QuestionB&S 280777 0639-E1 9902042D, ie Vanguard 16hp Single-cyl circa 1999, for Victa Corvette
ride-on.
Engine starts and runs fine, but within 5 or 10 minutes of startup it has recently begun to
develop a slight misfire (aka hiccup) and then to cutting out intermitently. At first it seems
related to engine-load because it clears if I disengage the mower deck (via electric switch).
However the cutting out soon lenghtens in duration, whether deck is engaged or not, into
inoperability. Will not restart unless 'rested' (cooled) for 10~30 minutes, then runs fine but
misfire soon reappears. If choke is applied (as 'temporary remedy') the motor immediately
clears, but soon reverts to as described above. The defect appears to be worsening in onset
and severity. I have replaced the spark plug, checked the petrol cap breather, air cleaner, the
external fuel lines and fuel filter - which all seem ok to my amateur perspective. Thank you
kindly for any advice.
AnswerHello Tim:
>>The Following is a Basic Instruction File I made for this Type of Problem. Any Input is Appreciated. I Usually Suggest you Check the Following in this Order for a Problem like yours.
>>1- Check the Gas Tank Cap and Ensure it is Venting the Tank. A Vacuum Builds in the Tank and the Gas Flow Stops or Slows (15 to 45 Minutes and if the Small Granular Sand is in the Tank it can Take Several Days of Constant Running to Bring All the Sand Particles to the Tank Outlet Port) to a Point it Shuts Off the Engine.
>>2- Replace All the Spring Style Hose Clamps with Screw Style Hose Clamps on the Fuel System.
>>3- Check the Carburetor Solenoid.
>>Sometimes the Plunger is Moving, Just Not Far Enough to Allow the Gas to Enter the Jets or it is Overheating and Leaning Out the Fuel to the Engine.
>>The Following is a Basic Instruction File I made for Checking the Carburetor Solenoid. Any Input is Appreciated.
>>**Check for Current/Voltage (10.5 VDC Minimum) to the Carburetor Shut Off Solenoid. If the Carburetor Shut Off Solenoid has Current, then On Some Solenoids you can Remove the Needle and Replace the Solenoid to Test them.
>>****PLEASE DO NOT OPERATE THE MOWER WITH THE SOLENOID BYPASSED IN THIS MANNER. THIS IS "ONLY" FOR TESTING.****
>>For Others, Remove the Carburetor Solenoid and Go to the Hardware Store. Purchase a Bolt of the Same Diameter and Threads. It Needs to be 1/2" to 3/4" Long for the Horizontal Mount Solenoids and 1/4" to 1/2" Long for the Vertical Mount Solenoids. Put this Bolt in Place of the Solenoid. If this Corrects the Engine Problem, then Replace the Solenoid.
>>***NOTE: THIS IS FOR CHECKING THE SOLENOID ONLY I NEVER SUGGEST YOU OPERATE THE ENGINE WITH THE SOLENOID OUT OF THE CARBURETOR EXCEPT FOR TESTING PURPOSES***
>>Sometimes the Plunger is Moving, Just Not Far Enough to Allow the Gas to Enter the Jet Properly.** **Use 440 Wet Dry Sand Paper and Engine Oil to Clean the Pin. Wet the Sand Paper with Oil Until it is Flexible and then Lightly Polish the Pin. There is Some Slop/Free Play in the Solenoid Pin. Usually the Electromagnet is Simply Not Pulling the Pin as it Should or there is a Small Bur on the Pin. Use 440 Wet Dry Sand Paper and Engine Oil to Clean the Pin. Wet the Sand Paper with Oil Until it is Flexible and then Lightly Polish the Pin. Clean and Lightly Oil the Pin before Inserting it Back into the Solenoid. Just a Film of Oil is All it Takes.**
>>4- Operate the Equipment Until it Starts Surging or Quits (15min to 1hr). Then Immediately Check for Fire from the Plug. If the Plug is Firing, then
>>5- Depending on the Model Mower, it can Also be the Pickup Tube in the Gas Tank.
>>If No Fire Or Erratic Fire, then Remove the Shut Off Wire from the Coil and Check for Fire.
>>If Still No Fire, then the Ign Module or Coil is Bad. **Even if the Coil is New or Fairly New, it can Still be Bad.** On JD Mowers; Remove the Igniter/Module and the Coil and have the Local JD Dealer Test them.
>>Usually on JD Mowers the Igniter is the Most Common cause for No Fire to the Plug.
>>You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select "Click Here For The Parts Menu". Then Select B. Then Select Briggs. Then Select "Click Here If You Don't Have Your Part Numbers". Now Select the File (using the first 2 Numbers of your Model Number) for your Model.
>>If you Hit a Snag or this Does Not Correct the Problem, I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 3 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. All Follow up Questions are Accepted at Any Time. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
