I NEED maf sensor possibly?

[Q45phill]

update i apologize gentlemen, i did pull the old pump and ran my finger around the collar only to feel where the screws had come thru the collar and subsequently pulled entire tank, with half tank of gas, wheww!!!, to find metal shavings, dirt and alot i mean alot of rust in tank, immediately checked fuel filter and was able to blow air thru it fairly easily, sock or in tank pick up filter was BLACK, absolutely filhty, but it still idles fine all the way up to 1800-28-3000rpms with the old loud , noisy pump then it starts sputtering anf stumbling like i've hit a dead spot...???still waiting for new pump and MAF

[Infinitiguy19]

On the new tank your going to want to clean it completely clean it so its like new.

But also search for posts on how to line up the sending unit so the low fuel sensor and fuel float sensor works.

[Q45phill]

YEAH, I KINDA LOOKED IN THE TANK / OLD TANK TO SEE HOW THE OLD PUMP WAS LINED UP IN THE (WELL) OR SUMP OF THE TANK??? oops sorry for the yelling...was wondering why the fuel pump going out would cause the engine to stumble /buck and sputter like it does or how that actually works, it idles fine and wot is fine i only did it once dont want to damage the FPCU, but the pump IS noisy...most pumps just die and dont run/spin??? any theories or ideas???

[maxnix]

Might want to open up the FPCU and see if the middle circuit is damaged.

You for sure need to eliminate the rust. Steam clean first!

[Q45phill]

hi maxnix, exactly what does that middle circuit control? and is this a 3-step motor? i'm familiar with other fuel pumps on american cars but not this one, exactly how does it work? just truing to learn as much about these cars(g50) as i can since i own one....but its strange that its ok at idle,just loud and its ok at WOT , just loud but between 18or 1900rpm and up to about 28or 3000rpms it bucks, sputters and stumble ALOT?...!!! never seen a fuel pump do that!!!

[maxnix]

Read Q45tech's posts. It is a 3 step pump controlled by the FPCU.

You could also measure fuel pressure and voltage under operation and determine the problem very quickly.

[MR. Q]

Slightly of subject but I once pulled a fuel pump out of a Q45 with a full tank of gas. Talk about vapors!