Fuel Primer Bulb issue??? Staying Flat on 91 yamaha 150 TXRP

[chefcj30]

I'm having an issue with my fuel primer bulb collapsing and staying flat. It
s a 91 yamaha 150, While running off the main 59 gallon tank the engine idle's fine but when you throttle it's seems like it's starving for fuel and the primer bulb stay like a pancake. So I figured to run a small 6 gall aux tank and this might solve the problem NOPE, same !@#$ no luck. I'm kinda stumped I just replaced both fuel pumps because I thought it was them but no. Some one mentioned anti siphon valve but if I'm running off an 6 gal aux tank and it's doing the same thing, so does that mean the anti siphon valve isn't my problem???
I also cleaned/ checked the small round clear filter where the fuel lines attach to and that was clean as day. I'm really stumped. All Help is appreciated

Thanks CJ

[rodbolt]

the pumps are trying to pump something.
for whatever reason someplace between the lift pump intakes and the liquid level there is a restriction creating excessive vacum in the fuel line.

[sdsaw]

Could be the primer bulb is defective.

Here's some info on primer bulbs
http://continuouswave.com/whaler/reference/primer.html

[kjhowayeck]

had the same problem a few months back

If blub is in questions make sure to change whole line with correct connection sizes as on connection to engine. this will eliminate air bing pulled through the line and isolate the problem. sounds like fuel pumps are working too good.

Make sure that auxilary tank has same size fittings as well (my problem was caused by connections to water seperator being smaller than connection to engine so it was pulling harder than line could supply)

good luck