Hey guys, 1990 3VZE pickup, I have a very strong fuel vapor smell when ever it's hot outside (100 degrees+) sometimes I can hear the gas cap venting vapors when the pressure in the tank is too great. My question is, shouldn't there be a solenoid or something that releases the pressure into the charcol canister & back into the intake to be re-burnt? If so my truck is not doing this & it smells horrible. The gas cap is good, just cant hold all of the pressure. No fuel leaks anywhere, just the vapors.

Thanks guys, Rich

 

"strong fuel vapor smell" is frequently caused by a problem with your charcoal canister. (You've pretty much figured that out.) The fuel vapor is vented into the intake manifold when there a) is vacuum and b) the engine is warm. So a vacuum line comes from the throttle body to a Thermal Vacuum Valve (TVV) on the block all the way at the back of engine, then to the canister.

That TVV has a plastic body, and where it sits causes the plastic to become very brittle after, oh, 150,000 miles. Many of us find out the hard way when we are trying to remove the plenum, and break off one of the nipples on the TVV. That might be your problem.

Before you try to find that TVV, do a simple test. Pull the vacuum line from the canister. Let the engine warm up, and then open the throttle a bit. Does it suck? Then the TVV is working.

 

Thanks for the advice. I will try this later today & post the results. I sure hope that valve isn't bad as I'm not looking forward to pulling the upper intake off.

 

OK guys, I thought it was only vapor because I couldn't find any leak. Well it turns out that the fuel pulsation dampener is what's leaking. It started to leak onto the ground today. The truck will not be driven until I replace it. Any tips on getting the upper intake off easily would help.

Thanks, Rich

 

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