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Amedee
Amedee, Oldsmobile Technician
Category: Oldsmobile
Satisfied Customers: 24399
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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My 2002 Oldsmobile Alero is having starting problems. Help

Customer Question

2002 Oldsmobile Alero - will not start

Have already changed fuel pump.

The car ran for appx. one day

Currently the fuel pump relay #  18 is turning on for 2 seconds when the key is turned to the ON position. This gives me 12 volts continuous back across the pump motor on the other side of the connector that goes up to the fuel pump. I have ohmed out the pump motor and it is the same resistance as the pump. The motor that I pulled which, if I feed 12 volts to, runs (old fuel pump motor). So, I do not believe that the old fuel pump motor was defective.

I hooked 12 volts directly across the fuel pump motor (new) and I cannot hear it running - black being the ground, gray being the 12 volt line

I have spark and no security light is on, no codes are displayed

Question - is there anything that might make the pump not to turn on when fed 12 volts --- (? Is there a pressure switch on the pump that it might pressure up when I turned on 12 volts, causing it to NOT turn on?).

I have also added a new fuel filter with the new pump (new, not rebuilt, pump)

I do not hear the new fuel pump coming on when I put 12 volts across it.

Submitted: 4 years ago.
Category: Oldsmobile
Expert:  Amedee replied 4 years ago.

Hello!
Is the fuel pump getting voltage when cranking the engine over?

Customer: replied 4 years ago.

Yes, pump indicates 12 volts (constant) when turning engine over.

Expert:  Amedee replied 4 years ago.

You are saying that the new fuel pump will not even run when it has power and ground directly supplied to it?

Customer: replied 4 years ago.

Yes, that is correct. Do you know if the fuel pump has a pressure switch that would shut it off if pressure was high -- such as might be caused by a clogged line or a sending unit not returning fuel back to the tank?

Expert:  Amedee replied 4 years ago.

There is no such switch for the fuel pump on this vehicle. The only switch like this is the inertia switch used by Ford vehicles. But this vehicle does not even have any sort of switch like this.
This fuel pump should run with power and ground supplies to it. It is as simple as that. You could remove the fuel pump and see if it runs when bench tested. This would be your best bet.
You could have an issue with the wiring inside the tank or even at the connection at the fuel pump itself.

Customer: replied 4 years ago.

The new fuel pump motor in the car has the same resistance as the motor I took out, measured from the plug so I know whatever caused the original problem that made the fuel pump look like the problem is not the problem. The old fuel pump works in a bucket of water so I have the original problem, but am still looking for the answer.

Expert:  Amedee replied 4 years ago.

A resistance check is not a good test. I have been doing this for 13 years and I have not ohmed out a fuel pump in over 10 years because it is not needed to see if the pump is bad.
If the pump does not come on when you power it up and supply a ground to it at the same time, the pump is bad. It is as simple as that.
If it is not coming on, then either the pump is bad or you have a bad connection between where you are powering it up and grounding it at to where the fuel pump is located.
Your overlooking something.. I guarantee it!

I am assuming you checked for a ground on the black wire correct? If so and it checks out good, then the problem will be the same that we have been talking about. If there is no ground on the black wire, this will be the root cause. If you need the locations, let me know!

Customer: replied 4 years ago.

If the pump is or was pumping, what would cause the car not to start if you have spark? Sprayed starter fluid into the air intake and the car starts for a couple of seconds.

Ground is good. Both pumps have same systems. What caused this to happen? Maybe too high pressure?

Expert:  Amedee replied 4 years ago.

Hello!

You need to check injector pluses when cranking the engine over. You would use a tool called a noid light. It connects to the injector connector after it is disconnected from the fuel injector and should blink when the engine is cranking over.

Customer: replied 4 years ago.

Is there any device that is in path with that gas line that could let the gas pressure in the line become so high that it could ruin the pump because I have lost 2 pumps that will intermittently work outside the car and I provided 12 volts across the gray and black lines (with gray having the 12 volts on it and black having the ground). Would a bad pressure sensor on the pump play into this problem or is there a return valve that releases pressure back to the tank (re-routes). The pressure if it builds too high back to the tank to relieve the pressure -- with spraying starter fluid into the air intake (which starts the car for a brief few seconds PLUS the car ran fine for appx. one day with the new pump). I have to believe that the computer and system is working and is trying to start the car.

Expert:  Amedee replied 4 years ago.

Based on the little information you have given me, it sounds like there is no injector pulse when cranking the engine over. This is usually due to the security system on your vehicle but if this where the case, you would have a security light on or flashing in the dash and a code in the computer related to this condition.

One quick note, if there is no injector pulse, this start stall condition is usually caused by a bad ignition switch. Sometimes this is fixed by doing an ignition switch relearn procedure.
This is the common failure with this vehicle you are most likely talking about.

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