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

[ivanuf]

Originally Posted by jpnovak

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?

Yes to all of the above

[ivanuf]

Originally Posted by HarryD

Cold start injector working?

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

[ivanuf]

Originally Posted by boyt911sc

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

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.

[ivanuf]

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!!!

[boyt911sc]

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

[boyt911sc]

Originally Posted by ivanuf

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!!!

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

[HarryD]

Originally Posted by ivanuf

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

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).

[HarryD]

Originally Posted by ivanuf

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

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

Thermotime switch:

This switch allows operation of the cold start valve at engine temperatures below 45 Degrees C (113 degrees F) and then only for a few seconds during starting. Power is applied to the switchs internal resistor from the starter. The internal resistor heats a bimetallic strip which interrupts the current flow on the ground side of the cold start connection. After engine warmup, engine heat is responsible for holding open the bimetallic strip, so that the cold start valve will not energize when the starter is operated on a warm engine. Also, after several unsuccessful starting tries on a cold engine, the internal resistor will heat the thermotime switch and cold start valve operation will be inhibited until the switch cools.

Failure modes: An open circuit at the internal resistor will allow the cold start valve to operate an excessive amount of time if the engine does not start soon on a cold engine. An open circuit at the bimetallic strip in the switch will prevent operation of the cold start valve.

[86 911 Targa]

Ignition switch.........

External or internal connection.

[kltarga72]

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.

[tperazzo]

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.

[proporsche]

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

Ivan

[ivanuf]

Originally Posted by boyt911sc

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

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.

[ivanuf]

Originally Posted by kltarga72

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.

Both check valves are new

[ivanuf]

Originally Posted by boyt911sc

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

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

[ivanuf]

Originally Posted by tperazzo

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.

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

[ivanuf]

Originally Posted by proporsche

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

Ivan

No yellow relay

[proporsche]

your 930 does not have that relay or you bypassed it?
it should be here..no 4

[ivanuf]

Originally Posted by proporsche

your 930 does not have that relay or you bypassed it?
it should be here..no 4

That one is bypassed to feed CDI no shutoff delay.

[kach22i]

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




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.