KP

Really would appreciate if someone can help. I'm worried that it 's the DME at fault. Started having problems few days ago. Car still drove fine except felt like fuel cutting off on boost on a few occasions, there wasn't any loss of power otherwise. Problem got more frequent and car finally won't start today.
Checked fuel delivery and pressure - normal
Spark plugs firing up normally upon cranking.
Air flow meter signal - normal.
Switched DME relay - no difference.
Used DME jumpers - no diffence.
I suspect the injectors are not firing up on start up, hence no start. I plan to take the injectors off to confirm this.
What signals do the DME need to fire the fuel injectors?
Could a faulty TPS cause this? I suspect the reference mark and speed sensors are working as my tach needle swings and I'm getting spark - am I correct?
I haven't checked compression or belts yet - can a slipped cambelt do this?

Tom M'Guinn

Have you checked the I/C and intake couplers to make sure one did not pop off or come loose? Under boost, they can start to work loose, causing your syptoms, and finally pop off completely. Just a thought.

If you are getting good spark, your ref sensors are likely ok.

KP

Thanks Tom,
Checked hoses, no leaks.

TRP951

maybe something to do with the dist rotor? I know ignition system problems can cause stumbling on boost

Keithr726

Normally the DME relay is the cause (was mine) but you said you tried that. Check the resistance of the injector wires.

xsboost90

check your fpr vac hose. Just a thought.

KP

Thanks everyone. So is there any chance its the TPS?

special tool

No.

How exactly did you check fuel delivery?

tod84944

You can hear the injectors clicking when you crank the car????

Papamurphdog

Mine was really weird; but I made spade jumpers for the DME and I jumpered the alarm system at the same time. Mine started, then I replaced the old DME and it would die, still not starting. I did it again, DME jumper and Alarm jumper and it started and ran. So, I installed new DME with alarm jumper intact and it starts and runs. (new problem for me is it is now runing pig rich and I think the O2 sensor is the cause -fouled -- so I am tracing other issues) but the dang thing started. Try that and see what happens. BTW, a found a water leak in the battery box, where it would trickle into the alarm box, so I think that was the culpret. Taking it to the shop for a once over next week, jsut to be sure.

Papamurphdog

BTW, just to be sure, check to see that the Tach is "bumping" when you crank the car. If so the crank sensors are good. If the Tach is dead and not moving you have an indication of a sensor problem... learnig the hard way, with help for all my friends on this forum and at various shops...

KP

Thanks everyone. Finally found the problem after alot of poking around. The fuel injectors are confirmed to be injecting when cranking. Sparks are rechecked and are present with correct firing order. The sparks are however on the "weak" side judging by sight only. Took the distributor cap off and found a crack on the rotor. Took the rotor off, and the crack had gone to the middle of the rotor where the lobe is on the other side. What happened was spark energy went straight through the rotor onto the camshaft instead of going through the rotor itself. I changed the rotor and it started right up. I am surprised that it didn't start up with just a weaker spark. I am very pleased though its not the ECU and noticed it is pulling alot stronger than before. Perhaps I need to change the rotor more often. Thanks for all your help and advise.