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

[unpredictable1]

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!

 

[unpredictable1]

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?

 

[unpredictable1]

I think at the very least, new plugs are in order...

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[unpredictable1]

I think I'm getting closer - question, try new cap and rotor or whole new distributor? It is still technically sending spark...

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[Schurkey]

95 4.3 TBI c1500 w/t

I have spark, I have fuel, but she just cranks.

Do you have compression?

Is the exhaust blocked? Plugged catalyst?

Yank the valve covers, verify that the valves open and close--none of the rockers only half-moving (or less than half.)

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.

The distributor is not 180-off.

If I pour fresh gas or starter spray down the throttle body, still just cranks.

Fouled plugs would be high on the list of possibilities.

No codes present, I jumpered the connector under the dash and it just reads 12,

No codes doesn't mean the computer is happy. It just means that the computer may not know why it's unhappy.

all lights come in the cluster when i turn the key, you can see oil pressure building on the gauge as I crank it.

Good.

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

Good.

I'm going to check the fuel pressure hopefully today (that fuel line fitting into the filter is fairly corroded)

Good. There's more than one place to test fuel pressure...but since it likely needs a fuel filter anyway, fixing the corroded section of fuel plumbing is a good start.

but I would have expected it to at least fire up briefly with what I poured down the throttle body.

Not if the plugs are fouled.

That's why I'm leaning more towards ignition or timing,

Worth checking.

I don't believe this engine has a coolant temp sensor (I read that can also cause a no start?)

Of course it has a coolant temp sensor. And if it's screwed up--or the wiring between the sensor and computer is screwed-up--the engine may not start, or run crappy if it does start.

The coolant temp sensor is almost certainly beside the thermostat housing on the intake manifold. There's a temp sending unit in the left cylinder head that operates the instrument cluster temp gauge.

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.

Verifying ALL the "tune-up" components is a wise idea.

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?

Looking at the color of the spark is not a reliable way to judge the spark power.

Test the ignition coil spark output using a spark-tester calibrated for HEI. There's a bunch of different designs and suppliers. My favorite is this kind.
www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

The 3 plugs I pulled were wet with gas

Fouled plugs explains a lot.

try new cap and rotor or whole new distributor? It is still technically sending spark.

LOOK at the magnet on the mainshaft. If it's cracked, you need a distributor. If it's not cracked, it's "probably" saveable with a new cap and rotor.

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YOURS is going to only have six points, not eight.


So we've covered testing fuel pressure and tune-up services.

About all that leaves is connecting a scan tool to look at the data stream--sensor signal, computer outputs, fuel trims, etc.

 

[unpredictable1]

I really appreciate this reply, thank you - hope to get more time with it today!!

 

[unpredictable1]

Never got to do as much as I wanted over the last couple days, on a fast approaching deadline with packing up the place. However, I did get new plugs, wires, rotor and cap - gapped them all to .045 and did some di-electric grease on the wires etc. Changed the oil because even though it looked ok - smelled like gas from god knows how times people tried starting her.

Either way she fired right up, needed some help at first with the throttle but seemed to get to an idle within a few mins but still needed some help here and there - has a bad stumble under load between 1500-3k or so but after she ran for at least 10 mins i got her up past 3k and her revs were really strong and she sounded good (IMO) despite the exhaust falling off her.

Tomorrow if I get the window of time needed I'll connect up the fuel pressure gauge - I'm not convinced the fuel pump is 100% and I want to rule that out, and I'm wondering if the gas isn't that good (only about 3/8s of a tank in it and it smells ok to me but I don't have the best sniffer)

I'll post back when I can with updates...cheers!

 

[unpredictable1]

I cut out the fuel filter, dumped some of the fuel into a firepit and it caught fire/burned easily and quickly when a lighter was put next to it so I think the fuel is good.

Hooked up the fuel pressure gauge and it sits at 10 psi during hard crank.


edit: maybe I spoke too soon because the above is not always the case, when you turn the key to prime, it's not reaching 10 psi and hits around 5 psi. Then upon hard cranking it got to 8, I'm thinking the pump might be flakey?

 

[unpredictable1]

Here is the pump when you turn the key forward to prime:

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Here it is during hard cranking (just a screenshot of a vid):

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[unpredictable1]

and now it's not even priming at all, nor increasing fuel pressure after hard cranking. Stays at 0.