81 SC died and will turn over & fire but not start

[Gunter]

Originally posted by HDBrown
If the AAR was not getting 12 volts, would it still eventually idle down to normal idle, or would it remain stuck at 2100 rpm?

It would take way too long, and may not at all in Winter.
Here is how you check the AAR: (It's on the right above #5)
When cold, open the clamp and carefully pry the rubber hose from the AAR. Use a small mirror and a light to peek inside.
You should see an opening shaped like a half-moon.
You can spray some WD-40 in there.
Replace the rubber hose temporarily.
Start the engine and run for about 5-10 Minutes.
Shut off, remove the rubber hose, look inside.
The opening should be closed completely meaning the AAR is working.
If not, check the power going to the AAR.
It's a little tricky to reach the plug and remove the tiny wire clip, be patient.
With engine running, you should have 12V between the 2 poles in the plug, brown is always ground.
If you don't have power there, the WUR most likely isn't getting power either; same type plug, careful with the clip.
I believe engine has to be running for power to be at the AAR and WUR unless someone can confirm that ignition ON is good enough.
Get the Bentley, you'll love it.
Major mistake in it is the wrong rotation for the distributor.
The right rotation for all SC's is ccw, not cw as stated.

[Lorenfb]

"I believe engine has to be running for power to be at the AAR and WUR unless someone can confirm that ignition ON is good enough."

Gunter is correct! The power for the AAR & WUR is provided when the fuel
pump gets power, i.e. when the sensor plate moves.

[HDBrown]

I havn't gotten around to spraying WD 40 into the AAR but I think it is the problem. When completely cold, the car starts right up and idles for 20-30 minutes at 2100rpm. It will eventually idle down to 900. If I turn it off, and attempt to restart after it finally warms up, it will fire right up. But, if I let it cool down for an hour, it will not start until it has been sitting for 10-24 hours. I think the AAR may be sticking in both the warm and cold position?! It wouldn't start today and I sprayed some starter fluid in the intake - it fired right up and ran great (at 2100rpm idle).

[VFR750]

On really cold days I have the same problem of high idle. I bought a good used AAR and replaced mine, and still had the problem. I checked power to the AAR and got >12V.

So I checked mine and put 12V on it. Sure enough the valve closed in about 5-6 minutes. But here is what really surprised me. I pulled air into the AAR (no power to it) and the valve immediately started to open.

I'm thinking that the AAR valve plate is leaking air around the plate and into the cavity with the thermal (bi-metallic) switch and overwhelming the resistive heater.

This would explain why I own two working AAR's, and yet still have a high idle when it's cold out.

To all: Could this be a wear problem? Do AAR valve plates and valve seats wear out? Is there a rubber seal that could be replaced? Anyone cut one open?

I also carefully cleaned the valve plate. It had a bit of gummy oil on it. So you might want to take the AAR off and take a closer look at it. It may be possible to have a sticky AAR.

One way to test your sticky AAR theory would be to press a small amount on the throttle when starting, that would give you a little extra airflow, which is what the AAR tries to do. (It is an automatic choke). If the car only starts with a little bit of throttle, then the AAR may have stuck closed.

Hope you get it all sorted.

[HDBrown]

After posting my last, I decided to look around a little and try to figure out what the AAR, WUR, Cold Start Valves were. While looking around, I found this wire plug hidden near the warm up regulator. Can anyone tell me where this plug is supposed to be plugged in?

[HarryD]

Hank,

I do not know, but move it around back there and see if you can find a connector that it can reach an it will fit with.

The female part cannot be any further away then the length of the wire.

[HDBrown]

Harry,

My thought exactly - how hard could it be? I looked for about 30 minutes and couldn't find it - probably staring me in the face. I don't own one of those little mirrors-on-a-stick so I probably need to purchase one of them. Next step unless someone tells me where it goes is to start taking hoses off until I can see better.... not my preferred course of action.

[Gunter]

Hank:
To really determine if the AAR is working, you need to look inside and check the opening when hot and cold as desribed above.
Guessing and spraying WD-40 is no guaranty.
Trouble-shooting is a process of elimination, find the parts that work.
AAR first, then check the WUR for Control Pressure.
The WUR has a tiny screen that may need cleaning: Open the line on top and look inside.
I check the heating element for AAR and WUR by removing the plugs and supplying 12V to them from an external source. I have a spare plug with long wires. You can feel the unit warm up within Minutes.

The plug you're showing could be for the blower or A/C.

Very nice, clean engine compartment.
The stock ignition harness has lots of ground-shield on it. Try this:
After dark, or inside a garage, see if there are some sparks jumping from the cables to ground when running.

[mack6820]

The plug looks alot like the one going into the frequency valve. Also turn your key on and listen for a rapid clicking sound from behind the airbox. That will tell you if your frequency valve is working or not.
BTW, When I first bought my sc last year, I had the same problems. It would run fine, then I heard a poof, and the engine would quit. After a few hours, it would start up again and a few minutes later, poof, quits again. My mech here in Virginia Beach changed the vacuum advance and its been great since.
Your in Maryland? How far are you from Virginia Beach? Maybe we could have a look.

[Gunter]

Originally posted by mack6820
The plug looks alot like the one going into the frequency valve. Also turn your key on and listen for a rapid clicking sound from behind the airbox. That will tell you if your frequency valve is working or not.
BTW, When I first bought my sc last year, I had the same problems. It would run fine, then I heard a poof, and the engine would quit. After a few hours, it would start up again and a few minutes later, poof, quits again. My mech here in Virginia Beach changed the vacuum advance and its been great since.
Your in Maryland? How far are you from Virginia Beach? Maybe we could have a look.

Definitely not.
The FV has the same type plug as the WUR, AAR, CSV and Airflow Sensor contact.
Also, the FV will only work with the engine running (Airflow Sensor Plate off the contact), not just ignition on.
Same for WUR and AAR power; engine has to run.

I checked mine; the plug shown in the picture is for the extra heater blower.

Hank: Consider servicing the ignition distributor, it can't hurt.
I just described an easy way of doing it, do a search.

[SCWDP911]

sub'd for future reference

[HDBrown]

Gunter et al:

I started to execute the trouble shooting procedure you outlined. I loosened the clamp on the rubber hose connecting to the RIGHT side of the AAR and as I pried it off I realized that short rubber hose is connected to a metal tube that may be rigid on the other end. Is it? Which side of the AAR am I supposed to disconnect so I can look into the AAR, the right (outboard) or left (under air box/ inboard) side?

[HDBrown]

With the car in a nice warm garage I started it (routed exhaust through out the window) and let it warm up for 8 minutes. With the idle still over 2k rpm, I took a wooden dowel, placed it against the AAR, and tapped on it with a hammer (someone suggested this) sure enough, I was able to "tap the idle down" from 2100 to 1100 rpm. Second time I did this so I don't think its an anomoly, I think the AAR is sticking.

[Gunter]

Don't worry about the Alu-pipe, it's connected to rubber ends all around.
Don't bend it too much, just enough out of the way to peek inside.
When cold, look inside. There should be an opening "half-moon" visible.
Put the hose back on temporarely. Start the car.
After about 5 minutes running, shut it off; the opening should be closed.
If not, you need to check one more thing: Ensure that the AAR is getting 12V when running.
With a very small screwdriver, carefully open the small wire clip on the plug and remove. It's a little tricky; don't lose the clip.
The engine has to be running for the Voltage check.
There are 2 pins in the plug, positive and ground.
Watch out for the fan belt.
If you find 12V, the heater inside the AAR may be kaput, or it may be sticky.
Your choice, a new one, or a used one, or WD-40?

[HDBrown]

Gentlemen,

I havn't had a lot of time and I decided to just drive the car some to see if I could "work out the bugs". No luck.

The car has continued to maintain a 2k+ rpm idle until it gets VERY warmed up (at the Autocross) or until I "tap it closed" by tapping on the AAR with a wooden handle.

When I do get the idle to go down to 1000 rpm, if I shut it down for more than a few minutes, it won't start until I let it cool down for several hours (unless I spray a shot of starter fluid in the intake).

Using a mirror I looked into the right side of the AAR with the hose removed. I see the half moon opening. I sprayed carb cleaner, then wd-40 into it. It seemed to help once, but then returned to the status quo.

I checked the power to the WUR and the AAR. With the ignition on, but engine not running, neither has power. With the engine running both have around 14 volts.

So, I have power to the AAR. If I tap on it it will close once the engine is warm. It appears to stick open as well. Solvents/ lubricants did not work.

Parts Heaven sells rebuilt AARs for $150.

Comments!?

Thanks, Hank

[Mavitec]

Hank, Next time your car stall check in the air box as your pop off valve could have open and get stock on the air filter because you said when you open the air filter box then the car restarted . It happenned to me a couple time when the car is back firing. Check wich way the pop off valve was installed; if the valve open to the outside it could be your problem. As a fix you can bend the wire mesh on the air filter to leave more space. As for the loose wire you are looking for, mine has the same wire not connected (SC 1983) and engine is running OK

Mario

[HDBrown]

Mario,

Thank you - I forgot to mention that I had the loose wire issue resolved. I don't think it is the pop off valve. I've had the air box cover/ filter off when it wont start and ensured that the pop off is seated.

I'm really focused on the AAR at this point. I've exhausted my understanding of the trouble shooting tips listed in the threads above. Hoping one of the experts will let me know if it looks like I missed anything.

Thanks again, H.

[SP2]

Hank,

That plug you found that wasn't connected, well mine isn't connected either. It might have been connected to the heater blower in the back as someone said, but I backdated my heat so I can't remember. Hope that helps with your differential diagnosis.

[Gunter]

Originally posted by HDBrown
Gentlemen,


The car has continued to maintain a 2k+ rpm idle until it gets VERY warmed up (at the Autocross) or until I "tap it closed" by tapping on the AAR with a wooden handle.

When I do get the idle to go down to 1000 rpm, if I shut it down for more than a few minutes, it won't start until I let it cool down for several hours (unless I spray a shot of starter fluid in the intake).

""""That would be an issue related to either Check Valve at the fuel pump or Accumulator. An open AAR does not prevent a hot-start""""

Using a mirror I looked into the right side of the AAR with the hose removed. I see the half moon opening. I sprayed carb cleaner, then wd-40 into it. It seemed to help once, but then returned to the status quo.

Are you saying that the opening in the AAR is there with the engine really hot?
If so, put a Wanted Ad on the PP Parts-board for a used AAR.
Once you have a working AAR, concentrate on the hot-start problems: Pump Check Valve, Accumulator, or vacuum leak.

Used AAR and Accumulators are cheap. A new check valve is cheap. Do a search on how to install these items.
Check Valve replacement requires an empty tank.

[HDBrown]

Gunter,

I was hoping I'd hear back from you on this! Yes, AAR is open when hot. You outlined my plan - confirmation. Thanks.