90 hp merc starting

[rider resting]

Hi I have a 78 90 hp merc the engine starts great but stalls as soon as I release the key. I have replaces the ignition switch no difference

 

[jimmbo]

Are you using the fast idle in neutral feature. In 78, the control box had a button on the shift lever, I'm not referring to the two trim buttons in the lever handle but the one lower at the pivot point of the lever. Pushing it in disengages the gear shift? Using the choke button?

 

[rider resting]

I will try this it does have a off switch on the control box

 

[rider resting]

same results start quit no spark

 

[jimmbo]

When the key is in the running position do you have voltage at the switchbox terminal with the white wire?

I am assuming you do have a 1978 engine and it has a distributor CD ignition

 

[rider resting]

yes I do

 

[jimmbo]

Was that yes to the voltage, or to the year and distributor?

 

[rider resting]

to all I have voltage at the red and white wire.In the run position the engine is a 78 with a cdi ighition

 

[jimmbo]

I suggest you check the connections on the switchbox. If that doesn't help, I would take the switchbox to a Merc dealer and have them test it.

 

[Chris1956]

Sometimes a bad trigger will do that. There is a spark test for the switchbox and wiring on the CDI Electronics web site. If those prove to be good, you might replace the trigger.