Antique Engines and Old Iron
[Home] - [HELP] - [Forums] - [Articles] - [Photo Gallery] - [Groups] - [Chat] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] - [Tools]

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion > Generac Generators (SEARS, etc.)
Forgot Password? Join Us!

Notices

Generac Generators (SEARS, etc.) Restoring, maintaining and operating Generac generators.

Generac Generators (SEARS, etc.)

Generac Guardian 8kW B&S 2 cyl standby pkg won't run


this thread has 39 replies and has been viewed 6324 times

Reply
 
Thread Tools Display Modes
  #1  
Old 12-10-2011, 06:20 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Generac Guardian 8kW B&S 2 cyl standby pkg won't run

So I know lots of you hate these, but I got it dented at a Home Dump for $1,500 with xfer switch and breaker box and installed this in 2000 and it's peen perfect until now.I just changed oil and filter every other year. But now engine won't start. Cranks fine. Good spark. Just put in new Champion plugs at .030 gap. I pulled the input hose off the regulator and natural gas pours out as soon as the motor cranks. Put that back, pulled off the hose from the regulator to the carb, no gas apparent when cranking. I think there's something about these regulators needing a vacuum so I sucked slightly on the hose but didn't spell or taste mat gas. So that's where I am. It's never hiccuped till now. Last week it ran continuously for 4 days, then wouldn't start for weekly excersize.

Guardian 8kW B&S 2 cyl standby pkg.
Reply With Quote
Sponsored Links
  #2  
Old 12-10-2011, 07:27 PM
Jim Rankin Jim Rankin is offline
Registered-III
 
Join Date: Nov 2004
Location: Faunsdale, Alabama USA
Posts: 4,084
Thanks: 42
Thanked 1,106 Times in 882 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

It sounds like the demand regulator either isn't getting a good vacuum signal or is leaking.

How is it set up? What components are between the electric shutoff valve and the carburetor? Any pictures? If it has a diaphragm type demand regulator, I would bet the diaphragm has some holes in it.

Might also be a good idea to check for the carburetor coming loose or other sources of vacuum leak on the intake of the engine.
Reply With Quote
  #3  
Old 12-10-2011, 08:09 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Thanks Jim,
Too dark here for pics now.
The NG flow is like this:
Inlet pipe to solenoid valve to hose to Garretson KM Demand regulator to "load block with nat gas adjusting screw" mounted directly to top of regulator to hose to carb. The regulator only has two connections; a flare nut hose from the solenoid valve and a plain end hose with screw hose clamps to the carb. The carb and intake manifold piping are physically tight.
Reply With Quote
  #4  
Old 12-10-2011, 08:14 PM
K D Redd K D Redd is offline
In Memory Of
 
Join Date: Nov 2004
Location: Southwest Missouri
Posts: 5,348
Thanks: 166
Thanked 1,202 Times in 1,063 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

What demand regulator does this set use? Garretson Model KN? If it is a Garretson KN, yes they need 1/2 inch Water column vacuum to open which supplies fuel to the engine.
Before I would condemn the demand regulator, I think you should get yourself a can of spray carb. cleaner. See if the engine will run on the carb. cleaner. The later Briggs OHV engines use a aluminum intake push rods. I have had a lot of problems with this push rod breaking where the guide plate wears the push rod on the single cylinder engine. I have NOT work much on the V-Twins and I have NOT seen this [problem with them. You may have one of the two intake push rods broken causing not enough vacuum signal to the demand regulator. I know you did a test that I would NOT do. If the engine will run on the carb cleaner, make sure that both cylinders are making equal power. I know this may be hard to do. Run the engine for a short period of time and check if both exhaust pipes seem to be the same temp. If you do have a broken intake push rod on either cylinder, replace both and DO NOT use the aluminum intake push rod. Use the steel exhaust push rod. This is what I do on the single cylinder OHV engines.
If all this checks out then I would think about replacing the demand regulator.

Kent
Reply With Quote
  #5  
Old 12-10-2011, 08:21 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Thanks Kent,

If one push rod was broken would the engine run at all?
Would it be noisy?
Reply With Quote
  #6  
Old 12-10-2011, 11:33 PM
Andrew Mackey Andrew Mackey is offline
Sponsor
 
Join Date: Nov 2004
Location: Rockaway, New Jersey USA
Posts: 9,366
Thanks: 1,193
Thanked 3,850 Times in 2,483 Posts
Exclamation Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

The twin uses alunimum pushrods, but has another problem: roving valve guides! If the engine gets low on oil, or runs under heavy load for a while, the exhaust valve guide tends to move and then seize in the head. This locks the exhaust valve, which then pretzles the pushrod. Using crappy 'Energy saving' oil, used in autos makes the problem worse. Have a look at the pushrod action, and rocker movement. Both valves in the head should move aproximately the same stroke, about a little more than a 1/4". If the pushrod fails, you usually won't hear muchn as it falls off the lifter, and the exhaust valve most times is jammed open. You might hear a difference between compression between the 2 cylinders. You will definately lose manifold vacuum.

If you provide suction on the demand side of the regulater, and you do not get gas flow, the regulater is at fault, or the vacuum hose has failed internally. Using another hose directly on the demand regulater, see if you get gas after providing vacuum to the demand side. No gas, NO GOOD! If you have gas, then hose or engine vacuum is suspect. Make sure that the vacuum source connection is clear to the manifold.
Andrew
Reply With Quote
  #7  
Old 12-11-2011, 12:08 AM
David C David C is offline
Registered-III
 
Join Date: Mar 2006
Location: Lake Jackson,Texas
Posts: 837
Thanks: 610
Thanked 484 Times in 332 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Most of the KN demand regulators that I have seen have a primer button for priming or purging the line. If it does, hit the primer button while cranking see if the engine will attempt to fire up.

I am not familiar with the Briggs engine that the set is equipped with but it sounds like Kent and Andrew are. If it wants to run with the primer pushed, you may have a bad demand regulator or an engine problem like Kent or Andrew mentioned.


David C.
Reply With Quote
  #8  
Old 12-11-2011, 02:54 AM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Thanks Andrew,

I don't think it ran low on oil, plus it has a low oil switch of some sort.
I've just been using the specified oil: Synthetic 5W-30 I think.
Can the guides be replaced fairly easily or do they weld or sieze themselves into the head?
I wouldn't think these things would be failing at 286 hours.
The hoses both seem very good. The regulator end of the hose that feeds the regulator wasn't too tight, it is now.

Thanks David,
Are you saying there is a vacuum control line? I don't see one.
I don't see a prime button but I'll look closer when the sun is up.
Reply With Quote
  #9  
Old 12-11-2011, 04:57 AM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 2,787
Thanks: 673
Thanked 1,446 Times in 912 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Don't let these guys scare you. Jeesh - now I am afraid to start my Briggs - what with moving valve guides, crumpling push rods, wearing guide plates.

pulled off the hose from the regulator to the carb, no gas apparent when cranking. I think there's something about these regulators needing a vacuum so I sucked slightly on the hose but didn't spell or taste mat

Your clue is above - I agree with Jim Rankin - look at the demand regulator
Reply With Quote
  #10  
Old 12-11-2011, 09:14 AM
David C David C is offline
Registered-III
 
Join Date: Mar 2006
Location: Lake Jackson,Texas
Posts: 837
Thanks: 610
Thanked 484 Times in 332 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

The KN has a small (3/8" diameter) button for priming and does not have a vacuum line for a signal. The button is in the middle, on the opposite side of where the incoming gas line is. I would also check the gas solenoid for proper voltage and operation. Here is a link with lots of good generic info on NG/LPG conversions.
http://carbturbo.com/installation.pdf

David C.
Reply With Quote
  #11  
Old 12-11-2011, 02:23 PM
K D Redd K D Redd is offline
In Memory Of
 
Join Date: Nov 2004
Location: Southwest Missouri
Posts: 5,348
Thanks: 166
Thanked 1,202 Times in 1,063 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

No ALL KN have a priming button. I have remnants of a Winco Autostart Stand-by generator with a KN that does NOT have a priming button. When the unit is all enclosed, the manufacture see no reason to use a demand regulator with a priming button. I installed a Briggs seven KW stand-by generator at my wife's aunts home. It uses a KN that does not have a priming button. The hose that supplies fuel to the engine also transmits the vacuum signal to the KN. There is NOT a separate line. I suggested using the carb cleaner to make sure the engine runs BEFORE money is spent on a new demand regulator that MAY NOT be need. Two buck for a can of carb cleaner is cheap for testing.
I was just suggesting areas to look to IF the engine did not run or ran poorly.

Kent
Reply With Quote
  #12  
Old 12-11-2011, 06:22 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

So here is what I found. The push rods I pulled and they seem OK, the valves seem OK, everything moves properly when cranking.

David, thanks for that link.

Kent, I can't find that button. But there is an adjustment on the block at the top of the requlator. I think one sets output freq with that via engi e speed.

If I do that test I want to use carb cleaner (Gumout), not starting spray?
In the low pressure gas line not the air inlet?
The engine coughs a little when trying to start but never really catches.

Larry
Attached Thumbnails
8kW Guardian sol valve.jpg   8kW Guardian carb.jpg   8kW Guardian reg rear.jpg   8kW Guardian reg.jpg  
Reply With Quote
  #13  
Old 12-11-2011, 06:59 PM
Douglas123 Douglas123 is offline
Subscriber
 
Join Date: Feb 2011
Location: Memphis, Tennessee
Posts: 429
Thanks: 139
Thanked 146 Times in 111 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

The block on top of the regulator is for your fuel mix not engine speed adjustment. Units were set up for vapor propane or natural gas. The engine speed is that knob in the lower right corner in pick #2. Are you sure you are sparking on both cylinders? Almost all of the generac units did not have the push button on the regular. On that demand regulator the only line is the one from the regulator to the carb. If you have 6 1/2" water column and the fuel lock off is opening properly you should have gas flow. Take the line loose from the carb, hotwire the fuel lockoff and suck on the hose. If you do not get gas flow the problem is in that neighborhood. If you suck on the hose and get fuel to flow it will stay flowing because the pressure passing thru will keep the regulator diaphram open until pressure is lost ie turning off the fuel lockoff. Do you have good compression on both cylinders. That engine will run on only one cylinder.
Reply With Quote
  #14  
Old 12-12-2011, 01:25 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Kent,

I tried starting while shooting carb cleaner in the carb's gas input pipe. It didn't fully start but there were a continuous series of almosts which was closer to running than anything I've heard since this came up.

Douglas,

I thought the big brass screw might be speed since manual says to use a freq meter in adjusting it.

There is strong spark to ground on both plug wires.

I guess I'll try sucking again. Wait a minuite, that doesn't sound right...

Larry
Reply With Quote
  #15  
Old 12-12-2011, 02:59 PM
Jim Rankin Jim Rankin is offline
Registered-III
 
Join Date: Nov 2004
Location: Faunsdale, Alabama USA
Posts: 4,084
Thanks: 42
Thanked 1,106 Times in 882 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Just for starters, you may want to take the hose loose from the demand regulator and crank the engine over to see if it creates any vacuum which could possibly open the demand regulator.

Probably wouldn't be a lot of vacuum, but should be detectable. Could even rig up a water manometer to measure it if you wanted.

I don't think a single chestful of natural gas will kill you
Reply With Quote
  #16  
Old 12-12-2011, 05:07 PM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 2,787
Thanks: 673
Thanked 1,446 Times in 912 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

I don't think he was referring to that, Jim
Reply With Quote
  #17  
Old 12-12-2011, 11:32 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Talking Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Just another of my dubious attempts at humor. Sorry.
Reply With Quote
  #18  
Old 12-13-2011, 11:15 AM
K D Redd K D Redd is offline
In Memory Of
 
Join Date: Nov 2004
Location: Southwest Missouri
Posts: 5,348
Thanks: 166
Thanked 1,202 Times in 1,063 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Remove the air cleaner to spray in the carb cleaner. This way you can leave the hose from the demand regulator connected. It also take a lot of spraying to keep the engine running.
This is what I do to get a engine started after I have done a LP conversion. I use the carb cleaner to run the engine until I get the LP mixture close for the engine to run. Then I can dial -in the LP mixture.
If you can not make the engine run with a "Carbon based computer fuel injection", This fuel system is your finger operating the spray button on the can of carb cleaner, you have a engine problem NOT a fuel problem.
I just reread you first post. You said you installed this generator in 2000. This means it is almost 12 years old. From My experience with Briggs engine on Lawn and Garden equipment, this is about the time frame when the Briggs Magnetron Armature, Briggs speak for the Electronic Magneto Coil, FAIL from age. Hours seem to have NO bearing on this. When these cols fail they, most of the time, will run when cold but fail when they heat up. some just get flaky and some just FAIL. You need to check the fire on BOTH plugs as these engine. Each cylinder has basically independent ignition system. There is a wiring harness that connects both kill terminals of the coils together that has ISOLATION DIODES. One of these diode may have failed. Remove your flywheel shroud and disconnect the kill wires that connect to the back of the coils on the side. Then try starting the engine. If it now runs, you need to replace this wiring harness.

Kent
Reply With Quote
  #19  
Old 12-13-2011, 12:42 PM
N1148X N1148X is offline
Registered-I
 
Join Date: Jun 2008
Location: Weston, MA, United States
Posts: 24
Thanks: 1
Thanked 0 Times in 0 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Jim,

Cranking with finger over gas input I could feel a little suction, not enough to raise a convex spot on my skin, but easy to tell some air was moving.

Kent,

I'll retry the carb-cleaner-with-digital-fuel-metering again but into the air pipe this time. Just from my ignorance: wouldn't that amount of carb cleaner de-oil the cylinders and possibally lead to wall damage? Or is the amount of time so small as to be inconsequential? I'm going to cover the Gaurdian plastic baseplate with aluminum foil so dripping carb cleaner doesn't melt a hole through it.

That's interesting about the magneto coils; there isnt much to fail in a coil! However as of a couple days ago I had healthy sparks on both cyls and new plugs so that wont be my #1 thing to suspect I guess.

If I'm following you guys correctly its seeming more like a regulator issue????

And if so, what?
Replace it? Rebuild? Pound with a hammer?
Reply With Quote
  #20  
Old 12-13-2011, 12:50 PM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 2,787
Thanks: 673
Thanked 1,446 Times in 912 Posts
Default Re: Generac Guardian 8kW B&S 2 cyl standby pkg won't run

Remove the air cleaner to spray in the carb cleaner. This way you can leave the hose from the demand regulator connected. It also take a lot of spraying to keep the engine running
If you take the air cleaner off, I suggest you use the straw on the carb cleaner or other means to keep your hand away in case of a backfire-and the flame that comes out. Don't ask how I know about this.
Reply With Quote
The Following 2 Users Say Thank You to Power:
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Minimum AC volts on Generac Guardian 15kw portable generator CraigWH Generac Generators (SEARS, etc.) 6 08-30-2011 07:35 PM
If not Guardian or Generac then what? Contaucreek Generators & Motors General Discussion 27 06-22-2010 08:15 PM
Guardian vs Generac Dave R Generators & Motors General Discussion 17 05-30-2010 09:33 AM
Generac Guardian 13kw Spyder Generac Generators (SEARS, etc.) 20 12-22-2009 09:49 PM
Generac Standby system kevink1955 Generac Generators (SEARS, etc.) 9 03-10-2006 11:39 AM


All times are GMT -4. The time now is 12:40 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark
A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2014 by Harry Matthews
P.O. Box 5612 - Sarasota, FL 34277