Offshoreonly.com - 496HO Pops and Backfires

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Quote:

Originally Posted by Brad Christy (Post 4912558)

BBaker,

I'm no wizard, but I have had my fair share of experience with the 496HO.

Do you have a Rinda TechMate scan tool? You can use it to do a cylinder delete sequence for both injectors and ignition to help determine if you are actually missing cylinders and which ones. It sounds like just about everything else in is order, so I'd start there.

Thanks. Brad.

I do not have one, maybe I know someone local with one to try this. But doesn’t the engine have to stay running to do this? Thanks

Quote:

Originally Posted by Bbaker3116 (Post 4912586)

engine should still run on 2 dead cylinders, hell even 3

BBaker,

Yup. Mine ran on 6-1/2 for an entire season. I knew something was wrong, just from the lack of power. I just couldn’t figure out what it was. To listen to it, idle through “WOT”, I couldn’t really hear that it was running wrong.

Thanks. Brad.

Quote:

Originally Posted by Bbaker3116 (Post 4912587)

I do not have one, maybe I know someone local with one to try this. But doesn’t the engine have to stay running to do this? Thanks

BBaker,

Yes. You set the throttle at about 1500 RPM, in gear, and delete a cylinder, one then the next, and listen for a lack of a drop in engine RPM. That's a dead cylinder. Do this with both injectors and ignition, and you'll root out any issues with these systems.

If the engine just won't stay running at all, I'm not sure what to tell you other than to have the ECM tested. They DO go bad. I'd think this would throw a code, but I don't discount ANYTHING when it comes to electronics. A faulty component could also prevent it from throwing a code. Electronics are just voodoo. John Mosetti at Boats Unlimited can test and repair them. This is all assuming there isn't some other, simpler solution; Occam's Razor and all. You might also send the injectors to Smitty (ArcticFriends here on OSO) and have him test and/or clean your injectors. Wouldn't hurt to send them from both engines while you're at it. Eliminate this as a potential cause. It's not like you're going to be using the boat in the interim.

Thanks. Brad.

Thanks. Brad.

I've had the tech mate scan tool get fault codes with just the engine barely firing for a few seconds before on a 496 FYI. In this case it was a crank sensor having issues.