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generac 17kw shuts off after 1 second run time

Posted: Mon Aug 12, 2019 4:31 pm
by dbishop
Hello working on a 17kw generac with pre nexus controller lcd screen. customer asked me to come change the controller because lcd screen was black, I changed the controller however unit would not stay running for more the a second however the lcd screen till shows running then it tries to start again and repeats the crank cycles until if finally goes into over crank. Put old controller in and still the same problem. checked spark on both cylinders and was good, generac told me to change out the mags because the diodes are bad on mags... did that (big job) didn't work, wire 18 to controller is measuring 3volts while cranking.
fuel solinoed is new and functioning fuel pressure 5 w/c NG, replaced wire 18 anyway, battery is charging cranking engine properly, 12.8 volts static 11.5 cranking. can see voltage a/c output of 160 volts before shut down, Possible bad new controller out of box? feel like customer didn"t give me the whole story when i started the job, have 6 hrs and no results what am i missing? please advise thanks Dave

Re: generac 17kw shuts off after 1 second run time

Posted: Mon Aug 12, 2019 4:49 pm
by Chris
Sounds like the unit was hit by lightning based on the things you've replaced...

When you put the coils in, are you SURE that they're facing the correct direction?

The front cylinder's coil wire points towards the back of the engine and you have to curl the wire around and out the front...

Re: generac 17kw shuts off after 1 second run time

Posted: Mon Aug 12, 2019 5:04 pm
by dbishop
Thanks Im positive they're correct I followed the instructions perfectly even filed down the post near the bolts that hold them, generac changed the part # for these coils and the installation is different from the old ones

Re: generac 17kw shuts off after 1 second run time

Posted: Mon Aug 12, 2019 9:13 pm
by Chris
Yes, and the kit also comes with a new ground wire since the older coils used a set of diodes in the ground harness which are no longer there. Have you tried running the engine on 1 cylinder by pulling a plug wire and see if it changes?

Re: generac 17kw shuts off after 1 second run time

Posted: Tue Aug 13, 2019 9:20 am
by dbishop
thanks again yes I did run on 1 cylinder by accident and it ran the same time, also wanted to mention that unit doesall of the same things that it was doing from the moment I opened the lid

Re: generac 17kw shuts off after 1 second run time

Posted: Tue Aug 13, 2019 9:25 am
by Chris
You mentioned that you can see 160VAC output before shutdown. Is that line to neutral or line to line?

Back to my question about running on 1 cylinder... Did you try to run on 1 cylinder for each cylinder? As in, run it on the back and then on the front?