95 c1500 4.3 TBI has fuel and spark, cranks, no start

[thinger2]

Hello all, I've been scouring the archives for threads on this and I'm trying to get this thing running at my inlaws. Bought this truck as a non-runner at an auction so I have no idea what happened leading up to it being in this current state. (although it appears to have been a one owner) Mileage is 290k km / 180k miles

It's a 95 4.3 TBI c1500 w/t (fairly basic truck), I have spark, I have fuel, but she just cranks. The very first time I attempted to start her she stumbled to life with a very very rough idle, needed throttle to stay running (albeit barely running) but it remained very rough. It only did this a couple times and that was it, she had enough lol.

If I pour fresh gas or starter spray down the throttle body, still just cranks. No codes present, I jumpered the connector under the dash and it just reads 12, all lights come in the cluster when i turn the key, you can see oil pressure building on the gauge as I crank it.

Oil and coolant all good, doesn't look that old either.

I'm going to check the fuel pressure hopefully today (that fuel line fitting into the filter is fairly corroded) but I would have expected it to at least fire up briefly with what I poured down the throttle body. That's why I'm leaning more towards ignition or timing, I don't believe this engine has a coolant temp sensor (I read that can also cause a no start?)

Also going to try to get her to TDC and check under the cap to see as to where it's pointing too. I understand the ICM could possibly provide spark but it still be faulty? Going to pull some plugs and see if they're fouled up.

If anyone can help with a couple of gotchas that might not pop up as easy while searching archived threads and various youtube videos, I'd appreciate it. I have limited time to get this thing running and off the property (this residence has been sold and possession date looming lol)

Thanks in advance!

I know this is your first post but that engine Has to have a coolant temp sensor in order to run.

 

[thinger2]

Also - it is orange spark that I have coming right off the plug wire, no blue/white. It's awfully bright out there with the sun pouring down but I'm to just going to reconfirm that because I just read that if it's orange spark that might not be enough to have her fire over?

The 3 plugs I pulled were wet with gas and they are all black/carbon at the end. Maybe between the orange spark, the sooted up plugs, she's not getting enough lightning?

They are wet with gas from you cranking the engine.
Are you sure its gas and not oil?
Black carbon and soot at the end means you have fouled plugs.
The color of the spark especially when looking at it in the sunlight doesnt really tell you much of anything.
That is an old man points ignition tractor engine diagnosis thats been lingering around since the 1920s.
It isnt the color of the spark.
I might see orange and you might see blue and somebody else might see green.
It aint about the color of the spark, its about the "Sparkiness" of the spark.
How intense is the spark and how long does it last?
Still not a good way to diagnose an ignition system.
Pull all of the plugs and lable each plug from the cylinder they came from.
If they are all fouled that might be bad ignition.
Does it smoke at hot start up in the summer?
Valve stem seals
If only a couple of them are fouled that could be just a misfire or maybe a stuck valve.

If you find a couple of really clean plugs and everything else is caked with crud? you have a blown head gasket.
Maybe.
And just stop with the whole lightning thing.
Its not lightning or a sparkelator or a fire making happener.
That youtube nonsense just makes you look like a dope and people will troll the hell out of you and watch you chase your tail over and over.
The gatekeeping and abuse is so normalized.
On a 25 30 year old truck it is safe to assume that the wiring is bad.
ITS THE BATTERY CABLES AND THE GROUNDS FER FLYING ***** SAKE.
Cut the ends of your ancient battery cables open and see the green crud .
ITS THE ******* BATTERY CABLES And The Grounds!
Like maybe after thirty years or so of wear and tear maybe its not a wiring problem.
Bullshit.
Im not really sure about the oddity that goes on with gmt400 trucks.
And you guys did really slam this guy for asking a question.
And that, you antique no hope gruesome people is exactly why and how we have failed.
If its playing the Bongo or knitting rugs or making dioramas from macoroni noodles.
Somebody will decide that they are in charge.
They will form a power base.
And they will rule the state fairground afghan display for years.
And those old blanket bitches would cut your neck to win.
Us old farts are killing our hobby stone ******* dead by being so damn egotistical that we think that we own car culture.
Car culture started way before we were born.
We inhereted it and learned it from our fathers and grandfathers.
You didnt crawl out of the ooze with a torque wrench in your hand either schmuck.
How about we try to help people.

 

[unpredictable1]

All the original plugs I pulled were the same, wasn't an oily residue present and none were worse than others or anything like that - and yes I certainly realize how dumb my comment was about no coolant temp sensor and I was corrected in short order lol Definitely a facepalm moment haha

I have new battery cables on that I installed in the early going and the battery is strong.

Coolant is bright green and the oil I dropped out was not a milk shake so they weren't mixing, if there was a head gasket issue I would figure the compression test would show that? I tried that sparktester and the spark still looks weak to me - definitely looks weaker than the spark I jumped off the coil and it's not consistent. I checked the wiring pretty close with the ignition control module to the coil, the rust on that distributor has my attention especially given the state of the cap and rotor when I first looked at them. However next steps will have to wait for when I get back up there (had to head home for a bit)

 

[unpredictable1]

Got back up here yesterday, redid the ground straps, the engine ground was severed at the base of the tube going up the back of the engine (that or it completely fell apart in my hands) and a new body to frame strap. It was still just cranking, but the spark looked better after the new grounds.

After that I also put in a new distributor, put her to TDC before removing the old one, took pictures of it's orientation and dropped the new one in - not long after I had her idling without any help/throttle input, once she was idling on her own for a bit it I had her revving like a banshee. She ran for a good 10 mins easy. (this was with the timing bypass still connected under the glove box) However the dang distributor bolt wasn't quite tight enough to hold it in place and she's after coming off her sweet spot.

But even now I can pretty much get her to fire every time by holding the TBI wide open but I can't get her back to what it was like this morning (i have the distributor bolt a little tighter) and the idle is rough. (I've tried this with the timing bypass disconnected as well)

I feel like I'm pretty damn close now.


edit: i didn't realize the tan/black timing wire till after this morning when I first did the distributor