Couple Questions about Gas Tanks etc...

[Madbomber88]

I'm trying to trouble shoot my gas gauge problem. The truck (91 K5) runs out of gas when the gauge reads 3/8 full. Would this be the sending unit? Also, I have done some research and all I see as the tank on my year is the 31 gallon. They didn't offer the 25 gallon that year?
Lastly, if/when I change the sending unit, is it a good idea to change the fuel pump? Best to go with a GM unit?

Thanks in advance.

 

[dyeager535]

'91? Pretty easy to test, nice weatherpack connector for gauge/fuel pump.

Disconnect the plug near the gas tank, and with the key in run, short the fuel gauge wire to ground. If it pegs the gauge, the gauge and gauge wiring should be good.

You can *probably* make your problem a whole lot better by removing the sender and cleaning it. There is a post on here that describes how to do it, but it's fairly self explanatory anyways. Once you've got the sender out, you don't have to re-install the tank to test, so you don't waste any effort trying to clean it.

The tank could be broken internally as well, thats fairly common. Probably not your problem in this case, but those plastic baffles do tend to break.

Of course, this all assuming you've got another vehicle while yours is down.

gastanks.com is the cheapest I've seen for TBI senders, but I think there was a post about some cheaper ones from another company. I believe GM wants $3-400 for theirs.