Emissions Catch-22

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1982FJoe40

1982FJoe40

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Apr 30, 2014
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Stupid question... I bought a vacuum tester and found an emissions manual so I can troubleshoot my emissions so I can figure out why my car shuts off when it gets warm. Even when it's cold, I have to run at high idle. I want to troubleshoot my EGR, but the manual states you need to run car at idle. This is true of a lot of the testing procedures.
How do I run some of these tests if I can't get my car to stay on long enough. Then, once it's warm, fugetaboutit, it won't turn on at all.
:bang:
 
Hummm, have you tried to remove the system completely as in a "de-smog" and see if that fixes your problem?
 
Start with the basics:
Manifold vacuum. It won't idle with a manifold vacuum leak.
Fuel: Obviously it has fuel because it runs at high RPM, but does it have idle fuel and is the idle fuel solenoid working?
Spark: Do you have a spark when it quits?

If I had to guess, I would pick manifold vacuum leak because it is common.
 
I agree with all of the above, my gut instinct was that the emissions wasn't the issue. I think the fuel idle solenoid is a suspicious part of the puzzle.
 
Thanks for all the replies. I will check the manifold. I'm sure there are some threads on this, but if anyone knows how you test for a manifold vacuum leak, I'd appreciate it. I also just removed the egr for inspection, since that was previously suggested to me also. Once again, does anyone know how to test the egr to see if it's working properly?
 
Today I replaced most of the remaining bad vac lines. EGR valve and modulator seem to work properly, as well as other emissions related valves I've tested. I seem to have spark up until motor dies. Still won't stay on longer than a few seconds, then won't want to restart at all until given a long break.

The fact that it even dies while I'm gassing it tells me it's probably not idle fuel solenoid??? What's strange about this is how these problems just started out of the blue.. I recently bought the car, test drove it and everything seemed fine. Problems seemed to develop with warmer weather.

I'm ready to look into manifold leaks, but I'm not sure where to start. Do I just look at carb mounting? Do I remove manifold and everything attached to it, and reassemble it?

Not having the car want to stay on is making troubleshooting a real bear.
 
To check for vacuum leaks:
Adjust idle speed screw until it will run at as low an RPM as possible. The idle speed screw is hard to see and it is in the cast iron base of the carb facing the firewall. It is not one of the screws on the linkage.
With engine running, spray carb cleaner around all gasket sealing surfaces. If the engie speeds up, you have a vacuum leak. The brake booster and EGR are also potential sources of leads as is a cracked intake manifold underneath the carb. You won't find these by spraying.

Do you have a spark after it stalls. Obviously, it it runs, you have a spark, so that is not very informative.
 
First of all, Happy Fathers Day!
I think I'm on to something. I'm now wondering if I do have a fuel issue. I have an electric fuel pump, which is working fine. Filter is clean. I get fuel in sight glass when I pump the pedal. After I start it up, car sounds great for a few seconds and dies. I look at sight glass on carb and it is totally dry. Could it be a float problem? One thing to note is that the car will still die even if I keep pumping pedal.
 
Last edited:
Probably not a float problem because it does fill. Probably a fuel delivery problem. Remove the fuel line at the inlet and see how much fuel it can pump in 15 seconds. It should be able to deliver about a cup of fuel. If not look for clogged filter or junk in the tank.
 
Ditto. If the carb bowl is empty, pumping the accelerator will do nothing.
If the fuel pump flow is good, one other thing to look at is some carbs have a screen where the fuel line enters the carb. If that clogs up, the bowl won't fill. Also, even though you changed the fuel filter recently, it can clog up really quickly if you have junk in the tank. That's why I like using clear filters when trying to solve fuel flow issues.
 
Just on a whim, if you have confirmed that Idle solenoid is functioning, you might want to check the condition of the printed circuit board on your Emissions control box under dash. I had symptoms similar and I'd test the solenoid by applying 12 volts and it would work, but could only maintain high idle with an advanced throttle position. what I found was a break in some of the solder joints inside the emissions control box, they were obvious and easy to find, but I checked the whole thing afterwards with an ohm meter and circuit diagram.
 
Thanks for the recent replies. Found a second hidden fuel filter underneath the frame. Filter was pretty clogged. Can't seem to now get fuel primed through the line. I have an electric fuel filter, but I don't think it's pumping. Will try to attach vacuum tomorrow to see if I can suck it through with pump running. Definitely looking like a fuel tank problem. Plan on attaching fuel line to spare fuel canister and see if car stays on. Hope to drop my tank this weekend to either replace or have cleaned. I can see daylight!
 
1982FJoe40 said:
Today I replaced most of the remaining bad vac lines. EGR valve and modulator seem to work properly, as well as other emissions related valves I've tested. I seem to have spark up until motor dies. Still won't stay on longer than a few seconds, then won't want to restart at all until given a long break.

The fact that it even dies while I'm gassing it tells me it's probably not idle fuel solenoid??? What's strange about this is how these problems just started out of the blue.. I recently bought the car, test drove it and everything seemed fine. Problems seemed to develop with warmer weather.

I'm ready to look into manifold leaks, but I'm not sure where to start. Do I just look at carb mounting? Do I remove manifold and everything attached to it, and reassemble it?

Not having the car want to stay on is making troubleshooting a real bear.
Click to expand...

Do you have a spark after it dies? Could be a bad coil that doesn't work till it cools off a bit.
 
I do continue to get spark even as I'm trying to restart it. I'm definitely not getting fuel to the carb. The interesting thing is that this started as emission problems. When I bought the car it was a rats nest of vac lines. Many lines were disconnected, missing or plugged with sticks. I've fixed all of that, then I think that's when my fuel filters got plugged. Little did I know about the second fuel filter under the frame, which had tons of debris. I've been chasing a lot of different problems since I got the car home. In the beginning my carb would flood and I'd have gas in the sight glass. Now I can see it's been totally dry for the last week or so. It's been tough troubleshooting a car that doesn't want to stay on.. Thank God for all the IH8MUD forum member input :)
 
Check the filter and if you have rust particles, you may need to get your gas tank boiled out and resealed at your local radiator shop.
 
I definitely had rust. What's strange is that I also had green particles that looked like paint. Can't wait to get tank off to radiator shop.
 
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