JETDOC

My port engine is strong until about 3800 rpm, starboard is fine. Happened last 2 times out, had the Sunny 3 years now & never an issue with this engine. I put the rinda scanner on it & no abnormal fault codes, said 100% power avail from ecm. Did the induced misfire test on all 8 cylinders 3 times, all passed. IAC valve test good. No smoke or abnormal sounds. Leading me to believe its not getting enough fuel, changed the 3 screw drop in fuel filter, same results. Thinking now its the fuel pump. Any suggestions? The fuel pump looks like a real pain in the butt, any suggestions? or is it easier to remove the whole housing? Am planning on swapping to the other engine & water testing instead of throwing cash at parts I may not need. Thanks for any help.

Sydwayz

iTrader: (1)

How many hours are on the spark plugs?

Did you put fuel stabilizer in it and also something to combat ethanol in the fuel? (If you have ethanol fuel in it) You may still have bad gas; and bad gas can ruin fuel filter.
Could you see any water in the fuel/water separator housing when you changed it?

On some 496HOs, there are two fuel filters, an inline "bullet" looking fuel filter as well as the fuel/water separator which you changed. I would call Sunsation to see if your boat has such, somewhere if you can't see them.

The fuel pump is not that difficult to change; as long as you can get to it. Check out diagrams on Mercury Mercruiser engines and parts

JETDOC

I did usestabilizer with ethanol treatment for the winter layup, it ran fine this spring, just the last 2 times has been underpowered. I thought the bullet filter was on engines prior to the water seperator. Or am i wrong again? There was no water or debris in the seperator. Any suggestions appreciated.

Sydwayz

iTrader: (1)

ALL of the engines have the fuel/water separator; just different types. The earlier model 496s have the type that remove like an oil filter, which I like better as you can remove them and pour the contents into a clear cup/glass and see the water/fuel content as well as garbage. The filter-in-canister type like you have does not exactly allow that. but it provides for easier maintenance in a boat without a lot room to get to that area.

I can't vouch for weather Sunsation rigged your boat with them or not, or if Mercury install requirements called for them during that vintage.

Do you have a single fuel tank, or separate tanks for each engine? This could weed out a fuel itself problem

JETDOC

Single tank, looked at the lines & no obvious place for a screen filter, unless its under the line fitting. But the ipc doesnt show one. Looks like 3 bolts 2 lines & the whole housing comes off, i think will swap assys & isolate from there

Sydwayz

iTrader: (1)

It's not bad fuel in the tank then. There is a port on top of the engine to check fuel pressure. Remove the plastic housing and you should be able to find it.