'83 SC was running great, now won't start

[brad951]

I'm tried everything I know so searched the internet thoroughly and I'm stumped - maybe an expert here might be able to give me a hint ! I am following another thread on this forum which sounds similar to my issue, but not the same unfortunately!

Problem:

'83 SC, was running perfectly, yesterday was checking/setting idle speed and timing in prep for a CA smog test. Car was warmed up and idling, running great as it always has. Idle was 910, timing was perfect, 5 degrees BTDC with both vacuum lines detached and plugged from the vacuum valve on the distributor. I was just about to shut it down and go get it smogged when I thought I would check the timing one more time. So I disconnected the vacuum lines from the distributor, expecting the idle speed to change a bit, and wham!, engine starts to run like crap, idle goes down to 300-400rpm, tach starts bouncing erratically, and eventually it stalls. I cannot restart it. It cranks solidly, won't catch. If I put my foot to the floor on the gas pedal while cranking, it catches sometimes, but runs rough, about 300-400 rpm, won't go higher even at WOT and if I take foot off gas it stalls.

I can't figure out what triggered this. Certainly removing the vacuum line from the distributor was a coincidence. I've done this many times and it doesn't have any big effect, including earlier yesterday.

So here is what I have tried:

- Battery is charged and strong. Engine cranks vigorously.
- Tried with engine fully cold. No change
- Checked fuel pressures. Main pressure is 70 psi. Control pressure is 51 psi
at 80 degrees, hot engine (in spec).
- Fuel pump relay is good (pretty new). Tested with the relay jumped, and tested pressure during cranking (70 psi).
- Checked spark - pulled boot on cyl 1 and tested with a plug. Blue spark during cranking.
- CDI box whines when engergized (good).
- Airbox has no visible cracks. Backfire valve is installed and looks good.
- No visible vacuum leaks - all lines in places and connected.
- Replaced fuel filter with a new one - no change
- Pulled cyl 1 injector, ran into a glass jar during cranking. Some fuel coming out but seems like a very small quantity.
- bleeding the fuel pressure gauge lines, lots of fuel comes out. Looks like fuel delivery quantity in the system is good.
- removed distributor cap - new cap and rotor, all looks good inside., rotor points to mark when engine at TDC.

So, seems to be a fuel issue, like something happened all of sudden yesterday while idling, possibly triggered by me pulling that vacuum line of the distributor that is resulting maybe in a low fuel delivery condition. Or it might be a massive vacuum leak?

Any ideas of what to check next ? Bad gas ? a blockage in a fuel line or in the FD somewhere ? Maybe the distributor is faulty, timing way off ?

I am getting spark and some fuel - just not sure if enough of both at the right time...

Stumped... Thanks !!

[tirwin]

Just a thought because you said you were checking the timing. Is it possible you bumped the distributor (maybe not tightened?) and threw the timing way off?

I'm trying to think of what you could've messed up that would coincident with messing with the vac lines. Did you plug the vac lines when you disconnected them?

Maybe you have some other leak source(s) and disconnecting the vac line pushed it over the top.

Also check the O2 sensor relay under the passenger seat. That is a rough running culprit.

[tirwin]

Also check that you didn't do something like accidentally disconnect the TTV wires. How does the green wire to the dizzy look?

[brad951]

Tim, thanks for the ideas!

Distributor is in right position (I have a mark on the slot indicating the right position), hold down nut is tight. plugged vac lines, didn't make much difference. It does sound like a vac leak but I cannot imagine how it would have happened so suddenly. I swapped the O2 sensor relay for a known good one, no difference. I took a look at the dizzy wire and it looked fine - I'll take a closer look. With spark and fuel, I'm thinking maybe something more serious, make the tensioner let go and the timing chain skipped a tooth...

[anthony]

If you looked at my current thread, I started with an alternator install. The car started and ran fine afterwards once and then wouldn't start. Going through basic troubleshooting, everything was testing good. The non-starting issue seems to be the ignition switch.

I'm just mentioning this because it could easily be something else not related to what you were working on.

[tirwin]

Scratching my head... double check you have power to the O2 sensor circuit by making sure your interior dome lights work.

[brad951]

Dome lights work. Anthony, I'll check your thread and take a look at the ignition switch. it had crossed my mind but I couldn't figure out how it might affecting things as the engine cranks, accessories run, and the fuel pump is activated when I lift the air valve (but it doesn't start).

If I put the accelerator to the floor, after a long crank it will sputter to life, run rough at about 400 rpm, and if I let up on the accelerator it stalls fast. smells of gas around back of car in this case.

[anthony]

I wasn't suggesting the ignition switch just that it could be something completely unrelated to where you were working. It sounds like you have fuel and spark there.

[Bob Kontak]

Wiggle your green wire. You were in that area.

Double check the connection at the CDI box.

Make sure your cap is seated and secured.

Pushing on the gas pedal provides air but no gas.

[simsalabim]

Don't forget that frequency valve ...

[Bob Kontak]

Originally Posted by simsalabim

Don't forget that frequency valve ...

Freq valve will not stall engine. It will run but with little throttle response. O2 circuit fuse out, bad relay will not kill engine - same root cause. Symptoms are not similar.

[Bob Kontak]

Originally Posted by brad951

I'm thinking maybe something more serious, make the tensioner let go and the timing chain skipped a tooth...

Doubt it.

Given these types of blowouts happen once in 20 years - if neglected, do you really think this happened while you were farting around with distributor stuff?

The chance that your gas gauge is wrong and you ran out of petrol is much higher.

[JJ 911SC]

Originally Posted by Bob Kontak

Doubt it... The chance that your gas gauge is wrong and you ran out of petrol is much higher.

+1, BTDT.

I was 1 mile from home and as the car stall and would not restart I started to think there was something wrong with my ignition systems, slightly modify like the rest of the car .

When the CAA guy show up, he even ask me if I was sure I had gaz in the tank... I said yeah

The next day my buddy said lets put some gas in the tank just in case. The sound of the gas hitting the bottom of the tank left no doubt where the problem was, the owner...

[boyt911sc]

Brad,

Please post these additional information:

Cold control fuel pressure.
Heater resistance (Ohms) for the WUR at cold state.
Confirm presence of ignition sparks (inductive timing light would be helpful).
Confirm absence of significant vacuum leak.

Keep us posted.

Tony

[brad951]

Originally Posted by boyt911sc

Brad,

Please post these additional information:

Cold control fuel pressure.
Heater resistance (Ohms) for the WUR at cold state.
Confirm presence of ignition sparks (inductive timing light would be helpful).
Confirm absence of significant vacuum leak.

Keep us posted.

Tony

Hey Tony

Yes, I'll get the cold pressure and WUR resistance numbers.
I put an inductive timing light on it during cranking and it is sparking. I also put a plug in cyl 1 wire grounded on motor mount and it sparks blue. I then put a plug in the coil wire during cranking it also sparks blue (much more frequently of course). I can't tell if the sparks are as strong as they should be, but they did look good to me.
I am not aware of any significant vacuum leak unless one formed exactly at the point
where the failure occurred.

The strange thing is the car was running great, idling right in front of me while I was looking at it, it had been idling fine for about 15 minutes since start from cold, and it has never had a rough running or no-start condition before. It started running rough, stalled and would not restart all of sudden - I did touch the retard vacuum line from the dizzy at that very moment, but I cannot see how that would have caused this. There was no backfire that would crack the airbox (and I have a functioning valve there anyway).

All of this to say it's hard to believe that vacuum leaks or the WUR could fail at the moment, but possible I guess.

I am starting to suspect fuel again. Maybe the pump isn't running when it needs to. I need to double check pump operation during both cranking and run position. Maybe the fuel pump relay isn't working as well as I think...

Thanks all for the help, I really appreciate it !

[brad951]

I figured out the problem this morning. After fully diagnosing the fuel system and determining that it was working fine, I turned back to ignition. I was getting spark but the car was really acting like a case of the timing being way off. The distributor was in the right adjustment spot though as I had just checked the timing the last time it was running and I had not moved the distributor.

So, I went back to the point where it stopped running, and that was when I removed the retard vacuum line from the vacuum advance diaphragm on the side of the distributor. I removed the distributor today and took it apart, and found the arm that goes from the vacuum advance unit inside the distributor had fallen off the pin it connects to. I reconnected it, put the distributor back together, reinstalled in the car and it started right up - set the idle speed, checked the timing to 5 degrees BTDC and it runs great again.

This indicates a concerning issue though. What caused the arm to fall off the pin ? What holds it on there ? When you fish the arm into the distributor and hook it on the pin, you cannot see inside or put any kind of retainer on it... When I pulled that vacuum line off to check the timing, it seems the removal of vacuum jarred the arm and it disengaged.

So it's running again, but I'm not comfortable with the way that vacuum advance works. I have a feeling I'll be dealing with this again in future.

Thanks everyone for your ideas and support - as always !

[brad951]

A little more research tells me that there is supposed to be a circlip on that pin to keep the advance arm from falling off, right ? I guess I'll need to take it apart again and get down inside the distributor...

[patz]

Give it a blast of kwik start/ether into the intake while cranking. If it coughs or tries to start Bob ain't that crazy.

[brad951]

It's running great after fixing the distributor. No ether required ;-)

[SCadaddle]

I would guess that if or when you grabbed the distributor rotor and twisted it against the spring tension to check the smoothness of the advance that is when the advance arm came loose.