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> 1.7l starting issues, motor starts if I disconnect cyl 4 injector cable
b.stirbu
post Aug 9 2015, 04:14 PM
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Dear 914ers,

I'm quite in a pickle with my 914 1.7.

The engine sometimes starts sometimes not (usually after it started, ran 5-10 seconds and then stopped and I couldn't manage to start it again).
Messing arround in the engine compartment I accidentally unplugged the cyl 4 fuel injector and surprise the engine started and idled low. Tried again one, two, three times and he started succesfully, but as soon as I plug back the cyl 4 injector cable does not want to start again...

What's wrong here? (the injector not, because I've swapped 3 with 4 and I still had the same problem). According to the attached current flow cyl 4 injector is in series with the cold start valve and the thermoswitch for the cold start valve.. Am I looking at the right diagram? I also don't know where current track 102 comes from.


Also very interesting is that I removed the injectors 3 and 4 and placed them in two cups to see if they work, and I could start the engine in two cylinders (although the cyl 4 injector plug was connected)

Cheers,
Bogdan


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JeffBowlsby
post Aug 9 2015, 04:29 PM
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Hi Bogdan, Welcome to 914world!

A couple of things first off:

You have the schematic for the 1974 2.0L, but you have a1973 1.7L. Do you have the correct schematic?

The cyl 4 injector is not in series with the CSV or the thermoswitch. While these are in the fuel injection harness, they are not controlled b the ECU, rather they are in a circuit powered directly from the relay board.
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Dave_Darling
post Aug 9 2015, 10:02 PM
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QUOTE(b.stirbu @ Aug 9 2015, 03:14 PM) *
According to the attached current flow cyl 4 injector is in series with the cold start valve and the thermoswitch for the cold start valve.. Am I looking at the right diagram? I also don't know where current track 102 comes from.


The injector on track 102 is not the #4 injector. It's just the cold-start valve, and it grounds through the thermo-switch (often called the thermo-time switch). The switch is grounded (the thin line to the bottom of the page). The CSV gets its power from one of the pins in the four-pin plug on the relay board.

As Jeff notes, the 70-71 1.7 wiring diagram should be a better match for what you have in your car. I believe that the parts of the circuit I describe above are the same for yours, though.

--DD
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Valy
post Aug 9 2015, 11:39 PM
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The qire diagram is not much different, especially not for the injection part you are looking at.
I would check the cable that leads to #4.
Sounds to me like there is a short on that cable. See if there is any damage along the cable.

What happend just before this started to happen?

Bine ai venit la noi in club! Succes cu reparatia. (IMG:style_emoticons/default/wink.gif)
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b.stirbu
post Aug 10 2015, 12:45 AM
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Guys, thanks for your replies. Multumesc frumos Vali!

I have no history of the car. I believe it was not used since 1990, but it was stored inside.

There was a lot of gas in the oil and also had problems starting.. The initial owner passed away.. I believe he also had this problem and tried so much to start it that he injected all that gas in the cylinders.
When I opened only the long block, and the rings where still looking good and the valves the same, no signs of lowered seat..
I am certain that's a electrical problem..
I interpreted the diagram in the wrong way. The IV on the diagram is related to the relay board 4 pin connector.

I've tested the other injecto connectors for continuity between both wires and they all buzz, that's rather strange..

I could draw two conclusions from this situation:
-The cyl 4 injector cable is faulty or cyl 4 electronics in the EFI are faulty and as soon as the solenoid is energised it affects the other cylinders also
-The fault in the wiring affects the spark...
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euro911
post Aug 10 2015, 04:14 AM
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Hello Bogdan. ECUs are fairly bullet-proof, but anything is possible.

I see that Jeff Bowlsby has already responded, but have you checked out the trouble-shooting guides on his Tech Notebook site? ... If not, Click here for a wealth of information (IMG:style_emoticons/default/aktion035.gif)

... and (IMG:style_emoticons/default/welcome.png)
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Valy
post Aug 10 2015, 08:56 AM
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There are 2 things I woud check more:
1. Make absolutely sure that the spark plugs are connected in the correct order. More specifically, does it start if you disconnect spark plug #4?
2. I'm almost sure you can mix the injection wires around. Check what happens when you switch between #4 wire and some other wire.
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b.stirbu
post Aug 10 2015, 12:10 PM
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Update. If I build up fuel pressure first and then remove the fuel pump relay the car starts.. I tried to power the fuel pump from an external power supply and still did not started or at least tried... Is there a fuel pressure problem?
Vali, i tried to remove the #4 spark plug cable but does not want to start without it.
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b.stirbu
post Aug 10 2015, 12:31 PM
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Should the fuel pump be electrically isolated from the body? I replaced the plastic fuel lines with copper ones...
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Valy
post Aug 10 2015, 12:34 PM
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the pump is not isolated from the body.
did you try to switch the injector wires?
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SLITS
post Aug 10 2015, 12:45 PM
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QUOTE(b.stirbu @ Aug 10 2015, 11:10 AM) *

Update. If I build up fuel pressure first and then remove the fuel pump relay the car starts.. I tried to power the fuel pump from an external power supply and still did not started or at least tried... Is there a fuel pressure problem?
Vali, i tried to remove the #4 spark plug cable but does not want to start without it.


The fuel pressure should be in the 28 - 32 psig range for proper operation. If to high (blocked return line or misadjusted pressure regulator) it can override the spring in the injector and flow fuel constantly (flooding the engine). Since you said that you built pressure and then removed the fuel pump relay and it started ... I would look at your fuel pressure first.
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b.stirbu
post Aug 11 2015, 02:36 AM
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QUOTE(Valy @ Aug 10 2015, 08:34 PM) *

the pump is not isolated from the body.
did you try to switch the injector wires?


Yes, it did not started.

I will install a pressure gauge and then test again.
I find it strange that it starts on 3 cylinders with the pump running and on 4 cylinders with the pump off..
I'm pretty sure there is a short circuit somewhere.
I've checked the pump power cables, and they buzz if the 12 pin connector is connected to the relay board...is that normal??
Does the short circuit comes from the coil?
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Valy
post Aug 11 2015, 08:50 AM
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Ok. Did you try to disconnect the new #4 wire or the injector connected to old #4 and start.
This will isolate the culpit to the injector or wire.

Too much pressure can hold the injector open but you said you tested them outside the car. Also, why is it a problem only when the wires are connected?
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b.stirbu
post Aug 12 2015, 04:20 AM
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QUOTE(Valy @ Aug 11 2015, 04:50 PM) *

Ok. Did you try to disconnect the new #4 wire or the injector connected to old #4 and start.
This will isolate the culpit to the injector or wire.

Too much pressure can hold the injector open but you said you tested them outside the car. Also, why is it a problem only when the wires are connected?



The injector is not the problem, because I've swapped the injectors. And i also know they work...I need to dig into this?


Is it normal that the fuel pump cables are buzzing(like they are short circuited?
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Dave_Darling
post Aug 12 2015, 08:42 AM
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What do you mean "buzzing"? Making a sound like a bumble-bee? Triggering the "yes these are connected" sound in your electrical multimeter when you measure across the wires? Something else?

--DD
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b.stirbu
post Aug 12 2015, 03:37 PM
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Dave, yeah it detects that fuel pump wires are connected. I do not find that a healthy sign...it detects this only if the 12 wire connector is connected to the relay board.
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b.stirbu
post Aug 16 2015, 01:22 AM
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Ok, the fuel pressure regulator is stuck closed...I've pressurized the fuel line, started the engine and the pulsed (from another battery) from time to time the fuel pump to keep the engine running...it seems to be ok, I think I just need to tune the ignition timing..
During initial troubleshooting I did not consider at all the fuel pressure regulator as being faulty. Everywhere I read, everybody says that is a very reliable..I guess after
20 years of being unused he also cosidered retiring..

I've noticed something rather intersting for me.. if I pulse too long the fuel pump the engine starts to run around 3000 for 10-15 seconds like it was creating a vacuum on the fuel line and also engaging the fuel pump...
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Tom
post Aug 16 2015, 06:41 PM
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I would check injector #4 with an ohm meter to see if it is shorted, pulling down the ECU signals to all of the injectors.
Tom
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b.stirbu
post Aug 18 2015, 03:36 PM
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Hij doet het!!!
The little beast starts. Ha ha!
But! as always... there is always a but, it idles around 3000rpm....niet goed..
I've unplugged the AAR suction from the air intake and placed my finger on the hose...the rpm drops to 1500....and it feels like a 2000w vacuum cleaner...
Is that normal?
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Valy
post Aug 18 2015, 03:49 PM
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The vacuum is normal and good.
The AAR should close after the engine warms up.
The idle is high. Something is not tuned right or you have some air leaks.
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