Running L15A for almost 2 year with TD04.

All the sudden this problem started since 2 week ago and till can't slove.

Example: When step hard from speed 30 mph, ( didn't full floor it)
the engine RPM cannot move up. My AFR gauge show 15.2 + - 1
I think either too much air or fuel but i didn't do any adjustment on piggyback until this 2 week. I had change spare plugs and same result.

Could it be the fuel pump cannot deliver amoung of fuel into engine?
2 year old pump need to change/upgrade?

 

running too lean (too much air).
stock fuel pump? what injectors you running?
id say yea, time to replace it. get a walbro.

 

I was thinking walbro too. but what will be the pressure setting?
Same as usual 50 PSI or increase it?

 

beside fuel not enough, is there other reason?
As u know, AFR Gauge not accurate as the digital always ratio different ratio at every sec. Sometime my eye see until blur.