Well, I joined yet another forum for this sole reason. I've searched, asked, looked everywhere I knew and am at my wits end. So here's the story.


1995, OBD1.5. When my uncle picked it up it had just had a used engine installed which the previous owners could not get to start. I now believe it was an earlier year engine but can't confirm. He brought it to me and I could not get it to run either. We took it in, the shop said they replaced the spark plugs and cleaned the EGR valve and it started, although it ran pretty rough. How true they were, who knows?


So the Blazer was driven for a couple weeks before the oil pickup tube fell out and the engine ran dry of oil, locking it up. So it came back to me, I found an engine from a '95 2WD, swapped pans and pickup tubes and so on and got it installed.


Now this is where it gets interesting/freakin' frustrating.


Right after I thought I finally got everything hooked up, no start.


Fuel pressure:
Key on, pump running- 59 psi
Key on, pump off- drops to about 50 psi immediately
Cranking- back to about 60 psi


Spark- it's there according to my timing light and pulling out two plugs and grounding them to the exhaust manifold and visually seeing spark.


Timing- TDC according to my timing light.


Injector pulse- nothing.


I have 12v at the red wire. Hooked up a noid light and I have nothing. I understand that the blue wire is a ground from the ECM and that signal is what pulses the injector. I'm not sure from reading all over the interwebs how or why I don't have the signal. I've been told either a crankshaft or camshaft sensor could be to blame. First of all, I've read a faulty crank sensor will cause no spark, which I have. Second, I can't find a crank or cam sensor????


I've also been told that a bad ground somewhere will cause this issue. Now, I hate to admit this, but I did find a ground (that I freakin' knew about but neglected) on the passenger side back of the cylinder head and hooked it up. Then there is another one on the driver's side, same place. Then one from the battery to the exhaust manifold and one from the battery to the frame. Am I missing one?


I've checked the fuses in the fuse panel, both ECM fuses are fine.


I guess I'll quit rambling.


Suggestions??

 

Injectors have to be driven by the PCM in order to deliver any fuel. If there is 12V to them on the pink wire and noid light shows no completion of the circuit, then you have to figure out why. Presence of spark indicates crank sensor is working. Cam sensor will not cause a no-start. Seems like PCM is not happy with something. If it was 1998 or later I would say it might be security system preventing injector pulses, but 1995 Blazer is not supposed to have this type of security system. Will it start and run on starting fluid? Any codes present? Are any of the injectors shorted? That could whack out the PCM and cause it to shut down injector drivers to protect itself. Injector resistance? Any voltage between engine and battery neg. Any voltage between firewall and battery neg?

 

With enough starting fluid it will start and run for a second.


Being OBD1.5 I don't have the correct scanner. I may be able to borrow one from one of the "real" mechanics here at work.


It just has one injector. It's a CPI system. The guy I bought the engine from said it had a new spider/nut kit/regulator thing. I also had a new one in the old engine so I swapped in just in case. No change.


Do I measure resistance with an ohm meter? Just between the two prongs?


Voltage between the engine or firewall to battery negative? Measured with a voltmeter? Would that be a short? I haven't checked.

 

Yes, resistance is measured with an ohm meter between the two prongs with connector disconnected.

If grounds are good you should never read a voltage between battery negative and other metal parts. If you do then the ground is bad or insufficient.

You need to be certain about the computer not completing the injector circuit. Otherwise you could easily have fuel pressure issues causing your no-start. What kind of tester are you using to check it.

 

I will certainly have to check both the injector and the grounds. I guess I've never had an issue where a bad ground was the problem.


I am fairly certain the ECM isn't completing the circuit. It's a noid light set I picked up at the parts store. They look pretty simple and I probably could've made something but these plug right in to the connector and it's not doing a dang thing.

 

Have you verified on another vehicle that the noid light set actually works? Just another possibility to check.

Probably grounds are OK if they are hooked up - just something to check that could make the PCM unhappy.

Once had a car to fix where the wipers would take one swipe across the windshield when you stepped on the brake. Was a blown fuse and bad tailight bulb backfeeding voltage to the intermittent wipers when the brake lights were activated. Strange things can happen.

 

That's a good point. Even just to make sure I'm using it right!


I did use two different lights. One plugged into the plug that connects right to the injector. The other light plugged into the harness. I didn't get anything from either.


I have just the vehicle to check, too.

 

1995 was a transition year that uses 2 different fuel injection systems and 3 different PCM's. A hodge podge year, that's for sure The components must all match if you want it to run.

OBD1.5 uses a crankshaft position sensor located on timing cover, lower passenger side. Also has EDI ignition which uses a camshaft position sensor in the distributor, and the plug wires attach horizontally to the cap. Most scan tools will not communicate with this system, gotta be one of the higher dollar jobbies.

OBD1 uses HEI ignition. No crank or cam sensor and the plug wires attach vertically to the cap. What systems do you have on the vehicle and the engine?

 

Oh this is getting more and more interesting.


Let's see. I can't find a CKP. 7 o'clock by the balancer right? Nothing there. Plug wires attach vertically (non-corrected).


HOWEVER! My OBD plug is the same as an OBDII plug. My code reader plugs right into it, just won't read it (go figure...).

 

Yup, you have two different systems going on, and they're not compatible. Either need to do some mods to the engine, or the electronics, (not sure which would be easier). PITA either way. What kind of supply of spare parts do you have? Do you still have the old locked up engine you can rob parts from??


You have an OBD1.5 vehicle, and an OBD1 engine.