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post #1 of (permalink) Old 01-25-2007, 11:54 AM Thread Starter
 
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OT- Daily driver having starting problems

Post subject: 2001 S10 randomly wont start, then starts after sitting?

My 2001 chevy S10 4x4 ZR2 4x4 4.3 liter vortec, 85000miles, pick up is having a wiered issue. Randomly, no apparent pattern at all, is having problems. After driving, or sometimes when cold, no obvious pattern, will not start. It will sputter, obviously firing, with some combustion, but wont start. It sputters for a few seconds then dies. If I let it sit for 10 minutes and come back I can get it to start, but if I dont let it sit and just keep cranking the battery will run dead. The rest of the time, probably 9 out of 10 starts, it seems to start up and run fine? What is going on, the problem seems to be getting worse, and happening more and more often?

Please help, what is going on.

thanks
Tony
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post #2 of (permalink) Old 01-25-2007, 12:18 PM
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Re: OT- Daily driver having starting problems

Look at the pick-up coil in the distributor. That's where my money is.
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post #3 of (permalink) Old 01-25-2007, 12:53 PM
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Re: OT- Daily driver having starting problems

We have to assume you mean it cranks fine, but just won't start?

Try turning the key on, you should hear the fuel pump run about 15 seconds, then stop. Do it two or three times in a row, then try to start it. If it starts then it could indicate a weak fuel pump. At 80,000 it's getting near it's time.

Check the coil wire - try swapping with another.

Check to see that you have good spark at the plugs.

Look closely at the ignition wires - if you see little gray marks or dots on it - looks like smoke marks because it is - the spark is jumping out the insulation and grounding. The 4.3's are famous for that due to the way the wires are routed.

Let us know what you find.
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post #4 of (permalink) Old 01-25-2007, 01:03 PM Thread Starter
 
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Re: OT- Daily driver having starting problems

Yeah it cranks over fine, not a starter issue, I would guess fuel or spark, it seems to me like it floods it self, then after sitting for 10 mins it drys out and starts up.

Could it be an ignition issue if the problem only occurs at starts up , and only once in a while? It seems like if it was a bad plug wire it would run rough sometimes, definetly more often then just a random starting occurance.

Once started, and when the problem does not occur, which is most of the time, the motor runs fine?

WTF? Fuel pump you think?

Thanks
Tony
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post #5 of (permalink) Old 01-25-2007, 01:42 PM
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Re: OT- Daily driver having starting problems

""""it seems to me like it floods it self, then after sitting for 10 mins it drys out and starts up."""""
POSSIBLE, BUT DOUBTFUL.


"""""Could it be an ignition issue if the problem only occurs at starts up , and only once in a while?"""""
YES!


"""""It seems like if it was a bad plug wire it would run rough sometimes, definetly more often then just a random starting occurance."""""
NOT NECESSARILY



"""""Once started, and when the problem does not occur, which is most of the time, the motor runs fine?"""""
THAT"S A COMMON OCCURRENCE

WTF? Fuel pump you think?

I'd certainly check the ignition before condemning the fuel pump. Replacing the pump is lots harder than looking at the plug wires. Take them off one at a time and look at then closely. TRY THE KEY CYCLING when it doesn't want to start.

Unplug and plug the fuel pump relay in - the terminals get corroded.

Look at the coil for the same smoke marks.
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post #6 of (permalink) Old 01-25-2007, 01:57 PM
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Re: OT- Daily driver having starting problems

My vote is going to be electrical....

When you say it sputters....do you mean that it will act like it is trying to start...a few plugs fire and then nothing?

If so...I would first thing fuel pump....but, a fuel pump would do that every time....once they go...they go.

Have you ruled out the ignition switch? Remember, when you go to start the engine, you have more than just the signal to the starter....in fact, you ignition has the following wires...

ACC
Ignition - Key is on
Ignition on + Bulb Test
Ignition On + Crank

Hence, it is possible to have the crank signal but not the Ignition On signal when the switch is in the crank position. Those switches do wear out.

Next time it acts up...have your timing light handy...hook it up to the spark plug to see if it's trying to fire the plug. As RRich noted, fell the injector....if the injector is not firing, the plug is not going to fire either.
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post #7 of (permalink) Old 01-25-2007, 07:22 PM
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Re: OT- Daily driver having starting problems

The schematics show that it's not much different than most EFI systems. You've got to define if it's fuel, or ignition related. It's easy to do. When it wont't start... just spray some starter fluid into the throttle body intake and see if it starts. If it does, it has spark and the fuel pump is bad. If it doesn't then you know there is no spark. That usually goes back to the CrankshaftPostionSensor, the CPS. It kills everything. It's symptoms are hard-long cranking when cold and not working again, after the engine's been shut down. The ECU, like all of them, will turn off the fuel pump after a 2 seconds if there's no crankshaft position sensor pulses seen, or they're flaky. The darn thing won't often throw a code.

So, that's where I'd look first.
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post #8 of (permalink) Old 01-25-2007, 08:06 PM
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Re: OT- Daily driver having starting problems

Well I feel your pain! I have been chasing this same problem on my wifes Jimmy. I would bet it isn't the fuel pump after putting three on mine. I think LEVE is on the right track with crank position senser. That's the only thing I haven't tried yet. I found if pushed the gas pedal slightly and I mean just a wee bit that it would start easier. Thought it had something to do with the TPS but it wasn't. I put a coil,cap rotor and wires and plugs and coil and still the same thing. Needed a tune up anyway. Let me know if you figure it out!
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