Community Forums

irishguy · 01-06-2018, 12:42 PM

Hello all,

Our Onan 7.5 HDKAJ11451H diesel genny has never started all that great in cool weather and seems to be getting worse. It is 5C/41F here today. I tried starting it but no go. I didn't crank it too long or too many times for fear of draining the batteries but It always fires up in warm weather.

I tried 3 cycles of preheat starting but didn't even fire.

I would like to try changing the glow plugs. Are they easily accessed and changed?

Would anyone have a part number?

I'm betting the OEM glow plugs are expensive...is there an NGK plug part number that would work?

Thanks in advance for any advice

Irishguy

oldguy70 · 01-06-2018, 01:35 PM

The glow plugs are easy to change. Check them out with an ohm meter as you want to
make sure that it is the glow plugs that are shot. It could be that you aren't getting any
current to the plugs. I think you can get plugs through Amazon. My generator takes less
revolutions when its cold out then when its 80 out. I have started mine at -5 F, it takes
17 seconds on the plugs and the starts immediately.

MSHappyCampers · 01-06-2018, 02:55 PM

Maybe you're not preheating/priming it long enough. When it's cold and/or I haven't run it for a while, I hold down the bottom of the switch for 60 seconds. Then when I press the top there is a steady amber light for about ten seconds or so, then it starts immediately. It is not trying to crank during the 10 seconds I am holding the top down.

Outbound · 01-06-2018, 03:01 PM

I have noticed mine will start faster when I haven't used it for long periods of time when I use the switch at the generator, not sure if that is due to getting a hotter feed due to shorter wire run.

oldguy70 · 01-06-2018, 06:00 PM

When I start my generator I hold the start button until it starts. Depending how cold it
is, is what takes how long the glow plugs are being heated until the generator turns
over. I'm sure your glow plugs aren't working. Your just want to find out for sure if it is
the glow plugs that are shot and it's not the wiring. I would be it is the plugs but make sure.

NHRA225 · 01-06-2018, 06:10 PM

Glow Plugs seldom go away! They are used initially to Start. That being said in the warmer months they need a shorter charge and in Winter months much longer to fire off Cold Diesel ! Keep trying and I'll bet it fires off .

irishguy · 01-06-2018, 08:06 PM

Quote:

Originally Posted by MSHappyCampers

Maybe you're not preheating/priming it long enough. When it's cold and/or I haven't run it for a while, I hold down the bottom of the switch for 60 seconds. Then when I press the top there is a steady amber light for about ten seconds or so, then it starts immediately. It is not trying to crank during the 10 seconds I am holding the top down.

Hello Joe, I pushed the switch down to prime for a minute then I hold the start button down until it's about to start then let go...I do that 3 times to get the glow plugs hot. That usually works when it is cold out but not today.

irishguy · 01-06-2018, 08:09 PM

Quote:

Originally Posted by Outbound

I have noticed mine will start faster when I haven't used it for long periods of time when I use the switch at the generator, not sure if that is due to getting a hotter feed due to shorter wire run.

That's not a bad idea...I usually start with the dash starter so will try the switch on the genny.

irishguy · 01-06-2018, 08:10 PM

Quote:

Originally Posted by oldguy70

The glow plugs are easy to change. Check them out with an ohm meter as you want to
make sure that it is the glow plugs that are shot. It could be that you aren't getting any
current to the plugs. I think you can get plugs through Amazon. My generator takes less
revolutions when its cold out then when its 80 out. I have started mine at -5 F, it takes
17 seconds on the plugs and the starts immediately.

Can you get to them through the top access cover?

irishguy · 01-06-2018, 08:12 PM

Quote:

Originally Posted by NHRA225

Glow Plugs seldom go away! They are used initially to Start. That being said in the warmer months they need a shorter charge and in Winter months much longer to fire off Cold Diesel ! Keep trying and I'll bet it fires off .

I'm going to try again but just worried too much cranking will kill the batteries or wreck the starter.

irishguy · 01-06-2018, 08:13 PM

Quote:

Originally Posted by oldguy70

When I start my generator I hold the start button until it starts. Depending how cold it
is, is what takes how long the glow plugs are being heated until the generator turns
over. I'm sure your glow plugs aren't working. Your just want to find out for sure if it is
the glow plugs that are shot and it's not the wiring. I would be it is the plugs but make sure.

Hopefully it is just the glow plugs as it sounds like they are easy to change.

Eagles16 · 01-07-2018, 06:41 AM

Had the same problem, there are three fuses under the access panel of the generator. One fuse 25 amp is for the glow plugs, if this fuse is blown the glow plugs won't heat...

YC1 · 01-07-2018, 07:46 AM

Quote:

Originally Posted by Eagles16

Had the same problem, there are three fuses under the access panel of the generator. One fuse 25 amp is for the glow plugs, if this fuse is blown the glow plugs won't heat...

Ditto:

I can't seem to find where I bought glow plugs for mine.

I got them for around $10 each.