Tts and csv question

[Johner]

Hi,

I'm still pursuing a cold start issue and testing various CIS parts. My tts tests at 25 ohms (yellow wire connection) and 0.5 ohms (red/black connection) which sounds good. Looking at the circuit diagram for an 83sc
http://cis911primer.com/pages/elec_csv.html it looks like I could check the csv coil resistance too by measuring across red/black and yellow wires. Does anyone know what resistance I should look for? I also wonder whether I could energize the csv by putting 12v across these wires and listening for the csv to 'click' (as described in the cis troubleshooting procedure). Does this sound reasonable?

Thanks,

John

[timmy2]

12 volts applies directly on the yellow wire may make your starter solenoid pick up and try to start the car.
It is a direct connection to the auxiliary switch in the starter solenoid circuit from the CSV.
Likely won’t, but if the switch on the starter is stuck closed it could. (Terminal 16 on starter)
Look at the 78 current flow diagram on Pelican to see the circuit wiring clearly.
You could Disconnect the small yellow at the starter to be sure..

[T77911S]

never heard of a bad CSV.

whats wrong, no start?

you might try removing the 2 wires from the TTS and measure the resistance of the CSV coil. don't know what it is but tony will

[Johner]

Hi

I'm having difficulty with cold starts (car only starts after sveral attempts and with throttle partially open, car runs and starts fine warm). My fuel pressures were out of spec so adjusted them following Tony's advice but still having trouble. I'm just trying to test as much as I can to rule out sources of the problem.

Thanks

John

[boyt911sc]

Originally Posted by T77911S

never heard of a bad CSV.

whats wrong, no start?

you might try removing the 2 wires from the TTS and measure the resistance of the CSV coil. don't know what it is but tony will

Ty,

It has been a while since I did some testing with the CSV. They are very robust and hardly go bad but they fail too. To fully evaluate a CSV you have to do two things:
1). Electrical & resistance tests.........12 volt supply and connected to a good TTS.
2). Pressure and leak tests...............connect to a fuel pump and pressure gauge.



The two (2) CSV in the center of the picture that have “X” were defective or bad and the good ones in the plastic bad. Shown is the special fuel line extension I use to test the CSV with the engine installed in the car. Test and confirm.

Tony

[Johner]

Hi Tony

Do you happen to know what the csv coil resistance is? I'm trying to do basic continuity and resistance tests as I don't have time to remove the csv at the moment

Thanks

John

[gazzerr]

I think all you can really do is test it like Tony does when you apply pressurized fuel and 12V. If it opens when powered and pressurized with a good spray pattern and closed when not and doesn't leak then it's good. That's the factory service manual test.

[T77911S]

tony,
what is the coil resistance on the good ones?
are the coils open on the bad ones?

[timmy2]

Coil will be open if it has failed.
Small DC coil, should be low ohms if good.

[boyt911sc]

Originally Posted by T77911S

tony,
what is the coil resistance on the good ones?
are the coils open on the bad ones?

Ty,

I have more than two (2) dozens of CSV and they all have resistance values (Ohms). Even the two (2) bad ones have 4.1 Ohms. On the average, the resistance readings range from 4.1~4.3 Ohms but found 4 with 10 Ohms (?). I tested them with FP running and energized the coil. Observed the spray pattern and checked for dripping after it was switched off. I was looking for good spray pattern and no dripping or leak at standby.

Without physically doing the pressure test with a test liquid, you will not know if the CSV is good or bad. This is one of the tests I performed before an initial start up after an engine rebuild. The only time I had problem getting a CIS engine to start and run was when I inadvertently installed the cam shafts in reverse. This was a stupid mistake that I discovered later.

Tony

[Johner]

Thanks everyone for the answers. That helps me at least check there are no wiring problems. Based on the inaccessibility of the location and the experiences with its failure rate I'll probably leave removing the csv until I've ruled out everything else.

John

[T77911S]

tony
so If the bad ones can still have around 4 ohms, what is failing? have you ever cut one open?
is the solenoid part inside sticking?

the 10 ohm ones are good?

[boyt911sc]

Originally Posted by T77911S

tony
so If the bad ones can still have around 4 ohms, what is failing? have you ever cut one open?
is the solenoid part inside sticking?

the 10 ohm ones are good?

Ty,

I don’t normally measure the CSV resistance (Ohms) because I have not tested a CSV with a bad resistance (coil). I focused on the fuel delivery instead:
a). Spray pattern.
b). Volume of fuel delivered.
c). Drips. There should be no drips at standby (FP running).

The two (2) CSV with “X” (defective) in the picture did not pass the flow test either they were clogged or restricted or leaking. I could not recall the specific test result because I did the tests a long time ago. I also dissected a CSV to investigate the internal operating parts and found no obvious conclusion to the cause of the problem.

The higher resistance (10 Ohms) CSV probably came from a different manufacturing plant or production batch. The resistance for the CIS components made in “France” are usually higher than those with “Germany” based from the collection of parts I have tested. I have ample documentation for this observation.

Tony