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-   -   Fuel Gauge problem (https://blazerforum.com/forum/engine-transmission-35/fuel-gauge-problem-29462/)

Phase Apr 7, 2009 05:41 PM

Fuel Gauge problem
 
I have a 1994 Blazer S10.

About 3 weeks ago the truck kept dying and eventualy just never started, and it was determined to be the fuel pump. We replaced the fuel pump, strainer, and the fuel pump relay all at once. (Before we replaced it and the old one was still in the gauge worked), However now it's not working, and the truck runs fine. Is there anyway to test to see where exactly the fuel gauge problem is originating from? The reason I ask is, I don't want to pay to drop the tank again only to be told the wires were hooked up properly and the problem is somewhere else. Any ideas?

Edit: It's not any of the fuses. All have been checked and are fine.

swartlkk Apr 7, 2009 06:22 PM

If it worked originally and does not now, then something got messed up in the process of changing out the pump. Either that or the pump itself had a faulty fuel level sending unit on it...

Phase Apr 7, 2009 06:38 PM


Originally Posted by swartlkk (Post 209798)
If it worked originally and does not now, then something got messed up in the process of changing out the pump. Either that or the pump itself had a faulty fuel level sending unit on it...

Is there a way to test the sending unit on the pump without buying a new pump to see if that fixes it?

swartlkk Apr 7, 2009 07:00 PM

The resistance values are based on fuel level. What does the gauge read?

If you were to disconnect the sender lead at the tank and ground it, with the ignition switch in the on position, the gauge should read empty. If it is already reading empty, then the sending unit wire may be pinched to ground somewhere along the way (most likely at the tank somewhere). If it is not reading empty now and it does when you connect the sender lead to ground, then the sending unit in the tank is at fault. If the gauge is stuck on full or beyond, even with the sender lead grounded, then there is either a open circuit between the sender and the gauge, or the gauge is bad.

If the gauge is stuck on empty even when the tank is full, but rises to full when the sender lead is disconnected with the ignition switch on, then the fuel tank sending unit is bad. If it remains on empty even after you disconnect it, then there is a short in the line that needs to be repaired.

The fuel level sender lead should be purple at both the back of the gauge cluster and at the fuel tank.

Phase Apr 7, 2009 07:15 PM


Originally Posted by swartlkk (Post 209809)
The resistance values are based on fuel level. What does the gauge read?

If you were to disconnect the sender lead at the tank and ground it, with the ignition switch in the on position, the gauge should read empty. If it is already reading empty, then the sending unit wire may be pinched to ground somewhere along the way (most likely at the tank somewhere). If it is not reading empty now and it does when you connect the sender lead to ground, then the sending unit in the tank is at fault. If the gauge is stuck on full or beyond, even with the sender lead grounded, then there is either a open circuit between the sender and the gauge, or the gauge is bad.

If the gauge is stuck on empty even when the tank is full, but rises to full when the sender lead is disconnected with the ignition switch on, then the fuel tank sending unit is bad. If it remains on empty even after you disconnect it, then there is a short in the line that needs to be repaired.

The fuel level sender lead should be purple at both the back of the gauge cluster and at the fuel tank.

Great. Thanks a lot, swartlkk :)

swartlkk Apr 7, 2009 07:29 PM

I aim to please. Let us know what you find.


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