SC runs only when in START

[larrym]

excellent old-school suggestion! - start first with the easy stuff:

Originally Posted by mreid

Ham fisted body shop broke your ignition switch (we all know that when a car is hard to start, you just twist the key harder). The ignition contacts in the switch are not made when you release the key from the start position. You can test it by jumping the switch and then replace the switch.

a very common symptom in a whole lot of older cars of all makes - the start circuit to coil bypasses the ignition run circuit (for reasons you can google)

- if the run circuit is damaged or disconnected or has developed a bad resistance you get exactly this symptom

[boyt911sc]

Originally Posted by blg5035

Thanks Craig! PM sent

I was unable to find real CIS hose locally, so I went to a hose fitting place and had this made up. They used the original banjo fittings, which Tony has said is the only real important part.



After installing the hose, I checked the fuel pressures. The first time it looked good:

System pressure: 4.7 bar
Cold control pressure: 1.5 bar

I checked it a few more times over a couple days and sometimes I would get similar readings and other times they wouldn't be quite right.

System pressure: 4.7-4.9 bar
Cold control pressure: 1.5, 3.5, 4.25, 5.3 bar

After seeing these, I checked the new fuel line. I disconnected it at the rear of the FD and ran the hose in the bucket. With this setup, the cold control pressure was 1.5 bar as expected. I reattached the hose and tested again and got one of the funny values. I am suspecting there is something wrong with my gages. I have also noticed the fuel that comes out of the gages has a redish tinge, which the fuel going in does not have.

At this point I said screw it and took the gages off and decided to crank the engine. It sustained an idle! However the idle speed is off. Sometimes it is towards 500rpm other times it'll be around 750rpm. It is also smoking out the exhaust. I took a video. When I give it throttle it is maybe 1/4 and held constant. Immediately after I let go of the throttle, it will sound like it is idling nicely then drop back down below 1000rpm and idle rough.

https://youtu.be/gW2e-NWDamY

What has changed from before all this is the WUR and decel valve. I am now using a -069 WUR from Tony and have the vacuum lines connected to the decel valve and thermal valve. Previously the engine had a -009 WUR that does not have the side vacuum port.

Ben,

The system fuel pressure should be steady and should not fluctuate. Either the pressure gauge or the primary valve is defective or maybe both. This is something you could confirm. This is like taking a tire pressure reading. The pressure reading should be stable at X pressure. And should be reproducible. I don't see that from your test data.

Your idle speed is also strange that it does not go over 1200 RPM during a cold start. You might as well test if the AAR (auxiliary air regulator) is open when cold and closed after 4 mins. This is easy to bench test. I am interested to see how the decel valve's vacuum hoses are connected particularly the one that goes to the WUR.

Could you make a sketch how the decel valve, TV (thermotime valve), and WUR are connected? Thanks.

Tony

[blg5035]

Originally Posted by larrym

excellent old-school suggestion! - start first with the easy stuff:



a very common symptom in a whole lot of older cars of all makes - the start circuit to coil bypasses the ignition run circuit (for reasons you can google)

- if the run circuit is damaged or disconnected or has developed a bad resistance you get exactly this symptom

Thanks for the input Larry. Although I have not directly jumped the start circuit, I have used a brand new genuine ignition switch with the same result. I think we are on the right path that the car is running too rich because of high fuel control pressure.

Originally Posted by boyt911sc

Ben,

The system fuel pressure should be steady and should not fluctuate. Either the pressure gauge or the primary valve is defective or maybe both. This is something you could confirm. This is like taking a tire pressure reading. The pressure reading should be stable at X pressure. And should be reproducible. I don't see that from your test data.

I think I figured out the pattern of when I get a good reading (CCP = ~1.5 bar) and when I don't (CCP = 5.3 bar). It seems that when the system has sat and completely bled off pressure, the first time I run the fuel pump, I get system pressure of 5 bar and CCP of ~1.5 bar. Then I let the car sit for a little bit and bleed off some of the fuel pressure. When I test pressures again I get the bad reading.

With regards to the primary valve, in my first post I replaced it along with the o-ring on the plunger. I pulled it out and both the valve and plunger looked ok. I can try the old plunger if you'd like. There was nothing wrong with it to my knowledge when I replaced it.

Originally Posted by boyt911sc

Your idle speed is also strange that it does not go over 1200 RPM during a cold start. You might as well test if the AAR (auxiliary air regulator) is open when cold and closed after 4 mins. This is easy to bench test. I am interested to see how the decel valve's vacuum hoses are connected particularly the one that goes to the WUR.

To be quite honest, I do not remember the car ever doing a fast idle when it was running previously with the -009 WUR and the TV and decel valve vaccum lines disconnected

Originally Posted by boyt911sc

Could you make a sketch how the decel valve, TV (thermotime valve), and WUR are connected? Thanks.

[blg5035]

It was the primary pressure regulator! The new one I bought to get the o-ring for the plunger is shorter than the one already in the FD. The difference is pretty clear when you put the large spring on (see attached photo).

Has anyone seen this before? The PPR I bought is 928 110 920 01. The US and UK PET's both say this part number. My FD is -031 for RoW



The shorter length prevents the passages that allow the WUR return fuel to return to the tank from opening. When I put the plunger (silver bullet) on the PPR and push on it, I can see the longer PPR's passages open. On the shorter one it took significantly more force to open the passages.

After reinstalling the old PPR, the pressures look to be good. I took a video of the pressure test: https://youtu.be/LSIM7FFvq7U . It looks like the residual pressure is failing with the old PPR installed, so I think the o-ring on the PPR is worn out. With the new PPR, the system maintained 1.1 bar for over 30mins after shutdown. Tony is going to send me a new o-ring

I took a video of startup and idle: https://youtu.be/OTUD7JVCscA. I also drove it around and it seemed to run well! First time it has been running since May! Thank you for your support everyone!

[boyt911sc]

Ben,

I am away from home and in Florida at the moment. There are two (2) o-rings for the PPR for FD-031. Will send the o-rings to you next week.

Tony

[boyt911sc]

Originally Posted by blg5035

It was the primary pressure regulator! The new one I bought to get the o-ring for the plunger is shorter than the one already in the FD. The difference is pretty clear when you put the large spring on (see attached photo).

Has anyone seen this before? The PPR I bought is 928 110 920 01. The US and UK PET's both say this part number. My FD is -031 for RoW



The shorter length prevents the passages that allow the WUR return fuel to return to the tank from opening. When I put the plunger (silver bullet) on the PPR and push on it, I can see the longer PPR's passages open. On the shorter one it took significantly more force to open the passages.

After reinstalling the old PPR, the pressures look to be good. I took a video of the pressure test: https://youtu.be/LSIM7FFvq7U . It looks like the residual pressure is failing with the old PPR installed, so I think the o-ring on the PPR is worn out. With the new PPR, the system maintained 1.1 bar for over 30mins after shutdown. Tony is going to send me a new o-ring

I took a video of startup and idle: https://youtu.be/OTUD7JVCscA. I also drove it around and it seemed to run well! First time it has been running since May! Thank you for your support everyone!

Ben,

In post #42, second sentence, it mentioned about the culprit. The troubleshooting became more difficult for you after you installed a different (wrong) PPV. Now that you have identified the problem and getting the right fuel pressures, time to tune the engine and enjoy driving the car. BTW, I will be sending you the o-rings after I get back home. Why don't you use the o-rings from the new PPR? And use the replacement o-rings in the 928 PPV? Send me a PM next week as a reminder. I will probably forget the o-rings after a day or two. Or I might remember it after several weeks. Thanks.

Tony