350 Chev Volvo Penta starting issue

We have this motor in our 1996 Bayliner. It has recently been serviced and we have been out on the boat several times. Today it just won't start. It turns over, has fuel and batteries are all good, however it just doesn't seem to want to engage - any ideas or help....please

 

How did you determine it has fuel delivery? Does the acceleration pump squirt fuel? Have you checked for spark?

 

Hi gonzo, confirmed petrol flow thru a visual inspection down throttle throat. Spark plug leads pulled all leads firing. Coil lead pulled at dizzy cap, firing into cap. Have not checked the electronic dizzy

 

I would next check the timing to make sure the timing chain has not jumped teeth.

 

Hi gonzo have sorted starting problem the advice given was much appreciated.the problem was finally tracked to the accelerator pump on the holly carburettor

 

you some other problem if you need the accelerator pump to start, how about the choke system?