How JustAnswer Works:

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

Ask J.R. Your Own Question

J.R.
J.R., Small Engine Technician
Category: Small Engine
Satisfied Customers: 7444
Experience:  Owner of outdoor power equipment business, repairing all makes and models.
13636126
Type Your Small Engine Question Here...
J.R. is online now
A new question is answered every 9 seconds

Have a 16 hp Kohler engine on a Craftman Mower - Runs fine,

Customer Question

Have a 16 hp Kohler engine on a Craftman Mower - Runs fine, but then sputters going up slight hill with loss of power and eventual stall. Have cleaned carb, replaced oil, fuel filter, and have only fresh gas. What I notice is that there is a lot of air in the fuel line - the filter is clear plastic and mostly full of air. When it's running, gas trickles into the filter at about the rate it is being used, but the filter is mostly full of air. It is as though the engine is starving for gas. If I disconnect the fuel line from the carb, gas runs freely through the line into a can. However, when the line is attached to the carb, no fuel runs in to replace the air that I can see in the filter. I have blown out the fuel line, between the filter and tank, and it appears to be clear, but I still can't get gas into the line to replace the air. Should there be this much air in the fuel line ? No change if I loosen the fuel tank cap ? Runs fine with little air in filter. Any suggestions?
Submitted: 5 years ago.
Category: Small Engine
Expert:  J.R. replied 5 years ago.
The problem is likely a bad fuel pump or the fuel lines are bad. Check the fuel lines for cracks and replace them if needed. The fuel lines can suck air, but not leak fuel.
Customer: replied 5 years ago.
The fuel lines appear to be fine. Plus, wouldn't small leaks allow air to escape and let the line fill with gas, which it doesn't ? I can jiggle the filter for several minutes and eventually gets all the air out of the filter, but then as the engine runs, I can see the air gradually (over maybe 15 minutes) replace the fuel. The problem has to that there is problem causing some sort of vacuum that is not letting the air go up the line into the tank ... otherwise, why does the fuel run freely through the line when it is disconnected from the carb ? The isn't a screen where the line comes out of the tank ? Lastly, I didn't/don't think it has a fuel pump.
Expert:  J.R. replied 5 years ago.

Does the fuel line go straight from the tank to the carb with only the fuel filter between it?

Customer: replied 5 years ago.
Yes. And I have disconnected it, blown it out, and replaced the filter but it is still mostly full of air. I thought maybe the fuel tank cap is vented and may be clogged, thereby creating a vacuum, but I loosen it an d no change. The only change is when I disconnect the line at the carb, the gas then flows freely through the line and out into a can.
Expert:  J.R. replied 5 years ago.

The gas will only flow for so long until the carb bowl fills up and then it will stop until the fuel level drops and the float opens the needle valve and allows more fuel in it.

Customer: replied 5 years ago.
But shouldn't gas flow down the line towards the filter to replace the air that is in the line ?
Expert:  J.R. replied 5 years ago.

It should remain full. I think I would replace the fuel line to eliminate a line that is sucking air to start with.

Customer: replied 5 years ago.
I'll give it a shot and see if it works. I'll get back to you later.
Expert:  J.R. replied 5 years ago.
Let me know.
Customer: replied 5 years ago.
Good morning.

Replaced the fuel lines and it didn't help.

Is there any kind of vent in the carb that might be plugged up, thereby creating this vacuum that isn't letting the fuel flow down the line ?
Expert:  J.R. replied 5 years ago.
The carb has a air bleed, but that is for the engine when pulling fuel out of the carb. The fuel line goes into the catb and the fuel passes the inlet needle and into the bowl. Once the bowl fills up and the float rises the fuel shuts off so at that point no more fuel can enter the carb. Pull the bowl off of the carb and work the float/needle valve by hand and see if you can make it fill up.

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. Jimmy Bagley, IA
< Last | Next >
  • 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. Jimmy Bagley, 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!!!! Alex Los 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. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, 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. Esther Woodstock, 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. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Curtis B.

    Technician

    Satisfied Customers:

    6989
    have worked on and around most engine models for 35 yrs./Polaris ATV expert
< Last | Next >
  • http://ww2.justanswer.com/uploads/KO/koboma/2012-6-6_20917_DSCF1022.64x64.JPG Curtis B.'s Avatar

    Curtis B.

    Technician

    Satisfied Customers:

    6989
    have worked on and around most engine models for 35 yrs./Polaris ATV expert
  • http://ww2.justanswer.com/uploads/SM/SmEngPro/2012-8-5_3564_Rick1206290005Edit.fullres.logo.scrn.64x64.jpg Rick's Avatar

    Rick

    Factory Authorized Trainer

    Satisfied Customers:

    4126
    Outdoor Power Equipment technical trainer since 1990, covering eight states.
  • http://ww2.justanswer.com/uploads/GI/giftindex/2011-11-19_2715_JamesLWells500.64x64.jpg James W's Avatar

    James W

    Small Engine Troubleshooting Expert

    Satisfied Customers:

    2978
    7 years as Mechanic & Parts Manager for Brother who has Owned Lawn & Garden Repair shop for 35 years
  • http://ww2.justanswer.com/uploads/jonrk/2010-1-5_22551_jon.jpg Jon K.'s Avatar

    Jon K.

    Small Engine Diagnostic Expert

    Satisfied Customers:

    2950
    Gold certified Stihl tech, Service Manager for a rental/repair shop.Certified in most small engines
  • http://ww2.justanswer.com/uploads/MR/mr2cycle/2011-3-12_03458_sears.64x64.jpg Vince O.'s Avatar

    Vince O.

    Small Engine Technician

    Satisfied Customers:

    2374
    Over 30 years experience repairing lawn and garden equipment. Chainsaws, mowers,blowers and trimmers
  • http://ww2.justanswer.com/uploads/rheisnger/2010-12-31_010856_41385_100001225699183_7012_q.jpg RUSS's Avatar

    RUSS

    SERVICE TECHNICIAN

    Satisfied Customers:

    1723
    28 YEAR SERVICE TECHNICIAN
  • http://ww2.justanswer.com/uploads/BriggsEngines/2010-02-26_230200_n1834842973_4823.jpg CJBennett's Avatar

    CJBennett

    Small Engine Technician

    Satisfied Customers:

    623
    Briggs and Stratton Master Service Tech, Kohler, Tecumseh, Kawasaki certified. 18 years exp.
 
 
 
Chat Now With A Technician
J.R.
J.R.
7223 Satisfied Customers
Owner of outdoor power equipment business, repairing all makes and models.