1998 DT 140 EFI fuel problem

rustyriver

Cadet
Joined
Apr 19, 2009
Messages
12
I recently bought this motor. It ran great. I replaced the fuel filter, Oil filter, Impeller. Drained the oil tank and blew out the lines. Rebuilt the fuel pump. Installed new fuel lines and bulb. I did all this to start fresh. It has run like a top for around 15 hrs. This weekend it was acting like it was losing prime after around 2 hours on the lake of blowing and sucking lines and the bulb switching tanks ect I completely ruled out an air leak. It runs if you pump the bulb every once in a while. I have a new complete fuel pump coming from browns point. I am going to try it first. The motor came off a boat with a built in vented tank so there is a fuel line nipple on the motor instead of a quick release fitting. I have a 12 gal portable tank with the vent you can close.
I have around 18' of fuel line with the tank in the bow. I have forgotten to disconnect the fuel line from the tank and shut the vent. I am wondering if the expansion and contraction pressure could have messed up the fuel pump diaphragm. I ordered a whole pump just in case and the quick replace fittings for the fuel line at the motor. The high pressure pump seems fine. Browns point says they hardly go bad. The pump is on its way and will be a good start. Any pointers? And could leaving the fuel lines connected and shutting the vent hurt anything?
 

rustyriver

Cadet
Joined
Apr 19, 2009
Messages
12
Re: 1998 DT 140 EFI fuel problem

I relpaced the Low presure fuel pump then went on a test run. Same problem. Next I replaced all the fuel lines, tank connector, Prime bulb, added a yamaha fuel water seperator, removed the vapor separator dismantaled it and cleaned it with a can of throttle body cleaner. Test run problem solved! I should have done one at a time but my river openes for salmon next weekend. PS don't spray your vs gasket with tb cleaner. Opps! It will last till I get a new one.
 
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