I had my '91 Camaro redone over the fall with a 383 Stroker swap and complete drive train rebuild. They also added a FAST EFI system to accomodate the horsepower. Basically ever since the conversion after driving the car the is a fuel vapor leak coming from under the hood. They've tried several times to pin point the leak but checking the hoses and there connections but haven't been able to solve it. My concern now is everytime I drive the car and it's parked in the garage it smells to high hell with gas fume and I'm around something is going to blow up. Is there a way to find and detect where this odor is leaking from?

 

What did you do to your fuel vapor canister ?
Make sure it is still hooked up properly.

 

Is that the same thing as a charcoal canister? If it is they said they did check that and it looked fine. I do know they took out the emissions stuff from the car, Would that have anything to do with the issue?

 

It is the same. Who did it? If you are in the Highland near me, then was it the shop with the Dyno?

The charcoal canister is for collecting fuel vapors and is part of the emissions systems.

I would use my nose to find where the vapor is coming from. You could have a fuel or exhaust leak.
Make sure your lines to/from the charcoal canister are hook up correctly.

 

If they have deleted the canister purge then there is nowhere for fumes to go now
If so ;at a min need to install old style tank vent below bumper and vented fuel cap so fumes can escape from tank as they are generated and not accumulate

 

I'm assuming your thinking of Gene's Performance. No they didn't do it, But I was thinking about taking it to them to have it looked at.

 

This I'm unsure of, I do know most of the emmision stuff they took out when they did the swap. Now as far as the canister purge, I'll have to ask them. Can this be added back easily to correct the issue, or is the tank vent and fuel cap the best way? All I know is I'm tired of getting high out in my garage.

 

It can easily be added back, assuming that is the problem.
You should be able to look under the hood above the power-steering box and track down your fuel vent lines to see if they are connected or open.

 

I'm taking it back to the guy who did all the work this weekend and I'll tell him that. I'm curious on one thing, Does the fuel vapor device require the cars computer? Reason I ask is they deleted the cars computer because we installed a after market FAST EFI system. The EFI system is great, But all the issues that have come up due to it being no longer hooked up hasn't been. I'm not sure if the cars computer might be a issue or if it's just how the lines might be run.

 

The canister purge (CCP) is a function handled by the factory computer. the computer signals a switch to vent the vapors into the engine at certain times.
You should check your new system to see if it can handle that function.
If not, then you will want to reconfigure the fuel tank ventilation system to prevent your smell problem.
There are many different ways you can do it. Most aren't quite as good as the factory set up, but some are satisfactory.

A low pressure check valve and a couple of opaque plastic case fuel filters in series on the end of the vent line can cut down some of the vapors. you could then go on to route the vapor line into the space between your air filter and your throttle blade.

Hopefully some other people will share their methods on here as well.

 

I figured the cars computer might be the issue after reading your posts. The computer is still there they just unhooked it since all the sensors are now ran from the FAST system. Is there a sensor the factory computer needs to read in order to signal the switch to vent the car?

 

To be honest I have never traced the CCP routine in the Hack.
I don't think it's any one sensor though.

 

I'd suspect it just senses pressure which send a electrical signal the computer which then opens the valve to vent? I mean the only sensors the FAST system uses are the TPS, O2, CTS and ATS so none of those are any longer hooked up to the factory computer. As long as the CCP doesn't use any of them I would think it should work as long as the factory computer has power i'd suspect. I'll let them know this and see if hooking the factory computer up changes this. I know before this swap I never had any issue with fumes so I know at least all the valves and cannister where working properly then.

 

A proper answer would take time for me to search through the hack, but from what I think I remember the ECM doesn't sense pressure. It uses key-on, engine start-up, and timer routines to decide when to trigger the CCP. I'm pretty sure of that, but won't swear to it at this point.
It might also use decreasing delta-TPS (not so sure here).

If you pm Rbob (a moderator here on DIY PROM) he would be able to tell you with certainty because he knows the ECM routines in and out.

Otherwise it would take me a while to track that down.

 

there are a few things that must be met before the factory ECM would allow canister purge, like time running, coolant temp, throttle position and vehicle speed are most of them. also certain codes can not be set and also the ECM would need to be in control of fuel. im probably forgeting a few things too.
so it would need all the sensor inputs along with outputs.

you can set up CCP like the old, non-computer cars were.
temperature control vacuum valves, time delay vacuum valves, ported vacuum from the throttle body.
even the early computer controlled carburetor systems used a number of vacuum control valves.
either way you would end up running a number of vacuum lines under the hood.
i like what 305sbc said about putting a hose with a fuel filter and running it between the throttle body and air filter.
as close to the TB as possible would probably be best.

 

Should I assume the purge valve is stuck open without the factory ECM this is why the constant vapor leak?

 

Well we don't know for sure yet if this is the source of the vapor leak until you check it out carefully, but if the canister was removed, then the removers may have left the vent line just hanging open.

 

I just looked in the ANHT hack and DennShah is right on about the CCP qualifiers.
I guess you should forget about factory computer control.

 

Yea, Another member pm'd me the same thing. The more I'm checking around the net I'm under the impression I can just replace the current cannister with a non-solenoid one which should work and also stop the vapors? Rbob also mentioned something of the same when I pm'd him upon your advice.