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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15190
Experience:  Certified on Onan and Generac generators
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I have a 1991 onan marine generator (gas) ensign series 4500/6500

Customer Question

I have a 1991 onan marine generator (gas) ensign series 4500/6500 No spark and no fuel...was hunting awile before it sudenly stalled and would not restart...
Submitted: 8 years ago.
Category: Small Engine
Expert:  Hank F. replied 8 years ago.
What is the complete model number of your genset?
Customer: replied 8 years ago.
MCE 6.5 MCE B 1A serial number k890278126
Expert:  Hank F. replied 8 years ago.


Check to see if you are getting 12V to the positive terminal of the coil while cranking.


Is the set available to test as we go, or is it somewhere else?

Customer: replied 8 years ago.
The set is somewhere else. Will be looking at it later today or tomorow in the am.
Expert:  Hank F. replied 8 years ago.

Glad I asked, then.


This is a very simple system to work on. Since you are getting no spark AND no fuel prime, the problem is in the control system.


First, check for 12V at the coil while cranking.


If no 12V is present, remove the control panel and locate the relays inside. The wires connected to one of them will be numbered K14 (X). On this relay, make sure there is 12V at pin number 30 all the time, and that there is 12V while cranking to pin number 87.

There should also be 12V to pin number 86 while cranking.

If cranking voltage is present at pin number 87, the wire is broken between the relay and the coil.

Hank F. and other Small Engine Specialists are ready to help you
Customer: replied 8 years ago.


Customer: replied 8 years ago.
I will try that tonight...can we resume this on monday after i check the coils and relay? and if that checks out ok is there somewhere else I should be checking?
Expert:  Hank F. replied 8 years ago.
You can get back with me whenever you are ready. The only components between the battery and the coil is the wiring and the relay K14. If it is not the relay, it is a bad wire, either on the hot or ground side.
Customer: replied 8 years ago.
thank you
Expert:  Hank F. replied 8 years ago.
No problem, just let me know when you are ready.
Customer: replied 8 years ago.
ok I checked the had 10.5 volts getting to it and even when I jumped it straight from the batt...heard the prime but still nothing.
Expert:  Hank F. replied 8 years ago.


Got voltage to the coil, but still no spark?


I am wondering whether we have 2 issues here.


To test for fuel, remove the fuel line from the carb and place it into a container to catch gas.. Jumper 12V to the coil. This will bypass the engine itself so we don't have to worry about engine noise or vibration.

If the pump runs but does not pump gas, there is not enough fuel in the boat, a fuel line is cracked/dry rotted and sucking air, or the pump is bad. To test the pump itself, get a piece of fuel line of the correct size. Remove the fuel line fro the pump and hook up the new fuel line. Place the fuel line into a container of gas and jump the coil again. If the pump still does not pump gas, it is bad. If it does pump now, we need to look at the fuel lines and tank level.


To test the coil, remove all wires from the coil. Ohm across the primary winding (the small terminals). You should get 2.9 - 3.6 ohms. Now ohm across the secondary windings (the spark plug wire terminals). you should get 14,500 - 19,800 ohms.


Does your coil have a red and black wire attached to it, that run down into the engine?

If so, this has an electronic iginition module. To test it, jumper 12V to the positive terminal of the coil. Set your meter to VDC. Place the black probe to ground, and the red probe to the negative terminal of the coil. Remove the spark plug wires and slowly turn the engine over by hand. The meter should read 12V for 180 degrees of revolution, and drop to about 1V for the other 180 degrees of revolution.

Customer: replied 8 years ago.
Ok from what i saw it was an orange wire to the coil. Also had a problem with the gas tank this year already and have a brand new external 6 gallon tank with new hose attached.
Expert:  Hank F. replied 8 years ago.

Y es, it could be orange. this will be the ignition module.

Then it probably shouldn't be the tank or fuel line. I would still disconnect the fuel line from the carb and jumper to the pump. It is very possible the pump is bad. If their is a filter before the pump, it may not be a bad idea to change it, as you have had gas problems.


Test out that igniton module and let's see where to go from there.

Customer: replied 8 years ago.
Thank you
Expert:  Hank F. replied 8 years ago.
No problem,just let me know what you find.