Install new plugs, add methel hydrate to the fuel to get any water out of the system.

And change your water fuel separator filter.

These have saved me in the past.

http://www.offshoreonly.com/forums/g...ome-ideas.html

definetley plugs dont put cheap one in it though. had this prblem in my old baja h2x single 496 mag, and just recently in my 36 outlaw twin ho's just put new plugs in it and it went away

So this started up all over again on the port side, swapped out the same injector that was the culprit last time and all the plugs and fuel filters, and had no improvement, actually the starboard side started doing the same thing, checked spark on all cylinders, did a compression check again, to see if I broke anything, then had it plugged in to a laptop, the program says I'm at 100% power, HA!!! So I sent all the injectors, 8 and 2 "spares" out to be tested and apparently cleaned. While shipping I realized that at $150 a piece, that was a $1500 box I sure hope this works.
Had to vent and if anyone else is having this type of problem I figured I would keep you posted on my progress.

Wow thats a a lot of $$ for a test ,how much are they new for a set of 8 ? keep us posted on the outcome , i read all the 496 probs/and fixes and try and store as much imfo as i can on thes motors just in case it happens to me , i want to be ready , some very clever and helpfull people on this site ,its great .

000joe:

I assume you are still discussing that your 496 engine is popping out the exhaust, or is it just a bad misfire that is something you are hearing out the exhaust when a particular cylinder does not fire like the others.
Usually injectors don't cause popping out the exhaust and a cylinder that dropping out does not make a popping noise as no cylinder pressure has built in that cylinder unless it fires.

Late injector timing could cause exhaust popping but that's pretty unlikely in this engine with its controls.

Is the engine performing with a power loss? Or is it just a noise?

You mentioned that some mechanical mods or redo's were done to the engine, could you describe those in detail as there may be issues with that work?

Best Regards,
Ray @ Raylar

Sounds like a bad plug, causing a misfire. I would change those first before anything.

I apologize, their about $150 each new, the box was worth $1500, it's $25 a piece to flow test and service them

it is a back fire, I believe, through the exhaust, it started on the port side and then on the starboard side. the engine was replaced last year and I had the same problem on the port side, replaced the last injector on that side and it ran perfect. The engine is stock. I checked spark on all cylinders, as did a mechanic and he used a lap top to check whatever. the motor has an extreme loss of power, and would only reach 3800 rpm. the only work that was done after the initial replacement was by me, oil changes, an injector, and traditional diagnostic, pulling plug wires, disconnected coils, to try to isolate the problem. I actually spoke to you when I was buying my engine Ray, your always a great source of info on these motors, thank you!!

changed all the plugs


thanks for all the responses guys!!

Did you try wires?

The wires look perfect and when checking spark, I checked at the plug.....