**ONAN GENERATOR WOES, THE EASY FIX..***

[2FORCEFULL]

Here's the problem...and how it happens... junk gas...it sits in the carb bowl and plugs the fuel jet....the fix, about 4 or 5 hundred and get a new carb...then make sure you start and run the gen monthly,and keep lucus fuel treatment in the tank...as some of you know, I for some unknown reason seem to end up with a lot of different rv's in my drive way.... I've gotton brand knew units that where hard to start..... even though you can take the new ones to onan….. it's a PITA to go there on opointment... then go back when it's ready... and every time the same story,... new carb...

so here's my at home fix.... works every time...little time consuming, but ,.. ways less than going to onan...

Go to Walmart, get a gallon of lucus, put a quart in the fuel tank,... and fill up the tank..


first thing is I shut both breakers,drain the old fuel out of the carb...if it's yellow and smells like paint thinner... you're gonna be awhile...next,.... get a gas catch container ( glass bottle).. push the pmine button.... it's the stop button on the start button...pump out the bad gas in the line...

now here's the problem,... onan made the carb bowl sealed and none removable.... so how to clean the jet....

soooo... I hold the fuel line as low as i can... some times if it's real bad I put an in line see through fuel filter and add a few feet of fuel line..


I then take a spray can of carb clean and and slowly fill the fuel line with the cleaner..... I put the end back on the carb.... make sure you close the bowl drain screw and push the prime button...when the fuel bowl is full....listen for the change in sound from the pump,.. then pull the fuel line again, dump out the fuel and fill with carb clean...put it back on the carb.... hit the prime for a secound...and go do something else.... let it sit... say an hour or so....I go back , hit the prime and then the start... if it starts and shuts down quick, you're in luck and almost done...at that point... let it sit again.... that means that you have gotton the cleaner working up the jet..

 

[stokerwhore]

...or you can replace that stupid solenoid that goes into the bottom of the float bowl with a metric bolt(I forget what size) and your done. $1.25. you're welcome. might run a little fat but it will start and run everytime. if it don't, drain the float bowl and reprime. water will collect in it if you got it in the tank. NOTE this is the fix for the older ones. I haven't seen the ones that were made since the "gold marque" series

 

[2FORCEFULL]

part 2...

most of the time I don't even take off the air cleaner.... but... some are real bad.... like the 10 year old units with 14 hrs on the gen...most like ly it got plugged the first year and wouldn't start... so it got sold 10 yrs latter with the "there's not enough fuel in the tank for it to start ,but it runs fine"...LOL..

for those.... I take the air cleaner off..... give a squirt of carb cleaner to get it to try to start..if you can get it to run on it's own for just a secound... it's almost fixed... that means the cleaner is getting past the jet...... some real bad ones you might have to drain the bowl and start over.... this also cleans the float needle and seat,... I also have found that to be the problem...but compared to the lost day to go to get it fixed and the 500 dollar bill....this is easy for me..

 

[DLow]

Sounds like a good system to get running again. Any time I have something with the potential to sit more than a month, I run straight AV in it (this is off-road, non cat application). You may want to look into that after you have them running smooth again.

 

[Hardly Satisfied]

Great info

 

[Singleton]

Or just get an EFI Onan and be done with it
That being said, bad gas still make start up after sitting for 2-3 months rough. Takes a few minutes to run the bad gas through the system

 

[2FORCEFULL]

Or just get an EFI Onan and be done with it
That being said, bad gas still make start up after sitting for 2-3 months rough. Takes a few minutes to run the bad gas through the system

preventive steps, drain the bowl to winterize...but the next step is ,... if you know it's been setting,... pump the old gas out of the fuel line before you try to start by holding the prime button with the carb bowl screw open... again, catch the fuel in a fuel safe container...

the trick is to get a high concentrate of cleaner in the bowl...my way seems to work every time with out getting my hands dirty

 

[2FORCEFULL]

...or you can replace that stupid solenoid that goes into the bottom of the float bowl with a metric bolt(I forget what size) and your done. $1.25. you're welcome. might run a little fat but it will start and run everytime. if it don't, drain the float bowl and reprime. water will collect in it if you got it in the tank. NOTE this is the fix for the older ones. I haven't seen the ones that were made since the "gold marque" series

yeah, that back fire is cool when you finally shut down the gen at night..make everyone think some one got shot... all the scare lights go on and the dogs in a 3 mile radis start barking.....cool....

 

[River Runnin]

Mine's a Diesel and hasn't skipped a lick in twenty years!

 

[2FORCEFULL]

I wanna add this also, and I see people do this all the time.. never ever ever ever ever ever touch the throttle on a gen carb with out shuttin off the breakers.. power levels on gens are set by engine RPMS,... holding the throttle wide open can put 240 volts to all you appliances... by by tv 's and electronic's in the rv

 

[2FORCEFULL]

Mine's a Diesel and hasn't skipped a lick in twenty years!

fill your fuel tank with gas... see if that helps...also, you might wanna remove the muffler so you can hear if it's even running...

 

[grumpy88]

I have bought more then my share of carbs . I added a fuel shut off valve and now when I run my generator I kill the gas and let it run dry . It has been flawless so far

 

[Ziggy]

I have bought more then my share of carbs . I added a fuel shut off valve and now when I run my generator I kill the gas and let it run dry . It has been flawless so far

I drain the carb fully when I put mine away

 

[ElAzul]

Small splash of marine 2 stroke oil in gas at all times seems to keeps things moving just fine for me. Helps keep seals and gaskets from drying out too.

 

[bagged97taco]

Steve. Since we are talking Onan generators I have a question. I have a 5500 in my tiffin. This past summer it would shit off while driving. Oil is full to the max. What else should I look at? Hard for the kids to ride in the rig when it’s 110 outside and no inside Ac

 

[Universal Elements]

Steve. Since we are talking Onan generators I have a question. I have a 5500 in my tiffin. This past summer it would shit off while driving. Oil is full to the max. What else should I look at? Hard for the kids to ride in the rig when it’s 110 outside and no inside Ac

Is the fuel tank less than 1/4 tank when this happens?

 

[bagged97taco]

Is the fuel tank less than 1/4 tank when this happens?

No. It’s full Also to add it will run for hours and hours sitting with both Ac units on full blast. But as soon as we start driving it shuts off. Was thinking it’s and air supply issue or possible fuel pump issue.

 

[Uncle Dave]

Steve. Since we are talking Onan generators I have a question. I have a 5500 in my tiffin. This past summer it would shit off while driving. Oil is full to the max. What else should I look at? Hard for the kids to ride in the rig when it’s 110 outside and no inside Ac

Couple things could be going on -

1. oil overfill shutoff is most likely - drain/suck (mityvac works great here) exactly 1 pint out - and try again.

2. generator fuel pickup is designed so you dont run yourself dry sitting and is usually placed between 1/8 and 1/3 off the bottom - if your fuel level shakes or runs below that it will die.

3. They flat out overheat on 100 degree days as black asphalt is over 120 and they won't run when the intake air gets that hot.
(the only fix for this is a high pressure mister pump)

UD

 

[Cdog]

Once you get it fixed, put a hose on the drain . Leave it open/ drain fuel when not in use. Works 100% of the time

 

[thmterry]

I just bought a Carb for my Onan 5500 Gold Marquis for $60 on Amazon.

Amazon.com: 541-0765 Carburetor for 5410765 48-2042 141-0983 141-0982 146-0774(PWY) A043B781 A041P558 Onan 5500 Grand Marquis Gold generator HGJAA HGJAB-901D HGJAB-900 5.5HGJAB-6755K: Automotive

Buy 541-0765 Carburetor for 5410765 48-2042 141-0983 141-0982 146-0774(PWY) A043B781 A041P558 Onan 5500 Grand Marquis Gold generator HGJAA HGJAB-901D HGJAB-900 5.5HGJAB-6755K: Carburetors - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[rrrr]

I wanna add this also, and I see people do this all the time.. never ever ever ever ever ever touch the throttle on a gen carb with out shuttin off the breakers.. power levels on gens are set by engine RPMS,... holding the throttle wide open can put 240 volts to all you appliances... by by tv 's and electronic's in the rv

This is incorrect, with the exception of generators that have electronic inverters that convert DC voltage to AC voltage while regulating the frequency at 60 Hz. Varying the RPM of a typical generator changes the frequency, not the voltage.

The voltage output of the generator (it's actually an alternator) is regulated by an automatic voltage regulator. The AVR is fed voltage from a shunt, or tap winding from the alternator's stator. The AVR then uses that voltage to produce the generator excitation current, which as it changes alters the strength of the stator's magnetic field and thus regulates the voltage.

A typical RV generator operates at 3,600 RPM, and has two sets of field coils, or operates at 1,800 RPM and has four sets of field coils. If the RPM changes, then the frequency does too.

Some small generators that have electronic output inverters, the Honda 2000i being the most familiar example, do vary their RPM. They are true DC generators, and the electronic inverter converts the DC voltage to AC and regulates the frequency at 60 Hz. The RPM varies with the load demand with this type of generator, and the inverter creates a true sine wave voltage and current at the proper frequency.

This is a basic schematic of a typical shunt winding generator with an automatic voltage regulator

.

 

[TCHB]

I started and ran my generators and loaded them up with air conditioner running every month. A generator likes to run and get hot to keep moisture out.

 

[Dalton]

This is incorrect, with the exception of generators that have electronic inverters that convert DC voltage to AC voltage while regulating the frequency at 60 Hz. Varying the RPM of a typical generator changes the frequency, not the voltage.

The voltage output of the generator (it's actually an alternator) is regulated by an automatic voltage regulator. The AVR is fed voltage from a shunt, or tap winding from the alternator's stator. The AVR then uses that voltage to produce the generator excitation current, which as it changes alters the strength of the stator's magnetic field and thus regulates the voltage.

A typical RV generator operates at 3,600 RPM, and has two sets of field coils, or operates at 1,800 RPM and has four sets of field coils. If the RPM changes, then the frequency does too.

Some small generators that have electronic output inverters, the Honda 2000i being the most familiar example, do vary their RPM. They are true DC generators, and the electronic inverter converts the DC voltage to AC and regulates the frequency at 60 Hz. The RPM varies with the load demand with this type of generator, and the inverter creates a true sine wave voltage and current at the proper frequency.

This is a basic schematic of a typical shunt winding generator with an automatic voltage regulator

.

I was thinking this....I have a few backup generators that can do 50 or 60 hz....it just changes the RPM, volts stay the same. Not 100%, but they are diesel and I think 1600 RPM is 60hz on them

 

[rrrr]

It's 1200 RPM. You were close.

And today's trivia bit...the generators at Hoover Dam run at 180 RPM.

 

[RCDave]

God i love my diesel onan genset.

 

[Carlson-jet]

yeah, that back fire is cool when you finally shut down the gen at night..make everyone think some one got shot... all the scare lights go on and the dogs in a 3 mile radis start barking.....cool....

It's weird. I don't remember that happening prior to these fuel shut off solenoids.
One can avoid this this by shutting it down with the choke on.
Still got a good chuckle because your description is dead on. LOL

 

[JUSTWANNARACE]

Isnt there a plug on the side of the carb you can pull(sometimes have to drill it out) to get to the jet? If the bowl is not removable they had to get the jet in there some how. I'm sure it's not cast into the body.

 

[Carlson-jet]

Isnt there a plug on the side of the carb you can pull(sometimes have to drill it out) to get to the jet? If the bowl is not removable they had to get the jet in there some how. I'm sure it's not cast into the body.

thmterry has an old carb you can experiment with. Emissions have gotten out of control to where pulling the bowl could lead to actually making the genset run for a few extra years. Better just to throw the old one away and pay thousands for new. It's the new green way.

 

[HB2Havasu]

After buying 2 Carbs for my Onan 5500 at $500 a pop, I bought a $5 Dollar In-Line Fuel Shutoff Valve and run it dry when I'm done for the weekend. Haven't had 1 issue in 7 years since adding the $5 Shutoff Valve! (FYI - Always add Stabil to the Fuel Tank. Ethanol Fuel starts to turn to Varnish after 6 weeks without stabilizer)

 

[2FORCEFULL]

I just wanna add this....and it's your choice.... when fuck'n with the gen ,.. shut the power breakers off...it's just a common sense pre caution.....

 

[Bigbore500r]

I fire mine up at least every 2 months (try to do it every month, sometimes i forget) and a run it under load for 5 minutes, AC on. Seems to keep it dialed. Motorhome goes thru a tank of fuel every 2-3 months, so the gas doesn't get too old and that probably helps.

 

[pkrrvr619]

I was told to just open the screw under the altitude adjustment knob and drain the gas out of the carb after each trip. Seems to work quite well thus far.

 

[2FORCEFULL]

I was told to just open the screw under the altitude adjustment knob and drain the gas out of the carb after each trip. Seems to work quite well thus far.

that's the best way to not have a problem...

 

[2FORCEFULL]

and one more thing...… when the gen surges.... the lights will go dim and bright.... the ac fan will change speeds... and it will fuc up your tv to where you have to buy a new one...so what ever holding the throttle wide open does..... it's not good....lol

 

[C08H18]

I have bought more then my share of carbs . I added a fuel shut off valve and now when I run my generator I kill the gas and let it run dry . It has been flawless so far

I do the same along with an online filter and longer fuel line so the shutoff is really easy to get to it. Lately I’m doing the same on my mowers


Sent from my iPhone using Tapatalk

 

[guest hs]

Hey Steve next time try Mercury’s Power Tune instead of carb cleaner.

 

[La13russell]

Here's the problem...and how it happens... junk gas...it sits in the carb bowl and plugs the fuel jet....the fix, about 4 or 5 hundred and get a new carb...then make sure you start and run the gen monthly,and keep lucus fuel treatment in the tank...as some of you know, I for some unknown reason seem to end up with a lot of different rv's in my drive way.... I've gotton brand knew units that where hard to start..... even though you can take the new ones to onan….. it's a PITA to go there on opointment... then go back when it's ready... and every time the same story,... new carb...

so here's my at home fix.... works every time...little time consuming, but ,.. ways less than going to onan...

Go to Walmart, get a gallon of lucus, put a quart in the fuel tank,... and fill up the tank..


first thing is I shut both breakers,drain the old fuel out of the carb...if it's yellow and smells like paint thinner... you're gonna be awhile...next,.... get a gas catch container ( glass bottle).. push the pmine button.... it's the stop button on the start button...pump out the bad gas in the line...

now here's the problem,... onan made the carb bowl sealed and none removable.... so how to clean the jet....

soooo... I hold the fuel line as low as i can... some times if it's real bad I put an in line see through fuel filter and add a few feet of fuel line..


I then take a spray can of carb clean and and slowly fill the fuel line with the cleaner..... I put the end back on the carb.... make sure you close the bowl drain screw and push the prime button...when the fuel bowl is full....listen for the change in sound from the pump,.. then pull the fuel line again, dump out the fuel and fill with carb clean...put it back on the carb.... hit the prime for a secound...and go do something else.... let it sit... say an hour or so....I go back , hit the prime and then the start... if it starts and shuts down quick, you're in luck and almost done...at that point... let it sit again.... that means that you have gotton the cleaner working up the jet..

Okay so Onan 5500 .it starts ..runs like 5 seconds shuts down. I open the drain 9n the carb. Nothing. I know fuel pump is working because I removed the hose pushed the prime and there was gas. Should I try the above steps as well??

 

[NorCalRiverRat]

(FYI - Always add Stabil to the Fuel Tank. Ethanol Fuel starts to turn to Varnish after 6 weeks without stabilizer)

oh shit, I have to do this, like 6 weeks ago.....or more

..

 

[HB2Havasu]

Okay so Onan 5500 .it starts ..runs like 5 seconds shuts down. I open the drain 9n the carb. Nothing. I know fuel pump is working because I removed the hose pushed the prime and there was gas. Should I try the above steps as well??

Check your oil levels. Too little or too much will send a signal to shut down the engine. Have you checked your fault codes?

 

[La13russell]

Check your oil levels. Too little or too much will send a signal to shut down the engine. Have you checked your fault codes?

I get code 36

 

[La13russell]

Check your oil levels. Too little or too much will send a signal to shut down the engine. Have you checked your fault codes?

I get code 36

 

[La13russell]

Code 36

 

[Bpracing1127]

I solved this problem by putting a valve on the fuel line. When I know I am not gonna use it for some time. I turn the valve off and let it run its self out of fuel. Boom no more problem. No need to drain the bowl or anything like that. Valve is 3-10$

 

[La13russell]

I solved this problem by putting a valve on the fuel line. When I know I am not gonna use it for some time. I turn the valve off and let it run its self out of fuel. Boom no more problem. No need to drain the bowl or anything like that. Valve is 3-10$

I just need to know what steps I can try if there is no gas coming from the bowl

 

[Pesky Varmint]

This is incorrect, with the exception of generators that have electronic inverters that convert DC voltage to AC voltage while regulating the frequency at 60 Hz. Varying the RPM of a typical generator changes the frequency, not the voltage.

The voltage output of the generator (it's actually an alternator) is regulated by an automatic voltage regulator. The AVR is fed voltage from a shunt, or tap winding from the alternator's stator. The AVR then uses that voltage to produce the generator excitation current, which as it changes alters the strength of the stator's magnetic field and thus regulates the voltage.

A typical RV generator operates at 3,600 RPM, and has two sets of field coils, or operates at 1,800 RPM and has four sets of field coils. If the RPM changes, then the frequency does too.

Some small generators that have electronic output inverters, the Honda 2000i being the most familiar example, do vary their RPM. They are true DC generators, and the electronic inverter converts the DC voltage to AC and regulates the frequency at 60 Hz. The RPM varies with the load demand with this type of generator, and the inverter creates a true sine wave voltage and current at the proper frequency.

This is a basic schematic of a typical shunt winding generator with an automatic voltage regulator

.

Absolutely spot on. Even an inverter generator cannot deliver excessive voltage. And those Onan carbs allegedly sealed and everyone tells you they cant be rebuilt. The bowl is removable, I've done it many times, pull the jets and an assortment of other passages, all made of metal, soak them in acetone and put them back in. No need to buy new carb. However, take meticulous care of the gaskets, if you ruin one you can't get them, and you'll have to make one which I hate doing. So for me, these carbs are rebuildable. All the rest of my generators are diesel.

 

[Nanu/Nanu]

Yeah I pull my bowl out and clean it every year I have a Onan microquiet 4000. Fuel pump just went tits up on me .

 

[DarkHorseRacing]

I didnt know Onan gennys in RVs ran on gas or diesel. I thought they ran on propane from the tanks you can remove and refill. I've looked at a bunch of 5w's and I dont recall seeing a fuel fill on any of them for the generator they can come with. Or is this more the norm with Class A's which already have a fuel tank in them for the main engine they can also use?

 

[HB2Havasu]

I solved this problem by putting a valve on the fuel line. When I know I am not gonna use it for some time. I turn the valve off and let it run its self out of fuel. Boom no more problem. No need to drain the bowl or anything like that. Valve is 3-10$

This is what I did on my last Onan 5500 after I gummed up 2 carbs. After I installed the in-line fuel cutoff valve I went 10 years with zero problems. This is the only way to keep it from happening!!

 

[outboard_256]

I didnt know Onan gennys in RVs ran on gas or diesel. I thought they ran on propane from the tanks you can remove and refill. I've looked at a bunch of 5w's and I dont recall seeing a fuel fill on any of them for the generator they can come with. Or is this more the norm with Class A's which already have a fuel tank in them for the main engine they can also use?

my toyhauler has a 30 gallon tank for the gen and toys. It has a it's own fuel pump and hose to fill toys from. All the other trailers I know of with generators also have a fuel tank. Not sure I have seen propane generators on RV's.

 

[TPC]