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New problem with my 450

Started by Bulba, 22 August 2008, 07:58 AM


Cleaned up the breaker contacts, didnt work either. =/


Quote from: 13B on 22 January 2009, 05:10 PM
In the side of the distributor.
I was talking abaut the breaker contact for the ignition. It's located under the distrubutor cap (the red/orange cap).
Clean the contact points with a very fine sand paper and blow away all dust. A little grain of sand is enough for making it not start.
If you don't have any spark now disconect the ignition points an measure with an electrical tester that it opens and closes.
You can also check the opening distance of the breakers, it should be set by a dwell angle meter but if you start with 0,3mm it will run.



But i have spark, and its really good. Forgot to write that, sorry.


Nutz once wrote this, it's fantastic.
(On mine the temp sensor was connecte to pin #11 (instead of #13) so I guess there are different wiring diagrams.)

Have you tested the wiring?

Main relay;

1)There should be 12 volts at pin # 24 of the ECU.

2)If not,check for 12 volts at pin # 24 of the relay.

3)If 12 volts is not present at the relay but it clicks,replace with a new relay.

4)If there is 12 volts at pin # 24 of the relay,repair
# 24 wire between relay and ECU.

5)If the relay does not click,inspect the wire from the main relay pin # 45 to ground.

6)If the ground is good and 12 volts at relay pin # 38
when the engine is cranked,replace the main relay.

Trigger points;

1)With the engine not running and ECU harness disconnected from the ECU,check the resistance between
ECU harness 12 and 21,then from 12 to 22.One should show a low resistance and the other should show an open circuit.

2)Rotate the engine 360 degrees and check the resistance.They should have an opposite reading now.

3)If not,perform the same test at the trigger points themselves.This will tell you if it a component or wiring fault.

Temperature sensor 1

1)With the engine not running and the ECU harness
disconnected from the ECU,connect an ohmmeter between
ECU harness pin # 1 and 13.At an ambient temperature
the reading should be 200 ohms.

2)If the resistance is well above 200 ohms,check resistance at the sensor itself to determine if it is
a component or wiring fault.

3)Check resistance of all the terminals to chassis ground.There should always be an open circuit.

Temperature sensor 2

1)With the engine not running and the ECU harness
disconnected from the ECU,check the resistance between harness terminal 23 and ground.The resistance should be 2000 ohms at ambient temperature.

2)If the engine is near operating temperature,the resistance should be below 1000 ohms.

Throttle switch

1)Test the throttle switch with the key on,engine off.

2)Slowly open the throttle,and as it opens the injectors should alternately click.You should hear
20 evenly spaced clicks.

3)If this is not met,place a 0.016 in.(0.4mm)feeler
gauge between the throttle stop and throttle stop screw.Connect a voltmeter to terminal 17 of the throttle switch.The voltmeter should show voltage while the ignition key is in the on position.Remove the feeler gauge and the voltmeter should show no voltage now.

4)If this fails,loosen the screws and rotate the switch until it meets these requirements.

5)If they can not be met and voltage is always present no matter where you position,replace the throttle switch.

6)If the voltmeter reads no voltage,ensure voltage is
being supplied to the switch.If so,replace the throttle switch.

7)If no clicks are heard while performing test 1 and 2,check wire numbers 20,17,14 and 9 for continuity end
for end from the ECU to throttle switch.

Pressure sensor

1)With the engine not running and the ECU harness
disconnected from ECU,check the resistance from ECU
harness terminal # 7 to 15.Should be 90 ohms and then check the resistance between # 8 and 10.Should be
350 ohms.If this is not met,test the sensor itself.

2)on occasion,the sensor resistance will check out,but will not hold vacumm.Using a hand held vacumm pump perform this test again (step #1)

Injector circuit

1)With the engine not running and the ECU harness
disconnected from ECU,check resistance of ECU harness
pins # 3,4,5,and 6.All should have less than 25 ohms.

2)If the resistance is greatly higher or lower than
25 ohms,test the injector itself.

3)If the injectors pass,repair the wiring harness.


Ok i will check some of that stuff. The problem must be that the engine doesent get any fuel at all, because the spark is perfect and everything. When you turn the engine around it smells fuel, so i was thinking maybe a leak? But nothing under the car or anything. im gonna try and change the fuel pump. I accidently broke one of the "bolts" where you connect the wire, and just put it back and put a nut over it. THe pump builds up pressure, but i was thinking maybe its so poorly connected it doesent pump fuel?


I think the fuel pump either works or not. You should hear it pump for a second when you turn the ignition on.



Okey, it works then. Im gonna change the distributor this saturday or something and see if that helps ^^


It's quite easy to do the test above, just loosen the harness (the multi contact) on the ECU and follow the text. It takes about one hour.



Seems like one of the spare injectors was broken too. I tried another one and now it runs like a dream :D