crumby gas mileage please help

I recently rebuilt the 4.3 in my 99 sonoma. problems are as follows
1) fuel guage just stopped working shows empty all the time, low fuel light on. (im guessing its time to pull the fuel pump)

2)only getting about 220 miles per fill 17 gals = 13mpg

the truck runs well, at idle at a stopsign or light i get a little bit of shake thru the steering wheel (rough idle) but not bad. could this be related to the pump, or are we possibly talking about fuel regulator in the plenum? how do i check for the culprit?

What all was done with the rebuild?
What milkeage was it getting before?
Any codes or check engine light?

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

What all was doe with the rebuild? new rod bearings, crank turned, had bad bearing on #6
What milkeage was it getting before? believe i was getting 17-19
Any codes or check engine light? it did throw 0446, but i removed and cleaned the valve by the sparetire and reset, has not come back in 100 miles

Check fuel pressure and get it on a good scanner and check out all sensors and fuel trim data.
Also check basic tune up.

code 0446 just came back after 133 miles

I have the EXACT same problem.I replaced the wires,plugs,distributor cap,Coil pack,Fuel filter.was told it could be the EGR Valve,took it off was a little dirty,but the little rod thing went up and down perfect.the check engine light is not on.When i replaced the plugs 1 was fouled out.Any help would be SO appreciated.Thanks

I have the EXACT same problem.I replaced the wires,plugs,distributor cap,Coil pack,Fuel filter.was told it could be the EGR Valve,took it off was a little dirty,but the little rod thing went up and down perfect.the check engine light is not on.When i replaced the plugs 1 was fouled out.Any help would be SO appreciated.Thanks

Yours sounds like a fouled plug problem.
To save on hyjacking bills start your own New Thread/post.
And someone will help you.
Give year make and model and mileage and engine and infor.
Brand of plugs used.
Any aftermarket stuff added to it.

ok, plan on getting a pressure tester and checking this weekend. on another note, i am getting up to correct operating temperature, but it seems to take a long time. wonder if my thermostat is stuck patially open causing the sytem to run in open loop.

code 0446 just came back after 133 miles

You might to need to get the repair flow chart for 446 and go threw it to.
All data or factory replair manuals have the repair flow charts.
http://www.alldata.com/products/diy/index.html