CIS problem, car wont start.

[safe]

Hi
My car has not started i 2 weeks! Even when I brought her new Fuchs with SO3 to replace her cookie cutters did she start !!!

I have sparks so I´m guessing fuel problems...

I have Probst fuel injection book so I am going through the trouble shooting..
I have measured:
Fuel delivery, 1450ml in 30 seconds.
Fuel control pressure delivery, 125 ml in 30 seconds.

Today I made myself an pressure gauge and measured:
System pressure: 0.6 bar
cold control pressure: 1.2 bar

That is odd!!
In Probst book the pressure gauge had its valve on the FD side but when I read a post here (cant remember who) is said valve on WUR side.
What should it be?

Also when you jump the fuel pump. Does it circulate fuel in the system?
Because when I jump it the pump is very quiet and when I disconnected the return hose for the delivery test it "sounded" a lot more. Its almost as it is trying to pump fuel but cant, also when jumped it draws 16 amps!

[Paulporsche]

Magnus,
I can help you with some of this. The gauge should go between the connection @ the top center of the FD and the top of the WUR. Your cold cp seems OK, but your fuel pressure should be 4.7 to5.2 bar. Your residual fuel pressure after 10 min should be at least 1.3 bar, and after 30 at least 1.1. Your fuel pump should draw usually around 5 or 6 amps, w/ a max of 8. The tests should be done w/o the engine running.

[safe]

To answer my own question about pressure gauge: the valve pust be on the WUR side, how else could you meassure system pressure? It helps to think sometimes......

I will go back to the car and get correct values.

[Paulporsche]

I can get back to you in a few hours to verify cold cp.

[safe]

New values:
System pressure: 4.8 bar
cold control pressure: 1.4 bar

[Rex Walter]

Safe,

I have a CIS car, and the cold start injector was not working. The engine would kick when you initially hit the starter, but then the engine would not fire at all - just crank and crank.

The cold start injector is controlled by starter voltage and a thermotime switch.

It is in the back of the CIS unit, and probably really hard to get to, but it might be worthwhile to unbolt it and see if it is spraying fuel.

Rex

[Paulporsche]

Your values are OK. Now check the residual pressures I mentioned earlier. Could be your fuel accumulator or fuel pump check valve. A search will give you lots of info on this.

[ianc]

Check the cold start valve as Rex Walter suggests. Even if all else is OK, the car will be difficult if not impossible to start if it's not working properly,

ianc

[safe]

I will go and try to check the cold start valve.

Problem is I cant see it or get to it.

Does someone have a good close up picture of the back and what kind of fastener that is used?

[ianc]

It's true you need a third elbow to get at the damned thing with the engine in the car. Mirrors re helpful.

I believe it's secured by a couple 6 mm allen heads,

ianc

[safe]

A small breakthrough maybe.

When checking cold start valve I had it disconnected to see if it got any power while cranking.

I had ignition on and jumped the starter from the 14pin connector and the engine fired for a second and died. Wow !
I connected the cold start valve again and jumped the starter and the engine fired as long as I cranked it and then died with a backfire.
The I remembered that I didn't have the fuel pump relay connected so I installed that and cranked again, but from the key. As dead as before.....
I then tried without the relay but with a wire from 30 to 87a so the fuel pump would pump on ignition. Still dead!

Any theories?

[Paulporsche]

Fuel accumulator, fuel pump check valve, vacuum leaks, blown or open popoff valve, blown airbox, leaks around injector seals, stuck or out of adjustment sensor plate or plunger, boot over sensor plate.

[safe]

Paul: But those thing dont explain why it starts when I jump the starter from the engine bay and not when I try to start it from the ignition.

The car has never ever backfired before.

When I jumped it it is like it started but when the starter lost power the fuel pump stoped.

[Paulporsche]

Check around behind the fuel dist/ throttle area. There is another connection near the cold sv. It is green. It isdesigned to turn off the pump in case the car tips over. See if you have one of these. If so, make sure it is connected and receiving power.

You may have a starter wire/ switch problem separate from the run problem.

Check the round black connections under the dash/ steering wheel.

[safe]

That switch seam to work. When I removed the connection the FP relay lost power.
I also think that this is not my older start problem.

Forgot to check connections under the dash.

I found this in another thread:


I set up a test on a bench:
I put 12v on 86 and 87a and ground to 85.
When I then put 12 v on 87 (starter) then 30 gets 12v. But when I remove 87 I lose power to 30.

What is responsible for powering the fuel pump when the engine runs?

[Paulporsche]

Are you doing this w/ a relay in place? Have you tried another relay? Checked fuse box wires and connections for contact and corrosion?

Were you able to start the car by raising the sensor plate?

[safe]

I have tried another relay, did nothing.

I sprung a fuel leak in the enging bay so I decided to take a brake letting it dry up.
Im also giving up for the day, it´s late over here now.

I finaly understand how the relay work now!

When the Air plate switch breakes it breakes power to the relay and it goes back to its "Normaly Closed" position and supply the pump by 30-87a.
So the relays only function is to kill the pump when the engine isn´t turning over.

[Paulporsche]

I think that is the only difference between the red and black relays.

[ianc]

The red relay has a diode in it while the black ones don't. What the diode does I don't know. You can use the black relay for the fuel pump and it will work fine.

The reason the car ran when you cranked it is because it was running off the fuel supplied by the cold start valve alone. The CSV supplies continuous fuel while cranking until the bimetal in the thermotime switch shuts it off. It's like 3 or 4 seconds, depending on ambient temp. Sounds like the injectors are not receiving fuel when the key is in the run position.

Turn on ignit and raise the sensor plate. Does the fuel pump run?

ianc

[safe]

Originally posted by ianc
The reason the car ran when you cranked it is because it was running off the fuel supplied by the cold start valve alone. The CSV supplies continuous fuel while cranking until the bimetal in the thermotime switch shuts it off. It's like 3 or 4 seconds, depending on ambient temp. Sounds like the injectors are not receiving fuel when the key is in the run position.

First time I didnt have the electrical connection to the CSV connected.

[
Turn on ignit and raise the sensor plate. Does the fuel pump run?

Yes, it runs.


/Magnus