QuestionQUESTION: I have a 5hp Briggs horizontal shaft motor on a water pump that runs good with no smoke but it bogs down and cuts off after about 15 seconds of pumping water. If you run it without trying to pump anything it runs perfect but dies every time under load. I cleaned the carb and replaced the diaphram no change so I had a local guy check the compression and it only has 60 psi of compression. How can it have such low compression and not smoke/
ANSWER: Hello Matt:
I have Never Seen a Small Engine Run with Less than 70PSI Compression and then they Idled Rough and Would Stall. If this is an Easy Start Engine (has the Compression Release on the Cam that Opens the Exhaust valve a Slight Amount before TDC), then a Compression Gauge will Show Low Compression. Did you Soak the Carburetor Overnight in Carburetor Cleaner? If No, then the Carburetor is Still Dirty. Does this Carburetor have Air Mixture Adjustment Screws? If Yes, then the Main Jet Mixture Screw is Set to Lean. ****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Farthest from the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws: ****Turn the Idle Air and ****Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** From your Description, it Sounds like the Carburetor Mixture Screws are Improperly Set or the Carburetor is Dirty and Requires a Good Soaking. Send me the Model and Type or Spec Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model (5 or 6 Digits) and Type Numbers (first 4 digits Only). Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. 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 10 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. Thanks.
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: Thanks John,
I did not soak the carb overnight but it seemed fairly clean. I don't remember seeing any adjustment screws other than the idle screw, but its been a couple weeks since I have had it apart.
Model: 135232
Type:0317 01
Does this carb have the adjustments you are referring to?
AnswerHello Again Matt:
Soaking the Carburetor Overnight is the ONLY way to Really Clean a Small Engeine Carburetor. The Varnish that Builds Up when the Engine is Not in Use Builds Up in Layers. Spraying ONLY Removes the Outer Layers and Sometimes Loosens the Other Layers so they Break Free During Engine Operation and Cause the Engine to Malfunction Again. The Breakdown for this Carburetor Shows 1 Carburetor Without Mixture Set Screws and the Other Carburetor has the Idle Air/Low Speed Mixture Screw. If your Carburetor has the Idle Air/Low Speed Mixture Screw (Valve Idle Mixture #173 in the breakdown), then Turn it In Completely (SNUG; DO NOT JAM) and then Reverse 1 1/2 Turns. Start the Engine. Now Set the Idle Air Mixture so the Engine Throttles from Idle to Full Throttle without any Hesitation if Required. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model (5 or 6 Digits) and Type Numbers (first 4 digits Only). Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. 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 10 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. Thanks.
Respectfully
John
