I'm having a weird problem with my dual tank switch. I did try searching the forums, but couldn't find anything about this exact topic...

When front tank is selected, the gage reads the front tank fuel level, uses front tank fuel, all is well. However, when I select the rear tank switch, it shows the rear level, but still takes fuel from the front tank. Any ideas on what might be the issue?

I do a lot of long distance driving with this truck, so I'd like to be able to use both tanks.

It's an '89 2wd with the 4.9L straight six.

Thanks in advance for the help!

-Ryan

 

Not sure but might be the fuel pump in the rear tank

 

I'll check that out. I initially didn't think that was it because it still pulls from the front tank... When one tank empties, does it automatically switch to the other? I guess I just assumed that if the fuel pump had gone then it just wouldn't run when that tank was selected...

Are there any good ways you know of to check the fuel pump?

 

It might not be your pump i don't really know if we could get Sean in here he'd probably have a better idea of what's going on

 

Seeeeeeeeeeeeeeeaaaaaaaaaaaaaaaaannnnnnnnn!

Halp! Halp!

 

How do you know it is only pulling from the front tank? Sounds like some switch testing is in order.

 

Well, the initial conditions were these knowns:

Front Tank Full
Rear Tank Full

After driving for 200 miles with the front tank selected, the gas gauge read half full (and had shown the gradual decline in fuel level along the course of the trip).

After refilling the front tank and confirming the rear tank was still full, I drove 200 more miles with the REAR tank selected. After those 200 miles, the rear tank still read completely full, and had not moved during the trip. When I flipped the switch to the front tank, however, the fuel level showed only half a tank, meaning fuel had been taken from the front.

I'm so confused with this!

 

Sounds more like the gas gauge isn't woking right. Fuel level sending units, common problem. Very hard to find one of these trucks with a working fuel gauge.

 

The gas gauge seems to be working properly; it shows the correct level in each tank at all times. Hmm... may just have to take this one into the shop...

 

Assuming you get the same mileage as my 4.9, after 200 miles the gauge should read 1/4 or less.