bean 85 #1 Posted December 24, 2011 I have a '73 8hp 4 speed that has a vaccum fuel pump. it has a bad diaphram, so I bypassed it and hooked the fuel line directly to the carb. it is a gravity feed now and works well, as long as you keep the tank over 1/4 full. i have a mechanical pump that I put on today and it wouldn't even fire. it is pumping really well. I put it back to gravity feed and it fired right up.anyone ever experience this before? Share this post Link to post Share on other sites
Kelly 1,033 #2 Posted December 24, 2011 Did you hook the lines up on the right sides of the pump?, you say its pumping well, is that on the engine using the starter? Share this post Link to post Share on other sites
bean 85 #3 Posted December 24, 2011 yeah, lines are on right. when turning over with starter, it shoots out gas pretty well. certainly enough to keep the bowl full. may be an air gap or something.. it was just making me scratch my head. Share this post Link to post Share on other sites
buckrancher 2,694 #4 Posted December 24, 2011 check and see if there is a piece of crap inside the fitting before the inlet needle on the carb pressure from the mechcanial pump could be forceing it over the in the hole over the inlet needle and stopping the flow were the gravity feed does not Brian Share this post Link to post Share on other sites
bean 85 #5 Posted December 24, 2011 check and see if there is a piece of crap inside the fitting before the inlet needle on the carb I will do that. it is a tractor that sit for a whike and I had to clean the fuel bowl a few times, but haven't actually properly cleaned the carb. it runs great, though Share this post Link to post Share on other sites
tunahead72 2,546 #6 Posted December 25, 2011 favoritemodel: elle macpherson THAT'S FUNNY! :handgestures-thumbup: Share this post Link to post Share on other sites
JC 1965 1,532 #7 Posted December 25, 2011 favoritemodel: elle macpherson THAT'S FUNNY! That is funny! I didn't notice it until I read your post. :thumbs2: Share this post Link to post Share on other sites