Continued optimax issues, 2007 75hp

[bbcman]

Well I just can't figure this one out. Sounds like a common problem I have. So where I launch I have about a 3-5 min no wake zone, after power up everything is fine. Motor runs strong. But after a run or 2 bulb loses prime if it ever had it. Engine loses rpm but does not stop running. If I retard throttle and power back up sometimes that helps. But if I leave throttle where it is it will pick rpm back up, most of the time only to lose rpm and start sequence over. If I prime again issue clears for a period and the starts over.
So I had a Merc bulb I replaced it with a new Merc bulb (arrow towards motor), no help. Replaced all fuel lines to motor, no help. Today I changed the anti-siphon valve out but it was just a fitting with no ball. While that was out I put some shop air to it in case my pickup was plugged. None of this helped.
Today when I squeezed the bulb it never got hard, and I could hear air or fuel going back into the tank when bulb is released. I feel fuel passing through bulb but seem like it just goes back into tank when released. No idea where to go next, could there be some loose in the tank?
I also pulled out fuel filter, no debris. Removed low pressure fuel pump, looks good an junk in it.

[bbcman]

Also checked vent, and tried bulb with cap off tank.

[bbcman]

Bought a portable fuel tank and now bulb stays hard after a few pumps. Is there a check valve in the fuel tank pickup besides the anti siphon valve that can be replaced?

[bbcman]

Removed pickup tube, no check valve, threads around bayonet some what stripped from original install or previous owner. Going to order new pickup tube assembly and from from there.

[SilverFox579]

Bought a portable fuel tank and now bulb stays hard after a few pumps.

Think you found your problem.

[rickdb1]

Good job troubleshooting...

[bbcman]

I certainly hope so. Going to try a new pickup and anti siphon valve and see what happens.

[bbcman]

Replaced pickup tube and anti siphon valve, no help. Works good off of a portable tank, won't work off boat tank. Whats next?

[rocketman6965]

Did you replace/rebuild pulse pump?

[bbcman]

pretty sure it's not that because it is good with the portable tank. I do have a rebuild kit for the pulse pump might give it a try.

[JOE54]

which line and bulb did you use with portable same or diff ????

[bbcman]

Same

[JOE54]

if you used [same hose and bulb assy] on separate tank and engine runs fine prob is in boat tank check venting and inside tank for trash hope this helped ya JOE

[bbcman]

Thanks Joe. I have been in touch with Moeller which is the manufacturer of my tank. They have no real answers either (Engineering). . The tank is vented though the cap, which I have opened while pumping bulb. Which leaves me with the tank. Thinking of replacing the tank, but of course the do no make that model any longer. Unfortunately I just fueled tank last trip out.

[JOE54]

can you see any trash or anything floating around in tank,make sure new pic up tube is not bottomed out on floor of tank [may need shortened]

[bbcman]

Due to location of tank I really cannot view contents except for level. I did cut tube on an angle and measured it against side of tank for length.

[bigboyztoyz]

With the pick up tube out of the tank can you pressure check it? As in check for leaks? Plug one end and blow air pressure through it. I'm guessing you still have a air leak/ vacuum leak some where

[JOE54]

^^^^^^^ agree