasking again ----- if you quick start the engine before the one beep at the dash goes off you can run this boat all day long without any problems and NO WARNING HORN going off is this correct ??

If you start the engine after you here the one beep from the dash ---- so describe what happens with the engine running for X amount of time and then do you get a warning horn going off ???

KEY ON ONLY ONE BEEP IS NORMAL FYI but after starting the engine and running what happens ? asking again to be clear here.

Has anyone ever hooked up the battery wrong ? I am suspect about this one 3 sure

Yes that is correct if I quick start the boat with no key on beep the boat will run fine.

If I start the boat after it HAS done the key on one beep, after a few seconds of idle it will almost die and then rev up real quick and all gauges will cycle and single beep just as if you turned the key of and then back on real fast.

To my knowledge the batteries have never been hooked up backwards

Also once it does that it is very irrational and continues to do so at random times while idling around and running wot down the lake.

Had a similar issue on the 496 HO.. After a year of the mechanic throwing parts at it, IAC, fuel pressure regulator, relays, fuel pump, filters, grounds, ect. Finally it completely turned into a no start condition.

End result that fixed the issue was a very expensive $2K PCM. Video form my thread happens around the 20 sec mark

https://www.youtube.com/watch?v=YjpOWyRCmk0 http://www.offshoreonly.com/forums/g...off-video.html

Thank you for your reply. I been thinking that was my problem. I been trying to find one to put on my boat to try before I bought one.

Last sentence right ^^^^ here IMO is your problem. Meaning agree with PCM needing to be changed or tested.

Also both problems in the last post as well could have happened from a battery being hooked up wrong or a battery charger hooked up wrong and or even someone whom spliced in the PCM feed side wiring harness when adding an accessory of some sort.

Thank you for all your help BUP. You've been a tremendous help.
I'm trying to find someone to allow me to borrow there's to verify before I buy one but not having much luck. Hopefully someone will step up and let me soon.