Skip navigation

Engine starts then dies

Post

Back to the top
Hi

Can anyone assist with my 1983 DX Gti engine on my resto which starts then immediately dies, i have checked various things but at a loss now so would appreciate any help so i can get it running to set the timing with the strobe light

Timing
F
lywheel dimple set to 0tdc mark
Cam dimple inline with valve cover tin and lobes pointing upwards correctly at TDC.
Rotar arm lined up with notch in dizzy
HT leads on correctly

Vacuum leaks
Cant see any and hoses in good condition with no splits

Fuel
Metering Head and WUR are refurbed by Grey goose
New Bosch Fuel pump and Accumulator and filter
New Hoses and injectors which have tested sprays fine
New Fuel pump relay which primes on ignition
Cold start valve works correctly
AAV works correctly opens and closes
**Pressure test gets just under 5 bar**

Ignition
New Rotar arm, plugs, dizzy cap and HT leads and Coil
Earths present with good grounds



Have tested all sorts but notice when i have tested the hall sender by using the voltmeter into pins 3 and 6 of the TCI i get 7 volts, when i move the dizzy to the left of the notch at TDC it goes to 0 volts, and when move to fire position only get 7v (Should this be 12v ?) it stays at 7 volts when rotating the dizzy half way round could this be the issue as
I also note the fuel pump doesnt prime when moving the dizzy in the test

Appreciate any help









 

Post

Back to the top
Place the car in static time, 0 the cranks finger, at the 0 cam dimple on the valve cover tin dizzy at the hash.

Check the all sender, by removing the rubber boot off the connection at the diz, be careful as plastic gets brittle.

Using earth ground, place your red wire from a dvom on the green and white wire.  With the  Dizzy loose, measure the voltage it should switch from 0-to-11V as you slightly rotate your diz, and yes your fuel pumps should prime as you get closer to the hash.

If it isn't 10-11V then you have a bad ICM or main frame to engine ground.

The bentley has the tests for the  ICM
Screen Shot 2024-03-13 at 7.12.48 AM.png

I would suspect the main battery to frame and frame to engine grounds, as if the Hall signal test is off.  

Do my quick tests for grounds using a set of battery jumper cables.

https://www.volkswagenownersclub.com/threads/brianos-quick-grounds-test.134637/

If it now goes from 0-11, then replace your main grounds.  if it is still low then the issue is either your ICU or ICM that Powers your Hall Generator in the diz.

Or your coil.



What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

Post

Back to the top

Briano1234 said

Place the car in static time, 0 the cranks finger, at the 0 cam dimple on the valve cover tin dizzy at the hash.

Check the all sender, by removing the rubber boot off the connection at the diz, be careful as plastic gets brittle.

Using earth ground, place your red wire from a dvom on the green and white wire.  With the  Dizzy loose, measure the voltage it should switch from 0-to-11V as you slightly rotate your diz, and yes your fuel pumps should prime as you get closer to the hash.

If it isn't 10-11V then you have a bad ICM or main frame to engine ground.

The bentley has the tests for the  ICM
Screen Shot 2024-03-13 at 7.12.48 AM.png

I would suspect the main battery to frame and frame to engine grounds, as if the Hall signal test is off.  

Do my quick tests for grounds using a set of battery jumper cables.

https://www.volkswagenownersclub.com/threads/brianos-quick-grounds-test.134637/

If it now goes from 0-11, then replace your main grounds.  if it is still low then the issue is either your ICU or ICM that Powers your Hall Generator in the diz.

Or your coil.




Thanks very much for that i will run through and update

Post

Back to the top
I forgot to add, you don't have to replace the dizz cap but if you replace the dizzy cap after you verify time.  You don't have to remove the main coil wire but you can.

In my experience every time you move the diz and it goes from 0-11V the fuel pump should prime. The DVOM should show 10-11V on the hall wire when the rotor is in the middle of the hash.

I had the plastic part of my my diz break where the hall sender comes out of the body, I repaired it with JB-Weld, which lasted about 4 years, and when it broke again, it shorted the hall sender to ground, which took out my ICM as well as the diz.

 

What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

Post

Back to the top
OK

Tested the ignition coil unit pins 2 and 4 and got 12v so that must be good.

Then tested the green/white dizzy wire and still getting 7.5v only and the fuel pump doesnt prime when hitting the voltage even with the jump leads connected to grounds as your link so is it pointing to the dizzy being the issue ?

Many thanks

Paul

Post

Back to the top
It sounds more like a fuel problem to me, as if the engine is starting on the fifth injector, is the air metering flap free.
After it stops have a look at the plugs, see if they're wet or dry.
1 guests and 0 members have just viewed this: None.