G9 sputters/back fires

[kantuckian]

Good Info

[davekayse62]

ok did some testing today, I picked up a inline spark tester at harbor freight for 5 bucks . What I found was when the motor is running like crap I have a weak light, when it snaps out of it and runs good the spark is significantly brighter. so im thinking a have a spark issue.

the voltage at the battery when running good and high rpms is about 16 volts, when its running bad and the rpms are a little lower its about 13v

the ground from the battery to the starter is clean and its testing out ok, im going to now check all the electrical connectors now for loose or corroded terminals.

[1989Marathon]

Did you check the ground to the motor?

[CAMPERCART2013]

Double check all grounds and start looking for a ignitor

[davekayse62]

Originally Posted by 1989Marathon

Did you check the ground to the motor?

the ground wire goes from the battery to the starter, and that tested ok and its clean

[davekayse62]

Legend: 5 Ignitor
6 Pickup coil
7 plug
8 ignition coil


On the orange wire from the ignitor to the coil the voltage is jumping around from 1-14 volts DC while running

the R/W wire from the ignitor to the coil is steady at 13 volts while running

both wires W/R and W/B from the pickup coil to the ignitor are reading only 3 volts AC while running.

[1989Marathon]

This is the motor ground. Without it, the plug won't fire. If it is loose or corroded, the plug won't fire consistantly.
If you can't find the ground wire going to the motor block, just run another one from the battery negative to the engine block and see if that fixes the issue.

[davekayse62]

my main ground from the battery goes to the starter as shown, I don't have any grounds that go directly to the engine. the diagram shows 2 wires coming off of the Battery - but I only have 1

[1989Marathon]

Connect a wire(at least 16 guage) from the battery negative to the engine block, and see if that solves the issue.

[davekayse62]

ok ill do that tomorrow, thanks