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Mercury XR6 fuel loss

colaynug

New member
Hello,
I appreciate any and all input ….. this issue has me stumped
2001 Mercury XR6 serial 0T303736
90% of the time after fishing when I go to start up and move to another location the fuel prime bulb has gone soft, if I don’t reprime the engine will start , run a very short time the die.
When this first started it was much worst in hot weather… now this winter it has gotten much worst than it has ever been in the past.
The odd thing is I can prime it at home , let it sit an hour and the bulb is still full primed and hard.
I don’t know if it is a coincidence or not but this problem started shortly after my tech removed the auto oil pump drive shaft and bypassed the oil lines so that I add oil manually.

I have rebuilt the fuel pump twice….. the last time with OEM parts
I have replace the prime bulb twice… again the last time with OEM parts.
The bulb is mounted at about a 45 degree angle. I can take it off prime it with water and it may leak off a tablespoon in a couple hours. Have done that test several times.
I have pressure and vacuum tested every line, joint and connection from the bulb to the bottom of the fuel tank and found nothing.

I have experimented by adding a high grade ball valve on the input side of the bulb and then later moved it to the line on the output side. If I shut this valve off when I finish running to a new spot and fish no matter how long I am there the bulb stays hard and fully primed.

Outside of this problem the engine runs like a dream .
Thanks for you help.
 
The primer bulb is nothing but a manual fuel pump.-----Once carburetors are full it serves no purpose.---Does not need to stay hard when motor is running.---I believe your problem is something else.
 
The primer bulb is nothing but a manual fuel pump.-----Once carburetors are full it serves no purpose.---Does not need to stay hard when motor is running.---I believe your problem is something else.


On the rare times I check the bulb before starting and it is firm it idles and runs fine. If the bulb is soft and I don't prime it the engine will start but die within a few seconds if I try to take off. Have to squeeze it several times to refill the fuel system
 
I have the same issue. I replaced the check valve at the tank and replaced the primer bulb. I was thinking is there a check valve in the fuel pump to keep fuel from siphoning back. I also noted that the check valve and the primer bulb both need a slight pressure in order to stop the back flow. Sorry I didn't give motor info: 2001 XR6 Carbed 150hp.
 
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