What should the fuel pressure be at 3500 rpm. Have a 3.0 bar fuel pressure regulator & at idle the pressure is 40#. Drops to 36.5 at mid range. Can pinch off the return line & the pressure will go above 70# so i don’t think i have a pump problem. A different pump & old regulator is producing the same results. I have 12 v. at the pump plug. Thanks for the input.
Fuel pressure
FishMan
#2
Your pinch test may not be highlighting your issue because it sounds like your fuel system can’t pump enough volume to maintain proper pressure at all speeds. Under load, you should see 43 psi at any RPM. Loaded at midrange and higher speeds will require the engine to consume more volume of fuel and clogged filters, pinched supply lines, a week pump or a rusty tank will cause you problems. The rusty tank is particularly easy to miss because they rust will clogg the fuel pump screen, but often fall to the bottom of the tank by the time you remove the pump.
Idle pressure should be 36 to 38psi. Remove the vacuum line from the regulator, cap the intake vacuum port, and retest just to make sure you don’t have some strange vacuum system interaction.
rcofer
#3
With the vac. line off pressure is 45 psi. at idle. Yes, probable a volume problem. Tank & pump screen are clean Will order a new pump. Thanks for the input.
jlevie
#4
I’d suspect the FPR first. Your idle pressure is too high. You might also have a worn pump that can’t deliver sufficient volume under load.