3100 Will Not Fire

[neophile_17]

I think it was mentioned before but have you verified that the spark plugs go to the correct cylinders?

You probably don't want to hear this but I suspect you're in for a head gasket looking at the front bank compression readings.

[3400-95-Modified]

paper clip will not work, its not a prom style OBDI computer it's a flash style. What reader are you using? I had an Actron OBDI tool and it would read OBD1.5 systems perfectly fine.

I doubt it's a head gasket causing the low compression... Its more likely the valve seal or ring seal that's causing those readings... especially if it hasn't been run in quite some time.

[Heartbeat1991]

Something is wrong on the front bank for sure. But nothing that would cause a no start.

I agree that you need to take all your plug wires off and do them again, to make sure they are right. It's easy enough to mix something up when you're putting them on. I'm sure we've all done it.

[Braddock]

I really wish it was the wires. I re-did them before and and after I replaced them.

FIREWALL
1 3 5
_2 4 6
FRONT


I have just pulled the timing cover off, what a b*tch that was.

I am inspecting the chain and want to determine if it has skipped a tooth, however what the Haynes manual is telling me is different from what AllData is telling me. Can someone tell me if this looks correct?

From AllData:


On my vehicle:

[Heartbeat1991]

It looks right. It has to be a huge vacuum leak or no fuel.

[Braddock]

Hmm. what's the best way to check for a vacuum leak if I can't start it?

[Heartbeat1991]

Use a cigar and blow smoke into the brake booster hose. A cheap $10 air pump will do the trick if you're not up for puffing a cigar. The pump is a little easier anyway. Wherever the smoke comes out is where it leaks.

[Braddock]

Thank you for the tip. I found something suspicious today before I had a chance to try that, but I will definitely still do that if this lead I think I have doesn't pan out.

I bit the bullet and bought a fuel pressure tester this morning. I hooked it up, turned key to Run and got 41 PSI, which is within tolerance for this motor. However, if I reset my gauge after that and crank the motor, my gauge stays at zero. I reconnect it and the same thing happens. Turn key to off and back to run, then crank it, still no pressure. If I let the car sit for a while then turn it to run, it will prime again and my gauge will go back to 41. It seems like there is no new fuel pressure when cranking. Does this make any sense to anyone or am I reading this wrong?

EDIT: I connected a vacuum line from a port on the manifold to a bottle of gasoline and it finally fired up. Seems spraying into the intake with the butterfly open doesn't get it in enough. So either my injectors are not injecting, or the mixture is way off. Any suggestions? I am going to hunt for vacuum leaks again.

[Heartbeat1991]

Sounds like it could be a fuel pump problem. Maybe a bad relay.

[Braddock]

There was air in my tester. I feel like such an idiot.

Anyway, after priming my tester, I get a consistent 45PSI after prime, and it builds immediately when cranking as well. I can confirm fuel pressure at all times. Now I am wondering if my injectors are functioning correctly.

I wanted to rule out it being poor mixture due to a large vacuum leak so I checked around carefully and couldn't find anything. I didn't hear any hissing when it ran on the fuel it sucked in but I really need to connect my vacuum gauge to it and feed it fuel though that vacuum port to get a better idea. I will supply that info tomorrow. Regardless, the motor wont even sputter without the external fuel source.

I wanted to test the power to the injectors and I drove all over town trying to find a noid light kit and nobody had one in stock.I soldered up my own home-made noid(SEE LINK) light and tested each wire from the the battery (+) terminal to PNK/BLK, LT GRN/BLK, YEL/BLK, BLK/WHT, and BLK(SEE LINK). which are the PCM controlled grounds for the SFI injectors. My home-made noid link pulsed as the motor cranked. The pulse was dim but I am not sure if that was because I was using a standard LED & resistor vs whatever they put in a proper noid light or not. I confirmed +12v on pink as well when the vehicle is in run. I tested the Fuel Pump relay which supplies the +12v to the injectors and it checks out.
Any ideas? Could the PCM not be providing a good enough ground? It seems odd that all the injectors would fail at once. This entire time I can now confirm 45 PSI at the rail at all times. I can release pressure in my tester and then crank and it builds to 45 PSI right away.

EDIT: If I pull the upper manifold and remove the rail and injectors, then crank it, would it spray out fuel at me? Is this an appropriate way to test them?

DIAGRAM & HOME-MADE NOID LIGHT:

http://imgur.com/a/dc9qG

[neophile_17]

I've had injectors freeze shut from sitting on other motors. That may be your problem. I would apply power/ground to each injector. You should hear them click when you do. If not they're stuck and need to be cleaned or replaced.

[Braddock]

OK. So using a ground to the frame and the power supplied from the relay. I could toggle the injectors manually and I could hear them spray fuel into the lower manifold. I then took my homemade noid light again and connected it directly to the plugs that connect to the injectors and all I got was a constant dim light or 12v on my meter in run or when cranking. Since I had 12 volts I connected an incandescent test light and got nothing from it. It seems there is a ground as the led lights up. However my meter reads 195 ohms when set to 2000 ohms scale when I test the PCM negative pulse connections to the frame.

As it appears to me, the PCM is supposed to provide a pulsing ground with a width determined by throttle pos and a few other things. I am not getting any pulse from the ECM at this point. Last night I had a very faint pulse which was not enough to toggle the injector. Perhaps this diference is due to a different time of day or moisture from the night. Either way, my injects will not fire as there is no good ground pulse from the PCM.
Does anyone have any idea why the PCM may not be providing a pulse?

[bszopi]

Next time you crank it over, look in the oil fill cap to see if the valves are moving. Might be a broken cam.

[Braddock]

I've already pulled a valve cover and confirmed all rockers are moving evenly. I've pulled the timing cover to confirm the chain is good too.

[neophile_17]

I don't know about your computer but the OBD1 computer needs a separate ground to the engine block which it switches to the injectors. If your system is set up the same way and that ground is weak it could cause your symptoms. You'll need a schematic to figure out which wire it is.