Small Engine

Small Engine Troubleshooting Problems? Ask a Mechanic Now.

Connect one-on-one with {0} who will answer your question

This answer was rated:

★★★★★

I have a give 399. Not enough vacuum when starter cranks to…

I have a give...

I have a give 399. Not enough vacuum when starter cranks to open propane lock off to start. If I manually send vacuum to lock off it starts and runs fine. Then I quickly hook vacuum hose back to engine and it works fine. Any ideas.

Mechanic's Assistant: Have you checked the engine's fuel supply? And the spark plugs -- are they all working?

Yes.

Mechanic's Assistant: What is the model/year of your Honda?

The model is gxv390. No idea year.

Mechanic's Assistant: What year is your Honda?

The model is gxv 390. No idea what year.

Mechanic's Assistant: Are you fixing your GVX yourself? What have you tried so far?

Yes I am. Well it’s a customers. I am a licensed mechanic for 25 plus years and repaired a lot of things including a lot of small engines so don’t be afraid to go in depth. Well took me a while just to get it to start as the guy before me had things wired wrong. So I repaired al that. I adjusted valves. The wear very tight. So thought that might be it. Nope. Checked compression. 155 psi. So that good. Like I said. If I take vacuum hose off carb and suck on it the lock offs open and it fires right up. I then quickly put vac hose back on carb and works perfect. Until I shut it off of course. I can get it to start on its own if I reach in to the throttle linkages and close the choke a bit. But shouldn't have to do that. No choke required for propane fuel system. Any thoughts.

Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you?

Ya. Tell them to tell me something that will help. Lol. I have two Honda dealers here stumped. They want me to let them no what I find.

Show More

Show Less

Ask Your Own Small Engine Question

Answered in 11 minutes by:

2/28/2020

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

bgsengineclinic, Small Engine Technician

Category: Small Engine

Satisfied Customers: 357

Experience: Over 20 years of experience in Small engine repair, Kohler Certified Expert Technician, Self-Employed in my own dealership.

Verified

well I am by no means certified on propane (in fact have only had a couple propane engines in the last 20 years in the shop in this small town here) but as a former ASE master auto tech in addition, when dealing with what appears to be vacuum issues, I'd want to check the vacuum port on carburetor to see if it is actually drawing vacuum while cranking. Considering that you'd be seeing more vacuum when engine is running , throttle valve would be more closed at that time, maybe see if it shouldn't have throttle valve closed to idle already when cranking? If it is an actual vacuum issue, might also want to consider any intake manifold leaks, possible exhaust back-pressure (a clogged cat converter on a car can cause vacuum problems, any sort of similar exhaust restriction might also do so.) maybe those ideas can help narrow down the issue.

Customer reply replied 1 month ago

Don't think exhaust issue as it run perfect when I do what do to get it running. It's not a fuel issue. As it runs perfect. Wide open throttle or at idle. Not hiccups. No misses. Purrs like a kitten. I Checked for possible vacuum leaks. Found nothing. I'm stumped. I haven't had carb off yet. Maybe a gasket installed wrong partially blocking vacuum port? Don't know. I never had this problem before. That's why I'm here with you guys. Lol.Propane fueled engines are basically the same as gas or even diesel. Just different fuel system. But the fuel system is not the problem here. So think ofsomething I haven't

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

OK yeah that is what I was thinking - anything at all that may cause low vacuum readings - partial blockage from carbon buildup is always possible as well, any cracked fittings or pinhole in a hose - basically any automotive vacuum gauge that can be hooked to the port to check vacuum readings.. matter of fact I think I'd probably break out the trusty old mity-vac vacuum/pressure tester that is part of a 2-stroke tech's tool kit , in automotive use, it's used as a brake bleeder and tester as well. could use it to pull vacuum on the lock-offs while testing for vacuum at the carburetor port, can be used to test vacuum hoses for leaks and blockages, etc.. (its also used to test 2-stroke carburetors) But from the sound of it your only problem seems to be one of not being able to get enough vacuum while cranking, and as I noted, exhaust backpressure, possibly a valve issue (though that would seem odd given 155 PSI compression) , or any leak past the throttle plate - gaskets, etc. (Honda is notorious for having many, MANY different carburetor and intake gasket combinations, the wrong carb mounting gasket can block off a vacuum port, or if it is too big an I.D. it results in a vacuum leak, etc) - any cracks in the manifold, or perhaps it is simply the vacuum pull-off for the lock-out - if diaphragm stiffens or hardens (as they do over time as diaphragm ages) might simply be it is requiring more vacuum than the engine can produce during cranking..

Customer reply replied 1 month ago

Ya. Though of that too. But I’m using my mouth for a vacuum. It take very little “sucking” on my part to get the lock offs to open

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

Yeah I'd definitely be looking at the vacuum port, maybe a new hose just for the heck of it, but if someone else been into it and put a "Looks like it fits" gasket on the carburetor, instead of the correct honda part number for the model/spec/serial and type , could be as simple as a new gasket needed.

Customer reply replied 1 month ago

Where are ya. I don’t have plan for states. I’m not paying for the that. It says $35. I’m not paying that. lol and i can’t charge customer for that. I agree better talking. Easier.Well I’m glad that I got the experts stumped. I don’t feel so stupid. Lol.So that it.

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

Hmm sorry was in the shower. almost my bedtime here (semi-retired old guy) not sure what you're seeing at $35 but I would hazard a guess they auto pop-up an opportunity to do live phone call as a premium service.. I don't do those anyway since I am deaf. But yeah it is a puzzler. I'd be really curious to know the final solution if it gets figured out.. But I think you are on the right track thinking it may be a vacuum port blockage of some type. It'd be helpful to have the full serial number and engine type number (both engraved or etched in the crankcase , usually on starter side or behind starter in some cases) so we could look at the parts breakdown for that exact engine.. but other than that I agree a vacuum issue is there somewhere during cranking..

Customer reply replied 1 month ago

Well thanks for your input. When I find the issue I'll let ya know. Not if... when I figure this out I'll let ya know. I won't stop till it's fixed. Sure it's something stupid. Just over looked by all I've been talking to. Has everyone stumped. How do I get back to ya about what us the problem. ThanksActually I'll look hard for those #'s again tomorrow. This is a personal thing now. Not work. Lol. I need to get this thing fixed. For me. lol. I will figure it out. But how do I let u know what the problem was.

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

I believe you can always reply back to this thread, but if not, no worries...

Customer reply replied 1 month ago

K. Thanks again. I don't feel stupid anymore. No one else I've been in contact with can figure it out either. So. WHEN I figure it out I'll try to let ya know what problem was so you can pass it on.

Technician: bgsengineclinic, Small Engine Technician replied 1 month ago

OK

bgsengineclinic, Small Engine Technician

Category: Small Engine

Satisfied Customers: 357

Experience: Over 20 years of experience in Small engine repair, Kohler Certified Expert Technician, Self-Employed in my own dealership.

Verified

bgsengineclinic and 87 other Small Engine Specialists are ready to help you

Ask your own question now

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

Related Small Engine Questions

CARB FOR A HOMELITE VAC ATTACH II MODEL UT08934. 10 TO 15

ONLY RUNS IN THE FULL CHOKE SETTING. I TOOK CARB OUT AND CLEANED IT BUT NO CHANGE. … read more

Curtis B.

Retired service manager

Associate Degree

3,540 satisfied customers

SECOND OPINION, DON'T CLOSE, NOT A DUPLICATE PLEASE! ) I am

SECOND OPINION, DON'T CLOSE, NOT A DUPLICATE PLEASE! )I am not getting fuel to the carb and it won't start obviously. cleaned the carb changed plugs new fuel pump new plugs and nothing. the wire from … read more

Vince O.

Small Engine Technician

High School or GED

3,068 satisfied customers

Briggs vtwin 44l777 idles fine will run at full under load

briggs vtwin 44l777 idles fine will run at full under load less than 10 min then dies cleaned carb new kit, new intake gaskets, new head gaskets new fuel pump , new plugs new air filter … read more

Curtis B.

Retired service manager

Associate Degree

3,540 satisfied customers

Have a LT 4200 Huskee powermate 42 in lawnmower. Run for ten

Have a LT 4200 Huskee powermate 42 in lawnmower . Run for ten minutes and quit . start right back up and then quits again . thought it was the coil shorting out after getting hot . But it starts back … read more

Wayne

Grand Pa

Vocational, Technical or Trade Scho

4,575 satisfied customers

I have a question on a honda 390 gas generator (black max

I have a question on a honda 390 gas generator (black max brand) … read more

JON

Master Service Tech

MASTER SERVICE TECHNICIAN

4,784 satisfied customers

I have a Stihl FS 55 trimmer. I just wouldn't start a couple

I have a Stihl FS 55 trimmer. I just wouldn't start a couple of years ago, so, bought a new one. As the Stihl is s straight shaft handlebar model, I'm needing it to clear some brush with the blade att… read more

Donald

Owner / Technician

High School

6,732 satisfied customers

I have a 4000 Onan Micro quite K series. It was in the body

I have a 4000 Onan Micro quite K series. It was in the body shop for a long period of time. When I got it back the generator would not run. I cleaned the carb and ran sea foam through it and after sev… read more

Hank F.

Service Technician

High School or GED

1,541 satisfied customers

I had a similar issue that engine will only run when choke

I had a similar issue that engine will only run when choke is fully closed. Here's a hint, the guy I bought it from said he cleaned the carb, when I picked it up from him he handed me a sandwich bag w… read more

Curtis B.

Retired service manager

Associate Degree

3,540 satisfied customers

I have a gxv390 DET3 engine I mounted on a 28" snapper RERabout

I have a gxv390 DET3 engine I mounted on a 28" snapper RERabout 4 years ago. This summer I began to have rpm hunting at all but full throttle and some backfiring at idle (when it will even run at low … read more

Briggs-Fan

2,794 satisfied customers

I have a Sears riding mower with 10hp Tecumseh engine with

I have a Sears riding mower with 10hp Tecumseh engine with electric start. It was flooding out so took carb off and cleaned with carb cleaner and installed new needle and seat, idle and main jets. Flo… read more

Richard

Senior Mechanic & Technician

2,345 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.

Service Technician

High School or GED

1,541 satisfied customers

xc125n- starts, but will not keep running, as if running out

xc125n- starts, but will not keep running, as if running out of fuel. Fresh clean tank, petcock and carburator. Vacuum line does not seem to be pulling fuel- clear gas line has very little gas any ide… read more

Doug E.

Vintage M/C restorer

Vocational, Technical or Trade Scho

2,485 satisfied customers

Ive got a John Deere LX289 with a 17 hp Kawasaki and the fuel

I've got a John Deere LX289 with a 17 hp Kawasaki and the fuel pump does not work. (unhooked fuel line and turned over and no fuel). Is that something I can replace myself? I've replaced a fuel pump o… read more

Curtis B.

Retired service manager

Associate Degree

3,540 satisfied customers

27 HP Kohler motor, Wont start unless you keep you hand over

27 HP Kohler motor, Won't start unless you keep you hand over the carb and throttle back the air going in the carb. Take your hand off the carb and the engine dies out. Cleaned out the carb the best I… read more

Delsley

Handyman & JustAnswer Expert

IT Certificate

43 satisfied customers

I have a sears garden tractor with a kohler 23 hp liquid cooled.

I have a sears garden tractor with a kohler 23 hp liquid cooled. I ordered a new carb from sears (kohler). After installing it the tractor will only run with the choke all the out. The tractor runs fi… read more

Al Mancini

Bachelor's Degree

30 satisfied customers

I have apropane powered fork lift that I am unable to get running

I have apropane powered fork lift that I am unable to get running is anyone familiar with Impco propane systems?… read more

Al Mancini

Bachelor's Degree

30 satisfied customers

Dingo 150cc wont run. Dealer replaced auto choke when picked

Dingo 150cc won't run. Dealer replaced auto choke when picked up new. 5 mo. later they cleaned carb added filter. Worked for 2 wks. won't start. I cleaned carb auto choke worked for first time, (high … read more

Al Mancini

Bachelor's Degree

30 satisfied customers

hello,i have a 5hp b&s that seems to run out of fuel after

hello,i have a 5hp b&s that seems to run out of fuel after a very short time,i have replaced the carb and checked for obstructions,none found,i put a clear fuel filter inline and fuel is always suppli… read more

PK.

Owner

High School or GED

790 satisfied customers

Show more

Disclaimer: Information in questions answers, and Show More

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.

JustAnswer in the News:

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:

Rick

Factory Authorized Trainer

4,218 satisfied customers

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

Vince O.

Small Engine Technician

3,068 satisfied customers

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

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

Small Engine Troubleshooting Expert

2,987 satisfied customers

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

RUSS

SERVICE TECHNICIAN

1,723 satisfied customers

28 YEAR SERVICE TECHNICIAN

CJBennett

Small Engine Technician

624 satisfied customers

Briggs and Stratton Master Service Tech, Kohler, Tecumseh, Kawasaki certified. 18 years exp.

Chris Huber

Small Engine Technician

576 satisfied customers

20 years experience. Briggs and Stratton Master Service Technician. Dealer for most engine lines.

< Previous | Next >

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