Engine spins, but won't start

[buc]

I'm interested in what other steps to take to trouble shoot problems with my Aurora.

It stranded at the gas station the other day. It has spark and the engine turns over readily on its 3 month old battery.

I have no fuel flow. The fuel pump fuse and relay are good. I have 12VDC at one leg of the relay as I do for the trunk opener nearby. When I turned the key to the "on" position, there is no other voltage to any of the other 3 plug-in points for the fuel pump relay, as if it is not being energized.

A) Should I expect to find another (of the 4 small plug in points) energized with 12 volts from the engine computer when the ignition is turned to actuate the relay?

AT THE FUEL PUMP ITSELF:
I have 9.4VDC to one leg of the (4 plug) socket that plugs in to the pump. (The other plug I assume is for the level sensor since it has 5VDC). I assume this 9.4 Volts is a poor version of the 12VDC "limp-in" power that is supposed to come from the oil pressure sending unit.

B) I do not know where terminal 87 is to run 12VDC directly to to see if the pump or wiring to same is bad. Where is terminal 87?

C) or, I assume I have an engine computer problem AND some sort of poor ground to/from the oil pressure sensor. Where is that oil pressure sending unit source of power located under the hood? (So I can try to fix the ground).

D) Does this sound more like an idle speed motor problem?

Last night, after the car sat for 4 days without being cranked, I turned the key. The engine actually caught for 1 second or so, but coughed and sputtered to die quickly. It would only crank after that with no hint of turning over.

It is a 1998 Aurora with 156,000 miles on it. I do love the car.

Thanks much,

buc

[ghutchin]

How have you verified that the fuel pump relay is working?You say that you have 12 volts at one of the prongs, but nothing at the other three. That is not a conclusive test that the relay is working....anyways. it sounds like you have a bad fuel pump. The low voltage would indicate that the fuel pump motor is shorting which is pulling the voltage down from 12 volts to 9.4. I would replace the fuel pump after you have verified that the fuel pump relay is working. The best thing to do would be to swap the fuel pump relay with a different relay and see if the fuel pump gets going.

[dflip]

the oil pressure switch is located on the side of the engine facing radiator.dont buy aftermarket if you do replace. buy oem. trust me already went through it on my wifes.

[ponchonutty]

Yes, you gotta check that relay circuit out better than that. Personally, I'd suspect the fuel pump itself too but you need to check things out correctly before tearing into it.

[dflip]

quick way to check fuel pump. run a jumper wire directly to power wire on pump from battery

[buc]

Thanks much for the replies. By the way, the guys at work looked funny at me when I told them my username was buc. "buc" is what my family named the Aurora.

Checking the relay- Yes, I swapped it to verify that it was good last week, once again from reading some former threads before I posted.

9.4 volts- The 9.4 volts is actually measured at the plug (to chassis ground) when it is disconnected from the fuel pump and the ignition key is in the on position. (Of the 4 sockets on that connector, I get the 9.4V on the top socket that is closest to the lock tab on the side of the connector).

12V directly to pump- I tried to do that just yesterday by having 12V connected to a small lead that I could stick up in the connector (correspondng to the socket getting 9.4V disconnected) on the fuel pump because I didn't know another place to put the 12V positive. I had finished with no success when I realized that the fuel pump probably isn't grounded and I would have to know which of the other 3 contacts would be a ground.

Which wire is the power wire on the pump?


Thanks again, buc

[ghutchin]

From the diagrams I have the positive wire should be the gray wire and the ground should be the black wire.

Here is the thing to remember, the fuel pump is only turned on when the engine is running, or for 2 seconds after the ignition is turned to the on position. So if you put the key in the ignition and turn it to on, the fuel pump positive lead should read 12 volts, but only for 2 seconds. You will need 2 people to do this test. Chances are then 9.4 volts you are reading is a reference voltage for the fuel gauge.

[ghutchin]

From the diagrams I have the positive wire should be the gray wire and the ground should be the black wire.

Here is the thing to remember, the fuel pump is only turned on when the engine is running, or for 2 seconds after the ignition is turned to the on position. So if you put the key in the ignition and turn it to on, the fuel pump positive lead should read 12 volts, but only for 2 seconds. You will need 2 people to do this test. Chances are then 9.4 volts you are reading is a reference voltage for the fuel gauge.

[buc]

That is vital information for me. I'll check in the morning and let you know what happened.

Grateful, buc

[buc]

This AM, I had my lovely assistant (wife) turn the key, and yes, with gray as positive and black as ground, I got 12V at the plug very briefly, putting the fuel pump itself into the position of prime suspect. Thanks very much, I'll try to buy a fuel pump only rather than replacing the whole sending unit etc.

Have any of you heard of having problems doing that?

Thanks much, buc

[ponchonutty]

GM fuel pumps fail almost as fast as well, I better not say