Before I start this let me say thank you to all of you that have helped me over the last couple of years. Your help has been awesome and saved me a lot of time and money.

So......1985 GSL 12A - RB headers/exhaust, removed air pump and stuff. Intermittent problem. I can drive it 5-6 times 15 miles or so, no issues, runs great. Then, out of no where, it starts to run like crap, very hard time idling and if it dies, there is no restarting any time soon. I can wait a couple of hours and it will start right up...??? What have I done (in no particular order) - drained fuel tank with paper filter to catch any debris...clean fuel. New fuel filter and fuel pump. New coils, New dizzy, rotor, wires and plugs (it ran even better after that...LOL!!). Verified fuel to the carb. I can hear the fuel pump, so I know it's running when the issue arises. drilled a hole in fuel cap (vacuum issue?...yeah, this was a long shot).

With all of that said I am thinking an intermittent shutter valve failure. I understand what the shutter valve does (removes fuel from the #1 rotor for decelerating) and have read all the posts concerning shutter valves on here. I know one way to check is to feel for vacuum over the associated hole on the air filter assembly, however, I can't do this when it dies if I don't "pedal" the gas. I understand it is definitely possible that a shutter valve failure can be intermittent.

My questions to you 12A Savvy Mechanics..
1. Is a intermittent shutter valve the possible defect?
2. If so, I understand the "butterfly valve" at the bottom can be wired open. Anyone have any pics of that?

I really don't want to remove the valve at this time as my plate is full. I would like to keep the valve open with minimal effort as at this point as I am still troubleshooting. If I can keep the valve open, and drive it a bunch of times without a failure, I will then do what is necessary to either change the valve or remove it all together...

Thanks so much for any help what so ever!!! Pictures are very much welcomed!!

 

I plugged the hole in the air box where the shutter valve hose goes.

 

Are you speaking of where the hose is plugged into the air filter assembly?

 

exactly

 

Thank you!!! Will do exactly that! Keeping my fingers crossed that this will identify the problem!!

 

It could also be the an ignitor failure as well. When ignitors fail, they usually don't do so until hot. So it will run fine on short trips but then exhibit behavior as you described on longer or repeated outings. When the trailing fails it usually effects the tach causing bouncing or zero readings. When its the leading its like you lost a rotor or its just refuses to restart hot. Keep it in mind if the shuttervalve modification doesn't change things. Good luck!

 

I certainly will!!! That is something that I never even considered....duh!!! Thank you!!!

 

I had my trailing ignitor go out and it tripped the fuel pump relay turning off the fuel pump. That was the first time I learned how to jump the relay connections.
That would go along with the ignitor heat factor so when it cools down the pump starts again. Putting in the jumper wire when it will not start could confirm the trailing ignitor is faulty.

 

Thanks Tim. My fuel pump relay bit the dust long ago and I have it straight wired (with a switch of course). The switch is now "dual purpose" as it is not easily visible, so it acts as a theft device as well, LOL!!! The ignition modules are cheap, so I ordered them yesterday. If the car continues to act up, I will then be able to say a couple more things that "aren't" the problem (shutter valve and ignition modules). Hoping between the two, it is fixed because I have been pulling out my white hair!!!

 

So…the car didn’t want to start. I have the pump going and pedaled the gas, got out a checked the carb..dry! So I squirt some fuel in there and it started and continued to run (didn’t idle worth a hoot). I turned it off and same thing. Tried to restart and it wouldn’t. Dry. Squirt fuel and it started. Bad floats?

 

Sounds like bad pump or clogged filter. If u recently rebuilt the carb and messed with the floats ? Then I would say that's the problem. If u decide to remove the shutter valve and remove the butterfly valve inside the manifold. U will need to cut a passage between runners. Or get a 79-80 intake manifold that has even runners and no butterfly valve. It will run like **** if u don't modify the manifold. With the valve removed u will get little pops and spits out the exhaust.

 

New pump and new filter, drained the fuel tank with a coffee filter, no debris. Verified the pump is working at the carb (the pump is on a switch as my relay died long ago). I capped off both ports on the shutter valve. Once started, it basically runs fine (I need to adjust the idle fuel mixture/idle speed screws because idle is off). I can "gun" it and it is very responsive. What initiates fuel into the "bowl" for starting? I can squirt fuel in there and it starts right up. When I shut it down, again, it will not restart without a squirt of fuel.

 

You can jumper the fuel pump relay plug and not have to use a switch.

 

Yeah..had a jumper in there but when this mess started I straight wired it to make sure it wasn’t part of the problem…

 

After shut down, it will start back up right away, or is there a delay between shut down and start up.

My bowls' levels will go down with time making it harder to start. If I shut it down it will start back up fine that day, but harder the next day.
I have not driven it for a few days and just checked and again the front bowl is low. Rocking the car I can see gas splashing but no level on the glass.
I too have a jumper installed so the fuel pump runs whenever the ignition is turned on. Now I will give it 10 to 30 seconds with the ignition on only, before turning the key to start. This seems to help.

Gas is being siphoned out of the bowls. I do not understand why.
Maybe related to your issue.

 

It’s immediate meaning I can shut it down then immediately try to restart and it won’t…darn it!!!

 

Have you recently rebuilt the carb?
The accelerator pump is part of the process.

I mine failed and it was leaking gas. Not good. I replaced the diaphragm with the carb installed. It can be done.