1993 Century 3.3L Problems

[ITPMenace]

My daughters 93 3.3L Century is running like absolute crap! The car will barely reach 35mph, idles like crap and almost stalls if you put more than the weight of your big toe on the accelerator pedal (not kidding). She tried a "tune up" (plugs, wires, coil packs) recently and that did nothing.

I spent a bunch of time today on the car, here is what I did and the results:

• Ignition Module Replaced - No Change
• Mass Air Flow Sensor Inspected / Cleaned - No Change
• Idle Air Control Valve Inspected / Cleaned - No Change
• Fuel Pressure Regulator Replaced - No Change
• Numerous Vacuum Hoses/Connections Replaced - No Change
• Fuel Filter Replaced - No Change
• Numerous Engine Electrical Connectors Inspected / Cleaned - No Change
• Fuel Pump Circuit Voltage Drop (6v) Repaired - No Change
• Fuel Injector Impedance Checked - All 12.1 - 12.5 ohms
• Fuel Pressure Checked - 16psi @ Idle

According to the Haynes manual we have, Fuel Pressure for this engine should be 30-44psi at idle with the regulator vacuum source connected. If that is correct, there is obviously a fuel pressure problem with this car.

Our next step will be a new fuel pump (yippee, I love dropping fuel tanks) which I'm hoping will resolve the pressure problem and the running issues. Still, I have a few questions...

1. Is the fuel pressure spec in the Haynes manual correct (30-44psi @ Idle) for this engine?

2. Any recommendations for other common problem areas that should be checked on this car (it has roughly 57k miles)?

THANKS IN ADVANCE!!!
Dennis

[GTP Dad]

Sounds like you hit them all. You might want to change the fuel pressure regulator before changing the fuel pump, however, the regulator could be bad and not allowing the proper pressure to build up. Cheaper and less time consuming than a fuel pump. You might also want to check the egr circuit to make sure it is operating to spec. simply cleaning out the carbon may eliminate some of the problems. Just some thoughts.

[ITPMenace]

GTP,

Thanks. The FP Regulator is the 4th item on the list above, and it proved to be a waste of $83.

I have not looked at the EGT circuit at all. I'll check that out in the manual I have and take a look at it on Wed. when I get the car back to do the pump.

Any other suggestions?

Any good recommendation for getting better mileage from this engine (she's on a tight budget, every mile counts!)???

Thanks Again!
Dennis

[Jaice]

Is the check engine light on? If so, it could be the throtle position sensor, it cost about $30

For better Gas millage, you already did everything on my list.

For better miles millage, make sure to keep up with the oil change, and use high quality oil and filter.
I have a 89 Century with 162,000 and running strong, I'm thinking about changing to a Max Life or High Millage oil.

[GTP Dad]

Sorry about missing the fps. As far as gas mileage we are all looking for that magic item that will increase mileage. I recommend that she use a good fuel injector cleaner routinely. The cleaner the injectors are the better the mileage will be. As far as other suggestions the only thing I can think of is the fuel pump which you already suggested. Good luck and let us know what the problem turned out to be if you ever get it solved!

[nick0750]

is your cat convertor clogged ?

[ITPMenace]

It was the fuel pump. Put a new pump and screen in and suddenly we have 30psi at idle, increasing to over 40psi as the engine revs. Car runs good again.

Checked the TPS while I was at it and it appears to be working fine. .45v closed to 4.25v at WOT.

Thanks for all the help.

Dennis

[y2icon]

well i have the same car same problem and no clue what was wrong. i am going to try a fuel pump and hopefully this will be it

[Bravo Garage]

If the fuel pressure is lower the 40 on most GM FWD vehicles it is just about always the Fuel pump. They are a pain to change due to the fact that you have to drop the tank to change it. But you will save yourself money in the long run. Most of the GM pumps usually only last 100K to 150k.

[trackpin]

Just put a used fuel pump in wifes century....oops....has same problem as yours did except when the thing that has A and B + - on it near the throttle body air intake is unplugged it runs much better,check engine light is on now though.

[Bravo Garage]

The item that you unplugged next the the throttle body is most likely the M.A.F. Mass Air Flow sensor.