The ol 94 won’t run, cranks, fuel, spark, no start.

[CanadianNorth]

hi folks,I’ve had this v6 94 TBI K1500 for a couple years.
Few issues, but the engine was running good all summer.
I replaced coil, wires, spark plugs when I purchased it.

I noticed a bit of occasional hesitation when accelerating, particularly from starting off, but didn’t think much about it.

A few weeks ago she had trouble starting, I checked the injectors and spark at each plug, all good.
I replaced the ignition control module.
An extra ground had been temporarily added to the fuel pump for some reason (previous owner) and I cleaned that up.

The truck started up and was working fairly well (still a little hesitation at times).

I used the truck for a few days without issue around town.

Yesterday I decided to check the timing, and left the truck idling for a few minutes to warm up.

The engine would idle normally, then bog down and put out tons of black smoke, then Settle down and idle normally again.
This cycle would happen every couple minutes. I didn’t check the timing at that point and shut down the truck.

Today I was going to move the truck into the garage and replace the fuel pump, just in case. Unfortunately the truck tried, got close, but would not start.
Spray from the injectors looks good, spark is there but it will not start.

Hopefully someone has some suggestions, not sure where to start.

Thanks
Stewart

 

[Schurkey]

Connect a scan tool, verify EVERY sensor. In particular, the coolant temp sensor, but all of them in general. Verify the computer outputs, also.

How old are the usual "tune-up" parts 'n' services? Cap, rotor, plug wires, plugs, PCV system, initial timing check, EGR check, heated-air-cleaner flap, air filter?

What is the fuel pressure? How old is the fuel filter?

 

[pgutier1]

I had a similar situation, thought it was the 10yr old fuel pump...nope. Ok, next was the fuel relay...nope. Fuel filter...nope. It was the ignition module in the distributor...ugh.

@Schurkey is right, scan and do homework before you start replace stuff.

I didn't have a scanner so I did the latter until I gave up and towed it to my mechanic, lol.

 

[CanadianNorth]

Connect a scan tool, verify EVERY sensor. In particular, the coolant temp sensor, but all of them in general. Verify the computer outputs, also.

How old are the usual "tune-up" parts 'n' services? Cap, rotor, plug wires, plugs, PCV system, initial timing check, EGR check, heated-air-cleaner flap, air filter?

What is the fuel pressure? How old is the fuel filter?

Thanks,

-coolant temp sensor replaced yesterday
- newish plug wires 1 year old, same with plugs,
- fuel Filter 1 year old, air filter 6 months.

I haven’t tested the fuel pressure, as I don’t have a tool for that yet.

I’m wondering if I should get an ALDL to usb and go with Tumer Pro software, or buy a Simple obd1 tool.

I have used VCDS with Volkswagen cars before, but I think tuner pro is more complex.

 

[ben2go]

Thanks,

-coolant temp sensor replaced yesterday
- newish plug wires 1 year old, same with plugs,
- fuel Filter 1 year old, air filter 6 months.

I haven’t tested the fuel pressure, as I don’t have a tool for that yet.

I’m wondering if I should get an ALDL to usb and go with Tumer Pro software, or buy a Simple obd1 tool.

I have used VCDS with Volkswagen cars before, but I think tuner pro is more complex.

Did you get a definitive answer on why your truck wouldn't start. I'm having a similar issue on a 5.7 engine. between me and a shop, we have all given up. Good spark good fuel, engine checks good, exhaust isn't plugged, nothing can be found with computer scans either.

 

[Rustyjunk]

Hi, had a 93 with similar issues. Odd hesitation, sometimes it would just die, then restart, sometimes no start. It was the positive battery cable going to the starter shorting out on the frame where it had worn thru the insulation. It grounded just enough to cause all these issues, but never acted like a dead short. Just something to check. Often the hardest things to diagnose are something simple that's easily overlooked.
Hope this helps

 

[Schurkey]

Good spark

WHERE do you have "good spark"? If it's not "across the plug gap" it doesn't count.

Fouled plugs are a common, hidden cause of "cranks but won't start".

good fuel,

You've taken a sample from the injectors, and it burns?

engine checks good,

WHICH "checks" were performed?

nothing can be found with computer scans either.

WHICH "computer scans" were performed?

 

[CanadianNorth]

Hey folks, thank you for all the replies. I was at a loss. I ended up replacing the distributor and doing the timing, and replacing the fuel pump. Everything works good now.

 

[GoToGuy]

You replaced the distributor, what was broken? Did you do a fuel pressure test? If so what did you find? Or did you just replace fuel pump for age or guess?

 

[ben2go]

WHERE do you have "good spark"? If it's not "across the plug gap" it doesn't count.

Fouled plugs are a common, hidden cause of "cranks but won't start".


You've taken a sample from the injectors, and it burns?


WHICH "checks" were performed?


WHICH "computer scans" were performed?

I have a thread on this. It doesn't matter now. The truck is going to the crusher friday.