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Need advice on Onan 5500 carb repair.

Don Batman

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Let it sit too long without starting and something internal is plugged as far as I can tell. No clue on how float bowl comes off so I can see what is wrong. Thinking about trying one of the cheap E-Bay 60$ carbs. Trying to locate a shop manual on it. 2004 vintage MH. I may try the local MH service / parts shop and see if any OEM replacements are available. It will kinda run with starting fluid. Priming it with the start switch and drain screw open has decent gas flow out of it , so float bowl must be getting full. Just another adventure with the beast. Any help would be appreciated.
Thank you.
 

Waffles

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Let it sit too long without starting and something internal is plugged as far as I can tell. No clue on how float bowl comes off so I can see what is wrong. Thinking about trying one of the cheap E-Bay 60$ carbs. Trying to locate a shop manual on it. 2004 vintage MH. I may try the local MH service / parts shop and see if any OEM replacements are available. It will kinda run with starting fluid. Priming it with the start switch and drain screw open has decent gas flow out of it , so float bowl must be getting full. Just another adventure with the beast. Any help would be appreciated.
Thank you.
The old style or new style marquis?
I was able to successfully clean the in-laws marquis gold carb like twice.
 

Clearmax

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Just buy a new one. I have tried to clean a couple of them and it wasn’t worth it. It is an easy change out, make sure to start it once a month.
 

Rbcconst

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Let it sit too long without starting and something internal is plugged as far as I can tell. No clue on how float bowl comes off so I can see what is wrong. Thinking about trying one of the cheap E-Bay 60$ carbs. Trying to locate a shop manual on it. 2004 vintage MH. I may try the local MH service / parts shop and see if any OEM replacements are available. It will kinda run with starting fluid. Priming it with the start switch and drain screw open has decent gas flow out of it , so float bowl must be getting full. Just another adventure with the beast. Any help would be appreciated.
Thank you.

Get one of amazon. Spent hours cleaning my last one and it never worked right. Bought a $50 replacement on Amazon and it worked amazing.
 

dspracing

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Will depend on your carb cleaning skills. If you are a master or at least advanced, you can save it, If you're looking for a manual, probably not. I fyou go to the shop they will tell you it's not serviceable????

I got in the habit of always treating fuel with startron, especially in toyhauler applications, that way you treat the gen as well as all the toys down the line. I buy it by the gallon and I put it in everything.

Startron and run it once a month, cheaper than a Chinese carbureutor.
 

WTR&PWR

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I would strongly recommend just buying one off Amazon. Those carbs are known for being a bitch to service. I’ve bought the one off Amazon and it’s worked great I just turn the petcock off and run it til it’s dry. There is a lot with air filter too. Worth the money.
 

Icky

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My rv guy tried 2 of the ebay ones before replacing with oem on my weekend warrior. Last summer I let it go too long between starting and had to tear It down and clean it.
 

farmo83

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187 customs has a video about an Onan generator, it's hilarious.
 

Wmc

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Get one of amazon. Spent hours cleaning my last one and it never worked right. Bought a $50 replacement on Amazon and it worked amazing.
This^^^^^
I did the same thing for two days. Bought a replacement. Boom done. What was I thinking. SMH
 

pronstar

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They’re cheap enough that you can keep a spare carb on-hand [emoji106]

It sucks when you have carb issues while camping, because Amazon doesn’t deliver to the middle of the desert [emoji854]

Sent from my iPhone using Tapatalk Pro
 

bldrinker

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Buy the cheapie And just replace every year. Most of the onan carbs are not serviceable
Instead of replacing it every year. Use Stabil and start it every 2 weeks and let it run.
 

Uncle Dave

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The way you repair it is by throwing it away and replacing it.

You can also make it live by running dry before storage then sloshing a gallon of race fuel in the tank and running it.
 

yz450mm

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Plumb in an inline fuel shutoff just before the carb, along with a clear inline fuel filter. When you're done using it for the weekend, shut the fuel off and run it dry. Use Stabil if it's going to sit for a while, and change the fuel filter once a year. And if you get the chance to fill the TH tank with ethanol free fuel, do it!
 

bldrinker

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That’s the simple solution but you wouldnt believe how difficult it is for many

While doing my weekend chores I just walk out and push the button.

I guess the people who store their RV away from their house it would be a pain.
 

Mikes56

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I have a 40 gallon fuel station on my toy hauler. The fuel tank also feeds the generator. Double up on the Stabil and run it every few weeks for half hour. I haven’t had a problem with it since I bought it in 2016.
 

2FORCEFULL

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heres how I fix them... fill the bowl with carb clean and let it sit... when you crank it over it will try to suck the cleaner up through the jet on the bottom ,of the bowl... the way to do it un hook the fuel line, plug it off, get about 10' of fuel line and hook to the carb... and tie it to a ladder our something similar... open the drain on the carb and drain out all the old fuel.... start spraying the cleaner to fill up the bowl , just enough that you see the yellow coming out... when it's clear.... shut the bowl drain.. and fill the hose with cleaner... now crank it over a for a few seconds at a time... this will suck the cleaner up in to the jet.. after that, fill the hose again.... and give it a couple cranks...then let it sit over night... I don't like to change out the carbs because they set the voltage that the gen puts out,... you could fry the electronics in the rv with the voltage spikes..... that reminds me,... never mess with the gen with out shuting the breakers off,.. pushing on the throttle causes power surge..
 

Bowtiepower00

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Can a fuel shut off valve be put on these to run them dry between trips? Or are carb issues a constant thing?
 

spectra3279

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Buy a new one and don't worry about. They are cheap and plentiful. My mover uses an onan p series. Carb was buggered up. Cleaned it and no change. Got a new one for 25 bucks and have had no issues since.

Sent from my SM-G973U using Tapatalk
 

Uncle Dave

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heres how I fix them... fill the bowl with carb clean and let it sit... when you crank it over it will try to suck the cleaner up through the jet on the bottom ,of the bowl... the way to do it un hook the fuel line, plug it off, get about 10' of fuel line and hook to the carb... and tie it to a ladder our something similar... open the drain on the carb and drain out all the old fuel.... start spraying the cleaner to fill up the bowl , just enough that you see the yellow coming out... when it's clear.... shut the bowl drain.. and fill the hose with cleaner... now crank it over a for a few seconds at a time... this will suck the cleaner up in to the jet.. after that, fill the hose again.... and give it a couple cranks...then let it sit over night... I don't like to change out the carbs because they set the voltage that the gen puts out,... you could fry the electronics in the rv with the voltage spikes..... that reminds me,... never mess with the gen with out shuting the breakers off,.. pushing on the throttle causes power surge..

Good technique Steve.

I use a kill-o-watt on an extension cord to help set the frequency after new carb and don't run anything until its dialed in.

very handy device and well worth the 25 bones if you dont have one.
 

LazyLavey

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Can a fuel shut off valve be put on these to run them dry between trips? Or are carb issues a constant thing?
Can’t speak from experience but I’ve read a few forums where guys have done that.
I’ve considered it but I use stabil religiously and have never had carb issues. Fuel pump issues? yes, I always carry a spare
 

2FORCEFULL

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Good technique Steve.

I use a kill-o-watt on an extension cord to help set the frequency after new carb and don't run anything until its dialed in.

very handy device and well worth the 25 bones if you dont have one.
your needed in angies this damn rv thread about batterys, solar and solar chargers
 

2FORCEFULL

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Good technique Steve.

I use a kill-o-watt on an extension cord to help set the frequency after new carb and don't run anything until its dialed in.

very handy device and well worth the 25 bones if you dont have one.
you'd be surprised at the people that tell me they just changed the carb and no problems,.. next the roof ac quits...power spikes take hostages
 

TPC

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Onans can haul the mail but they ain't the best quality. Always some nagging issue.
Dump Startron in the gennys tank next time.



 

Don Batman

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Good technique Steve.

I use a kill-o-watt on an extension cord to help set the frequency after new carb and don't run anything until its dialed in.

very handy device and well worth the 25 bones if you dont have one.
so adjust generator for 60 hz ?
 

Bpracing1127

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I bought a cheapei and it didn’t work. I put a valve in line with the fuel hose so I can turn off the fuel when needed.
 

HB2Havasu

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When you swap out the carburetor make sure to install an in-line fuel shutoff switch. I went thru 2 carbs in 2 years before I did this 12 years ago. I just run the genny dry now when we’re done camping. Haven’t had 1 problem since!
 

wzuber

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heres how I fix them... fill the bowl with carb clean and let it sit... when you crank it over it will try to suck the cleaner up through the jet on the bottom ,of the bowl... the way to do it un hook the fuel line, plug it off, get about 10' of fuel line and hook to the carb... and tie it to a ladder our something similar... open the drain on the carb and drain out all the old fuel.... start spraying the cleaner to fill up the bowl , just enough that you see the yellow coming out... when it's clear.... shut the bowl drain.. and fill the hose with cleaner... now crank it over a for a few seconds at a time... this will suck the cleaner up in to the jet.. after that, fill the hose again.... and give it a couple cranks...then let it sit over night... I don't like to change out the carbs because they set the voltage that the gen puts out,... you could fry the electronics in the rv with the voltage spikes..... that reminds me,... never mess with the gen with out shuting the breakers off,.. pushing on the throttle causes power surge..
Sounds like a great method 2FF. Would this process free up a stuck float? How many spray cans does it usually take to complete the cleaning. Would a stuck float cause fuel in the crankcase?
 

Sherpa

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Our coach has a Onan 4500 and I went through the same issue. I had to drop the whole unit to service and pull the carb. actually bought a new OEM carb, but
rather than just R&R the original, I pulled it and cleaned it. reinstalled. tried to start. nope. repeated this about 3 times and finally back to working normally. I now do my monthly gen runs at the end of each month.......... i kept the OEM carb just in case. it was about $355 bucks. ouch
 

Cdog

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When u get it fixed. Put a small fuel line on the bowl drain and leave it open when in storage. Flush with a prime and close when ready to use.

I’ve done this since 2006 and have Zero issues
 

wzuber

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Our coach has a Onan 4500 and I went through the same issue. I had to drop the whole unit to service and pull the carb. actually bought a new OEM carb, but
rather than just R&R the original, I pulled it and cleaned it. reinstalled. tried to start. nope. repeated this about 3 times and finally back to working normally. I now do my monthly gen runs at the end of each month.......... i kept the OEM carb just in case. it was about $355 bucks. ouch
How abt $1,149.75 for a single barrel carb for a generac guardian carb.?
That's holley dominator $$. Haha
crazy what these phuks ask for some of this stuff.
Here's a website that has a lot of rv parts in general but also eng. parts for Onan and Generac gennys etc. Www.anyrvparts.com
Also searching allrvparts.com brings up a bunch of various rv website to poruse and get lost in.
 
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wzuber

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In a "pinch" you can pinch off the fuel line with vise grips, quickgrip clamp etc. to empty fuel bowl until you can install the shut off valve. Just use enough clamp force to stop fuel flo. Remove clamp once genny's off to prevent hose damage.
 
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