90 hp no start

[mossboss]

I have a 1986 90hp, I can take my boat to the lake and it starts fine, I will run to my first spot to fish and shut it down. After a whileof fishing I will try to start it and all it will do is turn over but will not start and no spark, Sometimes if I let it sit some more and try again it starts other times it will not start again. This past weekend I had it out and it did this , loaded up the boat and when I got home I put the muffs on it and it started right up. and it will continue to start. I can not duplicate the problem when the boat is out of the water. Been dealing with this for a long time and about to take my boat and sink it. One other thing when it des not start I disconnected the white wire on CDI for kill switch and that did nothing.
Any help would be welcome

[99yam40]

You will have to make sure if it is a spark or a fuel issue to start out with.
Spark tester or inductive timing light should show if getting spark to plugs while no start issue is present.
Then you can test voltages that feed onto CDI and out to see if in spec.

If spark is good during no start , then you are left with the fuel issue to chase

[mossboss]

Have checked, there is no spark when it won't start

[99yam40]

Then you will have to test things to see where you have and where you do not have spec voltages while problem is there

[robert graham]

The random nature of the problem points to a bad connection or component in the firing circuit. Maybe a failing ignition switch? Good Luck!

[fishon195]

Ii was having this issue with my F115, and my fix was just to let the motor idle down for a few minutes after a long run especially if its hot, I live in Fl so Its always hot here, have u considered it may be a vapor lock problem Is there a vent on yur gas cap, Check the fuel line from the tank to the motor if its original,it may be collapsing I've seen that problem. See if yur main power relay is heating up if u have one,or a voltage regulator

[bosvark01]

had similar but on a yamaha motor cycle xtz 750 twin but same spark coils/ignition coils as outboard although only one was faulty gave both weak or nil spark had technician explain that with temp difference and a break in the coil binding ( ie inside the sealed coil out of sight) the motor can run and when you stop the gap between the broken wires then differs then have a breakdown or nil spark. have you got nil spark on all spark plugs as obviously if nil then you could rule this out, as rare, that all 3 would break but if one is broken it can have an effect on the others(weak spark)

[mossboss]

Yes I have no spark on all 3 plugs. I do not have to run it long for this to happen, Sunday I only went a 1/4 mile with it

[bosvark01]

so there goes that theory then........

[99yam40]

could be charge coil, pulsar, or CDI, or maybe something I have not thought about .
best to measure voltages to see where problem is unless you just fell like throwing parts at it and hoping

[mossboss]

Pulsar and charge coil checked out ok, hoping it is not cdi, not sure it is worth putting $800 into a 27yr old motor