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Fast and Easy Fix for Your Generac Wheelhouse 5500 / 5550 Portable Generator

My Generac Wheelhouse 5500 / 5550 generator (made by Briggs and Stratton) was sitting in my shed for years without seeing much action. I knew I had to test it every month but without any need, it was sort of forgotten and unused. So when it refused to start with Hurricane Sandy bearing down us, all I managed to do was flood the engine when I repeatedly pulled the starter rope.

If you found this article via a search engine
You may want to read Fast and Easy Fix for Your Generac Wheelhouse 5500 / 5550 Portable Generator (Part 2) and/or Engine Tune-up for Generac Wheelhouse 5500 / 5550 Portable Generator

Hurricane Season
Hurricane Season officially begins June and ends on November. Please check and service your portable generator well before June, especially if you have not recently tested your generator.

Although I was fortunate enough to purchase a new Briggs and Stratton 5500 Storm Responder generator from Home Depot at 3 AM, I shudder at the thought of not having electricity with 2 young children (by the way, my electricity was out for 14 straight days).

While my new generator was up and running, I was able to get my Generac generator to up and running, thanks to Internet and some fine folks at DIYChatroom (thanks again guys!).

I wrote this article to capture what I learned in hoping that it might help someone else to get their generators up and running.


There are 2 main problems you may face with a generator that has been sitting around:

  1. Generator runs fine but there is no electrical output
  2. Generator runs poorly or does not start at all
    • Engine starts but quits after running for about 10-15 seconds;
    • Engine does not start but gas leaks from the air filter
    • Engine will only start for few seconds with a squirt of starter fluid
    • Engine will run rough under full choke but dies when choke is opened
    • Engine sputters, guzzles gas then dies

If there is no electricity, you may need to field flash your generator or troubleshoot the automatic voltage regulator (AVR). Please see my other post titled “Troubleshooting a Portable Generator with no Voltage Power Output” (LINK -TBD)


Briggs and Stratton engine found in Generac Wheelhouse 5500 / 5550 generator came with either a Walbro or Nikki carburetors.

Information in this post pertains to only Nikki because my particular Generac Wheelhouse generator came with it (B&S OEM part # 697978 G02523 4312 A).


Generator’s inability to start of remain running has lots to do with old, stale gasoline. Most research I’ve read indicates that the gasoline goes stale after only 30 days after it is manufactured. After 30 days t starts to form varnish that looks like red rust flakes.

Varnish tends to stick and clog internal components like a needle valve, emulsion tube, etc. where tiny holes are critical for the engine to properly work properly.



If you don’t have the time for an overhaul / rebuild (i.e. a storm is coming!), you will want to buy a replacement Briggs & Stratton Carburetor – Part # 591378

Installing a replacement carburetor is basically a drop-in that takes less than 20 minutes. If you do buy one, you need re-use the choke handle bar because the new one is shorter than the original one (this involves simply removing a choke plate).

Nikki Carb Part #697879 has been discontinued and official replacement part is not available. Although the packaging on the new carburetor #591378 does not state that it can replace #697978, it works.

You can also use the generic part as a replacement carb. I have personally not used this part though.


Overhauling a carburetor is more labor intensive process and may not be a good solution if you need to get the generator up and running and you need to do other things to get ready.

I am going to share my detailed step-by-step instructions with you so that if you have some spare time,


I think you can agree with me that spending 100 bucks for a new Briggs & Stratton Carburetor Part # 591378 is far cheaper than buying a new generator


I had three choices in trying to solve my problem:

  1. VARNISH REMOVAL – Costs may be $10 or under; least expensive route but may develop leaks if old gasket is damaged during cleaning process
  2. OVERHAUL – Costs about $25 for an overhaul / rebuild kit
  3. REPLACE – Costs about $100

I ultimately chose to go with option #2 because I felt confident that my generator will be working after the engine tuneup (replacing air filter, spark plug, oil change, etc.) + overhauling my carburetor.



If you don’t want to purchase the kit, you can buy these individual components separately (but will not be as cost effective):


My next post will cover engine tuneup and Nikki carburetor overhaul (UPDATE: Fast and Easy Fix for Your Generac Wheelhouse 5500 / 5550 Portable Generator (Part 2)

Please don’t forget to check the reference links as this section contains links to lots of useful information that are not easily found on the internet.

In the meantime, if you found this article to be useful, can you do me a favor and sign up for my newsletter? The signup form is found at the top of the screen on the right side.

Thanks and wish me luck!



Wednesday 14th of June 2023

My wheelhouse runs great for about hour or two, but suddenly you hear the generator/motor idle down to nearly complete stop, but then revs back up to full. I always burn fuel out line via shutoff valve when done with my jobs to remove fuel line. But this is getting too common now. Thoughts?

Dana Maker

Wednesday 28th of December 2022

I've had mice make a nest inside the starter cover and the on/off switch cover on my Generac 5550. The black wire under the on/off switch cover is connected to the switch but the other end is loose. Can anyone tell me what that should be connected to?


Friday 30th of December 2022

I was short on time so I could only take one picture...I will see if I can take a better picture tomorrow..


Thursday 29th of December 2022

Hi Dana.

I no longer own Wheelhouse 5550 but have Storm 5500 which is almost identical. I will take a look tomorrow morning and get back to you

John Matthews

Wednesday 15th of June 2022

I have one with a bad coil. I can't find the engine code anywhere to start to get a replacement part.


Thursday 23rd of June 2022

engine code is usually by the carburetor. which specific model do you have?

Eugen C

Sunday 3rd of October 2021

Hi, I’m getting a lot of oil in the air filter. What might be the cause? Thanks


Thursday 7th of October 2021

Hi Eugen,

It probably means your engine piston ring is compromised

kris cooper

Wednesday 27th of January 2021

i cant find parts for mine. the one i have is missing the air box, the blower housing and the pull start


Saturday 30th of January 2021

Hey Kris-

because Generac Wheelhouse 5550 is 20+ years old, you probably will not be able to find parts like that from a store. Your best bet is to look at Craigslist / OfferUp / Ebay.

Good luck