$100 Prize for the Guru that solves my Itermittent long cranks problem!
 

First let me clarify that this has been going on for a couple of years, and during that time I have read all topics on this forum of no-start, cold, warm, you name it I have read it.

The car:
1977 930 with 3.3 Pistons, and Ignition (counter-clockwise rotation, dual vac.) and all
The 77 CIS including 8-pin CDI with replaced internals with modern electronics by another vendor. Engine out all new top end service. The car runs great and it always starts.

Sometimes it will take just a touch of the key and it will start right up, cold or warm. Quick after a drive or after a couple of weeks parked it does not matter, if it in the mood it will start right up.

But 1 out of 3 it fells like it misses that sweet spot and you will have to crank it for several long no-start cranks until it starts. The amount of time it takes is completely random. It could be warm, or cold it does not matter.

What I have troubleshooted and replaced during the last 2 years.

1. Both fuel pumps and check valves.
2. Fuel Distributor and WUR set to Tony to repair and calibrate.
3. Removed MSD and replaced with CDI with modern internals.
4. New Distributor for 3.3 bottom end
5. New engine wire harness
5. Spark plugs and cables with proper OHM ends
4. New coil and coil wire proper OHM end
5. Ignition switch
6. Fuel Filter and New Fuel Accumulator
7. New high torque starter.

Ignition timing: I do not recall now, but we have verified several times and it is within specs.

Fuel Pressures: Also all values are in spec as per my WUR as per CIS Primer hand notes for Turbo Cars.


It is not a big deal because it always starts, but if really frustrating having this issue plus my SC starts right up every single time and it just feels good.

Any suggestions on what to try or test next, I ran out of options. The person that submits a suggestion or proper help to solve the problem will receive $100 via paypal as a token of my appreciation.:)


Merry Xmas!

Ivan



http://forums.pelicanparts.com/uploa...1608815128.jpg

Somehow you have to find out if it's spark or fuel. On one of the times it wont fire right up check for spark. If you have a strong spark then you know it's fuel related and you can proceed from there. Do you have a fuel pressure gauge? If yes install it and drive the car until you have the issue then check the the pressures.

the green ignition wire,, mine was always a problem..

Distributor

My 86 930 does this too. I kinda think it’s related to the massive inter cooler I have in it. I *think* you need to have vacuum for the distributor to have the correct advance to start.

Having no IC on your 77, this may not be the case.

I would start by checking for vacuum leaks if I was you, particularly your Turbo which were notoriously bad on the 76 and 77 cars. I know the turbo on my 86 needs to be rebuilt and I think this is my issue.

I had similar symptoms with my 77 930.
Turned out to be that the front fuel pump had a mind of it's own.
The car will run fine with just the rear pressure pump working.
Take away the front suction pump, for whatever reason, and the car may take several long cranks to fire up. When it finally fires, it ran like it was only firing on 3 cylinders until the lines filled up, and the rear pump built up enough pressure.
Just because you have replaced the pumps does not mean that they are performing as designed.
Bill K

It is new

It was purchased new for the 3.3 bottom end. How can we confirm that is having issues?

.
I have done that several times and fuel pressures are on spec. So I eliminated fuel as the reason. Also on the long cranks you smell the fuel fumes.

I thought about this, the only way to make sure I guess it will be to install 2 pilot lights inside the car form the 12V of each pump, that way I can confirm that both pumps are working when cranking. Any better Idea to discard this option?

I will put the fuel gauges back (again) and post the numbers. I will also try to install the (2) lights for the fuel pumps (or better idea) to have all the fuel data for reference.

I have smoked and applied carburetor cleaner all over the engine after assembly and so far have not found any leaks. But I am always looking.

Have you verified control pressures on the WUR?
Have you verified the air flow metering plate is moving while cranking?
Have you verified that the air flow metering plate is moving off the fuel pump switch?
Have you cleaned the fuel distributor - especially the fuel plunger rod and matching cavity?
Have you verified the CIS injector flow pattern?

Does this happen with full or empty fuel load?
Have you cleaned the siphon screen on the fuel tank?

Tony ....... to the courtesy phone.

He stated that Tony rebuilt and checked the FD and the WUR.

I like the siphon screen idea though.

Just a thought, have you checked or replaced the fuel pump relays? I believe there's a upgrade kit for the turbo fuel pump relays.

Here it is: https://www.google.com/search?source=univ&tbm=isch&q=1977+porsche+turbo+f uel+pump++relay+upgrade+kit&client=firefox-b-1-d&sa=X&ved=2ahUKEwjakp62neftAhVFElkFHTpADOQQjJkEeg QIBhAB

And there's this: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&ua ct=8&ved=2ahUKEwjakp62neftAhVFElkFHTpADOQQFjALegQI CxAC&url=http%3A%2F%2Fforums.pelicanparts.com%2F91 1-930-turbo-super-charging-forum%2F424622-930-fuel-pump-relay-wiring-once-all.html&usg=AOvVaw3fijoEBWsK4b9U5kUoIcxX

The issue is fuse 16 gets overheated.

Flaky WUR. The diaphragms can be good but the bi-metallic thing can be erratic.
If I’d done everything you’ve done ignition wise, I’d borrow or plunk down for another WUR.

Check these suggestions......
 

Ivan,

Install the CIS gauge and measure:

• CCP (cold control pressure) electrical plug to WUR disconnected.
• Check the system pressure.
• Install the WUR electric plug and start the motor.

Have you done a smoke test to verify the absence of unmetered air going into the system? I would be curious to know how the CSV and fuel injectors delivered fuel looks like during the initial start stage. You want a mist-like V patterns and not a jet-like flow spray pattern. Keep us posted. Thanks.

Tony

Cold start injector working?

Sounds like you’ve taken a thorough approach.

What about the basics?
Leak down and compression numbers?
Valve adjustment?
Cam timing checked?

Usually temperature based?

Yes to all of the above

I removed it (pain in the butt ) verified that is was working when voltage applied with power probe. Long cranks happen cold or warm., it does not get any colder than 75 degrees down here:)

Hi Tony,

I did a smoke test at the beginning but it will be a good idea to do again.
I have not verified the injector pattern, they are new with the exeption of the CSV. One thing I notice is that I can not use the typical CSV base with the AAR valve hose connection. It will not fit. The car had the hose port blocked off and I had to do the same for the new one. So the CSV does not have a direct air supply at the injector connection. that hose is going into the intake. See pic below.

http://forums.pelicanparts.com/uploa...1608850176.jpg

Here is a video of what happens sometimes.

https://youtube.com/shorts/xi5c9DS-gjg

After that I went inside for about one hour and when I tried again it started right up in 1/2 a crank
CRAZY!!!

Auxiliary Air Regulator...........
 

Ivan,

If I understood you correctly, the supplementary air from the AAR is not connected to air box but rather to the intake manifold? Do you have a picture to share? So that could be the reason your engine is grasping for air during a cold start. Are you experiencing this problem with a warm engine? Has anyone have good results using this configuration?

I am still interested to know your cold control and system pressures. Thanks.

Tony

Multiple attempts.........
 

Ivan,

From your video, I counted the number of times it took the motor to start. Six (6) was my count and that’s a lot of raw fuel delivered by the CSV in the air box. After getting the motor to run and you turned it off, could you re-start it in a single attempt?
Keep us posted. Thanks.

Tony

Does it get energized when you hit the starter? I know I had a start issue for a while until I discovered my CSV power lead was disconnected. Could be a bad connection. If you have a failed thermotime switch (not sure if your car has one, my 1973.5 does not and is energized when ever the hand throttle is fully pulled up and the starter engaged).

From: https://jimsbasementworkshop.com/CIS/pages/comp_page.html#ttswitch

Switch.
 

Ignition switch.........

External or internal connection.

What about the fuel pump check valve? Fuel could drain back towards the tank. I have had similar issues but do not have a turbo.

Does your gasoline have ethanol in it? Puerto Rico right?

Does this only happen when the engine is warm and then you try to restart after about 10 minutes? After the engine cools down the problem goes away?

Is it worse on warm days?

Is the car parked on a slight downhill slope?

Does it matter how much gas is in the tank? The problem is worse when the tank is less than half full?

Sorry for all the questions, but you may have bubbles in your lines. That's why I ask.

is your yellow relay working correctly???try to change it for red relay....and see

Ivan

Tony, here is a pic of where the AAR hose is connected.

It happens cold or warm, it makes no difference.

This morning it took several long cranks to start, then it started a couple of times quick and then it required long crank again to start.

I will re-do my system pressures as soon as I get my new set. But I used the car for a while with the gauges installed and fuel pressures were on spec for a 022 WUR.

http://forums.pelicanparts.com/uploa...1608896530.jpg

Both check valves are new

It can start form a single attempt but not 100% of the time.

91 Octane no ethanol, engine warm or cold.
All days are the same temp.
Car parked flat
Tank full

No yellow relay

your 930 does not have that relay or you bypassed it?
it should be here..no 4
https://rennlist.com/forums/attachme...r-fuse-box.gif

That one is bypassed to feed CDI no shutoff delay.

REPOST of mine from a few days ago, if it helps you then just great. If not, then maybe it will help someone else.
.................................................. .................................................. ..........

The brake booster operates off vac pressure from the intake manifold. There could be a leak in this line.

Until I can replace the line via partial engine drop I put some goop on the large flexible hose running along the firewall that connects under the car to a metal junction. My leak was near the connection under the car.

This improved both cold and hot starting.

No leaks using starting fluid method at intake manifold gasket.

I have never seen a thread on this topic.

Hose may be weak and collapsing.

You can order new hose from Pelican and cut to length.

Pictures
http://forums.pelicanparts.com/uploa...1607706927.jpg
http://forums.pelicanparts.com/uploa...1607706927.jpg
http://forums.pelicanparts.com/uploa...1607706927.jpg

I also readjusted the fuel/air mixture for cool weather prior to this, and think that helped.

EDIT:

In short, a leak in this vacuum line path anywhere in the car will mimic an intake manifold gasket leak and may cause unpredictable starting issues.

I did not notice any braking issues until a bunch of other braking components failed, this hose leak would not have been found otherwise.

If you have boosted brakes your actual leak could be anywhere in the path from booster to engine.

I'm not sure how MFI and carbureted engines supply vacuum assistance to brake booster, my engine is CIS.