Rubberman 10 #1 Posted June 20 1992 Wheelhorse 312-8 with M12 engine. I have bypassed the mechanical fuel pump. Added an electric fuel pump along with a fuel pressure regulator (set to 1psi). Also changed the spark plug. But occasionally it will start back firing and sputtering. Once I disengage the blades it will run fine but if I try to engage blade it will backfire again. Seems that shutting off engine for a sec and starting it back up fixes the problem for a while. Thoughts? Should I scrap the electric fuel pump and purchase a Kohler mechanical pump? 1 Share this post Link to post Share on other sites
ebinmaine 72,435 #2 Posted June 20 Have you checked and adjusted the engine valves? Decarboned the cylinder head and combustion chamber? 2 Share this post Link to post Share on other sites
oliver2-44 10,689 #3 Posted June 21 The electric fuel pump should be fine. Have you tried adjusting the carb a little leaner? See the carb adjusting procedure in the Kohler manual. Its available in the Manuals Section if you don't have one. How long has it been since the fuel system was gone through? All fuel hose replaces, tank pulled and cleaned, fuel shutoff with screen in the tank pulled and cleaned or replaced. Fuel filter after electric pump replaced I just did all that to my C160 after about 5 years and it needed it. 2 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,450 #4 Posted June 21 You want to try one thing at a time so you determine the cause of the problem. One more try is to add a shot of Marvel Mystery oil or 2-stroke oil to the fuel tank. That will lubricate the valve stems in case they are hanging up. Some engines love it because the valve springs are not that strong. 3 Share this post Link to post Share on other sites
kpinnc 14,587 #5 Posted June 21 Dump the fuel bowl. Marvel mystery oil is good stuff. It never hurts anything. 3 Share this post Link to post Share on other sites
peter lena 9,235 #6 Posted June 21 @Rubberman run in a number of used engine s , on a seperate gallon of heavily treated fresh gas , drop carb bowl , verify settings and all related linkage/ movement sweep , also like , sta bil fuel additive , have had zero rubber related hose break down , in filters or carb . probably a collective issue , not at one place , personally use , car bole low pressure fuel pumps , no issues , pete 2 Share this post Link to post Share on other sites
Horse Newbie 7,395 #7 Posted June 21 52 minutes ago, kpinnc said: Dump the fuel bowl. Marvel mystery oil is good stuff. It never hurts anything. Will it stop my Onan surging ? Share this post Link to post Share on other sites
lynnmor 7,802 #8 Posted June 21 30 minutes ago, Horse Newbie said: Will it stop my Onan surging ? You clean out the carburetor to stop surging. 1 1 Share this post Link to post Share on other sites
lynnmor 7,802 #9 Posted June 21 17 hours ago, Rubberman said: I have bypassed the mechanical fuel pump. Added an electric fuel pump along with a fuel pressure regulator (set to 1psi). Since you have a regulator and it is set real low, I would try a higher setting. It sounds like fuel starvation under load. 3 Share this post Link to post Share on other sites
peter lena 9,235 #10 Posted June 21 @lynnmor agree with the pressure increase , the probable fuel hose break down , in the fuel flow is also a a very common issue , pete, Share this post Link to post Share on other sites
