QuestionQUESTION: I have a Simpson pressure washer with a Honda GX270 engine. What makes the engine surge under a load? It also will backfire with no smoke. Mechanics here is Maine don't know what is causing it. It is only 2 years old and has only been used about 100 hours. Fuel is fine. Oil is fine. Stumped. Jim
ANSWER: Hello Jim:
>>Since this is a Honda, you can Use this Site Addy; http://www.honda-engines-eu.com/en/welcome.html and Select "Service Information" from the Drop Down Menu of the Service Tab. Now Select "Shop Manual". Now Select your Engine Model Range. Now Select your Specific Engine Model and then Download the Shop Manual. The Shop Manual should have the Procedures for Checking and Setting the Timing on your Engine.
>>The Following can cause Surging Under a Load for this Engine.
>>Improper Spark Plug and/or Plug Gap.
>>Carburetor Requires Soaking Overnight in Cleaner and New Parts Installed.
>>Carburetor Mixture Screws Require Adjusting.
>>A Bad/Sticking Carburetor Solenoid. Sometimes this Solenoid will Look like it is Moving, but it May Not be Moving its Full Travel.
>>The Following is a Basic Instruction File I made for Checking the Carburetor for Blockage and the Carburetor Solenoid. Any Input is Appreciated.
>>Remove the Air Filter and Place your Hand Over the Carburetor Intake.
>>Try to Start the Engine with your Hand Over the Carburetor Intake and then Remove it when you Feel the Suction Pull the Palm of your Hand.
>>If the Engine Starts and Runs After doing this, then
>>The Blockage was Pulled Thru the Carburetor Jet and you should Not have any More Trouble.
>>If the Engine Still will Not Start, then
>>**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.**
>>Valve Clearances Require Adjusting or a Weak Push Tube that Requires Replacing Due to the Push Tube Flexing During Heavy Operating Loads.
>>Governor Requires Setting. Sometimes even During Normal Operation the Governor Arm will Slip on the Governor Shaft a Small Amount and cause Surging when under a Load.
>>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
---------- FOLLOW-UP ----------
QUESTION: John'
Thank you very much for your response.
My wife made the first entry in my name but she made one mistake. The surging doesn't happen when it is under a load. It happens when I let up on the trigger of my wand. Then the engine starts sputtering, surging and backfiring. Also, the problem only occurs after the machine has warmed up for a while. When I first start up the machine everything works well. But the machine works fine when under a load. It's just when I let up that it happens.
Hope you can help,
Jim
ANSWER: Hello Again Jim:
>>No Worries.
>>It Happens to All of Us from Time to Time.
>>Tell your Wife, I Forgive Her; Just Don't let it Happen Again. LOL.
>>Now this Brings the Complete Unit into the Situtation.
>>Could you Possibly Send me the Make and Model Numbers Off this Unit, Please.
>>With these I can Locate the Correct Manual and Better Assist you.
>>So as Not to Delay things, I am Going to a Diagnostic Review of the Engine.
>>How Long does the Engine Surge?
>>Does it Continue to Surge All the Time when at Idle and with No Load?
>>Have you Checked the Idle Control Solenoid (if Applicable)?
>>You have Described a Valve Clearance or Flywheel Key Problem.
>>I Spoke with the Mechanics in the Shop and was Reminded that I had Failed to List the Flywheel Key in My First Response to you.
>>Have you Checked the Flywheel Key?
>>Make that your First Check.
>>If the Flywheel Key is Slightly Damaged you can have this Problem at Idle.
>>If the Flywheel Key is Good, then
>>Are you Sure the Valve Clearances are Set to the Correct Specifications?
>>If they are, then
>>Try the Following;
>>Sometimes you have to Open the Clearances a Small Amount (.002in to .004in) above the OEM Specifications.
>>When the Engine Reaches Operating Temperature, the Valve Clearances will Usually be Slightly Closer than when the Engine is Cold.
>>This causes the Compression Release to Open when at Idle and cause the Problem you Described (Rough Idle, Sputtering, Surging and Backfiring).
>>I have had Several Generators in the Shop that had the Same Problem, but the Cause was Different with Each Generator.
>>Once we (myself and the Mechanic that was Repairing the Generators) Set the Valve Clearances to approximately .002in or .003in more than the Specifications on 1 Generator and the Problem was Corrected.
>>The Shop had Researched this Problem for Several Weeks before they Asked me Almost the Same Question.
>>You have to be Careful or you can get the Clearance to Wide and the Compression Release will Stop Operating Correctly.
>>I have Noticed over the Past 10 Years that these Engine have More and More Problems that are caused by the OHV Engine Valve Clearances Not being Correct or Requiring a Slightly Larger Clearance when Used for Some of the Special Applications such as the Generators and Pressure Washers.
>>If None of These are the Cause, then
>>The Last Thng to do is;
>>Open the Crankcase and Check the Cam and Crank Timing Marks.
>>It is Possible, (although Rare) and Not to be Forgotten that the Cam can Jump 1 Tooth and Still Run.
>>Depending on if the Cam Jumps Forward (Revving) or Reverse (Slowing) will make the Difference between the Engine Surging at High RPM's or Surging at Idle.
>>If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and 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. Follow Up Questions are Now Accepted Anytime. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
>>PSS: Thanks for the Comments and Ratings.
Best Wishes Again
John C Bridgers Sr and Family
---------- FOLLOW-UP ----------
QUESTION: Could you Possibly Send me the Make and Model Numbers Off this Unit, Please.
>>With these I can Locate the Correct Manual and Better Assist you.
THE PRESSURE WASHER IS A SIMPSON WATER BLASTER 4200 SERIAL#12071600
THE HONDA ENGINE IS A GX390 13HP
>>So as Not to Delay things, I am Going to a Diagnostic Review of the Engine.
>>How Long does the Engine Surge?
ALL THE TIME WHEN THE MACHINE IS WARMED UP. IT SPUTTERS, BACKFIRES, SURGES CONTINUALLY BUT AS SOON AS I PULL THE TRIGGER AND BEGIN PRESSURE WASHING THE ENGINE RUNS SMOOOTH AND I HAVE PLENTY OF PRESSURE. WHEN I RELEASE THE TRIGGER THE ENGINE STARTS SURGING, SPUTTERING, BACKFIRING AGAIN.
>>Does it Continue to Surge All the Time when at Idle and with No Load?
>>Have you Checked the Idle Control Solenoid (if Applicable)?
WHAT'S THAT? I'M A DUNCE WHEN IT COMES TO SMALL ENGINES.
I'M A HOUSE PAINTER
John, the best I can do is to bring all these suggestions that you have sent to a local small engine man. He has looked at the machine already but was timid about working on it. But with all that you have suggested maybe will have the courage to look into it.
In the meantime, with the added information as to the model number etc., I look forward to any further suggestions you might have.
Thank you for the thoughts concerning the holidays but because of all the abuses connected with them, as Christians, we cannot participate. I'm sure you know what I mean...drinking, partying, whoring, excessive spending, commercialization,etc.,etc.
Yours,
Jim
AnswerHi Jim:
>>I Do Understand where you are Coming from about the Holiday Seasons.
>>We All Celibrate in Our Own Ways.
>>No Worries:
>>This Problem is Going to be Corrected by the Carburetor Mixture Adjusting, Carburetor Cleaning or the Valve Clearance Adjusting.
>>Thanks for the Unit Make and Model Numbers.
>>I Reviewed the Unit Breakdown and Verified that there is Nothing in the System that would Create/Cause this Problem.
>>I Look Forward to your Update.
>>Till Next Time. May All Your Mechanical Problems be SMALL ONES and as Always, May the All Mighty Bless You and Yours. Be Safe and Happy.
Best Wishes and Good Luck
Respectfully
jbridger (John)
