Help out a friend/Tank switch problem.

[Big Paul]

My friend just bought a '80 4x4 and he's got a problem with his tank switch.

He can't get one of them to work so he can only use the right side I believe.

I know some of you guys have had this problem. What can he do to fix it?

[swervin ervin]

Paul, it's one of two things. The dash switch, or the switching valve. Mine messed up on me and wouldn't switch right. Sometimes it would, others it wouldn't. I bought a new dash switch for it. Didn't help. Bought a new switcher valve, problem solved. If I were a betting man, I would bet on the valve. Of course, before someone says something, it could also be as simple as some bad wiring.

[Big Paul]

How much does this valve cost? And is it pretty simple to install?

[swervin ervin]

I bought both at my local Chevy dealer. The dash switch was around $8 bucks. The selector valve was $75 bucks. Now, I know that they list these in the J.C. Whitney catalog for less. But, if I understand what everyone says, they don't fit right. Personally, I can't stand things that don't fit right and need to be rigged to get them to work.

Mike

[swervin ervin]

Oh, sorry, the install is not too bad. It really helps if you have small hands.

[gchemist]

I paid $68 for A/C delco replacement. Having small hands sure does help when replacing the valve. It's a good idea that if anyone ever takes the bed off the truck, replace the valve.

[79BIG10]

Paul if you can give me more info on his problem I can diagnose it for you. If he has fuel only but has reads on both sides his wiring may be messed up. If he has one wire (green) going to it tell hi to switch the power to the left side on the switch and take a test light to the green wire. If it does light up then bad valve if not then either bad wiring or bad switch.

[Big Paul]

All I know is when you switch it to the left tank the gauge goes all the way past "F" and sits at about 5 o'clock on the gauge.

The right hand tank reads correctly. But my friend tells me the other day that now it will only stay at "F".

Maybe it is just the wiring thats wrong.

[79BIG10]

Tell him to change the swtich out. He'll need to get the ashtray out to get to it better. It should be like mine was and it has 2 speed nuts on back (make their own threads) just take them off then the cover and the switch will come out. On the gauge I would also have him check his grounds on the tanks. But with both acting funny I would tell him to change the switch to see if it helps.

[ElGracho]

Originally posted by Big Paul
All I know is when you switch it to the left tank the gauge goes all the way past "F" and sits at about 5 o'clock on the gauge.

I'm going through these troubles on my 84 right now, and have before too.

Based on what you said here, it is the selector valve (under the right front corner of the bed) that is bad. It is not moving all the way when your buddy selects the left tank. There is only one moving part in the valve and it ports the 3/8" fuel line, the 1/4" return line and makes the contacts for the fuel gage. By not moving all the way, it makes the fuel gage see an open circuit causing it to go past full and stay there. Also the ports aren't lined up to take fuel from the left tank so it will quickly run out of gas. The fact that it moves somewhat means the dash switch is doing its job.

On a separate note, my 84 switches just fine, but about 2 minutes later the truck dies on the left tank. I would say I just have a bad tank of gas, but as it starts sputtering if I switch it back to the right, it immediately clears. If I had bad gas, I would expect it to take a minute for the bad gas to run out. I'm wondering if my gas cap went bad so it's drawing a vacuum on the tank or something. Anyone heard of this one?

[87 STEPPER]

Originally posted by Big Paul
All I know is when you switch it to the left tank the gauge goes all the way past "F" and sits at about 5 o'clock on the gauge.

The right hand tank reads correctly. But my friend tells me the other day that now it will only stay at "F".

Maybe it is just the wiring thats wrong.

This condition can be caused by a poor or missing ground you say he just got the truck so maybe the previous owner had the tank out and damaged the tank wireing or failed to reconnect the ground wire.