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Propane and Natural Gas Fuel Delivery and Tuning Discussion about the care and feeding of Propane and Natural Gas Engines.

Propane and Natural Gas Fuel Delivery and Tuning

Onan Propane House Back-Up Won't Cold Start


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  #1  
Old 03-21-2019, 06:40:23 PM
soundtechmike soundtechmike is offline
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Default Onan Propane House Back-Up Won't Cold Start

Engine model is P224G-L/116148. When it trys to start on its exersize cycle it fails. If you reset and try manually. still won't start. while its cranking the throttle lever on the throttle body hooked by a rod to the solenoid fluctuates back and forth. But if you hold the throttle against the idle stop screw it fires right up and runs fine. Also starts right back up on its own with only short warm up. but cold does not start. Any help would be greatly appreciated!
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Old 03-22-2019, 04:23:05 PM
old sparky old sparky is offline
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Default Re: Onan propane house back-up won't cold start

Double check gas reg preasure possibly install a demand reg
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Old 03-23-2019, 11:02:04 AM
soundtechmike soundtechmike is offline
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Default Re: Onan propane house back-up won't cold start

Will do. Thanks Old Sparky.
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Old 03-23-2019, 02:21:11 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: Onan propane house back-up won't cold start

Cold start on propane was a prblem on propane powered sky lifts i used on jobsites. Cold gas, cold engine - no start! We used to keep a little gasoline in a squirt type oil can. One shot of gasoline, and the engine would start - no matter how cold it ws outside (-10F one day). You might try and adjust the throttle selenoid so the throttle stays closed for cranking, and opens after the engine starts.
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Old 03-23-2019, 03:11:00 PM
cornbinder89 cornbinder89 is offline
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Default Re: Onan propane house back-up won't cold start

When we ran manlifts on LP, we found that the spark-plug gap needed to be reduced from the gasoline setting for best results. Look in the manual if they list a setting for LP.
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Old 03-31-2019, 11:51:38 PM
dkamp dkamp is offline
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Default Re: Onan propane house back-up won't cold start

The reason why it's not starting with throttle wide open, vs, throttle at idle, is simple: Dynamic compression with throttle at full open is too high for the ignition to fire off a hot enough spark to ignite the fuel/air mix.

Shortening the spark plug gap will increase arc current, perhaps enough to make it fire. Clean the points good, check the condenser and coil.

Also make sure that the diaphram in your fuel controller hasn't dried out and become hard.
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Old 05-31-2019, 08:49:49 AM
kwil kwil is offline
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Default Re: Onan propane house back-up won't cold start

you should be able to adjust selenoid close your plug gap 5 thousands and advance timing 2 to 3 degrees LP is 140 octane it needs a hot spark kwil
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Old 06-03-2019, 11:29:18 PM
dkamp dkamp is offline
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Default Re: Onan propane house back-up won't cold start

Quote:
Originally Posted by kwil View Post
you should be able to adjust selenoid close your plug gap 5 thousands and advance timing 2 to 3 degrees LP is 140 octane it needs a hot spark kwil
No, it's closer to 112 RON... but it DOES need a very hot spark. More than likely, his demand regulator's diaphragm has degraded enough so that it's developed a slight leak or too stiff to respond.

Closing the throttle would, under normal conditions, reduce the regulator's demand flow, but the fact that it fires with the throttle closed clearly identifies that mixture while cranking at WOT is too lean to get ignition. Closing the throttle decreases dynamic compression which increases spark energy intensity, thus, igniting the lean condition.

If it was running on propane previously (and it sounds as if it has been), then altering the timing is not a proper solution here... something degraded and needs to be replaced.
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Old 06-16-2019, 07:49:47 AM
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grub54891 grub54891 is offline
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Default Re: Onan Propane House Back-Up Won't Cold Start

I'd go with regulater also. I've rebuilt many with the same issue. One place I worked the owner had the kohler specialist up twice to find the issue.
The no start persisted. I offered to rebuild the regulater, and it's been fine for the last 9 years.
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