1997 Force 15 hp Is there a hotter spark plug available ?

[pecheux]

Good day,
For this 15 hp OB normal spark plugs are BP7HS Question: Could I use an appropriate hotter plug ? If so what number ? Reason for wanting to use a hotter plug is that it seems the lower cylinder plug fouls when idling for some time. thank you

 

[pnwboat]

Plug fowling at idle speed can be caused by a problem in the fuel recirculation system. Make sure the check valves and screens are not plugged and operating like they should. See items 19 and 20 in the diagram below. Also make sure the fuel pump diaphragm is intact and no holes or tears in it.

http://www.crowleymarine.com/mercury-outboard/parts/1695_3.cfm

 

[pecheux]

Hi pnwboat. I beleve you may have recommended to me to change the gas pump kit. Did that, The motor runs great at WOT and let's say the upper half of trottle. Starts missing at the lower half (idle +) once warmed up. After replacing gas pump kit I changed the plug gap to .35 (from .30) and tried it out on the river only to find the problem worsen. And when it stalls it become difficult to start which is not usual for this OB since it normaly fires on first pull. I misinterpreted the FOULING for MISSING. Seems like no gas is getting to the pistons or it's flooding. I'm turning in circles with this problem. Tx for you help and suggestions.

 

[jerryjerry05]

Missing at idle: How's the compression?
Recirc system cleaned not blocked(pnwboat).
The air screw set right?
Remove the needle and check for damage.
1 and 1/8th turn from lightly seated.
Then once it's running and warm.
Turn the screw in till it bucks or stalls and then out 1/2 turn.

 

[pecheux]

Jerryjerry05: tx for your help. At this time I am looking for idle jet to clean, since all is well at upper half of trotte since I presume it's then running on high speed jet.
I suppose that would be inside the carburator ? Tx