Generator Won't Turn Over

[10forty2]

Onan 5500.

Soooo...... We camped this past weekend at the local lake/state park. Had an awesome time! On the way there, as I always do, I ran the generator so I could run the house A/Cs and to exercise the genset. When it was time to leave, I unplugged the shore line, and noticed that the slide was abnormally slow coming in on the house battery alone. Went outside to crank the geset, and it would only give a loud click and then smaller clicking like the battery was too weak to turn it over. I figure the house battery is dead or going dead. We head home, and when I get home, I replaced the house battery (I was using a single 12VDC combination battery) with 2 6VDC Trojan Golf Cart batteries. Genset still clicks loudly and then little clicks like the battery is still too weak....but I know it's not....testing the new batteries when trying to crank the genset shows only a slight voltage drop from 13.6 to 12.8.

Things I've checked already...... battery cables...good connection. Genset engine oil... good and recently changed at the beginning of the season. Ran out of daylight before I could get any further....

And.......GO!

[tropical36]

10forty2 wrote:
Problem solved. Pulled the generator, replaced starter, hit the switch, and BAM! Started right up. I must say, pulling the generator wasn't as bad as I had anticipated, but it definitely took two people and a couple of bottle jacks. Not sure WHY any RV manufacturer wouldn't put those things on a slideout tray..... I guess they planned on getting the repairs themselves.....

EDIT to say, that after following all the diagnostic steps outlined by everyone here, I traced it to the starter. New batteries, all cables were cleaned and tightened, solenoid jumped and 12vdc applied directly to the starter via jumper cables....all did nothing. Measured the voltage before and after pushing the start button...not drain on the batteries, which indicated the starter was not pulling any current. Sooo, the only thing left was to replace the starter. Replaced it with Onan OEM....didn't like reviews of any of the aftermarket starters. More pricey than I wanted but found it on ASAP Parts online. Good website for Onan generator parts....

ASAP Parts for Techs

On an old 87 Pace Arrow we once had, I was able to remove the starter from below, repair it and reinstall it on the morning we were set to leave. Only held us up for a few hours and we were underway, after lunch. Not so sure about the last one we had with a Generac, as I did have to drop it, using a floor jack and homemade platform to replace the Stator.
Now with our present quiet diesel, it had to be dropped, just for replacing the water temp. sensor, so.............

[10forty2]

Problem solved. Pulled the generator, replaced starter, hit the switch, and BAM! Started right up. I must say, pulling the generator wasn't as bad as I had anticipated, but it definitely took two people and a couple of bottle jacks. Not sure WHY any RV manufacturer wouldn't put those things on a slideout tray..... I guess they planned on getting the repairs themselves.....

EDIT to say, that after following all the diagnostic steps outlined by everyone here, I traced it to the starter. New batteries, all cables were cleaned and tightened, solenoid jumped and 12vdc applied directly to the starter via jumper cables....all did nothing. Measured the voltage before and after pushing the start button...not drain on the batteries, which indicated the starter was not pulling any current. Sooo, the only thing left was to replace the starter. Replaced it with Onan OEM....didn't like reviews of any of the aftermarket starters. More pricey than I wanted but found it on ASAP Parts online. Good website for Onan generator parts....

ASAP Parts for Techs

[bjbear]

10forty2 wrote:
Looks like I'm going to have to pull the generator to replace the starter. I can manually turn the engine and it turns freely. The starter solenoid seems to be working good, and the voltage is getting there, but all that happens when I hit the button is the solenoid "CLICK" and the fuel pump running.....but not turning the engine. Gotta plan another day with a couple friends, some bottle jacks, and boards to slide the genset out so I can get to teh starter to replace it. Guess that'll be a good time to do all the other servicing too.....

Before pulling the generator, I would recommend that you connect a voltmeter to the studs on the 12V supply on the generator itself. Try to attach to the end of the threaded section and not to the cable itself.

Step 1 - Then take a reading. Should be same as batteries.

Step 2 - Then have someone attempt to start the generator and observe the voltage reading. You may find that the voltage droops very low (i.e. < 9 volts).

If voltage is less than battery volts in step 1, check your ground cable
If voltage drops low in step 2, it means you probably have a bad/dirty connection on the 12 V cable(s). If voltage does not drop in step 2, then it is probably a bad starter or solenoid.

Note... a low voltage on step 2 could be the starter/solenoid, but a bad connection is more likely so should be checked before removing/working on generator.

[10forty2]

Looks like I'm going to have to pull the generator to replace the starter. I can manually turn the engine and it turns freely. The starter solenoid seems to be working good, and the voltage is getting there, but all that happens when I hit the button is the solenoid "CLICK" and the fuel pump running.....but not turning the engine. Gotta plan another day with a couple friends, some bottle jacks, and boards to slide the genset out so I can get to teh starter to replace it. Guess that'll be a good time to do all the other servicing too.....

[10forty2]

old guy wrote:
one thing many people over look is even if the cable ends are clean and tight there might be enough corrosion inside the cable under the protective cover. it happened to me and I was dead in the water. had to be towed in and the mechanic was smart enough to find the problem

That's something I haven't checked, but will put it on the list once I get some time to get back into it! Thanks!

[10forty2]

wa8yxm wrote:
That ALMOST happened to me... Thankfully I caught the problem before it happened.

The Slow retraction was due to low battery power. This may be due to batteries at end of age or .. Read my story.

Might also be a tripped breaker in your breaker panel (CONV).

The story... Last October (29th) I came home from Church and noticed things were not right.. Very low voltage.. Seems my veneraboe old duodecade (12 years) old Progressive Dynamics 9180 had bit the dust... So Being sunday it was off to Auto Zone for a Deltran Battery Tender.. This is the big one. 70 amp jump start (no use in this case) 20 amp Bulk and 1-2 amp tender. Set it to 20 amps and 24 hours later it dropped to tender. I was packed so I pulled the slides in and off we went.

TO Marshall MI.. Where on Halloween I took my Debit card and the old 9180 and walked into the Progressive Dynanics Parts and Serivce department.

A short time later I walked out and it's been fine ever since.

All breakers and fuses are good. Converter is working and outputting 13.8vdc when plugged in to shore power.

[10forty2]

bounder39zman wrote:
Either I missed it, or you failed to post model and spec number of your generator. If you post that info, you have a better chance of getting help and advice from people who have had similiar issues or are experienced in repairing these gensets

Onan 5500 BGM-FA/11578H

[old_guy]

one thing many people over look is even if the cable ends are clean and tight there might be enough corrosion inside the cable under the protective cover. it happened to me and I was dead in the water. had to be towed in and the mechanic was smart enough to find the problem

[wa8yxm]

That ALMOST happened to me... Thankfully I caught the problem before it happened.

The Slow retraction was due to low battery power. This may be due to batteries at end of age or .. Read my story.

Might also be a tripped breaker in your breaker panel (CONV).

The story... Last October (29th) I came home from Church and noticed things were not right.. Very low voltage.. Seems my veneraboe old duodecade (12 years) old Progressive Dynamics 9180 had bit the dust... So Being sunday it was off to Auto Zone for a Deltran Battery Tender.. This is the big one. 70 amp jump start (no use in this case) 20 amp Bulk and 1-2 amp tender. Set it to 20 amps and 24 hours later it dropped to tender. I was packed so I pulled the slides in and off we went.

TO Marshall MI.. Where on Halloween I took my Debit card and the old 9180 and walked into the Progressive Dynanics Parts and Serivce department.

A short time later I walked out and it's been fine ever since.

[bounder39zman]

Either I missed it, or you failed to post model and spec number of your generator. If you post that info, you have a better chance of getting help and advice from people who have had similiar issues or are experienced in repairing these gensets

[DrewE]

10forty2 wrote:
I may be on to something with some research. It appears that the Trojan T-605s that I bought and installed for house batteries have no CCA rating, and the Onan specs call for minimum of 360/450 CCA. I'll try jumping it with a known good starting battery and see what happens when I get some time this weekend.......

The batteries should not be the problem; they can supply sufficient current to star the generator, even if Trojan doesn't list a CCA specification. You have a poor connection somewhere between the batteries and the generator's starter (or maybe, but less likely, a bad starter, or starter solenoid, or connection in the generator's control module, or....). The bad connection(s) may be along the positive path or along the ground path or both.

Using a battery and jumpers straight to the generator is helpful to verify that it is a bad connection somewhere, but don't misinterpret the results as meaning that your new batteries are insufficient for the task as I very highly doubt that to be the case. You could jump the other battery to them directly (assuming it starts the generator when connected to the generator directly) to demonstrate that the problem is with the wiring between them.

[10forty2]

I may be on to something with some research. It appears that the Trojan T-605s that I bought and installed for house batteries have no CCA rating, and the Onan specs call for minimum of 360/450 CCA. I'll try jumping it with a known good starting battery and see what happens when I get some time this weekend.......

[MrWizard]

I replaced the starter on two different Onan genset
Two different RVs

Had to drop the genset down both times

First was a swing down, pretty easy to do
The second one was tough
One by one I replaced the for four mounting bolts with long pieces of all thread
With double nuts for locking
Then with a floor jack under the Onan I slowly loosened each new all thread bolt taking turns and slowing letting it down to the point where I could reach the starter
The Onan was hanging from the all thread
Be sure to disconnect control wires, battery cables, fuel line and exhaust hangers before lowering it
So nothing snags or breaks

[Jim]

That happened to me once. It acted just like the starting motor wasn't getting voltage. Took a good long look at it and discovered the ball bearing at the end of the generator was toast. It had gotten sand it if from the road somehow and ground up the balls until one of them broke and stopped them all from turning. Which jambed the crankshaft so it just wouldn't turn.

It all happened so suddenly, and had the symptoms of a dead battery, so it was a head scratcher for a while.