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NO SPARK - NO START - HEEEEEELP (Read 2397 times)
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Aug 26th, 2011 at 6:43pm
with a little help from my friends

This has been extracted from a past post, authors Billysdad and John_AZ on a Start Problem.
Posts: 364
Re: 1987 starting problem
Reply #1 on: Jul 25th, 2009, 10:28pm
Hmmmm.... that could be alot! you really have to go step by step and check the ecu harness and voltages to each area as you go. Here is a list of some test you should do one by one and eliminate problems. 
start by making sure we have a battery that is in spec. 
all fluids topped off 
no obvious broken wires and all vaccuum hoses intact on visual inspection.
OK we have 12v at the battery with adequated cranking voltage we get in and turn the key. 
12v from battery to ignition switch
12v from pin 50 on switch to pin 4 on dme plug (start signal) 
12v on pins 1 (ignition pulse to ign. coil) and 18 (to G5 dme relay power supply) 
12v pin 30 at dme relay (fuel pump power supply)
12v to pin 86 at dme relay in the run position (primary coil voltage) 
12v to coil + black wire to ground 12v to - (green wire) to ground
12v to one side of the injectors
All ground contacts are clean
Fuel pump will run if dme relay is jumpered 30/87/87b
Fuel pressure at the rail is 29psig +/- 3 (jumpered 36 psig) 
20 minute leakdown not under 14.5 psig
Fuel flow rate is 28oz after 30 seconds
Ignition coil primary resistance across + and - is between .4 and .6 ohms
Secondary resistance is between 5000 and 7200 ohms
Ignition wires are good no cracks or splits including coil wire and seated
Plugs are properly gapped
Ignition rotor is seated correctly with the set screw
Timing belt is installed correctly
Firing order is correct  - 1 - 3 -4 - 2
Reference sensors are gapped correctly with .8mm clearance off the flywheel 
Reference and speed sensors resistance checks in spec pins 8 and 27 speed 600-1600 ohms and pins 8 and 23 >1m ohm 
Reference and speed sensors voltage checks 2.5 and 2v on oscilliscope (good luck) 
Reference and speed sensor wiring is not broken at connector to sensor or to dme 
Ok Im tired anyone else want to add or be more specific? 
Do a compresion test. 
Reference sensor tach bounce when attempting to start the engine. The tach bounce is very slight-1/16 of an inch. Clean connections as mentioned above. 
Injector "noid" light. Very basic tool but will tell you if the DME is sending a signal to the injector. An oscilloscope is the best. 
Clean connections at major parts like AFM, ISV, throttle body.


and here are the links to the reference sensors - and how to and where

same thing here with the spark light-
easy to use - if you have spark it will light up --

and we now have all the connector ends
for both the harness end  and the sensor end
« Last Edit: Oct 14th, 2016 at 8:19pm by XxSteve944onlinexX »  

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