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Since this problem got worse over a couple of years, I wouldn't suspect the sacred screw. That should not move over time.Maybe dirty TBs? Or all the fuel related ideas already mentioned. One other related thought is to spray gas into the TB before first crank.
The most likely culprit in this scenario are the injectors. When injectors leak the fuel from their supply lines, your circumstances are assured. A leaking fuel pump check valve is also quite possible, but that would still leave unpressurized fuel in the line, so only pressure would need to be built in the line from the pump. Leaking injectors mean not only pressure has to be built but also fuel moved. Air takes longer to compress than it takes to move fuel. The air has to leave by way of the injector opening and closing. There are many way to check for injector leakage, but probably the easiest is to simply have them checked cleaned and flow checked at an injector shop. This has been mentioned before. Please try this. You may be pleasantly surprised!Brian
Generally, the check valve is between the pump and injectors or fuel rail to keep fuel pressure up, not between the tank and pump. That's just suction. I'm pretty sure Huzo has already said his injectors are not leaking down.
I’m a bit hazy on this, it’s not something I have ever been involved with.I haven’t claimed that my injector/s are not leaking down, I wouldn’t know.When you say between tank and the pump, I don’t follow you, because the pump is submerged in the fuel.Why don’t I just remove the injectors from their position and watch them as I crank the starter to see if they deliver fuel immediately as I press the starter ?Wouldn’t that highlight the issue if there was one ?
Ah, my bad, I thought you said you had pulled them and let them sit outside the head and nothing was leaking or ripping. Must've been another thread.I know the pump is immersed in the tank, I was referring to the gas/liquid being pumped. The Fuel System goes as follows as I understand it. (INSIDE TANK) - STRAINER>>> PUMP W/INTERNAL CHECK VALVE>>> FILTER>>> (OUTSIDE TANK) >>> CONNECTOR>>> FUEL LINES TO INJECTORS. I would just pull them when the bike is off, leave them out and see if they drip down or are wet over a couple days. You MAY see some spray immediately, but is it the correct pressure and amount? Have you tried just cycling the key 2-3 times after sitting to see if it cures the issue?