496 MAG HO Help Needed....ASAP
 

Well it's Memorial Weekend and I'm having a small problem and need some help to correct it...I have a 97 32' Fountain Fever with a pair of 2006 Mercuray 496 MAG HO's... This has happned the last 2 times I have taken the boat out, last weekend and yesterday.

Starbord motor runs 100% perfect...

Port motor runs great then intermittently shuts down and immidiately starts back up...sort of like turning your car key off and right back on while your driving down the road...

After the motor cut on and off 3 or 4 times the motor will not restart on it's own or with the key, you cant hear the fuel pump running when you turn on the key. If you let the motor sit a while and what seems like cool off, motor will start up fine and run....

it wont do it on the trailer, it only does it when the boat is in the water and under load.

Scanned both motors early today and nothing...

I thought it possibly was a bad relay, or the beginings of a bad relay...

ARRRRGHHH.....Memorial weekend and it sounding like I may be on the trailer

Check and make sure your kill switch is on securely. I had that happen a couple a year ago. The plastic fork attached to the lanyard had relaxed and was no longer holding the switch securely. I would hit a small wake and it would cut out or die. Made me crazy until I figured it out. This was on a 1998 boat.

Good luck,

Thanks for the suggestion :D

I'm typically prone to dumb stuff like that, so I checked...lol The boat only had one lanyard so the starborad motor wouldnt run...

Thanks and have a good weekend

switch a couple things in the ignition sys to see if the problem moves .

it sounds like your fuel pump is heating up and quiting. I had this happen before on a car i had, pretty much the same type of fuel system. They can heat up and bind than after it sits for a while it'll cool off and free up.

Badly plugged fuel filters will do this. They pressure up and a little fuel seeps thru- enough to start and maybe idle or free-rev. But then when you need significant fuel flow, it won't pass that much. I've also seen fuel line restrictions/kinks do this. I had a motor once that had fuel tank debris stuck between the carb body and the seat of the needle & seat- just a trickle would get through and fill the fuel bowl- once it was used up, the engine would die. The bowl would refill and all was well again- for a minute.

Ignition modules can exhibit this behavior as well. Once they warm up, the heat causes a breakdown. Easy to test. Squirt them with a hose to cool them off.

Switching parts left to right is a good suggestion. If the problem moves, you've got it.

Fuel problem shouldn't be a quick on/off/on, and I would think should happen on the trailer. I would be looking at wiring, especially grounds. Put your hands on every connection and see if you can wiggle it. Possibly try swapping ecm's side to side.

?????? What the hack??? Now it's a fountain??
Did you buy my old 496's ??
See some of my old threads regarding engine quiting and starting up again.
HP fuel pump. not enough gas.. motor goes into guradian mode. Once lower fuel flow is neeeded motors runs ok.
I have a brand new HP pump for you. Sill in box plastic unoppened. I got two but only the port side was changed.
There may be a sensor throing the motor to Guard mode.
If you lucky,,, clean the filters inside the fuel pumps (both low an High preassure) and you might be ok.
Chris has the right ideas to.

Give me a call.

Check all connections on the back of the ignition (key switches).

I had bad ethanol fuel last year that ruined my fuel filters, fuel water separators, and fuel pumps on my 496HOs.
Do you have completely separate fuel tanks, two tanks with a crossover, or 1 giant tank? If its two tanks, you could have gunk in one that had hosed the fuel system.

When it won't start, listen to see if the power and fuel pump relays are operating when you turn the key on. If so, check the pump with a volt meter. If it has voltage and not running it's the pump. If nothing is powering up, you've got an open circuit. Try reseating the cannon plug. They quite often will cause these types of problems.

Guys, Thanks for all the replys....you guys kick @ss...

Here's what I did.

I swapped all the relays on top of the motors, port to starboard and vice versa. I took the boat to the water at 8am CST dropped it in and cracked the engine cover.....nothing, both motors ran absolutley perfect without cutting out for roughly an hour. The port motor would cut out 30 min into running it prior to swapping all the relays.

After an hour of riding with no problems I turned the boat around to head back and this time closed the hatch completely and 15min into the ride back the port motor beeped extremely loud but never shut down.

Looked at the temp gauge and it was between 200-240, the motor was running hot. Stopped the boat let the motors idle the temp dropped below 180, cracked the hatch and ran 100% perfect at near WOT....never had a problem again...

I think the impeller is out or is weak...I'm headed back to the water for more testing, I'll update if needed...Thanks Again for all your help!:cool-smiley-026:

:party-smiley-020:

I had the exact same thing happening to my 8.1/496 in my 2001 Chevy truck. It happened on and off for a year. Couldn't figure out wtf it was. Finally the part failed completely and it was the crank position sensor. I don't know if the 496 amrine use the same part, but GM also had a recall on them a few years later.

If you suspect ANYTHING is wrong with the impeller, just replace it. Its a BIG PITA if it disintegrates.

Well, I just got back in from running today, I wasnt out long but my 2 year old wasnt liking the heat...

I thought I had it fixed swapping the relays and water testing it early this morning. I got it to the boat ramp around noon, put it in the water...port motor wouldnt fire...got off the dock with the starboard motor.

I limped over to meet up with others friends of mine and all of sudden it started working again....ran fine without a hitch for at least an hour or so. We get to the sandbar tie up get it the water goof off and whatever go to leave and no port motor.

A buddy on mine jumps in my boat we raise the hatch....he grabs the main harness connector (you know the one that looks like a trailer lights plug) take it off, and spreads the connectors apart...plugs it back....not anohter problem....ran WOT without a hitch...

Like I said, "it my luck that it's alwasy something dumb"...

Thanks Again For the Replys...Have a Good Weekend!! :)

You can't complain about a free fix!