Crank No Start

[Trio3b]

1997 C1500 5.0L

Hard start problem has been getting gradually worse over the course of 6 months. Have to throw starter fluid and then she fires, especially when cold. After initial morning run, truck starts all day no problem.
About 2 months ago, crank but no start. Fuel problem right? So ran my starter fluid routine...NOTHING.
1. Fuel pressure a little on the low side of spec
2. Checked ignition with tester on one of the wires. Weak and intermittent, so checked coil wire... It disintegrated in my hands and.nothing on the tester. So Ran tester directly on coil ...SPARK! So bad coil wire right?
3. Spark tester on New coil wire..spark!
4. Spark tester again on a plug wire....spark!
5. Starter fluid direct into throttle body..NOTHING..not even a cough.

I've never had an internal combustion engine (car lawnmower chainsaw) NOT briefly fire as long as there's spark.
Even if there was no fuel, the motor should catch briefly.
If ANY part of ignition not working (cranksensor, IM, coil, dist cap, bad grnd) I would think there would be no spark.
If timing chain problem it would not be gradual. This truck ran smooth and powerful after the initial morning dose of starter fluid and would fire right up and run strong the rest of the day.

As long as mechanical timing and valves opening closing properly shouldn't the spark fire the starter fluid?

Or spark is too weak or completely out of time. Spark is not big fat and blue but is very noticeable.

Any ideas appreciated.

[Blue Bowtie]

As you have probably learned from research, the CPFI fuel system is very sensitive to fuel pressure. The specification is for a minimum 61 PSIG. I've seen them start at 58 pounds, and on occasion run at 54 pounds (as a record low running pressure).

If there is reasonable spark at the end of the plug wires, the next thing to check is the spark plugs themselves. I've seen a LOT of plugs still running the engine with over 0.090" gaps, and the some with side electrodes nearly eroded away to the rim.

[Schurkey]

Agreed. Spark at the plug-end of the plug wire does not mean spark across the plug gap. Spark across the gap is what matters.

When I see a failed coil wire, I immediately suspect excessively-high ignition voltage due to failing plug wires, excessive plug gap, even excess rotor-to-distributor cap terminal gap. Failed coil wires are also associated with a worn-or-missing carbon button on the distributor cap, that touches the conductor in the rotor.

Fuel-fouled (or fouled for any other reason) can cause a no-start situation. "Worn" plugs may require more voltage than the system can produce; and/or cause misfire.

Be aware that the Vortec distributor has a known history of wearing-out the distributor gear, which does not change the ignition timing, but does change the alignment of the rotor tip-to-cap terminal, increasing the chances that the spark jumps to the wrong terminal. The plastic distributor also has a tendency to wear the bushings for the mainshaft.

As you know, low fuel pressure is another problem you need to address. How old is the fuel filter? How old is the pump? Is the pump getting proper voltage/current, or is the wire harness/relay in disrepair?

[Trio3b]

Agreed about marginal fuel pressure but since I'm on a roll with ignition I'll stick with that for now. That starter fluid should ignite like it's been doing until the no-start issue. I've also noticed having to top off coolant quite often with no major obvious external leaks although lower hose has been moist.

Hoping a head gasket is not gone. Truck has 177k miles

Will pull all plugs and check compression all the way around. Then check rotor and cap for for proper alignment and any carbon tracks. Will inspect plugs for bad signs. Then new plugs w/ proper gap, new wire set and if necessary clean and or replace distr cap.
Assuming engine mechanical good and distr sending spark to the right cylinder, I'm gonna get that starter fluid to light up if its the last thing I do this year. Then I worry about fuel issues.
Thanks for the tips. Will keep posted.

[Blue Bowtie]

Before a head gasket, I would suspect an intake gasket, or even a cracked intake from backfire.

[Trio3b]

Fired up today.
New plugs and wire set.
Compression 165-195 psi with difference being within the 70% recommended by GM manual. All compression built up smoothly over 3-4 cranks. Rotor appears timed correctly at #1 wire when #1 at TDC so engine mechanical appears good.
Old plugs appeared ok. Dist cap mildly oxidized and cleaned with spring tab on rotor nudged up. Cap screws may have been a bit loose.
Fuel pressure still on low side so that's another issue.

Still can't figure why starter fluid I've been using for 6 months would not start the vehicle. Grab some old gasoline out of a chainsaw, poured that directly down the throat of the throttle body, and she fired right up for a few seconds. Then I reconnected fuel pump relay and she fired right up and ran nicely for several minutes while I put the tools away. My gut is telling me that something is intermittent along with the low fuel pressure issue, but at least I got some combustible fluid to light today and that was my whole goal. Going to button everything up and drive it for a few days and we'll see what happens.

[Blue Bowtie]

If it hasn't been done already, check the power supply and ground for the fuel pump. The ground connection on a C/K truck is just ahead of the LR wheel opening under the box. The power supply includes the fuse and its socket, pump relay, and connections between that and the pump.

[Trio3b]

Thanks for tips on fuel. The hard starting over the months does sound like fuel issue.
I'm also gonna check the expiration date of that d*mn starter fluid. Maybe it goes bad in the can!?! Sheeesh!

[Blue Bowtie]

Most starting fluids are based on ether and a propellant. Unless the can leaked, I can't imagine how the ether would evaporate.

These fuel pumps are very sensitive to voltage for producing sufficient pressure. A little resistance at a connection (including the ground) can make a substantial difference.

[Trio3b]

Suspicions confirmed, and more bad news. Ignition back up to Snuff and truck is running. More than likely that bad coil wire and the rotor spring tab seemed a little compressed . Still the hard start. Fuel pressure right at 40 which is way below recommended, so easy check will be ground circuitry to see if fuel pump starving for good ground path. If not, then it's pressure regulator or pump itself. (Fuel filter changed )

However, even more bad news. Remember that missing coolant I mentioned? Looks like oil is getting a little milky. I'll change the oil to flush out any coolant and then truck will be used on a minimal basis until I can figure out what I want to do.

Shouldn't be any coolant leaks into the cylinder because pressures are good. Possible coolant leaks from passageways into oil gallery? I don't know enough about this engine although I have read that there should not be any passageway between coolant and oil in the block itself .

Maybe an intake manifold leak as suggested earlier, like on the Buick 3.8 L intake manifold. Done several of those. Why did I think I was going to get off easy? Dang it.

Thanks for the tips. Will keep posted.

[Schurkey]

Originally Posted by Trio3b

Fuel pressure right at 40 which is way below recommended, so easy check will be ground circuitry to see if fuel pump starving for good ground path. If not, then it's pressure regulator or pump itself. (Fuel filter changed )

Don't ignore the "positive" side of the fuel pump wiring. Poor connections or corrosion on the contact points can cause low voltage and poor amperage delivery to the pump.

Originally Posted by Trio3b

Looks like oil is getting a little milky. I'll change the oil to flush out any coolant and then truck will be used on a minimal basis until I can figure out what I want to do.

Sure the oil isn't contaminated with condensation and/or fuel?

I would let the truck sit overnight, so the water has time to separate from the oil. Then pull the oil pan drain plug. If you see coolant come out, you'd know.

Originally Posted by Trio3b

Shouldn't be any coolant leaks into the cylinder because pressures are good.

What "pressures"? Cooling system pressure? Cranking compression pressure? Something else?

Originally Posted by Trio3b

Possible coolant leaks from passageways into oil gallery? I don't know enough about this engine although I have read that there should not be any passageway between coolant and oil in the block itself .

Maybe an intake manifold leak as suggested earlier

Intake gasket leak would be the most common...but a cracked head or block casting, or even a cracked intake manifold could leak coolant that would find it's way to the oil pan.

[Trio3b]

For fuel:
Will check fuel pump connections positive and ground visually. Then later move to some other tests.

For coolant issue:
Cylinder compression tests seemed normal.
Also going going to do a cooling system pressure test.

It's possible condensation but we're pretty dry here in the Southwest. This is not a daily driver . Only use the vehicle once every couple weeks so it's hard to gauge how often I'm refilling coolant but besides refilling coolant every so often with no visible leaks externally, there's Milky oil , and I'm smelling acrid odor around the vehicle and I'm seeing a little bit of white out the tailpipe. We'll also pull the drain plug and see if coolant is present.

Thanks for tips. Will post back.

[Blue Bowtie]

Intake gaskets are suspect if coolant is mixing with oil. Those have been updated from the original design. If you've seen it in a Buick 231 V-6, you know the situation.

However, it seems that isn't the only issue, since coolant in the oil should have no effect on fuel pressure.

[Schurkey]

Originally Posted by Trio3b

Will check fuel pump connections positive and ground visually.

Pointless. Connections can "look" good yet have high-resistance.

Verify voltage as close to the fuel pump as practical (typically at the rearmost connector before the harness goes "up and over" the fuel tank.) The fuel pump must be RUNNING, so do this with the engine running. GM uses undersized wire, so ~2 volts less than alternator voltage is probably acceptable.

Check for voltage on the ground wire as close to the fuel pump as practical. Again, the pump must be RUNNING. Same undersized wire, (but not as much of it) so ~1 volt is probably acceptable.

With two volts of loss on the positive side, and one volt of loss on the ground, the fuel pump will be running on ~11.x volts when the alternator is charging at 14.x volts. Sux, but that's GM's wiring harness. At 11 volts or less, you have wire harness problems.

[Blue Bowtie]

Originally Posted by Schurkey

... GM uses undersized wire...

Amen to that. I've seen that in other brands as well, probably since all of them are trying to trim weight and costs.