BF90a wont start and have checked everything

"My carburated 90 a wont start

"My carburated 90 a wont start, it only has 350 hours on it. There is spark and fuel. It was running just fine for three consecutive days for around 6 hours per day at trolling revs of around 2500. It was trimmed out of the water by clients on the centre console when I was driving from the fly bridge. I shut down the throttle as soon as I heard it over rev, it stalled and never started again. We found water in the fuel filter but i'm told it did not go into the Carbs..... The other engine is Fine and exactly the same
We did compression test on both engines:

Problem engine:
1. 120 psi
2. 130 psi
3. 100 psi
4. 100 psi

Good engine:
1. 100 psi
2. 145 psi
3. 100 psi
4. 105 psi

I have swopped complete set carbs over, swopped plugs, fuel pumps, coils, switch boxes, harnesses and still no luck - Everything from problem engine works fine on other engine.

Help!!!!!"

check the flywheel key did not

check the flywheel key did not shear

Ok it seems my man has sorted

Ok it seems my man has sorted it.....He said the timing belt jumped three teeth????
Would this mean the belt id too lose and needs replacing or is it the tensioners that need work??
Thanks for all your advice.

PS what is the correct spark plug for this motor?

Glad you found the problem.

Glad you found the problem.

It could be either. If the belt is worn or damaged...replace it. The same goes for the tensioner. If it does not turn smoothly or seems loose or lacking tension...replace the appropriate parts.

The correct spark plug for the engine is an NGK DR7EA. Do not use Densos or some other brand unless you absolutely have to. The NGK is the best plug for the engine.