fuel smell

[cape square body]

1987 Silverado dual tanks when i run off driver side I get a fuel smell kinda strong no leaks found
it seems fine when running off passenger side is there a vent that i should check or replace ?

 

[75gmck25]

On my ‘75 carbureted truck there is a vent line from each tank that is connected to a T fitting, and then a metal line that runs up to the engine compartment. At the engine compartment there is a rubber hose connecting the metal line to the charcoal canister. All vapor should be pulled into the charcoal canister, which is periodically vented into the carburetor or TBI.

My guess would be that one rubber vent line running to the T under the truck may have a hole in it.

If you can find the SAE J30R7 (TBI pressure) or J30R9 (high pressure) EFI fuel hose, it will hold up much better to new fuels with ethanol. Also look for EFI fuel hose clamps, which are full circle band clamps that works better with TBI pressure.

 

[goldpack]

problem with gasoline leaks is they dissipate fast and make a big stink. maybe a rubber line that is torn/ too old, or a metal line that is corroded.

in my experience rubber lines leak at specific temps,... so maybe very cold, or as the truck warms in ambient temp, or from the engine/ exhaust.

a little bit of dye really shows what you can't see (I have had a 8oz on my shelf for like 20 years,...as I use so little when hunting)

https://www.amazon.com/gp/product/B008PKWH6C/

 

[Ricko1966]

The problem is probably a small leak in the offending tanks return line. A hole in a vent hose would vent 24/7 not just when running off one tank or the other. A leak in a pressure line would probably make itself very evident very quickly. A return line has no pressure and is tied to the tank being used.

 

[RanchWelder]

You can start reading this thread and find a ton of information on leaks, rebuilding the TBI fuel system, do's and don't's:

https://www.gmsquarebody.com/threads/87-r30-crank-but-no-start.38382/page-15

Good luck!