496 issue. intermittent.

[vindicator101]

If you want to go with NGK here is that P/N PZTR5A-15. You can get them at any auto parts store. Though they probably don't have them in stock they can get them easy.

 

[240Hallett]

You ran your tank down to 6 gallons. If you had any shit rolling around in the bottom of the tank, the ratio of good fuel to bad sucks.
Change the plugs anyway.

 

[Deja_Vu]

You ran your tank down to 6 gallons. If you had any shit rolling around in the bottom of the tank, the ratio of good fuel to bad sucks.
Change the plugs anyway.

I try not to run my tanks below 1/2 for that reason.

And I won't fill up my boat if there is a tanker truck delivering at the station. I will go elsewhere so I dont get all the shit from their tanks.

 

[PVHCA]

Didn't Brian(BD Marine) say the plugs are different from auto vs boat or was that the wires? Dunno but I think he knows his shit.

 

[FreeBird236]

:deadhorse: As has already been said, you're not describing a plug problem, but it's certainly time.

 

[HBCraig]

McRib,
i had some sensor issues that plagued me for a year. If you have any inclination that it might be a sensor, change it out.... change them all out and get spares. It wont go away. If its not a sensor, I am of no help. :cool

 

[nowski]

496's have been known to fowl plugs. I had a similar issue last year and had trouble finding the culprit. Changed the water seperator filter and plugs but didn't solve the issue. I took the boat to Hallett and they found the culprit. Underneath the water seperator filter there is a disc like filter. The filter was clogged. That little disc filter is typically overlooked when changing the water seperator filter. Jim Frisbee changed that disc filter and I've been in boating heaven ever since...

 

[TBI]

And a regelled keel

Pull your pants up Ziggy....

 

[Captain Dan]

Instead of spending $200+, I would do the free inspection of the separator.

Yeah, the plugs might need to be changed, but the symptoms you described point to water in the filter assembly.

I always check the simplest things first.

Here's a cheap diagnostic...

Don't know if this has been covered in the previous pages, but If there is ENOUGH water in the fuel system, it could be beyond the capacity of the separator and be in your tank. Remove the separator and place a container under the filter housing, without the filter. Turn the ignition switch on and off - each time it will cycle a small amount of fuel into the container for inspection. If you have 2 tanks, switch and repeat. I got a bad load of fuel 2 years ago and went through this procedure with my 496 HO and pulled about a quart of water out of the tanks.

 

[gqchris]

I don't know if this helps McRib, but when my ECM went out a few seasons ago, it was an "all or nothing" type deal. It was completely dead, would crank, but no run.

My buddy chased this issue for months on his, and it was the High Pressure Fuel pump. His pump was going out and it was the same exact scenario, and anything over 3,000 RPM it fell on its face.

 

[shintoooo]

I had same issue last year. It was backfiring and had a hard time getting on plane sometimes. I took it to OD1 and had him change the plugs and that was it. Boat ran great after that.

 

[Ziggy]

Pull your pants up Ziggy....

I'll be sure to do that if I happen to go to a wedding where I'm required to wear pants, otherwise my shorts are in the right place when appropriate...lol
[emoji1]

 

[Shortdeck]

I've been having problems with the ethanol they put in pump gas. I have the same cool fuel module as McRib, and the ethanol would eat the adhesive they use to glue the metal end caps on the filter cartridge. Luckily the white disc filter would catch it. But I'm on my second pair of filters for he cool fuel this season.

 

[nowski]

I've been having problems with the ethanol they put in pump gas. I have the same cool fuel module as McRib, and the ethanol would eat the adhesive they use to glue the metal end caps on the filter cartridge. Luckily the white disc filter would catch it. But I'm on my second pair of filters for he cool fuel this season.

Were those Sierra aftermarket filters by any chance? I had the same thing happen to me last year and that was the start of my problems.

 

[jack14r]

There is a lot of good advice here but in the first post you stated that it took the voltage a while to come up,I have seen batteries that had a bad plate in them and they would short occasionally and when that happened the current to the ECM would not be adequate and the ECM would not operate properly.I would change the battery as that is a cheap insurance and as you stated it is a couple of years old.

 

[pronstar]

UKXPAT who used to post here had the exact same issue.
in his case, the insulator on a plug was loose....so basically a bad plug, like everyone else has been posting.

 

[jetboatmatt]

I have your same motor went down to Autozone and picked up the GM AC delco plugs!! Put them in myself really easy!!! They have around a 100 hours with Zero issue!! Don't put anything else in your Motor! It's a stock motor use the stock plug!! I want to say each plug was around 2 or three bucks!! Good luck!! Don't pay the bullshit $20.00!!!! All numbers matched up on my old plugs withy the New ones!!

 

[jetboatmatt]

 

[jetboatmatt]

A little more then I thought!!

 

[BDMar]

The AC Delco platinum plugs come in the engines because they are a less expensive option. A better plug is an NGK TR55IX Iridium plug. It is more expensive but burns cleaner and lasts longer. We've used them exclusively since the 496 came out.

 

[Shortdeck]

Were those Sierra aftermarket filters by any chance? I had the same thing happen to me last year and that was the start of my problems.

I believe that was a Sierra cartridge. The one in it now is a Sierra from West Marine.

 

[BDMar]

I believe that was a Sierra cartridge. The one in it now is a Sierra from West Marine.

I think you might find the genuine Mercruiser filter won't have that problem.

 

[jetboatmatt]

The AC Delco platinum plugs come in the engines because they are a less expensive option. A better plug is an NGK TR55IX Iridium plug. It is more expensive but burns cleaner and lasts longer. We've used them exclusively since the 496 came out.

Good to know but the stock ones work just fine for me!! No black soot on the back so far! Just letting a guy know there is a cheaper way then the 20 buck ones!! Good to know there are better ones!! Thanks for the info and the numbers!! Might try them when I switch these out!!

 

[Shortdeck]

I think you might find the genuine Mercruiser filter won't have that problem.

Thanks BDMar. I need to order a replacement before the McRaftup.

 

[purrfecttremor]

I have a 2004 496 HO and had exact symptoms and it was the separater like every is saying. By the way I have 280 hrs with original plugs so I guess I'm due!

 

[robby dmax]

496's have been known to fowl plugs. I had a similar issue last year and had trouble finding the culprit. Changed the water seperator filter and plugs but didn't solve the issue. I took the boat to Hallett and they found the culprit. Underneath the water seperator filter there is a disc like filter. The filter was clogged. That little disc filter is typically overlooked when changing the water seperator filter. Jim Frisbee changed that disc filter and I've been in boating heaven ever since...

X2..there is a little white disc type filter in side the pump itself.
plus buy the correct plugs for the marine application.

 

[Havasu Rehab]

Change the plugs. Had the same issue with my lavey at about the same hours. The change fixed it.

One weekend it was fine, the next...I needed plugs.

Never had any fuel and water problems.

Hey Mandelon, how's everything?

Do you remember about how many hours were on the boat when you did the plugs? Just so I have an idea...

 

[McRib]

I'm not saying it can't be the fuel filter separator cartridge but it's new. Changed in march. So.... to me that means one of 2 things.

1. On my first trip out while idling for 30 min the new filter element clogged again. Or 2. The person that did my service didn't change it and I'm pretty sure this guy wouldn't fuck me like that. Either way I'll be pulling the element next weekend and I'll be changing the plugs with plugs I'm getting on the highest recommendation of a very savvy mech board member here.

 

[rrrr]

The filter doesn't get clogged. It doesn't matter if it's been installed a week. When water accumulates in the housing some of it gets bounced into the engine causing it to run rough. I'm not saying that's your issue but it's possible.

 

[Mandelon]

Hey Mandelon, how's everything?

Do you remember about how many hours were on the boat when you did the plugs? Just so I have an idea...

20 less than when you got it. You should be good for a while still.

 

[Havasu Rehab]

20 less than when you got it. You should be good for a while still.

Awesome, thanks!

 

[Runs2rch]

The AC Delco platinum plugs come in the engines because they are a less expensive option. A better plug is an NGK TR55IX Iridium plug. It is more expensive but burns cleaner and lasts longer. We've used them exclusively since the 496 came out.

Exactly.

 

[McRib]

Plugs seem to have fixed my issue. My boat was running like a raped ape this morning. Thank you to BD Mar for hooking me up with plugs. NIGHT AND DAY! just on initial start up there was a huge difference. Stock plugs don't last. Lol. Fuel filter was clean as a whistle.

 

[Ziggy]

When you really think about it, how clean can a whistle actually be?[emoji4]

 

[Mandelon]

Whistles are spit shined.

 

[Runs2rch]

Plugs seem to have fixed my issue. My boat was running like a raped ape this morning. Thank you to BD Mar for hooking me up with plugs. NIGHT AND DAY! just on initial start up there was a huge difference. Stock plugs don't last. Lol. Fuel filter was clean as a whistle.

Bitchin!!!

 

[waterhorse]

Glad the plugs fixed the problem.:thumbup:
I am curious as to why these 496 engines are known for killing spark plugs?