At a regular idle, my fuel pump pulls about 12.65-12.7 volts. Today and other times when (I'm guessing) it's been hot out, the voltage will slowly increase to more than 13V to about 13.30 when it dies. The higher the volts get, the rougher the idle gets. The only time it runs rough or dies/wants to die is when i am at an idle or beginning to accelerate from an idle.

I have no idea whats going on, but i need to get this resolved. I have tried posting this problem other times but have never really gotten it resolved. Please people try to help on this one. I feel like a retard when my car is lunging through an intersection because fuel is cutting out.

Also if i have to buy a new pump, what would be a direct replacement. I remember reading it before, but i'm too lazy right now to search and im going to bed. HELP@!@

 

What?

 

What do you mean what? At an idle, my fuel pump, acording to my DMM, is running at 12.65-12.7 VOLTS.

 

What's a DMM?

I don't want to get all flamed and stuff, but electrics don't "Pull" voltage. Voltage is created(induced), and causes current to flow.

Now, if the voltage between your fuel pump inlet and ground is changing, and the voltage is getting higher as the car runs poorer, you need to look at what else is in the fuel pump circuit that is no longer a resistance.

If it is the amps (current) to your fuel pump that are rising, it suggests that your pump or filter or lines are clogged/blocked/generally not good. Thus, as the it gets harder to pump the fuel, the load on the motor goes up (resistance goes down), and so does the current. And since it's harder to pump the fuel, less of it gets to the carb.

 

He has an EFI car - so the fuel pump is drawing more current to push fuel to the fuel rail.

My suggestion would be to replace teh fuel filter first and foremost if you have not already done so, then look toward replacing the pump. If the filter is the cause (clogged, causing higher voltage at the pump), then this is a $30 fix. HTH,

 

Digital Multimeter. When i say pull, it's because the rougher it runs the more voltage my DMM is reading. Now i do have a clamp meter which i never thought about using, which can measure my resistance, AMPS.

Is there anything from my tank to the engine, besides the fuel flow and return lines that could be clogged. I replaced my filter not tooo long ago.

85 GSL-SE

 

The system voltage produced by the alternator should be around 14-14.5 V. As the pump draws a current the resistance in the wires to and from the pump cause the voltage remaining at the fuel pump to drop. So when the pump is working right the voltage at the pump is 12.6-12.7 V, and when its not working right, 13.0-13.3V. This means that for some reason the pump is drawing less than the normal current when the car isn't running right.

That means its not the external wiring, typically faulty wiring makes the voltage at the pump drop, meaning the resistance in the wires is higher than it should, which it is not. So there are only a couple things that could be wrong:

1) Fuel pump is dying electrically: internal resistance is increasing for some reason not allowing the pump to draw the nessasary current, thus not pumping enough fuel to keep the fuel pressure up. This is a posiblity, but I'm not sure how likely this is. Usually the increase in resistance will just run away very quickly until the the pump just stops working(open circuit).

2) Fuel pressure regulator/pulsation dampener are doing something funny, and the fuel pressure is below normal. This would make the fuel pump have to work less hard, causing the symptoms you mention.

3) You have a sticking fuel injector that is also causing the fuel pressure to drop. This would make the engine bog however and would likely get worse as the engine reved.

 

Well when i rev the engine the volts actually go down, so i think that 3rd one is out. Also my fuel pump had been whining, when it makes a loud whine the volts go up, which to makes me think it's struggling.

And why would this happen sparatically? I had this problem before winter and i never had it happen again, is just recently has started to happen again.