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 > Generator vapor locking

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Lantley

Ellicott City, Maryland

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Posted: 07/20/20 05:18pm Link  |  Quote  |  Print  |  Notify Moderator

It seems Doug is on to something. If its heat related I would think it would do it while you are parked as well. I would assume the compartment would still heat up when parked and there is zero air flow.
More importantly it happens if you shove or shake it manually which is not heat related. I don't think you can shove the genset it into vapor lock?
It appears from Doug's post the oil switch is a known issue.


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full-timer

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Posted: 07/20/20 06:27pm Link  |  Quote  |  Print  |  Notify Moderator

A new fuel pump fixed the exact problem on mine also.


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Lantley

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Posted: 07/20/20 06:32pm Link  |  Quote  |  Print  |  Notify Moderator

full-timer wrote:

A new fuel pump fixed the exact problem on mine also.

I like the fuel pump idea next I think it's just easier to bypass/eliminate the oil switch first.

dougrainer

Carrolton, Texas

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Posted: 07/21/20 07:26am Link  |  Quote  |  Print  |  Notify Moderator

For those than think fuel pump------There is a set amount of fuel in the Carb fuel bowl. The Pump does NOT supply continous fuel to the carb. There is a Float with a needle jet. The bowl continues to fill and the Needle valve shuts off excess flow. So, if the fuel pump was the issue, that would NOT cause an instantainous killing of the Genset. If the fuel pump was bad , then the Genset would kill at anytime. A "BUMP" would, if anything, cause a Pump to start running not kill it. Also, OIL problem(Switch) and viscosity will yield the Genset starting right back up when it dies. DOES THE GENSET START RIGHT BACK UP AFTER IT DIES? If so, you problem is not fuel supply or Vapor lock. I still state to replace the Oil pressure switch. That is a LOT cheaper than a fuel pump. DO NOT, install a regular automotive similar fuel pump. Those run at a higher PSI than an Onan pump. Doug

dodge guy

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Posted: 07/21/20 11:06am Link  |  Quote  |  Print  |  Notify Moderator

It very well could be a fuel pump. If it were weak Pump) and electric pumps are known to work at slower speeds when they get hot) would Cause the issue I’m having. I can’t see it being an oil issue only at hotter temps. I will try the pump first. If not then I’ll do an oil switch. If it were an oil switch issue it should give a code on why it shut down. I never get a code. There is no code to be set for low fuel flow. So if it died due to low fuel it wouldn’t set a code.


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dougrainer

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Posted: 07/21/20 11:29am Link  |  Quote  |  Print  |  Notify Moderator

dodge guy wrote:

It very well could be a fuel pump. If it were weak Pump) and electric pumps are known to work at slower speeds when they get hot) would Cause the issue I’m having. I can’t see it being an oil issue only at hotter temps. I will try the pump first. If not then I’ll do an oil switch. If it were an oil switch issue it should give a code on why it shut down. I never get a code. There is no code to be set for low fuel flow. So if it died due to low fuel it wouldn’t set a code.


OIL gets THINNER as it gets hot. You have not answered my questions but you seem willing to spend money. What Weight Oil is in the Genset? Does it start right back up after it kills? Doug

PS. NOTE that none of these state kill of engine.
Seven Fuel Pump Warning Signs
Engine Sputters at High Speeds. ...
Rising Temperature. ...
Fuel Pressure Gauge. ...
Loss of Power When the Vehicle Is Under Stress. ...
Surging. ...
Decreased Gas Mileage. ...
Engine Will Not Start.

dougrainer

Carrolton, Texas

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Posted: 07/21/20 11:30am Link  |  Quote  |  Print  |  Notify Moderator

Watch this video. Doug
I am giving you 41 years working on Onan Gensets. I did NOT base my advice on this video. I found it looking up codes for the Genset.

https://www.youtube.com/watch?v=Zqu2U_PGgj8

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Posted: 07/21/20 01:59pm Link  |  Quote  |  Print  |  Notify Moderator

dodge guy wrote:

It very well could be a fuel pump. If it were weak Pump) and electric pumps are known to work at slower speeds when they get hot) would Cause the issue I’m having. I can’t see it being an oil issue only at hotter temps. I will try the pump first. If not then I’ll do an oil switch. If it were an oil switch issue it should give a code on why it shut down. I never get a code. There is no code to be set for low fuel flow. So if it died due to low fuel it wouldn’t set a code.

It's your money so do what you want.

If it were my money I'd start with the oil switch as Doug suggested. Pretty cheap and easy to try, and 100% makes sense as to what is happening, as he explained.

With that said, we once owned a Ford powered MH that would die when it got hot - it was the fuel pump. The big difference is that one wouldn't immediately re-start and run well. Sometimes it would re-start and limp, sometimes it wouldn't re-start until it had cooled.


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dodge guy

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Posted: 07/21/20 05:22pm Link  |  Quote  |  Print  |  Notify Moderator

No I haven’t checked the fuel pressure. But since it is a low psi electric pump it’s max pressure will only be about 7 psi. So if it’s weak it will run slower. Not enough to die but not enough to keep the float bowl full. And yes it always starts right back up, but it needs to crank about 5-7 seconds before it starts. Like it has to fill the bowl. The oil I’m running is 20W50 IIRC. The RV is in storage right now. The 7 signs you listed are for vehicle engines, not a generator. I will watch the video. Thanks.

dodge guy

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Posted: 07/21/20 05:25pm Link  |  Quote  |  Print  |  Notify Moderator

Bruce Brown wrote:

dodge guy wrote:

It very well could be a fuel pump. If it were weak Pump) and electric pumps are known to work at slower speeds when they get hot) would Cause the issue I’m having. I can’t see it being an oil issue only at hotter temps. I will try the pump first. If not then I’ll do an oil switch. If it were an oil switch issue it should give a code on why it shut down. I never get a code. There is no code to be set for low fuel flow. So if it died due to low fuel it wouldn’t set a code.

It's your money so do what you want.

If it were my money I'd start with the oil switch as Doug suggested. Pretty cheap and easy to try, and 100% makes sense as to what is happening, as he explained.

With that said, we once owned a Ford powered MH that would die when it got hot - it was the fuel pump. The big difference is that one wouldn't immediately re-start and run well. Sometimes it would re-start and limp, sometimes it wouldn't re-start until it had cooled.


You guys are aware this is the Generator engine right? The generator runs In completely different parameters than the vehicle engine.

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