1997 c1500 5.7 V8 no start

[97c1500guy]

My 1997 GMC c1500 has a 5.7 V8. Last night I replaced the spark plugs and wires, and today I replaced the distributor. After the swap the truck was running better for a few minutes, then I heard a pop sound and the truck died while I was doing about 10 mph. Now the truck won't start.

When we looked under the hood here was what we noticed so far. Spark plug #1 wire completely blew off the distributor. After some testing, we are only getting spark on cylinder #3 when checking them all at the plug wires. Assuming that it was a big misfire that blew the plug wire off but still unsure what caused it.

The truck was already running with a random/multiple cylinder misfire, multiple O2 sensor codes, and a camshaft sensor code.

Any ideas what could have caused this problem? And/or how to fix it? I have tried swapping back the old distributor, and it's still cranks but no start

 

[WICruiser-97]

Not sure how a backfire would pop a wire off the distributor? Sounds more like the internals of the HEI distributor blew up and popped the wire off, maybe dislodged the cap such that it shifted relative to the base such that only cylinder 3 cap location was trigger by the rotor.

When you swapped back the original distributor did you check for spark again? Is it possible that when you installed the original you got the timing off?

 

[97c1500guy]

I am also unsure how the plug wire came off. I am pretty sure when it happened it damaged the new distributor, but when I look at the cap and rotor they appear to be in working condition. when I put the old one back in it still doesn't start, and still only sparks on cylinder #3

I'm like 90% sure that the timing was right because I had lined up the marks for top dead center and pointed the distributor cap at cylinder #1

 

[97c1500guy]

You must be registered for see images attach

These were my codes before the swap. I was searching for the misfire and noticed the old distributor cap was ziptied in place by the previous owner and damaged so that was why I was wanting to replace it. But it was actually running before I swapped the distributor

 

[WICruiser-97]

Having 2 different distributors only provide spark to cylinder #3 seems strange given all of the parts related to spark on one cylinder vs another would have been changed.

Have you pulled the spark plugs to inspect thier condition? Does #3 plug look different than the rest?

Having the distributor pointed to #1 may be 180 degrees off if cylinder #1 was not at TDC on the complression stroke. When I redid my '97 I was sure I had it at #1 TDC on the compression stroke but had a no start condition. After a lot of chasing my tail I reset the distributor 180 degrees and it fired right up.

 

[97c1500guy]

Having 2 different distributors only provide spark to cylinder #3 seems strange given all of the parts related to spark on one cylinder vs another would have been changed.

Have you pulled the spark plugs to inspect thier condition? Does #3 plug look different than the rest?

Having the distributor pointed to #1 may be 180 degrees off if cylinder #1 was not at TDC on the complression stroke. When I redid my '97 I was sure I had it at #1 TDC on the compression stroke but had a no start condition. After a lot of chasing my tail I reset the distributor 180 degrees and it fired right up.

I haven't pulled the spark plugs yet, I was just testing for spark at the wire. Will check them today for sure.

I'm sure that when I installed the new distributor it was correct because it started and I drove it down the road smoothly until something popped. It is possible that when I re-installed the old distributor that I put it in incorrectly and I will check that today.

The ignition coil is sparking but I am also going to replace that today

 

[97c1500guy]

xc_hide_links_from_guests_guests_error_hide_media

I have installed the new ignition coil and module, and double checked the distributor. It was not sitting 100% properly in the housing, as well as the cap was not on all the way. After fixing those things the truck started and was running. I let it run for a few minutes and then turned it off.

About 15 minutes later we are back to not starting. It sounds like it's trying harder to start and sometimes it starts to bite but it still won't start

Attached is a video of what it sounded like BEFORE I got it to start. Now it sounds similar but a little better

 

[WICruiser-97]

Glad to hear it was running, strange that it will not start again although your battery seems weak - cranking slows/stops on compression. If the voltage drops too much while cranking the computer that controls spark and fuel doesn't work. Take you battery in and have it load tested (most auto parts places will do it for free).

 

[97c1500guy]

Glad to hear it was running, strange that it will not start again although your battery seems weak - cranking slows/stops on compression. If the voltage drops too much while cranking the computer that controls spark and fuel doesn't work. Take you battery in and have it load tested (most auto parts places will do it for free).

When it started, I didn't have the intake put on so the mass airflow sensor wasn't on and it cranked up right away. The only thing I changed was putting the air box intake back on and reconnecting the sensors and it wouldn't start

The battery has a 2021 date and I've been cranking it over a lot the past few days so it is probably low

I will get the battery charged and also take the intake back off and see if that makes it crank up once again

I appreciate all of the advice

 

[WICruiser-97]

I am surprised it would run with the mass air flow sensor disconnected, the inlet air temperature sensor would not prevent it from running (I think those are the two sensors in the intake system but memory is a little fuzzy). If it will not start with a good battery I would try connecting/disconnecting the mass air flow sensor to see it you can isolate it's influence on starting/running.