Alfa 75 3.0 V6 Bogging on Acceleration & Slow to Start



I don’t recall, have you removed and cleaned / replaced the fuel tank yet? Given the trajectory you are on, that is looking like a job that will soon be in your future. The jet-tronic injection system is very unforgiving of grit in the gas supply. You new fuel pump may be clogged w/grit too btw. Have you measured the voltage at your fuel pump power supply connector yet? Have you figured out a way to measure fuel pressure while you are driving and experiencing this symptom?


I think the new fuel filter is too small (not enough flow). I’ll replace that first


Do you have a fuel pressure gauge so you can read the pressure near the injectors when this happens?


SOLVED! Looks like I’ve finally found the problem. The intank mesh fuel filter, although looked spotless, wasn’t letting much fuel through. So when the car was sat for a while, the pipe between the tank and the pump slowly filled with fuel so the car would run for 10 minutes, however not enough fuel was coming out of the tank, causing the pump to whine and the car to bog under acceleration.
I took out this old intank filter and the fuel flowed like it should. I’ve installed a new filter before the pump and the car runs perfectly.
Thanks for all your help over the past few months! Onto the MOT now.


Good for you OP, glad you’ve got a smoother runner again. So the in tank filter isn’t part of the fuel pump assembly then? B/c I thought you had already replaced the fuel pump.


No both separate. The pump is external and the in tank filter is, well, internal.
MOT coming soon


after 40 threads i was leaning towards fuel tank issues. how is tank built? is there a fuel outlet on the bottom of tank or is there a access panel on the top? the note about an external fuel pump leads me to believe the layout is a bit different


That’s the way it was configured on my VW Rabbit, the fuel pump wasn’t in the tank. It was located sort of in the rear fender-well area. I’m not sure if there was an in-tank fuel filter though. The main fuel filter was located in the engine compartment.


The external fuel pump simply runs underneath the car, and is gravity fed from the tank, so an outlet (with a mesh filter) at the bottom of the tank. There is then another (main) filter after the pump, also runs underneath the car


Best of luck on your Alfa’s upcoming MOT results.


Passed the MOT first time, running great. Now onto the paint! Any advice would be appreciated! Restoring red paint, tcut?


How about marking this thread Solved .