At the back of the sump, on the left hand side (looking forward)
There is two on a Discovery. Located on the lefthand & righthand of the engine block.
This is located at the top of the brake pedal, it is a twist fit and a cheap if awkward DIY repair. Don't forge to unplug the wiring plug first.
The location is engine specific. Which model Sentra do you have and which engine does it have?
recommended spark plug for a fd501v
They vary. The year, make, model, engine and freeze plug location info is necessary to answer.
The spark plug replacement 4.2 I6. MAY03LT·140 will fit on a 103 engine take. This does not go to any make or model with a 103 engine intake. This may vary from make or model type.
Probably a spark plug is fouled up.Also check plug wires if you have an older model.
On the engine shroud above the spark plug
The required spark plug for a 50 hp outboard engine would depend on the make, and year model of the engine.
normaly at the base of the engine, may have a short pipe with a cap on it or a plug, or under the engine
I need a make, model, year, and engine size in order to provide an answer.
need the engine model, type and code