1992 90hp Evinrude V4 fouling plugs

[SBA]

Recently bought this boat, seller said it had been sitting for 2 years. I drained the gas in tank and put in fresh gas. First time out was only running on three cylinders....turned out to be a bad coil. I put new NGK plugs in and it ran great at WOT, trolled for a very short time then fouled two plugs on left side, cleaned plugs but didn't do any good. Compression is 125-130 on all cylinders. I read that only Champion plugs should be used, are they a better plug for this motor? Also was told to only run premium/non-oxygenated fuel to help performance and prevent plug fouling. thanks

 

[BigBankWA]

Re: 1992 90hp Evinrude V4 fouling plugs

Had the same problem with my old 90 and yes...for some reason those Champion plugs perform better than the best high end ones. Make sure the idler jet gasket on the carbureator has been changed out and is not original, that can be a major problem at slow speeds and cause the fouling too. The original gasket covers the passage and over time becomes distorted from negative pressure and restricts the fuel flow. Causes rough low speed (trolling) and fouled plugs to boot.

 

[kenmyfam]

Re: 1992 90hp Evinrude V4 fouling plugs

Use champion plugs. (my opinion)

 

[SBA]

Re: 1992 90hp Evinrude V4 fouling plugs

Thanks BigBank, you wouldn't by any chance have a part number on that?

 

[Vic.S]

Re: 1992 90hp Evinrude V4 fouling plugs

Recommended plugs are Champion QL77JC4 gapped at 0.030" although if fouling is a persistent problem it might be worth opening the gap slightly.

The equivalent NGK plugs are BZ7HS-10

Idle channel gasket is #6, part number 334353, in THIS DIAGRAM ?

 

[ezeke]

Re: 1992 90hp Evinrude V4 fouling plugs

Spark Plug Part number is 0387633.

Plug fouling is reduced by the use of high quality TC-W3 oil, especially synthetics and synthetic blends.

You will find the carbon build-up greatly reduced when your thermostats are functioning properly.

Use of carbon-reducing additives to your fuel will help to reduce all carbon problems, but some oils, such as BRP/Evinrude XD-50 come with the carbon treatment built-in.

The annual de-carbon treatment specified in the BRP/Evinrude maintenance schedule is a practical necessity for a long life for your engine: http://www.evinrude.com/NR/rdonlyre...55-6BC1C69789FB/0/em_maintenance_schedule.pdf