# GTH2548 still surging with new carb??



## GTH2548 (Mar 1, 2013)

I’ve had a surging problem with my mower for a while. I tried cleaning the carbs many times but it didn’t solve my problem. The previous owner of the tractor didn’t take care of it and let gas sit in the carb for a number of years before giving it to me. I was thinking the carb was shot because I tested the vacuum gas pump and it looks like its pumping fine. So I found a great deal on a new carb. Here is the listing for the carb that will normally run you $250 to $300 new. They have it for only $85. 

http://www.ebay.com/itm/Nikki-Carb-...200891?hash=item210f097d3b:g:X7MAAOSwjVVVsnY1

I can now say the carb is not the cause of the surging. I ordered a fuel pump that should be arriving today. I’ll pick up some ¼” fuel line and replace it. If it still surges after that I’ll replace the rubber gaskets on the intake manifold to make sure it’s not sucking in are from them. After that I’m not sure what else I can do besides take it into a shop. 

I’m also posting pictures of the rebuild I had to do to the engine. 








[/url]DSC01295 by BRIAN OWEN, on Flickr[/IMG]








[/url]IMG_2530 by BRIAN OWEN, on Flickr[/IMG]








[/url]IMG_2539 by BRIAN OWEN, on Flickr[/IMG]








[/url]IMG_2542 by BRIAN OWEN, on Flickr[/IMG]








[/url]2013-03-03_12-29-37_806 by BRIAN OWEN, on Flickr[/IMG]

all cleaned up and ready to surge. 








[/url]2013-04-03_17-59-31_843 by BRIAN OWEN, on Flickr[/IMG]

I'll post a video of how it runs after I install the fuel pump and new gas line. 

If there is anything anyone can think of to stop the surging please let me know.


----------



## k7iou (May 8, 2016)

Did you check the governor? I'm making an assumption it has one as I'm not familiar with your model. If it does and it's surging you can watch the governor lever pulsing back and forth. May need adjustment or is out of wack. I recently bought a generator with a Honda engine that surged and you could see the lever moving back and forth, if I held it steady it stopped surging. I adjusted it but it didn't help. The mfg said it was an internal fix so I returned it. But I needed temporally as our electric was out for several days so I used a ball point pen spring to steady it. Just a thought. Good luck.


----------



## BigT (Sep 15, 2014)

Hello GTH2548,

Welcome to the forum.

Don't know if this is applicable to your situation, but I had a surging problem with a smaller Briggs engine many years ago, and a friend advised me to open the main jet a small amount. Solved my problem.


----------



## jhngardner367 (Apr 5, 2011)

Surging is not caused by the fuel pump,or lines .
In most cases ,it's due to a governor out of adjustment,or a governor spring too weak,or in the wrong hole position.
It can also be due to a dirty idle jet,or passage,or even water in the fuel.
Ethanol fuels tend to draw moisture,and many prefer to use non-ethanol fuel.
Also check the fuel cap vent,air filter,and the linkages.


----------



## GTH2548 (Mar 1, 2013)

I got all new fuel line and fuel pump installed. I also replaced the fuel filter and added a shut off valve and it’s no longer surging. I was able to take it around the house a few times. It’s not running perfect but it’s definitely running better. 

I will check the governor spring to make sure it’s not weak and it’s in the correct spot. 

I’ll take a video of it running so you can hear it.


----------



## k7iou (May 8, 2016)

In regards to fuel;
3 things I have learned,
1. Stay away from ethanol and if you live in a city that requires it, use racing fuel. Ethanol can go bad in as little as 2 weeks due to heat (hot weather). Spend the extra money for racing fuel it lasts much longer and won't damage fuel systems.
2. Use stabil, it really works.
3. Use Seafoam if you suspect gumming issues. I've used it on many atv's and motorcycles with great results.

One other thing I do if there is a fuel shutoff valve. While running, I turn it off and let engine run until it runs out of fuel. Some may disagree with this but I've done it for years.


----------



## jhngardner367 (Apr 5, 2011)

Good that it's running,........however ,racing fuel is NOT recommended for air-cooled engines!
Use non-ethanol unleaded,if you don't like the e-10 fuels sold today.
Racing fuel doesn't allow the engine cooling system to shed the extra heat,and has been known to cause seizures,in lawn equipment.
Also,using it will void any warranty on new equipment.
Non-ethanol fuel is slightly more costly,but it is available in most states,and isn't as costly a racing fuel.


----------



## GTH2548 (Mar 1, 2013)

A friend of mine showed me a website that has all gas stations that has non-ethanol gas. I'll start using that. 
I also ordered all new springs for the governor.


----------



## GTH2548 (Mar 1, 2013)

Here is the site that has the locations of all the gas stations around with ethanol-free gasoline. just click on the map to see all the locations. 

http://www.pure-gas.org/


----------



## GTH2548 (Mar 1, 2013)

When I get all my new springs in I’m going to have to adjust the governor. I’ve found a youtube video that shows some governor adjustment but it doesn’t explain which holes you put the springs in. If anyone can give me some kind of step by step it would help out. thanks. 

Here is the youtube video about adjusting the governor

Here is a picture of the setup when i got the mower.







[/url]2012-06-17_09-19-48_903 by BRIAN OWEN, on Flickr[/IMG]


----------



## GTH2548 (Mar 1, 2013)

I just ordered 2 Head Gasket Kits for it. When I rebuilt the engine the gaskets looked ok but now i'm getting a little bit of white smoke on startup and if i'm digging into it to fix the governor I might as well dig a little deeper to replace the head gaskets.


----------



## k7iou (May 8, 2016)

jhngardner367 said:


> Good that it's running,........however ,racing fuel is NOT recommended for air-cooled engines!
> Use non-ethanol unleaded,if you don't like the e-10 fuels sold today.
> Racing fuel doesn't allow the engine cooling system to shed the extra heat,and has been known to cause seizures,in lawn equipment.
> Also,using it will void any warranty on new equipment.
> Non-ethanol fuel is slightly more costly,but it is available in most states,and isn't as costly a racing fuel.


Wrong! I've used racing fuel for years in air cooled engines without any issues. In big cities out west you can't buy anything but ethanol based fuels and racing fuel is the only best option. With stabil added I've stored dirt bikes and chainsaws for extended periods of time and they usually start with two pulls or kicks.


----------



## GTH2548 (Mar 1, 2013)

After installing the Push Rods and Rocker Arms I noticed I don’t have any valve spring clearance. The manual said I should have a minimum allowable clearance of 0.25 mm. I don’t see any way to adjust them. I know some rocker arms have a little screw in the middle of the nut you can adjust but mine do not have that. Am I missing something? How can I adjust the rocker arm so I have the necessary clearance I need?








[/url]2016-05-19 (18) by BRIAN OWEN, on Flickr[/IMG]








[/url]20160518_223256477_iOS by BRIAN OWEN, on Flickr[/IMG]


----------



## FredM (Nov 18, 2015)

are you placing the flywheel just past TDC when checking the clearances, most mower engines have a decompression lift on the cam for starting.

did you tension the rocker stud with the pushrod not under the rocker ?? looking at your photo it seems like the rocker stud is the only point of adjustment, if you set the torque with the pushrods in place, then your reading will be incorrect.


----------



## FredM (Nov 18, 2015)

GTH2548 said:


> I just ordered 2 Head Gasket Kits for it. When I rebuilt the engine the gaskets looked ok but now i'm getting a little bit of white smoke on startup and if i'm digging into it to fix the governor I might as well dig a little deeper to replace the head gaskets.


the head gaskets should have been replaced at the time of head removal, but seeing that you reused these, if the gaskets are not sealing, then you should be able to hear a pffft sound as the engine is running, you don't say where the white smoke is coming from.


----------



## FredM (Nov 18, 2015)

just reread the adjustment specs, the lifters are hydraulic so no adjustment apart from the tension for the rocker studs.


----------



## jhngardner367 (Apr 5, 2011)

K7Iou,
It depends on the octane of your "racing fuel". 
Down here,and in Michigan,where I had my shop for 18 years,it was over 100 octane.....unless you mean the 96 octane,they have,now.

GTH2548, I was about to say that the CV series usually have hydraulic lifters,since it's a pressure fed oiling system.
Glad you got it worked out.


----------



## GTH2548 (Mar 1, 2013)

I got it all put back together and it's running great. Thanks for all your help. I'll post a video soon.


----------

