# Please help me diagnose S-10 that won't start



## clovis (May 13, 2002)

I have a 1995 Chevy S-10 (actually a GMC Sonoma) with a 4.3 V6 engine. It has 177,000 miles, and has run strong.

This truck has run great since I owned it. I drove it 44 miles yesterday, then ran errands around town, brought the truck home, and parked it in the drive.

This morning, the truck would not start. It typically starts on the first crank, just like a brand new truck would.

I have not had any rough idle. The service engine light has not come on.

This problem has come with no warning whatsoever...at least that I am aware of.

I have plenty of battery cranking power, and the truck cranks over easily.

Gas appears to be spraying from the two injectors in the throttle body while cranking the engine.

The #1 spark plug is showing spark. It is yellow-orange spark, and not blue. (Could I have not had it grounded correctly so it would only be yellow-orange?) The spark plug appears to be in good condition, but is dry as a bone.

I pulled the distributor cap, and while it shows wear and some oxidation, it appears to be usuable. Do they have to be perfect for the engine to run fine?
The same condition goes for the rotor.

I do not own a scanner, and have not put the truck on a scanner yet. How much do they run? Would it do me any good to scan it right now?

I don't mind buying quality parts, but hate to get into the game of throwing parts on it for pot luck results.

Ideas? Thoughts? Suggestions? Opinions? I could use them!!!! 

My money is tight right now, and don't have a ride since the wife takes the good car to work!!!!!


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## Cabin Fever (May 10, 2002)

> Gas *appears* to be spraying from the two injectors in the throttle body while cranking the engine.


Are you sure it's getting gas? Can you hear the fuel pump whine when you first turn the ignition key?


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## Wis Bang (Feb 20, 2009)

Throttle Body Injection is low pressure [9lb - 13lb] but it needs to have enough pressure. 

Double check that you have spark, try some starting fluid and see if it fires on that so you can confirm your spark. 

Corrosion in the Cap/rotor and old wires and older plugs could add up to weak spark, expecially in damp weather. The module, on the side of the distrib, can fail but the ones I've seen still started and cut out a cyl on aceleration.

Fuel problems w/ TBI usually resort from a clogged filter -or- a bad fuel pump. When yiou first turn on the key, do you hear the pump pressurize the system? It should run a few sec and shut down until you crank.

TBI Injectors are real simple. Avoiding the electrical connection at the top, you can clean the throtle blades, etc. w/ carb cleaner. They shouldn't be the problem.

Get the starting fluid & try it.


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## clovis (May 13, 2002)

Will give that a try fellas. I'll be back soon.

Could it be a bad coil? How would I test that....and if it was a bad coil, would I get any spark?

Thanks so much!!!!!!


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## clovis (May 13, 2002)

Okay...

I have owned the truck 4 years, and have never heard the fuel pump humm. I can't hear it today either. Some vehicles have a distinct sound when the fuel pump kicks on.

Gas is spraying out of both injectors in the throttle body. You can see it and smell it. It is spraying and NOT just pouring out.

The rotor is turning. This tells me it is not a timing issue.

I am going to the parts store to see what a new rotor should look like. This rotor does have some black gunk on the end of the metal cantact part thingamajig.

It will be several hours before I can check back. I have some stuff that MUST be attended to.

Your continued help is definately appreciated!!!!!


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## fixer1958 (Dec 12, 2005)

With spark and fuel it should start. Weak spark..... check your coil wire on both ends.
Check output right out of the coil...if good there, go down the line.

Disconnect the injectors and hold the pedal to the floor and try to start it.
If all is good spark wise and is flooding (assuming the timing chain is intact, which odds are it is) the coolant sensor can crap out and tell the computer it's -40 and dump buckets of fuel in the engine and cause a no start.
A scanner is the only option to find that out.


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## agmantoo (May 23, 2003)

With spark and fuel it should have attempted to run. Put #1 piston at top dead center and remove the distributor cap and see if the rotor is on #1 spark plug wire. It could have jumped time.


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## clovis (May 13, 2002)

fixer1958 said:


> With spark and fuel it should start. Weak spark..... check your coil wire on both ends.
> Check output right out of the coil...if good there, go down the line.
> 
> Disconnect the injectors and hold the pedal to the floor and try to start it.
> ...


This is a pretty good idea!!!!

I think the timing chain is okay...I pulled the distributor cap and hit the key, and the rotor spun to a new spot. The rotor wouldn't spin if the timing was out, right?

How do I test the coil? 

The truck should start even with weak, orange-yellow spark, correct? I did not see nice blue spark that everyone says that you should have. 

Going back to the coolant sensor: The truck did act as if it were it were flooded when I first tried to start it. In all actuality, I thought I had gotten it flooded by hitting the gas pedal accidently when I got in the cab.

It really smelled like gas when I pulled the breather cover off. It did seem like a ton of gas spraying out of the injectors for a normal, warm weather start. There was so much gas that it seemed to have dampened the air filter pretty well. I even joked with the neighbor that he shouldn't light up until the gas evaporated.

One other thing about the truck acting flooded: It cranked forever, and "coughed" twice...just like a truck trying to start after it was flooded.

I should be able to scan it tomorrow, but it looks like I'll be buying one. I don't know anyone that owns an OBD I scanner.

Thanks!!!!!!


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## radiofish (Mar 30, 2007)

Well with my 1986 2.8L V-6 engine in a S-15 GMC Jimmy 4X4 small SUV, I had a similar engine starting problem. It died in the middle of the private road here on the property!

After replacing the distrubitor cap/ rotor, ignition coil, sparkplug and coil wires - I finally got around to replacing the 'electronic ignition module', which is located on the rotor plate inside the distrubitor. Then my vehicle went from D.O.A. - to it starting right up... Just make sure to use the supplied dielectric grease on the underside of the module (to insulate it from the metal ground) when mounting the part. Ask at the parts store about how to mount it, if you decide to purchase that part.. 

I replaced all of those ignition parts, since I had no spark to any of the cylinders... 

Bad coil = no spark at all!!!!


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## agmantoo (May 23, 2003)

Clovis,
The rotor button can continue to turn.


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## Bluecometk (Jun 20, 2009)

clovis Get the truck ready to crank over and start.

Next put your foot to the floor and hold the accelerator pedal down with the key off.
Next turn the key on, still holding the pedal down.
Next crank the engine. This puts the car in a clear mode like sticking a screwdriver in a carb choke butterfly. This will turn the injector off until the engine tries to start and reaches a certain preset RPM.

It should at least try to start. If it does be ready to lift off the pedal as it will rev to the moon quickly.

If it has flooded very badly as in stuck injector you may have a condition called cylinder wash down. This is when the fuel washes the oil away from the cylinder/piston rings. This lowers the compression to the point of a no start condition.

You can fix this by pulling the plugs and putting two or three squirts of engine oil in each cylinder and then blowing dry the plugs and installing them. The added oil will coat the cylinders and rings restoring the compression. The engine should start but it will smoke for a few minutes.

Let us know what happens

Hope this helps 

Bluecometk


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## clovis (May 13, 2002)

Thank you for the replies!!!!

I don't think the coil is bad. Like radiofish said, bad coil = no spark. I have spark, but not blue spark.

*Where would I find the coolant sensor? Can it be tested?*


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## fixer1958 (Dec 12, 2005)

Use an ohm meter
-40F-1000,700 ohms
68F-3520 ohms
212F-177 ohms


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## cfabe (Feb 27, 2005)

I've had a GM vehicle with a bad coolant temp sensor reading -40 deg, it would start but run poorly and fouled plugs out real fast. But, if you have weak spark, it could have flooded it and not started. Try cranking with pedal down like others suggested.


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## cfabe (Feb 27, 2005)

Oh, coolant temp sensor is located on the thermostat housing, intake manifold, or engine head and it will be a small brass fitting with a 2-wire connector.


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## fixer1958 (Dec 12, 2005)

The sensor in the LS head is the for the guage. The one for the ECM is by the thermostat, 2 prong sensor.
I'm not saying that is the problem, just trying to rule it out if it isn't, then go from there.


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## clovis (May 13, 2002)

Okay....this is weird:

I didn't know anyone that owned a scanner that would read the S-10 I own. I decided to try to read the codes by using a paper clip as a jumper in the plug in.

When I tried the paper clip trick, it kept flashing a 12, over and over. I decided I was doing it wrong, and tried it again 5 times over a two hour period.

I decided I better put the distributor cap back on, just in case it wouldn't show codes without it. (I am pretty dumb).

It showed code 12 again and again, even past the first three times of flashing.

I decided to try to start it, and it fired up, and ran a little rough, but then evened out and ran well. I let it idle for at least 15 minutes, and ran some errands in the truck. It has run well and restarted just fine.

I am still getting a gas smell after I shut it off, but I think it is because the breather housing is still off of it.

I never hit the gas when starting, so I didn't flood it...unless I somehow hit the pedal getting into the truck....but I still can't imagine I hit the pedal long enough or more than once...but I sure don't remember hitting the pedal at all.

I am a bit nervous that the truck just fired up. My mind would be more at ease had I been able to identify a problem and repair it. 

Any ideas? Should it be showing any codes??? What gives????


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## fixer1958 (Dec 12, 2005)

Code 12 means everythng is peachy in the S10 world as we know it.
You might have screwed with a connection and made things all better.
In the FORD realm of testing it's called the 'wiggle test'.


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## clovis (May 13, 2002)

fixer1958 said:


> Code 12 means everythng is peachy in the S10 world as we know it.
> You might have screwed with a connection and made things all better.
> In the FORD realm of testing it's called the 'wiggle test'.


Well, I thought a code 12 meant that all was well, but wasn't 100% sure. I am a little more at ease hearing that. 

BTW, how do you know when it is time for a new cap and rotor?

Thanks!!!!!!!


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## Wis Bang (Feb 20, 2009)

clovis said:


> Well, I thought a code 12 meant that all was well, but wasn't 100% sure. I am a little more at ease hearing that.
> 
> BTW, how do you know when it is time for a new cap and rotor?
> 
> Thanks!!!!!!!


The GM OBD I flashes code 12 3x b/4 flashing any stored codes so as soon as you see the 4th 12 you know that there are no stored codes...

Look at the inside of the cap if there is a white crust forming on the contacts, it's time. If it is grey or blue look for black cracks/marks called carbon tracks, a sign of the juce going where it isn't supposed to go...

On my Jimmy I change it every 2 - 3 years. My ford Ranger needs a new one each year...


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## Beeman (Dec 29, 2002)

What condition are the plugs,wires, cap and rotor? This time of year dampness will get the best of old plug wires. Worn plugs are harder for the spark to jump across especially with worn ign parts. might just be time for a good old tune up. Also don't discount the change in gasoline blends this time of year, makes some vehicles hard to start during this in between time.


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## Sawmill Jim (Dec 5, 2008)

Well my S 10 only has a fuzz over two hundred thousand on it and still running so if it an't broke i an't going to fix it .


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## clovis (May 13, 2002)

Beeman said:


> What condition are the plugs,wires, cap and rotor? This time of year dampness will get the best of old plug wires. Worn plugs are harder for the spark to jump across especially with worn ign parts. might just be time for a good old tune up. Also don't discount the change in gasoline blends this time of year, makes some vehicles hard to start during this in between time.


They are in fair condition. Not great, but not awful either. I suspect it is time for a tune up. This is not something I am looking forward to. I had a time just getting the boot off one of the plugs without breaking it...and even though the plugs are relatively easy to get to, it is still gonna be a pain.


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## clovis (May 13, 2002)

BTW, truck is still starting and running great.


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## Beeman (Dec 29, 2002)

I would replace the wires while changing plugs. Your choice but I've never had any luck with cheapo wires. I always use Standard Motor Products brand wires. Boots should have a dollop of dielectric compound (silicon grease) in each one when installing/reinstalling. Then they will come right off with a twist. Don't forget to replace the fuel filter too.


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## Wis Bang (Feb 20, 2009)

Beeman said:


> I would replace the wires while changing plugs. Your choice but I've never had any luck with cheapo wires. I always use Standard Motor Products brand wires. Boots should have a dollop of dielectric compound (silicon grease) in each one when installing/reinstalling. Then they will come right off with a twist. Don't forget to replace the fuel filter too.


Good advise here, cheap wires don't last. It takes long enough to change 'em; no sense doing it every year when a set that costs twice as much will last for three years...you do get what you pay for w/ auto parts...

Since it is a GM stick to AC plugs...avoid Bosch Platnums...if you want a premium plug AC makes some. I always just jsued standard AC plugs.


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## Wis Bang (Feb 20, 2009)

Sawmill Jim said:


> Well my S 10 only has a fuzz over two hundred thousand on it and still running so if it an't broke i an't going to fix it .


My S10 2.8L started knocking at 196,269 and I purchased the GM replacement 3.4L crate engine, sold the truck 6 years later at 308,000 and two years later it is still being used by the guy who bought it...

My Jimmy has 189,000 on the 4.3L w/ no major problems. It is rusting away on me though...I've spent so much on things that I don't want to continue fighting the rust on a 16 yr old vehicle...I did change the front fenders andit was a real job...I need two doors and a rear gate and don't feel like doing it.

As much as I hate it, my '93 Ranger has zero rust...paint is peeling, no power, rides like it has square wheels but no rust...capable little 4x4 but I'll replace it as soon as I can...


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## clovis (May 13, 2002)

Thank you again for the replies!!!!!!

The truck ran perfectly over the weekend.

I started it today, and *I have a new problem.*

The truck started fine, but ran rough. It eventually smoothed out and ran fine, but with a high idle.

Along with the high idle, and drinking gas, the truck...well, I am not sure how to describe this.....

In town, from a stop, the engine idled high enough that you don't have to give it any gas. It just starts moving when you take your foot off the brake pedal. It moves faster than it should, and will climb in speed...and will even switch gears into second gear...and keep on going.

As well, when driving at 50 MPH, and let off the gas to coast (when there is a red light ahead) the truck does not slow down like it should. It will slow some, but will take for ever to slow down to 40 MPH, but keeps going at that speed.

Also, when coming to a stop, the engine is idling too high and it takes more than normal to get it stopped. Even at the risk of sounding like a total idiot....it is like the engine isn't idling or 'vacuuming' down like it should.

It did give a service engine soon light when idling for more than a minute today at a stop light. Does this mean that it stored a code in the OBD computer?

I haven't had a chance to read any codes yet. It has been a busy day, and it is dark and cold outside right now.

Thoughts? Ideas? Opinions? 

Thanks!!!!!!!


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## blufford (Nov 23, 2004)

I think its your TP (throttle position) sensor.


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## Cabin Fever (May 10, 2002)

It could be a loose nut in the driver seat...but, more likely a floor mat stuck under the accelerator pedal.


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## clovis (May 13, 2002)

I just did the paper clip trick, *and it shows a code 35*.

Two internet sources say this is the Idle Air Control Valve.

*Any idea where that is located on the engine?*

I have a guess...but it is only a guess.

*Thank you everyone!!!! I really do appreciate the help!!!!! It means alot to me!!!!*


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## seagullplayer (Nov 6, 2008)

Stuck throttle cable?




*BTW bad coil does not always mean no spark, I always thought that myself.*

Our Jeep quite on my wife a few years ago, I had fuel pressure and weak spark at the plug, I thought it must be a timing problem. Before I bought a part I called a local Jeep dealer and the service manager said, I have replaced a lot of coils on that model, try it before anything else.
I did, it ran fine...
I pulled a plug after the change, true blue.


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## clovis (May 13, 2002)

I've since learned this part screws into the throttle body.

I am also told that it can be cleaned.

Is this true????


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## blufford (Nov 23, 2004)

These may help

http://wiki.answers.com/Q/Chevy_S-10_IAC_throttle_body_diagram

http://autorepair.about.com/library/faqs/bl656f.htm

http://autorepair.about.com/library/a/1i/bl139i.htm

http://www.justanswer.com/questions/1doth-2000-chevy-s-10-need-picture


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## clovis (May 13, 2002)

Just as an update:

I pulled the Idle Air Control tonight, and replaced it with a used IAC that my friend owned. He had a spare trottle body from a Chevy 305 (I think). We swapped those parts, and the truck runs great!!!!! (So far, at least.)

I think that the IAC had gone bad in my truck, and caused the fuel mixture to be tremendously high, and therefore caused the truck to flood with gas in the throttle body, and would not allow it to start.

This is just a theory, of course, and I am not a mechanic, so take it with a grain of salt. 

I do want to thank everyone for their help!!!!!! I really appreciate it!!!!!


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