Ol' Blue won't start

tonycondon

tonycondon

Gastons CRO (Chief Dinner Reservation Officer)
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Tony
I'm almost at the end of the line with ideas. As some of you saw on my Facebook, Ol' Blue has decided not to start. Leah drove it last Saturday with no issues reported. Sunday morning it wouldn't start. Not just it wouldn't start but it wouldn't even try to start, would just crank.

Engine is a 4.3L TBI V6 with ~190K miles since last overhaul.

fuel, spark, air

first thing i did was remove the fuel line from the back of the intake then turn key on. fuel everywhere. perfect. later investigation has shown fuel scent on removed spark plugs and from the exhaust pipe so i have confidence that fuel is getting to the cylinders.

spark plugs are sparking. I was really disappointed by this as my first though was that the ignition module had decided to take the day off. they are sparking even better now that we replaced the distributor cap & rotor and spark plug wires. I'm 99.9% sure after checking the haynes manual 10 times that the right wires are running to the right cylinders. I also tried rotating the distributor one way or the other and then starting it in the new position, thinking maybe the timing had slipped out. As Chris has told me, the timing did tend to wander and I reset the timing the last time I did a bunch of tune up work about 3 years ago.

when I turn the key on the CEL comes on but I can't remember if it always did that or not. There were no CEL's before when it was running great (we drove it to Minneapolis and back plus some for the holidays). Just to be sure i grounded out the pins and no CEL codes were stored.

There is no reason there isn't air getting to the cylinders. the throttle is opening and i've tried starting it with and without the air filter installed.

natural thought is that something electronic took the week off considering the sudden decision not to run. the only other possibility I can think of is a broken timing chain. However I don't think this is possible since the distributor is turning. Can anyone confirm this? Would love to hear some of PoA's ideas since we have a lot of experienced mechanics and problem solvers. No Jesse, I am not going to buy a Ford.
 
Try replacing the ignition module anyway with a new one (get genuine GM). On those 4.3s the damn things go out every 200-300k or so. You'll still see evidence of spark and fuel, but something about the quality isn't what it should be. They fail the way you indicate.

Had the exact same symptoms and problems on a 4.3 of similar vintage in an Astro van, with about the same mileage. Worked great.

Give it a shot. If I'm wrong, I'll buy you a Crown and Coke next time we meet. If I'm right, I'll buy you one anyway.
 
Oh, and the distributor would not turn if the timing chain was busted. It's driven off of the crank.
 
fair enough. I think i actually replaced the ignition module during the last round of wild guesses 3 years ago, but i'm sure it was with an autozone part. My friend who was watching the spark plug fire described it originally as orange but after the new rotor distributor and wires said it was a nice blue.
 
You assume correctly. Sorry for the typo. Point is, your timing chain is fine.

When it comes to ignition components like modules, I've had terrible luck with the cheap aftermarket stuff. Try a genuine GM and give it a whirl.
 
tonycondon said:
I'm almost at the end of the line with ideas. As some of you saw on my Facebook, Ol' Blue has decided not to start. Leah drove it last Saturday with no issues reported. Sunday morning it wouldn't start. Not just it wouldn't start but it wouldn't even try to start, would just crank.

Engine is a 4.3L TBI V6 with ~190K miles since last overhaul.

fuel, spark, air

first thing i did was remove the fuel line from the back of the intake then turn key on. fuel everywhere. perfect. later investigation has shown fuel scent on removed spark plugs and from the exhaust pipe so i have confidence that fuel is getting to the cylinders.

spark plugs are sparking. I was really disappointed by this as my first though was that the ignition module had decided to take the day off. they are sparking even better now that we replaced the distributor cap & rotor and spark plug wires. I'm 99.9% sure after checking the haynes manual 10 times that the right wires are running to the right cylinders. I also tried rotating the distributor one way or the other and then starting it in the new position, thinking maybe the timing had slipped out. As Chris has told me, the timing did tend to wander and I reset the timing the last time I did a bunch of tune up work about 3 years ago.

when I turn the key on the CEL comes on but I can't remember if it always did that or not. There were no CEL's before when it was running great (we drove it to Minneapolis and back plus some for the holidays). Just to be sure i grounded out the pins and no CEL codes were stored.

There is no reason there isn't air getting to the cylinders. the throttle is opening and i've tried starting it with and without the air filter installed.

natural thought is that something electronic took the week off considering the sudden decision not to run. the only other possibility I can think of is a broken timing chain. However I don't think this is possible since the distributor is turning. Can anyone confirm this? Would love to hear some of PoA's ideas since we have a lot of experienced mechanics and problem solvers. No Jesse, I am not going to buy a Ford.
Click to expand...

What vehicle/year is this motor in? Some of what you said doesn't make any sense. If you grounded out the pins on an OBD1 vehicle 86-~95 that can give you the codes if any. If you did that on an OBD2 vehicle ~95 or newer then you didn't do the vehicle any favors you need a code reader.

If you have a traditional distributor and you are getting spark to all cylinders then it is not the crank sensor, ignition module, or cap.

You pulled off the fuel line, but you don't have to in most all cases there is a Schrader valve on the fuel line you can use to test fuel pressure. You can borrow a tester from Autozone. Pulling the line off does not mean you have enough fuel pressure to fire an injection based system. Fuel pumps are a common no start failure item.

Is the little key symbol staying lit on the dash? I don't know what vehicle we're talking about yet but the VATS key system on older GM's often cause a no start condition. It is a security system that matches the resistance in your key to a prescribed value set in the computer. If your ignition switch is going or gone then you can get a no start, since the computer will think the vehicle is being stolen and turn off the injectors. Try both keys just for grins.

The distributor turns off the cam shaft, so if the rotor is turning the timing chain is OK.

Maybe you can elaborate more on the distributor. If the car was running one day and the next day it isn't. How would that be a timing issue? Did you replace all of the ignition components you listed after it wouldn't start or sometime in the past? If the timing is truely wandering, not moving because of computerized advance then you likely have/had a worn distributor and/or camshaft gear (common problem on 4.3's). In that case you didn't address the problem.

Let us know some more information and we'll go from there.
 
it's a 1994 GMC Sierra. the fuel pump was replaced in the summer of 2011 in a hangar at the Goodland, KS airport. we removed the cap just to have a look, it was worn and so was the rotor so it seemed like a good time to replace them. I managed to wreck a spark plug wire when i decided to check if it was sparking so we got a new set of wires too. I also managed to break the spark plug too so i did replace the #1 spark plug. There is no key symbol on the dash.
 
Pull the distributor cap off and watch the rotor button while someone cranks the engine over to be sure the distributor shaft is actually turning. I've had that perplex me before.:mad2:
 
Since you have had the #1 spark plug out...:hairraise:....

I would remove it again, turn the motor over with your finger on the spark plug hole,, confirm TDC on the # 1 cylinder, look at the rotor to confirm it is pointed at the #1 wire on the cap... if that all matches up and the plugs have a decent spark then get a can of starting fluid and give the air cleaner a shot while cranking... It should try to start.....:yes::yes:
 
i suppose it is possible that the rotor was stopped on the contact for the one spark plug we pulled. although...i think the first time we checked it was the #1 and the next time we checked the #2.
 
tonycondon said:
it's a 1994 GMC Sierra. the fuel pump was replaced in the summer of 2011 in a hangar at the Goodland, KS airport. we removed the cap just to have a look, it was worn and so was the rotor so it seemed like a good time to replace them. I managed to wreck a spark plug wire when i decided to check if it was sparking so we got a new set of wires too. I also managed to break the spark plug too so i did replace the #1 spark plug. There is no key symbol on the dash.
Click to expand...

No VATS on Sierras until 1998, disregard that one.

You can pull the codes with a paper clip or wire. Have you done that? If not I can post a link.

Fuel pump may not be the issue then.

Let's start with the codes if any.
 
i used a wire to ground out the diagnostic pin, there are no codes stored.
 
tonycondon said:
i used a wire to ground out the diagnostic pin, there are no codes stored.
Click to expand...

You got code 12 though right?

Also TBI's don't have a schrader valve just the Vortecs so testing fuel pressure would be more difficult. Have you tried a little shot of starting fluid? Or just pouring a little gas down the throttle body? That would help us narrow it down some.
 
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N801BH said:
I would remove it again, turn the motor over with your finger on the spark plug hole,, confirm TDC on the # 1 cylinder, look at the rotor to confirm it is pointed at the #1 wire on the cap... if that all matches up and the plugs have a decent spark then get a can of starting fluid and give the air cleaner a shot while cranking... It should try to start.....:yes::yes:
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Try this. If it tries to start, start diagnosing the fuel system.

As a '94 I'm guessing its fuel injected. Although your statement about pulling the fuel hose off has me a little confused. Throttle body injection (most likely) or multi-point?
 
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dell30rb said:
Try this. If it tries to start, start diagnosing the fuel system.

As a '94 I'm guessing its fuel injected. Although your statement about pulling the fuel hose off has me a little confused. Throttle body injection or multi-point?
Click to expand...

94 4.3 Sierras are all TBI's
 
tonycondon said:
when I turn the key on the CEL comes on but I can't remember if it always did that or not. There were no CEL's before when it was running great (we drove it to Minneapolis and back plus some for the holidays). Just to be sure i grounded out the pins and no CEL codes were stored.
...
I am not going to buy a Ford.
Click to expand...

Check engine light should come on with the key and go off when you start to crank.

Throttle body or port fuel injection?

Could be fuel pressure issues, could be injector issues.

Re-think not buying a Ford. :D
 
yes code 12. yes throttle body injection. assume injection is working based on fuel smell on spark plug and out exhaust pipe after cranking. will verify rotor is turning, use bens advice to confirm timing and probably get a new ignition module and go from there.
 
tonycondon said:
good point. will confirm that to triple check fuel delivery. when it warms up later this week.
Click to expand...

Before you spend money pour a little fuel in the throttle body or a small shot of starting fluid. If it runs then you don't have an ignition issue. Please, lets not just throw parts at the problem.
 
tonycondon said:
yes code 12. yes throttle body injection. assume injection is working based on fuel smell on spark plug and out exhaust pipe after cranking. will verify rotor is turning, use bens advice to confirm timing and probably get a new ignition module and go from there.
Click to expand...

Fuel and air have to be in the correct proprtion. If the above doesn't work - you may be getting not enough fuel, Ether can fix that. Or, you may be getting too much fuel - some vehicles will shut off the injector if you have the throttle wide open (think IO-540 hot start ;) )

Causes for too much or too little fuel could be the injector dirty or leaking, temperature sensor bad but not bad enough to set a code (it thinks the engine is at -20F and gives too much fuel or it thinks the engine is at 180F and doesn't get enough), or fuel pressure or...
 
tonycondon said:
get a new ignition module and go from there.
Click to expand...

If you have spark at any spark plug it isn't the ignition module, or crank sensor, or coil as mentioned above. Those things all have to be working before you get spark at the plug.


sigh...
 
thats what i thought, but Ted had experienced similar issues on the same engine with similar symptoms and replacing the ignition module did help. Ted is a much better mechanic than I am so I tend to defer to his experience and judgment.
 
plus i can easily get the ignition module tested at o'reilly's and see if it is OK or not.
 
Alexb2000 said:
If you have spark at any spark plug it isn't the ignition module, or crank sensor, or coil as mentioned above. Those things all have to be working before you get spark at the plug.

sigh...
Click to expand...

I agree with every vehicle I've seen but the OBD1 4.3s, simply because of my experience with the Astro van.

Got fuel squirting in through the TBI (saw it with the air cleaner off). Got spark (confirmed visually and through my hand). Ignition module checked good at the auto parts store.

Replaced with new genuine GM part, van fired right up and ran beautifully. Had I not experienced it myself, I'd be saying the same thing as you.

I'll admit to not knowing why this was the case and why it worked, but my boss at the time (when I was a car mechanic) gave me this advice that I'm now giving Tony, and it worked.

Besides, since I've offered to buy him a Crown and Coke if I'm wrong (and I'd probably buy him more than one), that more or less balances it out. ;)

tonycondon said:
plus i can easily get the ignition module tested at o'reilly's and see if it is OK or not.
Click to expand...

See above. Said action on the Astro said the module was good. The test doesn't completely accurately represent the conditions the part goes through in use. So, I'd just buy the part.
 
Ted DuPuis said:
I agree with every vehicle I've seen but the OBD1 4.3s, simply because of my experience with the Astro van.

Got fuel squirting in through the TBI (saw it with the air cleaner off). Got spark (confirmed visually and through my hand). Ignition module checked good at the auto parts store.

Replaced with new genuine GM part, van fired right up and ran beautifully. Had I not experienced it myself, I'd be saying the same thing as you.

I'll admit to not knowing why this was the case and why it worked, but my boss at the time (when I was a car mechanic) gave me this advice that I'm now giving Tony, and it worked.

Besides, since I've offered to buy him a Crown and Coke if I'm wrong (and I'd probably buy him more than one), that more or less balances it out. ;)



See above. Said action on the Astro said the module was good. The test doesn't completely accurately represent the conditions the part goes through in use. So, I'd just buy the part.
Click to expand...

I always try to take a logical systematic approach to solving mechanical problems. When that fails, take an educated guess and throw the hail mary (In this case parts) at the problem, but I consider that a failure personally.

In this case we don't have the benefit of much in the way of diagnostics, but there is certainly a few things we can do to narrow down the possibilities.

We know (I think) that the engine is intact since it was just running and now over night it is not.

We know there are no codes, although OBDI sucks in that regard, it is a data point. Further, its reasonable to assume that the computer sending code 12 indicates it is probably functioning.

While there is fuel in the system we don't know if the engine is getting fuel or enough fuel for sure. That's why I suggested a shot of starting fluid or just pouring a little gas down the throttle body. Cheap, easy, and takes 1 minute. If the engine runs then no need to continue with the ignition system diagnosis.

If it does not, then continue with the ignition system diagnosis. Could be a lot of other simple things to check. For example, the wiring harness to the distributor is notorious for going bad, both the wires and the plug ends. We can test that, look at the wires, wiggle the plug ends, inspect all, in 5 minutes and go on from there.

Otherwise, you buy a factory ignition module (I agree about factory parts) and if it works great, you got lucky and someone owes a Crown and Coke. IF not then you have spent money on a non-returnable part and a lot of time fetching and installing it.

That was the basis of my thinking. Sounds like there is a personal bet going on here, so perhaps I should just stay out of it.
 
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Not a mechanic, so I've been letting the others armchair diagnose. But lemme know if recycled parts are needed.
 
Alexb2000 said:
I always try to take a logical systematic approach to solving mechanical problems. When that fails, take an educated guess and throw the hail mary (In this case parts) at the problem, but I consider that a failure personally.
Click to expand...

As an engineer who used to design and certify these systems, I agree fully.

That was the basis of my thinking. Sounds like there is a like a personal bet going on here, so perhaps I should just stay out of it.
Click to expand...

Nah, just a couple of old friends who are likely to buy eachother drinks anyway. :)
 
You can get spark outside the engine but not under compression - it takes a higher voltage to kick the spark off through the compressed mixture. Usually, if you see a good fat spark outside you are OK, but if it is at all weak...
 
I lived in Kansas longer than anybody here and can say with certainty that ether was always the answer in the winter. Well, along with Larry Palmquist's phone number if the ether didn't work.
 
Have you considered the possibility that Leah is sick of being seen in an old junky Chevy and sabotaged it so you'll purchase a proper truck?
 
leah has promised she did not sabotage. she claims to really want to see ol' blue hit 300K but seems to indicate that once the 300K party is over she'll be ready to move on. sigh. poor ol blue.
 
Alexb2000 said:
I always try to take a logical systematic approach to solving mechanical problems. When that fails, take an educated guess and throw the hail mary (In this case parts) at the problem, but I consider that a failure personally.

In this case we don't have the benefit of much in the way of diagnostics, but there is certainly a few things we can do to narrow down the possibilities.

We know (I think) that the engine is intact since it was just running and now over night it is not.

We know there are no codes, although OBDI sucks in that regard, it is a data point. Further, its reasonable to assume that the computer sending code 12 indicates it is probably functioning.

While there is fuel in the system we don't know if the engine is getting fuel or enough fuel for sure. That's why I suggested a shot of starting fluid or just pouring a little gas down the throttle body. Cheap, easy, and takes 1 minute. If the engine runs then no need to continue with the ignition system diagnosis.

If it does not, then continue with the ignition system diagnosis. Could be a lot of other simple things to check. For example, the wiring harness to the distributor is notorious for going bad, both the wires and the plug ends. We can test that, look at the wires, wiggle the plug ends, inspect all, in 5 minutes and go on from there.

Otherwise, you buy a factory ignition module (I agree about factory parts) and if it works great, you got lucky and someone owes a Crown and Coke. IF not then you have spent money on a non-returnable part and a lot of time fetching and installing it.

That was the basis of my thinking. Sounds like there is a personal bet going on here, so perhaps I should just stay out of it.
Click to expand...

i agree with your course of action. i don't have a can of gas around that isn't pre-mixed with oil for chain saws so that hasn't been an option for me. i also don't have a can of starting fluid but i can fix that tomorrow :) I appreciate all the suggestions. It's always nice to have other opinions and ideas.
 
a littl 2 cycle mix fuel isn't going hurt a bit.
 
wabower said:
I lived in Kansas longer than anybody here and can say with certainty that ether was always the answer in the winter. Well, along with Larry Palmquist's phone number if the ether didn't work.
Click to expand...

For a cranky old carbureated motor, definitely.

A fuel injected motor should start right up.
 
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