1990 Q45 acts like its not getting enough fuel...

[aliciaford]

I have replaced the MAF recently, car was running great. It seems like the car isnt getting enough fuel to me... Fuel pump makes noise from the back seat only upon start up, so that seems normal, however, I swear the car runs better with a full tank. I have also noticed that when I get fuel, it seems to let out a lot of pressure when I unscrew the cap. Should I start with a fuel filter? If so, whats a good brand, do I have to use OEM? Thanks

[maxnix]

OEM from Joe is best, especially with this month's sale.

Fuel pressure gauge after the filter will show if you need fuel pump or not. Check MAF connection for integrity first.
Modified by maxnix at 8:01 PM 2/24/2009

[goody90q45]

Check MAF connection for integrity first.

Look at the MAF connector wires for breaks or corrosion. Clean up the pins on the MAF connector with a toothbrush and solvent or penetrnt so they look like the center one in the pic. Coat with dielectric grease and use a pic or small finishing nail to adjust the tabs on each pin so it fits tight on the MAF pins. Make sure to use the wire clip to hold the connector in place on the MAF.

It seems like the car isnt getting enough fuel to me... Fuel pump makes noise from the back seat only upon start up, so that seems normal, however, I swear the car runs better with a full tank.

How many miles on your Q? If you're in the 120k-140k range you are overdue for a new fuel pump. The fuel pump controller has been known to give out and it's easy to test. Unplug the FPCU and run a jumper wire to ground from the connector pin shown in the pic. Easiest access is through the trunk. The fuel pump is now running on high speed only and excess fuel is returning to the fuel tank. If she has power back with the jumper installed the FPCU is bad. If no change it's time to install a fuel pressure gauge as Brian suggested and measure fuel pressure while driving up Mt. Hood.



Have you ohmed your injectors lately?

[aliciaford]

Ok. We started with changing the fuel filter and checking the lines. Old filter was extremely dirty even though it was changed about 15k ago. FPCU checked out ok, cleaned MAF sensor connector. Car seems to be running fine now, I will find a mountain to climb to test it out on the way home tonight. Thanks.

[goody90q45]

Did the connector have green corrosion? If it did you should think about doing the same cleaning and pin tightening for the connectors to the throttle position sensor (TPS), crank angle sensor (CAS), and at least #1, #2 and #8 fuel injectors. All the connectors are similar looking to the MAF connector.

[maxnix]

We started with changing the fuel filter and checking the lines. Old filter was extremely dirty even though it was changed about 15k ago.

Fuel and air filters should be changed annually as they are about $10 each. Now even less with a 7% additional discount this month.

Order 2 of each and 4 M1 oil filters and any other knick knacks you will need to save on shpping.

http://www.infinitipartsusa.com

He also sells BG 44K fuel injector cleaner. You should run one can now and a can in the last tank before each oil and filter change given the condition of your fuel filter.