Small Engine

Small Engine Troubleshooting Problems? Ask a Mechanic Now.

Ask an Expert,
Get an Answer ASAP!

I have a Honda GX620 engine that powers a thermalarc

Customer Question
predator welder/generator. This thing gives...
I have a Honda GX620 engine that powers a thermalarc predator welder/generator. This thing gives us fits all the time. I usually start it several times a year when its just setting. I started it probably 3 months ago. It starts right up as long as its choked. As long as the choke is out partially or all the way it runs normal. It does have an auto/run switch. I have it in the run switch but when in auto mode it throttles up as necessary when load is applied.
Again it runs fine in either position as long as choke is out. What it does is surges. High/normal rpm to low/normal rpm. I am guessing its probably a piece of dust in the carb as that is usually what gives it fits. But usually when that happens it wont start. The only other thing that stands out to me is that its in the back of our pickup so it isn't quite level and I know its very sensitive to being level. I really kinda suck at small engines. I am very mechanically inclined and can take just about anything apart and put back together very successfully. My real issue is I need to weld some fence for our dairy for animal/human safety and cant wait weeks while a shop gets around to fixing it. anyway you could get me through this?
Submitted: 1 year ago.Category: Small Engine
Show More
Show Less
Ask Your Own Small Engine Question
Answered in 2 minutes by:
7/29/2017
Technician: Hank F., Technician replied 1 year ago
Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15,983
Experience: Certified on Onan and Generac generators
Verified

Hello, my name is ***** ***** I am going to assist you with this.

What you are describing is a bad carburetor.

As gas gets old, it turns to varnish and clogs up the passageways inside the carburetor, not allowing enough gas to get to the engine.
Today’s gasoline formulation goes bad in as little as 30 days.
This condition is cumulative. Every time gas sits, the varnish builds up just a little more, like coats of paint, until eventually gas can not flow. It will not happen overnight, but the symptoms can show up all of a sudden, even while simply stopping to refill with gas.
The use of fuel additives, such as Sta-Bil or Sea Foam will not stop this process from happening. They will greatly slow it down, but the gas will still go bad.

This can also happen even on a brand new engine or brand new carb. When the carb is built, it is run at the factory to tune it.
After tuning, they do not always get properly cleaned, or may not have enough/any preservative injected. Believe it or not, this is actually fairly common.

When this happens, either the engine simply will not start, or it will not run without the choke on (this reduces the amount of air getting pulled into the engine, changing the fuel/air mixture), or it will run but surges.

Another issue that varnish in the carb can cause is that the varnish may not allow the float needle to seal properly against the seat, causing the flow of gas to not shut off when the bowl is full. The result will be gas overflowing the carb and running into the cylinder, and possibly out the air intake. If the gas gets into the cylinder, it will seep past the rings and down into the crankcase. This will be evidenced by your oil level being over-full and/or the oil smelling like gas.
If this is the case, you will need to change the oil and filter, if it has a filter.
Varnish can also cause the float needle to stick shut, and not allow any gas to flow from the carb bowl into the engine.

The only 2 solutions are to either replace the carburetor or give it a good, thorough cleaning.
When removing the carb, make sure to take a good picture, or make a good drawing of where all springs and linkages are attached. This will make reassembly much easier.
Most people believe that cleaning a carb involves removing the bowl and wiping it out, then spraying some carb cleaner through it.
This is simply insufficient. It takes months or years for this accumulation to build up – it just can not be removed in minutes.

To properly clean the carb, you must remove it, disassemble it (making sure to remove all non-metal parts), and soak it in a commercial solvent for several hours. Soaking it overnight is even better.
Then clean all solvent off with a spray type carb cleaner, making sure to get lots of cleaner into every hole and passage there is. Pay special attention to the tiny holes in the bore of the carb, under the throttle plate for the carbs that have these holes. Use lots of cleaner. And make sure to wear safety goggles to avoid getting the over spray into your eyes. There will be over spray.
Dry the carb with low pressure compressed air.
When reassembling the carb, make sure to use a carb kit, when one is available for your carb.

Occasionally, even a good cleaning is not going to be sufficient, and you may end up having to replace the carb anyhow. Be prepared for this.

Ask Your Own Small Engine Question
Customer reply replied 1 year ago
I will try cleaning it. I don't think I have the commercial cleaner. What I have is from John Deere and is what all their mechanics use and recommend. However these are much larger parts. I am not sure I can get a kit in a reasonable timeframe but will try. What do those kits usually have in them? It may be mid day tomorrow before I know if this helps. Possibly sunday.
Customer reply replied 1 year ago
I may need some further clarification as I roll along as some of the things you have explained I'm not completely familiar with. In the past carburetors I have dealt with just had gaskets that lost the seal or prime to the bowl.
Technician: Hank F., Technician replied 1 year ago

Not all carbs even have kits available. Sometimes you just have to replace the carb.

Even of the carbs that there is a kit available for, they differ in what is in them.

Gaskets, float needle, needle seat, jets - any combination or all of it may be in a kit.

Ask Your Own Small Engine Question
Customer reply replied 1 year ago
before I ripped everything apart I leveled the unit out and started it. Within probably 2 minutes it started to run normal. Choke is pushed in and its back in auto mode running nicely. I know that this particular setup is very very sensitive to the slightest incline. Such as the one that the pickup bed has due to the overload springs. At this point I find it very difficult justifying taking the carb apart. Also I forgot to add that we don't leave gas in any of our small engines. So it has new fuel put in on each use.
Technician: Hank F., Technician replied 1 year ago

I don't know how far out of level you had it, but it would have to be very off level for it to run bad like that.

Ask Your Own Small Engine Question
Customer reply replied 1 year ago
Not much out of level. Running really awesome now though. I know the thermalarc manual warns of this. I sure wouldn't think it would matter that little bit.
Technician: Hank F., Technician replied 1 year ago

Running off level has more to do with oil than anything. If it is too far off level, the oil flows to one side of the crankcase, where the pump can't pick it up.

Ask Your Own Small Engine Question
Customer reply replied 1 year ago
Sure. Makes sense.
Technician: Hank F., Technician replied 1 year ago

The same warnings are in RV owner manuals.

Ask Your Own Small Engine Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a technicianLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Hank F. Your Own Question
Hank F.
Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15,983
15,983 Satisfied Customers
Experience: Certified on Onan and Generac generators

Hank F. is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Curtis B.

Curtis B.

Technician

15,517 satisfied customers

have worked on and around most engine models for 35 yrs./Polaris ATV expert

Rick

Rick

Factory Authorized Trainer

4,218 satisfied customers

Outdoor Power Equipment technical trainer since 1990, covering eight states.

Jon K.

Jon K.

Small Engine Diagnostic Expert

2,995 satisfied customers

Gold certified Stihl tech, Service Manager for a rental/repair shop.Certified in most small engines

James W

James W

Small Engine Troubleshooting Expert

2,986 satisfied customers

7 years as Mechanic & Parts Manager for Brother who has Owned Lawn & Garden Repair shop for 35 years

Vince O.

Vince O.

Small Engine Technician

2,927 satisfied customers

Over 30 years experience repairing lawn and garden equipment. Chainsaws, mowers,blowers and trimmers

Wayne

Wayne

Engine Rebuilder

2,041 satisfied customers

many years on egine rebuilding, lawn mower,roto tiller,Truck,and small engines

RUSS

RUSS

SERVICE TECHNICIAN

1,723 satisfied customers

28 YEAR SERVICE TECHNICIAN

< Previous | Next >

Related Small Engine Questions
Engine will run fine on start up sometimes other times it
engine will run fine on start up sometimes other times it will start fine run up to rpm then die like you shut it off then wont start with several pulls let it sit awhile go start it it might run fine… read more
Donald
Donald
Owner / Technician
High School
2,586 satisfied customers
212 predator dies out full choke dies out without choke and
212 predator dies out full choke dies out without choke and runs high with mid choke … read more
JON
JON
Master Service Tech
MASTER SERVICE TECHNICIAN
1,872 satisfied customers
I have a 20000 cummins standby propane generator. it put out
i have a 20000 cummins standby propane generator. it put out a terrible smell. i don't think its propane im smelling. its 3 yrs old … read more
spankyjr1
spankyjr1
Retired
Vocational, Technical or Trade Scho
19 satisfied customers
My honda hrs 217 is only 1 yr old and I haven't used it this
My honda hrs 217 is only 1 yr old and I haven't used it this year, but it will not crank. I have always used non-ethanol fuel. Was starting fine when last used it. … read more
JohnF2015
JohnF2015
High School Diploma
1,260 satisfied customers
I have a 2500 watt predator generator it idles but shuts off
I have a 2500 watt predator generator it idles but shuts off when throttled. cleaned carb, changed plug, replaced fuel,replaced fuel filter, changed fuel hoses changed oil … read more
Curtis B.
Curtis B.
Technician
Associate Degree
15,517 satisfied customers
Toro Recycler 6.75 190cc model number 126T02-0299-B1 My Toro
Toro Recycler 6.75 190cc model number 126T02-0299-B1 My Toro had a spring come off the thingamagig and need part NO: or where can I find shop manual with schematics and diagrams of where things go? I … read more
Vince O.
Vince O.
Small Engine Technician
High School or GED
2,927 satisfied customers
i have a john deer la130 with the briggs engine. It started
i have a john deer la130 with the briggs engine. It started was running fine and now it starts will run for a few seconds and then shut down. it gets a new battery every year. I recently replaced the … read more
PK.
PK.
Owner
High School or GED
943 satisfied customers
I have a new Honda GX630 fitted to a 10KVA generator replacing
I have a new Honda GX630 fitted to a 10KVA generator replacing the old GX620. After much trial and error I found each has totally different ignition switch setups and a very different oil filter fitti… read more
Clamp-onTech
Clamp-onTech
405 satisfied customers
I have a Honda GX620 on a Thermal arc welder. It is not getting
I have a Honda GX620 on a Thermal arc welder. It is not getting enough fuel unless the fuel tank is almost full. When it gets around 3/4 tank it shuts down not enough fuel in the line. Is this a fuel … read more
Curtis B.
Curtis B.
Technician
Associate Degree
15,517 satisfied customers
We have a 12.5 HDCAB11506A ONAN GENERATOR in our 2001 monaco
We have a 12.5 HDCAB11506A ONAN GENERATOR in our 2001 monaco signature motorhome.The generator is will not start unless the coach motor is running with the RPMS at 1500 or better.The batteries start t… read more
Hank F.
Hank F.
Technician
High School or GED
15,983 satisfied customers
I have a Honda GX390 engine on a 500 watt generator. It has
I have a Honda GX390 engine on a 500 watt generator. It has performed flawlessly for 4 years. Then last week it wouldn't start. It has spark so I thought it must be fuel problem. It's getting plenty o… read more
Hank F.
Hank F.
Technician
High School or GED
15,983 satisfied customers
3 phase bullet welder into a diesel motor driven welder..shaft..revs
Hi, Can I convert a 3 phase bullet welder into a diesel motor driven welder? This means setting it up as a horizontal shaft. What is the ideal governed revs? What size motor should I use? Thanks, Tony… read more
Hank F.
Hank F.
Technician
High School or GED
15,983 satisfied customers
I have an old Hobart 250 welder with very few hours which does
I have an old Hobart 250 welder with very few hours which does not weld. This welder has been around in are family for quite a few years but hasn't been used a lot. the problem is when you start it up… read more
Hank F.
Hank F.
Technician
High School or GED
15,983 satisfied customers
I have a GLW 180 H WELDER/GENERATOR WITH A 11.0 HONDA GX340,
I have a GLW 180 H WELDER/GENERATOR WITH A 11.0 HONDA GX340, IT STARTS BUT WONT IDLE JUST SURGES,WONT TURN OFF THE IDLE JUST GOES UP AND DOWN,IF IKEEP IT CHOKED IT LEVELS OUT SOME WHAT… read more
Curtis B.
Curtis B.
Technician
Associate Degree
15,517 satisfied customers
hello, i have an ice cream kiosk fitted with a honda gx620
hello, i have an ice cream kiosk fitted with a honda gx620 engine running inside the generator, it was serviced last year and had new oil and air filter fitted, i have just started using it again and … read more
Curtis B.
Curtis B.
Technician
Associate Degree
15,517 satisfied customers
I have a lincoln ranger 8 with an onan performer 16 engine.
I have a lincoln ranger 8 with an onan performer 16 engine. The engine is not turning enough RPMS to produce enough power to weld. The carb becomes socked with gas. A) How can I speed the RPMS up or d… read more
Deere Dr
Deere Dr
service manager
Vocational, Technical or Trade Scho
236 satisfied customers
I have a honda gc190 that runs as long as the choke is engaged
I have a honda gc190 that runs as long as the choke is engaged when you push the choke off the engine quits… read more
Chris Huber
Chris Huber
President
Vocational, Technical or Trade Scho
501 satisfied customers
I have a 10kva elemax generator which has a manual choke for
I have a 10kva elemax generator which has a manual choke for cold starting.How do i convert it to automatic choke so that the generator could be started remotely durings mains failure? Kayode,Nigeria… read more
PK.
PK.
Owner
High School or GED
943 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x