no power to the fuel pump

[HotZ28]

The fuel pump relay is located in the fuse/relay panel under passenger side dash.

[mrd2001]

I spent the morning swithching like kind relays under the hood with no luck. I don't know if I should be chasing the fuel pump problem or the not starting problem first, (which seems to be a power to the injector problem) are they assosiated with each other. The car cranks so the VATs is not the problem and GM cars don't use an inertia fuel shut-off switch. I can get fuel to the rail by hot wiring the pump and I have spark so I know it's not there. Is there anywhere on the web that I might find all the schmatics for this car so I can start chasing this gremlin.

[HotZ28]

I spent the morning swithching like kind relays under the hood with no luck.

Once again, the FP relay is under the passenger side dash, not under the hood. Have you checked the FP fuse? In addition, the fuse is in the same location.

[mrd2001]

If you read my origanal post you would know that all that has been checked. Please re read so that you know were I'm at with this mystery. I was checking the relays under the hood to see if anyone of them would affect the PCM. I have 12 v. at both wires that go to my injectors? That is my biggest concern right now. Aren't the injectors grounded through the PCM? I really need a schmatic for the thing. Or someone who is up for a challenge to think about what to check next.

[maxwedge]

You should not have power on both sides of the injectors, I would focus, for now, on that issue.

[HotZ28]

Only the pink wire to the injectors should have power & yes, the PCM should pulse the ground on the other wire, provided that the TDM is sending the PWM signal to the PCM do do it's thing. Check your PM message.

[mcmalloy]

could be a safty issue, like if it looses oil pressure it will shut down the fuel pump or the ignition module to kill the engine to pervent any damage

[mrd2001]

TDM, PWM? I'm an old bodyman, whats that mean?

[mrd2001]

I replaced the oil sending unit after check pressure with manual gauge ( Origanal sending unit was showing low pressure. )

[HotZ28]

Originally Posted by mcmalloy

could be a safty issue, like if it looses oil pressure it will shut down the fuel pump or the ignition module to kill the engine to pervent any damage

Theft Deterrent Module = (TDM-VATS) Pulse Width Modulated = PWM (pulsing signal)

On this particular model Buick, the oil pressure sender is simply a variable resistor that controls the gauge. If you don’t have a gage, then there are a set of N/C contacts that are used to turn on the light with low pressure.

In addition, there are another set of contacts in the sensor that are N/O and close when the oil pressure reaches 4 psi. This is a bypass circuit used to supply a second source of power to the fuel pump in the event of a FP relay failure.

[mrd2001]

My wife's old 94 Le Sabre had a problem with the VATS, and it affected the cranking not the fuel or ignition. I bypassed it with an inline resistor, rather repairing it. Is the 95 P?A different?

[HotZ28]

The VATS system performs two functions related to starting. First is it activates the start enable relay that provides power to the purple wire going to the starter solenoid. Next, it sends the PWM signal to pulse the injectors. Some may use a BCM instead of TDM for these functions. The 94-95 are basically the same, using the same PCM and VATS system.

[mrd2001]

I'll be out checking everything out tomorrow, It's been rainning here all day. Thanks for all the info you have provided so far.

[fgibbs69]

Smae problem for me still too. I ran a code tester and got 1 code that was the tps. I know that wont stop the fuel pump but I replaced it anyway. Bought a new FP relay still no fuel to the pump. It cant be a fuse because the problem is intermittent. For anyone else reading this post, The FP relay is a pain to get to. Pull the glove box down all the way and look on the right side. There are 3 large relays (1.5 in. square) and 3 or 4 below that (.5" by 1.5") there is 1 single (small) relay by its self beside all the others. That single relay is the FP relay.
At this poing all I can think of is the PCM which I understand can come from a salvage yard and dont need flashed. New is 100 bucks. Kinda expensive for a hope that it is the problem..Does anyone know if the ignition module can cut power to the FP?

[Mickey#1]

PM me with an email address if you still want a wiring diagram.

There should be a lead by the battery that you can use to send +12 volts to the fuel pump. If the pump still doesn't run then you should check the driver's side ground bus for corrosion.

If you have fuel pressure & the engine still doesn't start:
Check for spark at each of the three front cylinders.
Check for fuel injector pulse.
Try starting with the MAF sensor unplugged.