I already had this problem. I will give you my 2 cents of how I would do it.


1st : To prevent too much gaz to go thru your cylinder, remove your injector and put the 6 nozzle inside a little bottle. You will be able to see if your injector works like it should. Remove the 12V at your Wur and your AAV to make sure the car acts like cold.

2nd : Remove the air filter, put the car at ignition, bypass the fuel pump to make sure it pumps all time and lift the fuel plate inside the airbox to ensure you have fuel coming from the fuel pump and the injectors spray.*

3rd : Put the filter back, remove the bypass at the fuel pump and crank the car to see if the injector sprays. Try the best you can to hear the cranking speed of the engine. We will need it further.

4 th : The Wur on a row car has a vaccum and a thermo valve in the vac line. The thermo valve is supposedly close when the car is cold, so it prevents the vacuum to go thru the wur and it richens the mixture for cold start. Unplug that vac line to make sure the wur richens the mixture. You can also check if the line has vacuum further.

5 th: Remove the air line going to the AAV to make sure the valve is open to provide enough air for cold start.

6 th : Put back your injector in the intake runner, and crank your engine. See if it cranks faster than in Step 3. If the speed is the same, you need more fuel. The car will crank faster if your cylinders are wet.
(Your problem can be your csv / thermo time switch, bad fuel pressure)

7 th : Remove your air filter and ask someone to lift up the plate a little bit while you crank. You should hear the car crank faster and the car should start. If not, the problem is somewhere else...(Ignition timing or air leak (smoke test)

Depending on what happens while you do this test, it will give us some more info. On my car, my fuel pump always runs when I put the key at ignition. I made it this way because I live in a really cold area and need more fuel for Cold Star (5 degre celsius).

Thanks

I'm going to pull the plugs and run the engine to make sure I didn't flood it. In all my tests it never seemed to run faster even with trying to lift the plunger with the FP running and force fuel into the cylinders.

After that I run through your steps.

Also, when I said I sprayed started fluid I originally shot it into the toilet cover hole, then thought I never got a good shot into the throttle body.

Is there a good place to shoot the starting fluid in? I don't think it will run with the throttle body boot off right?

Do not use starting fluid. You don't try to start an old Caterpillar diesel engine. Also, the starting fluid will go down the airbox and will only go inside the lower runner at the airbox (2 and 5)… In that case, if your ignition is off and the intake valve is open, when the spark plug ignites, it will burn the mixture, backfire in the intake and explode your airbox… The pop-off valve can do the job, but that may be an expensive mistake. It's the CSV job to richen under starting condition and the metal spider to make sure each runner has enough fuel.

Plugs pulled - all gray with a little brown, none were wet.

Turned it over a couple times with the FP off.

Been Watching By The Sideline……….
 

Nick,

You need to do a systematic test to identify the culprit/s. If this was my car, I would do the following not necessarily in this order:

• Install a WUR with the correct control fuel pressures.
• Test and confirm that the CSV is working.
• Test for air leak using a smoke generator.
• Is the starter cranking the motor fast enough to get it to run?
• Install a known good CDI.
• Are you getting any sign of fuel combustion?
• Etc.

The car was running before so something had changed to immobilize the car. Were you able to get the motor to start and install at all? Even for a second or two? If not, then you are not producing engine combustion at all. A squirt of Starter Fluid could tell you if the motor is capable of producing an engine combustion in the chambers. Keep us posted.

Tony

Read post #5! Many of the recommendations have been tried.

Nditiz1: Well, at this point in this thread, you're getting conflicting advice and suggestions.

You know what to do: Air (compression), fuel, spark. It was running last week, so it's something simple. The compression didn't suddenly change on all 6 cylinders, and it's very unlikely that you suddenly got a massive air leak, or that your fuel pressures suddenly changed, and you showed a picture of a nice blue spark.

Think like Roadkill Garage, simple stuff first. Get it to fire on starting fluid, then gas, before you start pulling things apart or checking pressures. It ain't rocket science...

If someone were to spray starting fluid in, where would be the best place? pull vacuum hose off boot and spray in the hole?

Does this look right for spark? Seems slow. I also sprayed a bunch of starting fluid prior to taking this video and still no catch, not even for a second.

https://youtube.com/shorts/Q-k9jvIoOao?si=RZbD_-zHM3CZBD9P

Low Batt…………
 

Nick,

Don’t expect to get your motor to start with your current battery status. The battery is too weak to crank and get it to START. Have your battery tested. I will bet you it will not PASS the test for CCA (cold crank amperage). Lastly, the spark signal shown in the video is a JOKE. The ignition signal is too weak. Try an inductive timing light. How old is the battery? Good luck.

Tony

Post #9 describes how to check for a STRONG 10mm blue spark! Additionally, remove all plugs and check for fuel fouling.
Replace only 3 plugs, after air blowing plugs, and spray starting fluid into air filter. Then try to start.

Tony battery is 6 months old, I will have them test it.

As long as it's cranking normally, the battery is OK. No need for unnecessary tests!

Something that "jumped" out at me from your video--the spark did not occur on every cycle. It missed several times. So maybe your ignition is at fault.

Do what Dave recommended.

An excellent way to check your battery under a real load is to measure the voltage drop when you are cranking the engine. If it drops much below 10 volts, your battery may be weak. I hope you put a charger on it after all your testing/cranking.

Thanks Peter, I have been charging it on a NOCO Genius 3500.

I just performed some more tests like in my video.
All with similar results even with a different CDI (MSD5520) and a different coil. I'm not ruling the CDI out, but I will say that Bob Ashlocks work is one of the best. I can easily send it out to him for free testing.

Maybe as Tony said my battery is crap. I did not test it under load. Could drop too low to create the needed spark. I have had 6 month old batteries die before (wifes Acura, factory battery)

I will swap it out tomorrow and report back.

EDIT:Maybe the hi-torque starter is masking the battery issue, enough to spin that little unit, but too weak to power CDI

Really? You're joking now, right? Anyone who's owned a 911, can easily hear whether the battery is weak by the sound of the starter.
Furthermore, why haven't you checked the battery voltage with a VOM while cranking? Good rebuilt CDIs should produce an adequate spark
for ignition at a battery voltage of 8.5V to 9.0V. Hopefully, your "rebuilt" CDI isn't one of those ones with a "re-design for better operation/performance"?
Have you done the spark test referenced in post #9? This will provide an indication of the energy level of the spark while cranking.

The key overlooked potential problem, i.e. the ignition coil! Hopefully, you have the original small black coil, and not the silver Bosch coil, right?
You can always use an original VW coil for testing.

Dave just mentioned something that I should have thought of earlier--the coil (I have suggested it in other threads--Doh!).

Coils do fail gradually and/or intermittently. High humidity or high temperatures can cause them to act up, or they just start missing or hard to start for no apparent reason. If there's any way you can get or borrow a spare, try swapping it out. Pertronix and MSD offer coils that are compatible with CDI. There was a thread a couple months ago where we listed out the electric characteristics of several coils and identified at least two that are good matches (I just can't find it right now). IIRC, one was the Pertronix 8222. They aren't expensive either, about $60. If you don't carry a spare coil in the car, that would be a good reason to buy it anyway.

The coil I had on is a bosch black. I tested it with a VOM and it looked the same as another bosch spare I had. I also have an MSD one that was used by another member when he was stranded. I have tried all 3 with no difference.

As far as the CDI. I am using an original rebuilt one one. Also, as I stated I tried an MSD 5520 which has also been tested and is working. I might even go as far as swapping the CDI into my other 911 to rule it out completely.

Are you sure the MSD CDI was connected properly? Have you checked the distributor pickup signal for about 600 millivolts AC. How about testing the rotor and the distributor cap?


That should've been one of the first tests!

Dave I appreciate the comments, but sometimes you come off as arrogant. As you stated I think I know how to wire an MSD after installing my CR AC.

Anyhow, just for sanity, I swapped the CDI out of the no working car into the working car and it fired right up. CDI box tests good.

I can swap over the coil and the battery as another sanity check, but I feel similar results will be supplied.

So, what would just stop the car from running one day to the next? All starting with the weirdness at the starter it might be time to get it up in the air and check the ground wires as well as the connections at the starter. Could a bad engine ground cause intermittent spark?