2.5L Merc 280 Fouled Spark Plugs

Hey Guys,

I have a 1999 2.5L merc 280 and had some spark plug issues this past weekend (or so I suspect). Recently I took the boat to a reputable shop in the Phoenix area to have him go through the motor with me and do a compression test, hook it up to the computer... basically give the blessing on my motor. Never had an issue with it before but just wanted some piece of mind.

They had put fresh plugs in (ran great the first weekend after the service) but not some much last weekend. The boat would almost fall on its face as it was loaded up and couldn't clear out. I took the plugs out and they were soaked. Called the dude to find out his son put the incorrect plugs in the boat. I had some BUH8's in the garage that I took out of my old boat a year ago.. cleaned them up and was able to run the boat.

Still ran not up to par as the plugs were acting fouled and decided to get towed back in just incase it was something other than that.

Any suggestions?? I have been told NGK BUHW plugs are what that motor calls out for... but if anyone has other input I would like to hear.

Also thinking about getting my injectors cleaned and flow tested for cheap insurance... just for safe keeping as well.

I run a half av-gas/91 octane mix with Mercury Premium Plus oil at 32:1....

Any help is appreciated!!

Thanks guys.

-Brooks

I think you posted onriverdavesplace also?anywho,i copy and pasted from Diamond website BPZ8H-N-10
NGK

BPZ8H-N-10

For 280hp Projected tip = less fouling Choice of top Offshore Racers

I think its necessary to have a leak down performed, it will tell the truth about health of nic bores, I'm far from expert,but how many hours you got on the rings? What did compression say?

When was injectors last cleaned.

Champ QL77CC

Also check your reeds

You can 't run gapless spark plugs on your motor you have induction ignition not cdi
You need sparkplugs with a ground electrode like the bpz

I did, thank you for the link!

Quote:

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Originally Posted by Merclover

I think its necessary to have a leak down performed, it will tell the truth about health of nic bores, I'm far from expert,but how many hours you got on the rings? What did compression say?

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I think I'm going to do that regardless now. I'm no expert myself but had a few buddies say I might need to get my ecu checked out again too. Might be dumping a bunch of fuel causing it to foul the plugs and load itself up.

The motor has 324 hrs on it and the compression has 150psi in each cylinder.

Quote:

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Originally Posted by R.grover

Also check your reeds

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I was told this as well... I'm going to bring the boat home this weekend.

That's some impressive #s , I dont hear of that many hours on one very often, must had been babied , good luck ,I'm sure once you go down list and check everything ,u will find it

Quote:

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Originally Posted by Merclover

That's some impressive #s , I dont hear of that many hours on one very often, must had been babied , good luck ,I'm sure once you go down list and check everything ,u will find it

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Yeah I was surprised when I saw that on the reader when we hooked it up myself. Hoping it’s just those few small details, plugs, injectors, or Ecu.

I am am going to take a look at the reeds too while I’m doing so. I’ve only had the boat for a few months now. Bought the boat as they just finished putting on the new power. Never skipped beat until this last weekend.

Heres a few pics of the boat and ecu. Kind of hard to see but it’s a Motorola. Attachment 416152Attachment 416153Attachment 416154Attachment 416155Attachment 416156

check the air temp sender

Flow injectors good oil 40 to 1 unless your turning it past 8 grand then32 to 1 plus try ql77cc champion for some unknown reason some ecu like them better for certain years