Flatspin631

At a total loss. I recently replaced the injector spider, distributor, plugs and wires to cure a CEL Misfire Code to get inspected. The code went away, and the truck was running great.

On my way to work the other week the truck died on the exit ramp of the parkway and won't re-start. It cranks, but won't fire. There are no codes in the computer.

I have checked the spark, it's nice and fat. Fuel pressure is close to 60psi cranking and holds over 45 for a while after cranking. NOID Light shows the injectors are getting a pulse. The distributor clamp was still nice and tight, and the distributor doesn't appear to have moved. If I crank the engine with the cap off the rotor can be seen turning. If I give it a good shot of starter fluid it still won't start, although I did get one "huff" through the throttle body. I tried moving the distributor 10 - 15 degrees each way, no luck.

As stated, I replaced the old style injector spider with a new Delco unit late last year. Also a new distributor/rotor/cap while chasing a #6 mis-fire and while I was doing that figured new plugs and wires wouldn't hurt.

Any suggestions please?

Sergio Lisboa Machado

Hi, have you checked if the coil is working?

a55bruce

When you checked the spark, did you pull a plug to see if the spark is jumping the gap? I'm thinking fouled plugs.

trainwreck91

pull the plugs, see if they're wet

73shark

Also if you are checking the spark w/ the plug out of the block doesn't mean that it will spark when subjected to cylinder pressures.

Paschen's law - Wikipedia, the free encyclopedia

Sometimes referred to as the Passion Curve.

GusRaby

sounds like it could be the crankshaft position sensor also, apparently there know for going out in these suburbans and not throwing a check engine light. mine done something similar and when i was reading reviews 80 - 90 percent was the crankshaft position sensor.

replace it on mine but now im not getting fuel pressure, so i think my pumps out :/

Flatspin631

Thanks for the suggestions guys. The coil is OK, I'm getting a nice healthy spark. I'm going to venture that the spark is hot enough to easily overcome Paschens Law. The plugs are showing signs of fuel, but aren't fouled.

I'm going to try the Crank Position Sensor, I have a known good one pulled from an identical Suburban that I parted out a couple of years ago. That's an easy sanity check.

However, a very competent "old school" mechanic friend of mine says it sounds like either a blocked exhaust or the cam timing has slipped. I'm going to test the exhaust by pulling the front O2 sensors and see if it starts - the "leak" through the sensor bungs provides enough volume for the motor to start and idle. He also suggests a compression test, which I will do if the exhaust doesn't yield a result.

I'll post my findings when I get them.

73shark

You can also use a vacuum gauge to check for blocked exhaust.

Flatspin631

Ok, heres a salutary tale.

When I originally checked for spark I pulled the #1 plug wire, and got a nice spark. This afternoon, when I went back to basics having exhausted all the other tests, I checked on #2 plug and got no spark. Re-Checked #1, spark OK. Anyhoo, to get to the point it turned out that the after-market distributor cap that came with the replacement distributor has broken down electrically, and I was only getting a spark to 2 cylinders. I re-installed the old cap I still had on the bench and she's running like a champ again.

Moral :- just because it's new it isn't necessarily good.

Thanks again for the suggestions.

trainwreck91

True. You can buy defective "new" parts. Glad you got it figured out.