1993 Chevy S-10 have fuel and fire but wont start

JBAGBY

MEMBER
1993 CHEVROLET S-10
6 CYL
4WD
MANUAL
199,374 MILES

My chevy s-10 with a 4.3 v6 recently quit on me while driving on the interstate. I had it towed home and put on a new distributor cap and rotary button. Along with that I put a new ignition control module on, and when I checked my plugs had plenty of fire. The 4.3 is tbi and is gets plenty of gas sprayed into the motor however it will not start. I can crank it and smell all the gas not being burned. When pulling one of the plugs out I can clearly see it spark. If the timing chain has jumped or broken could this be the cause of the problem. Your help is appreciated, I am baffled.

4 Replies

JMICHAEL8888

MECHANIC
45 POSTS

I could be from my experience. To check if the chain is broken take the dist. Cap off and crank the crankshaft by socket. If the rotor moves the chain is not broken but it still may have jumped.
To see if it jumped takes a little time and work but not much. You have to check the intake lobe centerline (the degrees after tdc(exhaust stroke!) That the intake valve is at its peak. The intake lobe centerline is 107 degrees for a vin Z (tbi)4.3.
That is crankshaft degrees. You can make make- shift marks on your crank.
Ex. At tdc your mark will be 0. Opposite (down) from that will be 180 with 90 between them. Now using a protractor, if you have to, find about where 107 is. Mark that. When you hit that, see if your intake valve is at its peak. If your timing chain is off 1 tooth it will be about 9 to 10 degrees off. (2 teeth 18 to 20)

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Monday, December 29th, 2008 AT 8:09 PM

JBAGBY

MEMBER
2 POSTS

Thanks for your help. I just took off the water pump and timing chain cover to discover that the chain and gears are still in great condition and are the timing marks line up exact. I havent got it back together yet but when I do I may have to consider a different cause of it not running. Im not sure what it could be now

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Tuesday, December 30th, 2008 AT 7:03 PM

JMICHAEL8888

MECHANIC
45 POSTS

I guess no service engine light. On a day you have time you could do a compression check. Thats probably not it, but it would be a peace of mind. Its been known to happen.

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Wednesday, December 31st, 2008 AT 8:26 AM

JMICHAEL8888

MECHANIC
45 POSTS

I was thinking there are 5 major things that are needed to start an engine.
1. Proper cranking speed (battery-starter)
2. Good compression (cylinder comp-proper valvetiming/timing chain)
3. Air (filter/even check iac motor)maybe unplug it and see if theres a difference)
4. Fuel
5. Spark
it seems you have most of them. The reason I asked about the service light, is that I heard a bad computer can cause a no start. I know a bad crank sensor can but you do not have one, pick up coil does that, but you have spark.
Maybe one of these technicians can better assist you.

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Wednesday, December 31st, 2008 AT 10:16 AM