VW Rabbit MK1 GTi 1.8 8V rebuild - NO SPARK

Hello from Finland!

I have quite rare US-built Vw Rabbit MK1 1.8 8V GTI restoration project. Car has been restored 100% and last thing would be to get it running and to the MOT and then special museum car register. But the car won´t start. Nothing hasn´t been changed during restoration although everything was removed from the car. Wiring is original, cleaned and earth points checked when reinstalled. Car worked perfectly before restoration. Car cranks okay, but won´t give spark. New parts in ignition:
- ignition control module (have three of those, two new one old..)
- hall sender unit in distributor
- new spark plugs and cables (Bosch)
- new rotor and cap
- new Beru coil (also another cheap one for spare…)

Also fuel pump relay doesn´t seem to work. It wont prime (KAE 3.300.300, not the same as in euro-GTi, pinout is different) but pump works fine with jump wire (30-87). Relay needs pulse from coil, so this must be the problem for that issue, I have no pulse what so ever…

Cheched so far:
- ignition control module gets battery voltage ok (pins 2 and 4)
- hall sender plug removed and coil primary side measured when starting. Jumps to 5V (not 2V like said in workshop manual) and goes to 0 in less than a second
- ignition on, distributor cap HC lead was removed and grounded. Voltage should get to 5-6V, nothing happened, voltage stayed at 0V.
- hall sender input voltage measured, pins 1 and 3 gives battery voltage 11.5 or so. Should give 5V according to manual.
- hall sender tested and no "blinking" when test lamp fitted to coil primary side (HC lead grounded)
- hall sender also tested when distributor is on the table with multimeter and 12V power source. Won´t get voltage alteration from center pin (green wire), tested from 5-12V gradually. Tested also old hall-sender. New doesn't give anything to center, old gives continuous voltage, less than input voltage. Does the distributor has to be in car to measure hall sender?

What next? New hall sender? Can some grounding fault cause this all? Should fuel metering head make any noise when starting and listening to it?

I´m getting frustrated, so close but still so far..

Greetings,
Jani




 

Check external pump under the car. I've had issues with internal tank pump and external one. 1 needs to work for the whole system to kick in.

Hello

Thanks for the tip. Petrol tank new, Bosch fuel pump and accumulator new, all fuel lines new. Fuel pump works when poles 30 and 87 are attached with jump wire from the fuel pump relay socket. Pump seems to prime the accumulator and I can hear when pressure gets higher. Can pump still be faulty? What is the mechanism that fuel pump could cause this lack of spark?

How about ECU ground? Does that effect to this? Ignition wiring loom is practically separate fron everything else. Does some info go or come to this circuit elsewhere, continuous 12V and signal from ignition key of course, but how about ECU or CIS?

Are coil and distributor groundings crucial to the function? Shoul I double check those or make new ones? Where does distributor ground originally go? To head like many others?

Jani

Welcome to the club first of all. 👍🏼

Well this is way beyond my knowledge but Briano1234 is one of our members in the US and is an encyclopedia of Mk1 knowledge so he might have some ideas. 😉

But it sounds like you know what you are doing so I'm sure we'll find a solution. 👍🏼

Sent from my Smartphone 📱

Well lets look at this a little differently.

Parts in the circuit are (Fuel pump relay) Coil, hall generator (if electronic ignition) ICM , HV leads, Cap, Rotor,

Now with that said, be sure that your Hall effect Generator in the Dizzy is not shorting out on the bottom to the case.  As you stated that you have not got the sender to go from 11V to 0V as that is the make or break side of the window and the mag or inductive pickup.  This is what causes the ICM to Fire, and turn the coil on and off.

The fuel pumps not priming is a indication of the Fuel Pump Relay or wiring to them as an issue as the fuel pump relay gets its voltage from the battery via the coil, and hall generator.

So the indications are that is your fuel pumps don't prime,  issue with the fuel pump relay being incorrect, and or wiring to the relay or to the fuel pumps, I would suspect that latter.

Grounds are very important….. You shoudl have a ground wire from the left rear of the valve cover over to the frame bracket that holds the coil.

The dizzy is grounded at the case via the finger clamp that bolts down to hold the Dizzy in position.

The Hall Generator in the Dizzy has 3 wires two of the wires are power and ground from the ICM.  The White/green is the signal out from the hall generator to the ICM.

SO if you don't have a switching signal from the Hall Generator on the dizzy, usually going from 0-11V as you rotate the diz then you never get the pulse to fire the icm/coil.  

First I would test out the fuel pump relay/pumps and grounds,  If you haven't replaced the main frame to battery and frame to engine grounds do it.  
Make sure that your case of the coil has ground applied.

Make sure that your wires to the coil are in the correct position, as if you have them reversed I don't know if that would be the same indication that you have now.

I do know that when the plastic hall sender connector breaks and shorts to the dizzy frame, then you will never get spark. as it usually takes out the Hall sender (ICM).

So it wouldn't hurt to inspect the clearance of the hall generator in the dizzy to the frame.

To verify that the Hall is getting the hi-low switch, you need to statically set the timing of the engine.  That is Crank at 0tdc on the tranny finger, Dimple of the Cam even to the Valve cover tin.  Loosen the Clamp on the diz and rotate the diz so the rotor is in the middle of the hash mark on the diz frame,  I never use the pulley marks to align the diz as you never know where it was to begin with.  Once you have statically set the time, then with the main coil wire disconnected and key in the run position, you can rotate the diz to make or break the shutter to the hall generator.  The nice thing is that if all is working correctly, as the signal goes from 0 to 11 V on the Green/white wire of the Diz connector you will hear the fuel pumps fire/or run.

I would first start by trouble shooting the Fuel pump relay and why it isn't priming.

Once that condition is repaired, then you can concentrate on the sparking…..

You said that if you jumper the FPR out, then the fuel pumps run, so I would start as to what is preventing the voltage from turning on the fuel pump relay first at key on the run (prime), if you follow the "pick" side of the Fuel Pump relay back through the ignition switch then to the battery you may resolve your issue, it might as easily be the ignition switch itself… as in being bad, or the wires to it…..

Sorry that I can' be more specific, as I am totally bed ridden and have been for the last two weeks, and getting to my older Westy Haynes is very very difficult…shoot trying to use a puter is a exercise in Pain, and comfort as well.  

KISS (keep it Stupidly Simple),,,,, I would think it is a wire issue with something being plugged in wrong, or possible a pin on a connector has backed out…..

Thanks Briano!

I´ll start with the wiring and fuel pump relay.

One question though. All repair manuals says that hall sender supply voltage should be 5V. I have three ignition modules (one original US Fairchild, one new universal and one new Hella). They all send 10-11.5V to the hall sender from ICM pin 5. Are my ICM´s broken, or is this 11,5V okay? Hall sender can take this 11,5V and it won´t brake it? I phoned to two different Bosch services and both said that hall sender needs 5V and other suggested 5V regulator to lower the voltage. What is the truth?

Just for clarification. How hall sender can be grounded? The black plastic plug cover is broken and pins touches ground or something inside the dizz touches ground?

Jani

The green white wire on the diz is usually between 0 and 12V actually 11.  So I don't know where they are getting 5v from.

I had the connector bracket break and it dropped and shorted out on the frame of the diz.  But there isn't a whole lot of clearance and if the soldered wires aren't trimmed flush….

The Bentley had a write up on testing the ICM's and that was looking for a ground and a hot, then seeing the green/white changing….IIRC.  

I know that when my diz broke, it took out the ICM.
but IIRC the Bentley tests nailed that for me.

Hello

Last weekend was not a successfull but some progress did happen.

I manufactured new harness connector for fuel pump relay. Old connector wasn't looking too good, for example ground pin was very loose.. Still pump doesn't prime, but I have learned that all relays doesn't prime at all. I tested two relays, KAE 3.300.300 (Rabbit original type?) and euro GTi version that required some wiring work to be done. No priming but all wires are live and connections are good, pump works.

Ignition module wires doubvle checked, all connections are fine and plugs are intact as far as I can tell.

I changed old hall-sender back. No pulse what so ever. Only progress is that with one specific ignition module multimeter showed +7V (other wire in - and other in center pin) to hall sender middle wire. Others showed 0V. When I grounded it, fuel metering head started to work and coil gave spark to HT-lead. So can I narrow down this to distributor and hall sender? Maybe I get new dizzy, I'm tired to play around with this problem. I can get new hall sender, but it has been in storage for 15 years now. Does that time affect to magnet?

Few new questions raised:
- why fuel metering head started to work when I grounded hall sender middle wire? Where does it get it's signal? US-Rabbit has a magnet valve in fuel line that euro-version doesn't have. K-jet has also lambda-sensor, but as far as I know, it is not KE-jet.. Sound must have came from the valve, there is not other electric functions in metering head,. or are there?
- I dont have idle stabilization module, plugs are just joined together. I never had one before and car worked fine.  Should I get one? That doesn't effect to this pulse problem?
- is there connection between ignition and CIS-system in US-Rabbit that could cause problems?

Jani

Magnets do go bad.
Photo-optics can go bad as well as they can internally corrode or tarnish.

I was under the impression that the Diz was photo-optical or Inductive can't remember which it is….
They are very dependable, and resilient.  The issue with storage is that buggies, and crawlies love to investigate things, gnaw, and chew items.  

Don't have a real good feel for CIS, Digi yes, Diesel Yes, CIS no first hand knowledge.

Spark has been found and engine is running!

New factory rebuilt dizzy came from RockAuto and I also renewed ignition module to sligthly different type, referring US Rabbit part code. Hall sensor was dead although it was new…

Fuel pump relay works, but it won't prime.

Second problem occurred. Idle is around 3000rpm and when idle screw is almost closed around 2000rpm. Mixture is lean? I measured fuel pump and it gives around 1200ml/min and it should give at least 1800ml/min. Fuel pressure too low? Fuel line is slightly bend and I ordered new one, hope it helps.

How to check air flow sensor plate? Can it be reason to high idle? Or air leak somewhere?

Jani