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Craftsman/Briggs&Stratton surging won't start


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#1 gunns OFFLINE  

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Posted January 20, 2017 - 02:16 PM

I posted the below write-up on another forum.  I tried to provide as much info as possible to including all the trouble shooting that I did.  It was obvious that those that responded to my post either didn't read the whole post or just scanned it.  Initially the the tractor would surge at slow RPMs.  Weeks later it wouldn't start.  As you can see from the write-up I eliminated an electrical  problem as the fault by bypassing the carb by putting gas straight down the throat of the carb.  The carb and fuel pump were disassembled cleaned and reinstalled with no change in the problem.  The write-up also reflected that after the carb was cleaned and reinstalled I was unsuccessful in getting the tractor to start.  I then removed the top of the carb while the carb was still attached and there was sufficient gas in the bowl.  As before I could get it to start by putting a little gas down the carb throat.  I concluded that it was not an electrical problem but a fuel problem.  Fuel was getting from the gas tank all the way to the carb bowl.  So it would appear that it is an internal problem with the carb.  I'm suspecting I didn't clean the carb well or there is an internal leak in the carb.  Is there an area in this carb that needs extra attention and is a typical problem area to get completely clean?  I understand my original post is indeed lengthy and some won't want to take the time to read all of it.  Any help is appreciated.

 

Below is my original post:

 


First off this is what I have:

Craftsman Lawn Tractor model 917.270812 with a Briggs & Stratton model 42E707 type 2631-E1 code 9905035B engine.

Here's the problem:
The tractor had been running fine for years then for no apparent (at least to me) reason it started surging at Idle and low RPMs. At higher RPMs it would smooth out. At idle it would smooth out if you choked it a little. OK so it was running a little lean. I made a mental note (not a good idea for me) to remove and clean out the carb. I was too busy and never got around to it - ah heck all I had to do was pull the choke out a little - right.

Well finally it just wouldn't start at all. It would turn over like a champ but wouldn't fire up.

The battery had a full charge and YES it had gas in it. LOL!

I checked for spark at the plugs and there was.

Thought it wasn't getting gas to the carb so I checked the fuel lines and filter and they're good.
So maybe a bad fuel pump? I pulled the fuel line off the pump and gas flowed out the end of the fuel line at the 
pump end. This was checked after checking the fuel lines so they were empty of fuel so pump must be working.

I put a little gas down the throat of the carb (didn't have starter fluid) and it fired right up and ran great until it ran out of the gas I'd poured in so that eliminated a possible electrical problem.

So now I finally got around to doing that long awaited carb cleaning. I pulled the carb off and disassembled the carb and fuel pump. Cleaned out everything. I've had this unit since the 1990s and there was hardly and debris in the bowl. This was it's first cleaning too. Ran small copper wire through the jets and any small orifices and used compressed air to blow everything out. I reassembled everything and reinstalled the carb.

With a full charge on the battery it turned over like a champ but it still would not start. Nothing changed. It'll turn over but not start at all. Got 
starter fluid now so I gave it a shot and it momentarily ran until it ran out of the starter fluid. With the carb still installed I pulled the top of the carb off to see if it was getting gas. The bowl had plenty of gas in it so the pump was working fine. So electrical is fine and it's getting gas to and into the carb but that's as far as it gets.

So.... I must not have done a good enough cleaning or it's a bad gasket/internal leak? Any Ideas. The carb is the one that has four screws that hold the fuel pump on. It's not the three screw version. Before I throw money at a 
carb gasket kit is there a problem area on these carbs that frequently cause this type of problem? I know the kits aren't that expensive but its the down time waiting for the kit that's the problem. If there is a problem area in these carbs that I need to re-clean I can get to that right away.

Your help/advice is appreciated!

 

 



#2 MH81 OFFLINE  

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Posted January 20, 2017 - 03:18 PM

:welcometogttalk:
Thanks for the very detailed writeup. I hope you get better answers here.

Questions. (And I really hope I didn't miss this in your writeup) does your carb have the plunger in the bottom?
And even tho you have bowl fuel, have you tried a suspended fuel tank above the carb level?

Thanks for joining.
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#3 DougT ONLINE  

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Posted January 20, 2017 - 03:42 PM

:welcometogttalk:


Questions. (And I really hope I didn't miss this in your writeup) does your carb have the plunger in the bottom?


 

I think what Alan is referring to is the electric solenoid fuel shut-off in the carb. I didn't go look up your carb but one suggestion is to study how the fuel gets from the bowl and into the main metering circuit. Usually a hole in the bowl into the main jet area. the solenoid is made to shut that off if it has it. I've also seen crud plug that circuit.


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#4 MGP59DB OFFLINE  

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Posted January 20, 2017 - 03:42 PM

With what you say - my guess would be you still have a clogged jet - in the carb. It is adjusted wrong . Or there is a leak in the gasket to the head and you are not getting enough vacuum to pull the fuel in.

 

Edit : electric shut off , I am not familier with.


Edited by MGP59DB, January 20, 2017 - 03:43 PM.

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#5 jimmy G ONLINE  

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Posted January 20, 2017 - 04:15 PM

The valves on that pump have to be centered completely over the port with no distortion,they shrink with age and constant pulling from pump spring.the solenoid needs to be checked for voltage first,if good unscrew and ground it,apply voltage,solenoid should click once and retract plunger
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#6 MiCarl ONLINE  

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Posted January 20, 2017 - 04:20 PM

It appears from the parts fiche that your carburetor should have a fuel solenoid on it.  It won't run without +12V to the wire on that solenoid.


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#7 KennyP ONLINE  

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Posted January 20, 2017 - 04:37 PM

From what I saw in a parts breakdown, it has a fuel solenoid in the side of the carb. Is this a 3-bolt or 4-bolt carb?


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#8 jms180 ONLINE  

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Posted January 20, 2017 - 05:35 PM

http://outdoorpoweri...airs/#id_briggs

Try this link for Briggs and Stratton carburetor cleaning


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#9 boyscout862 OFFLINE  

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Posted January 20, 2017 - 05:37 PM

Welcome to GTT. It sounds like you are doing the correct troubleshooting but have reached a point where there isn't a clear test. I agree with the guys above that the problem may be in the fuel solenoid. It may not be opening or crud got in there. It needs to be removed and tested away from the carb(don't want a fire). Please post pics to show the situation. Last week, I fixed a generator for a friend. The problem was stale gas in the tank. Good Luck, Rick



#10 Bruce Dorsi ONLINE  

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Posted January 20, 2017 - 06:07 PM

The troubleshooting described does not confirm that the problem is in the carb.

 

One has to remember that fuel/air mixture is drawn into the cylinder by the suction created while the piston moves downward. 

 

Any loss of this suction can affect starting.

 

Loose carb mounting, leaking or broken intake gaskets, warped flanges, valves not seating properly, faulty compression release,etc,etc, can call be the culprit.


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#11 gunns OFFLINE  

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Posted January 20, 2017 - 11:47 PM

[quote name="MH81" post="742421" timestamp="1484943522"]:welcometogttalk:
Thanks for the very detailed writeup. I hope you get better answers here.
Questions. (And I really hope I didn't miss this in your writeup) does your carb have the plunger in the bottom?
And even tho you have bowl fuel, have you tried a suspended fuel tank above the carb level?
Thanks for joining.[/quote

MH81 thanks for a quick response. That would be a no to both questions. No solenoid and didn't do the tank suspension text. Just put some gas down the throat. I'm getting a much better response from this site. What a relief. Based on the responses its obvious that everyone actually read my post. Go figure. LOL!

Since making my post I went ahead and ordered a carb rebuild kit which also has the parts for the fuel pump. It should be here next week. I hope! Ill do a more thorough cleaning before installing tube kit. Ill post the results. Thanks again guy!

#12 gunns OFFLINE  

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Posted January 20, 2017 - 11:57 PM

I think what Alan is referring to is the electric solenoid fuel shut-off in the carb. I didn't go look up your carb but one suggestion is to study how the fuel gets from the bowl and into the main metering circuit. Usually a hole in the bowl into the main jet area. the solenoid is made to shut that off if it has it. I've also seen crud plug that circuit.


Hey DougT. No it doesn't have the solenoid. I thought I was careful enough in cleaning both jets. Well, maybe I wasn't. I did my best to follow the rout that I thought gas would take to get from the bowl to the carb throat. There were some goobers in the pilot jet but the main was pretty clean. Ordered rebuild kit as mentioned to MT81. Will post results. Thanks for your input!

#13 gunns OFFLINE  

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Posted January 21, 2017 - 12:23 AM

:welcometogttalk:
Thanks for the very detailed writeup. I hope you get better answers here.

Questions. (And I really hope I didn't miss this in your writeup) does your carb have the plunger in the bottom?
And even tho you have bowl fuel, have you tried a suspended fuel tank above the carb level?

Thanks for joining.



#14 gunns OFFLINE  

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Posted January 21, 2017 - 12:29 AM

Thanks MGP59DB and Bruce Doris.
There was enough vacume to pull the gas and starter fluid I put down the throat and start up. But you are right it might not be enough to pull the gas from the bowl. Ill check it tomorrow. Talks again for tube lead!!
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#15 gunns OFFLINE  

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Posted January 21, 2017 - 12:33 AM

Jimmy G, MiCarl, KennyP, There's no solenoid and the fuel pump is the 4 bolt version/carb. Thanks for your input!!




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