1981 sc engine stalled will not restart

[81white911]

Prior to the last successful engine start:
new spark plugs
new distributor cap rotor
vacuum leak check as best as possible
changes oil and filter
new rubber airflow injection boot
capped off connection from boot to oil fill, to eliminate vacuum questions
capped off the other connection at the boot to eliminate all that other crap.
new oil temp sensor
new O2 sensor
catylitic converter is gone, bypass pipe.
fuel distributor plate moves freely
I started the car and it started and ran rough at idle eventually warmed up and ran pretty good.

Twice around the block and it just started to loose power and stalled.

Towed home. Let it cool off for hours. Restarted but ran rough and stalled.
Could not restart.

Checked primary fuel pressure 70 psi.
control pressure was also 70 psi. connector off
WUR had 11.5 volts and measured 9.9 Ohms
leak down pressure held at 22 psi for at least 20 minutes.

Took warm up regulator out and apart. Blew out the screen and verified that the WUR is the correct part number.

Reinstalled WUR, and replaced the fuel filter.

Control pressure was 35 psi and primary was 70 with the connector off.
Car stumbles to start and quits the wont start and had some frightening backfire.
lucky i have a pop off valve.

slowly knocked the plug down on the WUR from 35 to 20 psi and tried starting as it dropped no luck.

control pressure is now at 20 psi connector off, it will rise to 55 psi in 60-80 seconds with the connector on. and the primary pressure has remained 70 psi.

All measurements done at 70-75 degrees.

Did a fuel flow test today taking the discharge of the fuel filter. Got 1 liter in 15-20 seconds which is more than enough.

What should i check next?

There is a plug, two pin female, red/white and brown wires, made in germany and has 9886 marking. comes up around the distributor and could reach about 8" from there. I think its always been laying there unplugged but what is it?

Im thinking the fuel distributor could be gummed up like the wur.

Can i safely check the spark with this high voltage system. I highly doubt its ignition just how it sounds.

HELP!!!!!!!!!!!!!!!!!!

[VFR750]

I'm not an expert, but I have to ask, why did you cap off the boot to oil fill line? and "All that other crap"?

You might want to hook all that "other crap" back up.

What temperature did you measure the control pressure at? Per the manual, at 20C (~68F) the control pressure should be between 2.0-2.4 bar (29-35 psi) cold, engine running. Why did you drop it to 20 psi?

[Paulporsche]

Have you checked the fit of your plug wires on the plugs? How about the wires' resistance? Possibly your CDI and/or coil is going bad.

[81white911]

I stared at 35 psi control pressure with no luck, tried dropping it because it just sound like its not getting enough fuel.

as for capping the line that go to the rubber boot. i was trying to isolate any other vacuum or other problems hoping it would run without all that stuff. and it was before it stalled.

Im going to hook up the line that goes to the aux air flow and see if that helps.

One thing i messed with and maybe i should not have is the screw on the throttle body, the one that you can turn with your fingers.

Does anyone know how many turns from all the way in, would be a good starting point?

[jtfreels]

Not much help but to say I have a very similar problem. Mine quit on me very suddenly with a back fire. I replaced the "green wire" as it appeared I wasn't getting any spark. I got the car started Thursday night and it ran a few minutes (couple of trips up and down the alley) and then died, at least we could push it back in the garage. Was busy last night so didn't do anything with it. Today.... it starts up just great!
Really puzzled.

Jay

[ischmitz]

To test spark simply unplug one spark plug wire at the engine and hook it up to an old spark plug. Ground the spark plug to the engine block while an assistant is cranking. Use leather gloves or a pair of pliers so you don't electocute yourself in the process.... If you see a spark chances are you CDI unit and coil are O.K.

However, some CDI units "do" work intermittantly and quit once they get up to operating temperature.

Do you smell fuel when you crank the engine?

Ingo

[81white911]

I see alot of comment about the Green wire, mine looks like its been spiced. Is it just a matter of a good ground?

I plugged the line that would go to the right side of the rubber injection boot(when looking at it from behind) the two injection boot connections were already capped. This at least got the engine to sputter.

Ill check the spark today, will any old spark plug due? I have some i just took out of my 85 corvette.

Since my warm up regulator screen was obviously plugged up, probably bad gas and sitting for so long, whats inside the fuel distributor that could be starving the engine from fuel? could fuel be going to the fuel distributor and just recirulating back to the tank? How could you clean the fuel distributor? Can you flush it out with out removing it?

[LFogelson]

Sounds exactly like the problems I had with my CDI. If you can borrow one from someone and swap temporarily, you can quickly know if yours is bad.

[81white911]

Originally Posted by LFogelson

Sounds exactly like the problems I had with my CDI. If you can borrow one from someone and swap temporarily, you can quickly know if yours is bad.

if i get spark could my cdi still be bad?

[81white911]

will i get spark if the cdi is bad? can a cdi work and then fail when it gets hot?

[ischmitz]

Yes, for a quick test any old spark plug will be fine. If you get spark you have verified that the CDI box is not completely dead and your trigger signal is working. This is a good first step.

Originally Posted by 81white911

will i get spark if the cdi is bad? can a cdi work and then fail when it gets hot?

Yes, that is one comon failure mode of these CDI units. Once hot they start cutting out or more likely quit. As soon as you cycle the ignition they start working again for a brief moment (longer if you let them cool down)

Ingo

[jtfreels]

Is 5 minutes running enough to get the CDI "up to temperature?

Jay

[ischmitz]

Depending on how bad the box internals are yes. Feel it with your hands once it stops if it is hot to the touch. This failure has a spectrum from several hours all the way to complete and instant failure.

Another test is this:

Once the car dies DO NOT swtich off the ignition. Open the engine lid get out and listen to the box and its whisteling tone. Then turn the ignition off and back on and listen to the tone again without starting the engine. If the tone has changed from a much higher almost inaudible pitch back to the 3.5kHz whining you have found your problem. The much higher pitch is a result of the box "latching up" and the DC/DC converter working against a short.

Ingo

[jtfreels]

Thank you very much!

Jay

[Gunter]

I doubt that the CDI module is bad.
Do the spark test as suggested.
The screw on the TB you're refering to is the Fast-Idle-Screw; if you turned it cw, it'll restrict air-flow with the butterfly closed. Open it by going ccw one turn to get a faster idle.
It sounds like you disconnected/changed a lot of vacuum lines necessary for cold-start.
Without knowing exactly what components are connected, it's hard to give advise.

To check your fuel distributor, you can pull the injectors and place them into 6 glass jars.
Remove the air filter, with ignition ON, briefly push the Air Sensor Plate up for 2-3 seconds.
You should hear a sqeel from the injectors and see fuel in the jars.
The amount of fuel should be equal in all jars.
Injectors also have a tiny screen inside and it doesn't hurt to soak them fully submerged in injector cleaner for 24h.

[mca]

Originally Posted by Gunter

To check your fuel distributor, you can pull the injectors and place them into 6 glass jars.
Remove the air filter, with ignition ON, briefly push the Air Sensor Plate up for 2-3 seconds.
You should hear a sqeel from the injectors and see fuel in the jars.
The amount of fuel should be equal in all jars.

Wouldn't he have to jump the fuel pump relay in order to do this test?

[81white911]

Does anyone have a guess at how many turns from all the way in the throttle body idle screw would be set as a starting point? Ive messed with it so much before the engine quit, im wondering if this isnt part of my restart problem.

[Gunter]

Originally Posted by mca

Wouldn't he have to jump the fuel pump relay in order to do this test?

No, provided all wiring is unmolested stock, no jumpering is necessary because the moment the Air Sensor Plate is lifted, the Air Sensor Switch on the metering body tells the pump to run. (With ignition ON)

If the above doesn't make the pump run, a closer look at the fuse, pump relay, wiring and pump is in order.

Problems arise when someone made changes to OEM and without knowing what changes were made to the engine, long distance advise is almost impossible.

I would need to know if WUR, AAR, AAV, Decel. Valve, CSV, TTS etc. is connected OEM.

[Gunter]

Originally Posted by 81white911

Does anyone have a guess at how many turns from all the way in the throttle body idle screw would be set as a starting point? Ive messed with it so much before the engine quit, im wondering if this isnt part of my restart problem.

I think it doesn't hurt to unscrew it until almost no pressure from the spring is felt.
It sounds to me that you have problems with cold-start.
The Cold Start Valve (CSV) gets power from the Thermo Time Switch (TTS) located on the left chain cover.
The TTS gets power from the other yellow wire on the Starter Solenoid when cranking.
Is your TTS and CSV getting energized during cranking?

Besides that, I assume that the other components like WUR, AAR, AAV and Decel. Valve are connected OEM to enable cold-start.

[fredmeister]

Originally Posted by 81white911

I see alot of comment about the Green wire, mine looks like its been spiced. Is it just a matter of a good ground?

I plugged the line that would go to the right side of the rubber injection boot(when looking at it from behind) the two injection boot connections were already capped. This at least got the engine to sputter.

Ill check the spark today, will any old spark plug due? I have some i just took out of my 85 corvette.

Since my warm up regulator screen was obviously plugged up, probably bad gas and sitting for so long, whats inside the fuel distributor that could be starving the engine from fuel? could fuel be going to the fuel distributor and just recirulating back to the tank? How could you clean the fuel distributor? Can you flush it out with out removing it?

The green wire being spliced is likely the reason. Most people dont realize this is a coaxial cable. You cannot simply splice the wires together because it is actually an inner wire surrounded by a layer of insulation then a second wire around it and the final green insulation you see. Make sure that this is done properly or replace it with a new one and eliminate this as potential problem.
Also, if your car was running before with the adjustment you made to the idle air bleed screw like you mentioned, then it shoudl not all of a sudden stop running if nothing else changed.
If you pull the plugs do they look wet and smell of gas.....then the injectors are working fine and it is ignition related.