Gas Tank Switch makes motor die.

[JohnnyPopper]

Hey here's a weird one: Started my 3+3 yesterday, switched to right side tank and the motor dies. Repeat a few time, same thing.

Any ideas?

[bd]

Which system: cable operated, solenoid valve, or motorized valve?

[JohnnyPopper]

Great question! I'll take a look but it's on a '89 C30, electric switch is in the same location (relatively) as my '78 K10.

I think we can rule out manual, still will have to check if it's solenoid or motorized.

Thx!

[VileZambonie]

Loosen gas caps and see if it changes anything.

[Irish_Alley]

the switch itself can be bad and have poor contact on the inside. you can take it apart clean it up and see if it helps but theres some springs inside of it so be careful when you take it apart. if im not mistaken chris did a write up on here on how to clean them

[Irish_Alley]

this isnt the one i was thinking of but its something
http://forum.73-87chevytrucks.com/smforum/index.php?topic=23517.15

[Irish_Alley]

here it is http://forum.73-87chevytrucks.com/smforum/index.php?topic=6537.0

[JohnnyPopper]

the switch itself can be bad and have poor contact on the inside. you can take it apart clean it up and see if it helps but theres some springs inside of it so be careful when you take it apart. if im not mistaken chris did a write up on here on how to clean them

Thanks Irish! I don't know why it would kill the motor, it's not for lack of gas. It's more like electrical.

[Irish_Alley]

well technically it is an electrical problem. but the injectors need pressure to run and if the switch itself goes bad it will cut off the electric to the pump in the tank causing it to loose pressure and not be able to feed the engine. its really speculation that it could be your problem but its something to check out

[JohnnyPopper]

Well, when covid hit two years ago, I filled both tanks bc it seemed the prudent thing to do.

This truck sat at my office parking lot since then.

Seems some tweekers needed my gas more than I did.

Relocated her to my home, and on buying 40 buck for the driver side, there was a severe puddle of gas, that I thought for sure would catch fire as I left. I pushed it away from the puddle before starting it. No fire.

Here is what I found. Nice...

BTW, bd asked for the type of tank switch I have. Here's a pic. Still kills the ignition when I switch it out.

I haven't had time to see if said tweeks diddled with the wiring.

[bd]

See: Dual Tanks Theory of operation.

You have a motorized valve.  Is the engine TBI or carbureted?  One of my initial thoughts was that if you have a TBI engine, the valve may not be traveling full rack, starving the engine for fuel.  TBI engines are EXTREMELY sensitive to fuel pressure.  So much so that a loss of pressure that might be considered unimportant on a carbureted engine can prevent a TBI engine from running.  A sudden drop in pressure such as may occur when switching tanks if the valve hangs mid-travel, partially or completely blocking one or more valve ports, can cause the engine to die as if switching off the ignition.  Of course, this is just one possibility of several.  Can you hear the valve "click" when you switch tanks or is it more of a raspy "zzzziiiiipp" noise?  Does the valve make any noise when switching tanks?  Can you hear the in-tank fuel pumps whirring?

[JohnnyPopper]

Thanks bd, will check all Q's tomorrow, will be working on her all day. (did worship today )

Just a curiosity, I picture motors as something that runs continually, does this device operate that way?

[Mike81K10]

Is it possible you got some debis in your tank that got into the fuel system from the hacked up hose that might cause some problems?

[JohnnyPopper]

Great question Mike!

That hackery happened on the left tank, the one that work.

When I switch to the right it dies.

To your point, I expect that the left will experience problems from the hack.

I just started to read bd's link to 'dual tank theory' so will have a better idea of how all this works.

[JohnnyPopper]

bd,

I worked on her today for a bit, not as much as I had planned...

First, TBI.

Second, noticed that the engine dies about 2-3 seconds after I switch to RH.

Third, heard a whirring sound switching to RH, but nothing going back to LH.

I was alone, will have my girlfriend (read wife) help me do a deeper dive and get back with the results.

Thanks!