Bredd1

I'm still getting a lot of pressure in my fuel tank. Originally I found that the tube going to the vapor canister was clogged. I replaced the clogged tubing but yet I'm still getting a lot of pressure. After I have driven the car for a while and then park it, I can smell the fumes from the tank and can hear the gas cap hissing. I had also replaced replaced the gas cap previously. Any thoughts or suggestions? Thanks.

vetteoz

Canister purge solenoid locked closed not allowing the system to vent

On my '87 it is beside / above the canister ,has two rubber lines ( one from the canister and one to the engine)
and a 2 wire elec connector with a red latch to it.
Pull off the line to the canister and see if you get any pressure release

Bredd1

OK, I'll try this. There is also another vacuum type valve in line at the canister, what is it for?

vetteoz

leesvet

Mine has always left a nice layer of soot in that headlite well... is that normal? Hoses as good, just that single vent hose laying in there...
I can wash it out and within a few weeks there will be that layer of charcoal dust on everything again....is this going to eventually become a problem with the canister?
anyone?

Bredd1

I don't know if this is normal or not. I've had my bar about 2 years & I don't think my system has worked sinced I got it. I do however get a lot of soot on my hands from the piping when I am working on it in that area.

Bredd1

Here's the deal. After looking at the drawings of the emmission hose routings online, it appears that my setup is like an '86 vette instead of an 87. When I purchased the car, the guy did tell me that the engine had been swapped and he thought it was an '87. The vacuum hose on my car goes to the PCV valve then to the intake manifold instead of to the throttle body as it shows for the '87. I did find that the diaphram in the "tank pressure control valve" is leaking so I've got to replace that. I also checked to see if the purge solenoid was getting power and it is, I can feel it energize when I plug in the connector. I'm not sure if it is actually opening though. I will check that next.

Bredd1

Ok, I remove and bypassed the "tank pressure control valve" until I can get a new one. Is it OK to drive the car with this bypassed. Can it harm anything by driving it this way?

ROME

From what I'm reading, the Pressure Control Valve is normally closed when the car is parked, Bypassing the valve would mimic the valve being open, just as it should be when you are driving, with no restrictions on the line. If the purge side of the system is operating correctly, you should be shedding tank pressure as the car is running.

FWIW, one wire to my purge valve solenoid is broken, and the valve has defaulted to the open position (I can blow pressure through it).

I've got the same problem, and I plan on pressure testing the vacuum lines to see if they are holding the control valve(s) open. I had a massive pressure release when I opened my gas cap a couple days ago, so my vent system is blocked somewhere. The fuel tank pressure control valve is the only potential bottleneck I can identify, unless the line is blocked en route to the rear of the car.

Bredd1

What year is your car? On mine I found that just in front of the back drivers side tire, there is a pieced of rubber hose that connects the two metal pipes that hade deteriorated. In checkin I found that both metal pipes hade become blocked, I was able to clear the one going to the fuel tank but not the one going to the purge canister so I ended up running a new line. Although I still get some pressure at the fuel tank when I open the cap when filling up, I don't get the smell of raw gas or even here the gas cap hissing anymore after normal driving.

ROME

My car is an '89. I'll be inspecting the line you mentioned in the rear wheel well to see if that could be part of the problem too.

exitwound

Hi..

On my '87, the pipe routed out to the tank from the rubber hose has corroded quite badly, so rather than replace the pipe (it's in an awkward postion and hard to get to), how about if I just removed it entirely and also the charcoal canister system too? Would that cause me any unforseen problems?

I'm sure I could affix a non-return valve to the pipework that I leave attached to the tank itself so any pressure could vent easily and also stop dirt from getting back into the tank.

I live in Scotland, UK and we don't have the strict emission/inspection tests to go through here as in other countries.

Bredd1

I've ready other posts where people have done away with this system and went with a vented fuel cap. I guess that is an option. Personally, I didn't like the idea of the vapor / open fuel venting at the rear of the car where you have your hot exhaust piping & mufflers. I haven't heard of any incidents that occurred but this is just my personal thinking.

exitwound

Good call.. I hadn't considered that. Fuel vapour building up under the car might not be such a good idea especially when its stationary or slow moving!

I'm always looking to remove stuff to declutter my car, like the AIR, a/c, cruise, and associated pipework and switching items etc. so the charcoal can looked like a good candidate too..

Cheers..

JackDidley

When my 86 did that, I just left the cap a little less than tight. It vented under the gas door and I guess out the edges of the door. I did not have the car long after that so I never got around to fixing it right but at least it wasnt pressurized.