I'm trying to get my flathead(40 merc) running for more than about a minute! With the original style fuel pump(new) and a new fuel pump rod, my engine cranks forever trying to get fuel to the carb. I added an inline electric pump back by the tank to try and build more pressure quicker. That seems to help but it still runs for a short time , until the float bowl empties and doesn't refill quick enough. Should I remove the mechanical pump entirely? Is it too hard for the electric to pump through the mechanical? The carb inlet valve seems to be okay. Anyone else run both pumps? Thanks for the help!
Check stock pump pushrod movement--it should be I think about .2" or more. I would be real suspicious of the float valve--I'm just in the process of putting together a 94 with a new viton tip valve, and noticed that the needle doesn't want to drop freely. Try the old one if the garbage hasn't gone out yet--it doesn't seem likely that neither pump is capable of keeping the carb full.
As a bypass/test, try rigging a can with a hose to the carb--if it won't run on gravity feed, that valve ain't right. Drop a wrench first to be sure your gravity is working.
[ QUOTE ] Drop a wrench first to be sure your gravity is working. [/ QUOTE ] LMAO! Ya gotta check the basics!
[ QUOTE ] As a bypass/test, try rigging a can with a hose to the carb--if it won't run on gravity feed, that valve ain't right. Drop a wrench first to be sure your gravity is working. [/ QUOTE ] That's hilarious!
You could have a faulty fuel line (rusty). A faulty gas cap(no ventilation). an airleak in the fuleline/connection's preventing the pump to suck. Rustflakes in the tank, clogging the fuel line. An original fuelpump will provide fuel to four carbs. The Viton needle can stuck, bought an outboard engine cheap cause of this problen, just took a piece of thin pianowire and conncted the needle to the float, and the weight of that got it working OK. I have checked the gravity here in Sweden an it works OK ;-)
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