Its been a while... maybe too long...

[dvdswan]

this might help you out
http://i333.photobucket.com/albums/m387/rebel_cowboy_83/Diagram/fuelvalve_zpse5885df3.jpg
the two ports on the top front side are the mains from your fuel tanks. the port thats closes to the solenoid is your main/rest tank. follow that line see which tank is your main/rest

thanks that makes sense.  incidentally, I don't have a return on my system.  that picture looks like the selector valve I bought for my Nissan dual tank system.

[rich weyand]

Did you try putting a 2-gallon can of gas in the empty tank and see of that solved the problem starting the engine?

[dvdswan]

Did you try putting a 2-gallon can of gas in the empty tank and see of that solved the problem starting the engine?

actually, that's is exactly what I did.  2 gal. (fuel gauge didn't move) and cranked a little to fill the line up to the carb and then pumped the gas once and tried again.  it cranked 3 seconds and fired right up.  I did flip the tank switch to see if I could hear the solenoid switch...  I do hear something, not sure if its a relay or the solenoid but didn't go any further than that.  tomorrow I'm taking a short day so I will climb under the truck again and see which tank is the closest to the solenoid and test for power, I'm guessing its the pass. side.  I don't know how long the gas has been in the left tank either.

being the truck is 35 years old and it has what looks like original fuel hoses I'll test for power and get new fuel hose and possibly a selector valve.  I would think 2 gal. would move the fuel gauge, am I wrong in thinking this?  its a 16 gal tank, so 1/8 of tank, maybe I'll go fill it up and see if it moves then.  when it was empty it showed between E and 1/8 tick mark and still shows the same.  I'm just typing my thoughts here.

I am sort of glad I wasn't going insane... lol.  the fuel pump was wet so I believe it was weeping and on its last leg, certainly not helping with the quick start.  thanks for all the advice.

[rich weyand]

OK.  Excellent.  So we know the solenoid isn't switching.  And for now you can just drive around like you only have one tank.

Note that some wiring diagrams show the solenoid switching the sending wires, and some show the dash mounted switch switching the sending wires.  I don't know which applies to what years or models.

As for the gauge, I have one that will not move off full for the first four gallons, and then falls 1/8 tank per 1.5 gallons until Empty.  I have a second gauge (in the blank instrument slot where the clock goes) for the other tank.  It starts falling off of Full right away, and falls 1/8 tank per 1.5 gallons to Empty, at which point you still have four gallons left.

So, yes, some of the gauges are idiosyncratic.  By my experience, you could put four gallons in there and still maybe not move the needle.  After that though it should show up on the gauge.

[dvdswan]

so a little update.  the truck starts now on the 1st half of a crank.  so most of the hard starting was due to the fuel pump.  i installed a new selector valve and it seems to be working.  I put some more gas in the right side tank so I'm showing 1/2 tank in each side.  I drove it yesterday on the left side tank so I know that side sender is working cause I started with 3/4 tank.  just need to switch over to the right side now.  the new selector made the l/s tank the main tank as its nearest the solenoid now. 

question:  can i flip the switch while driving or do i have to be stopped with the truck off?  I know this is really a basic question but tried it while driving and the engine didn't sputter a bit between the 2 tanks switching like I would think it would.

[rich weyand]

You can switch them while driving.  You are correct that there is a little gap in fuel delivery to the carb while the fuel pump gets flow going from the other tank, but the carb has internal fuel reservoirs (the float bowls) that hold more than enough gas to tide the engine over that short gap.

[dvdswan]

got it.  thanks Rich.