1996 Chevy Truck

PALATZO

MEMBER
1996 CHEVROLET TRUCK
6 CYL
2WD
AUTOMATIC
170,000 MILES

I have a '96 Chevy C1500 6cyl 4.3l pickup. On my way home from work last night, the truck stalled after about 3 blocks. Haven't had any issues with it since my last no-start problem. Made it to work without a single hick up. I tried repeatedly to start, and it would crank but no start. Pushed it into a parking lot and called AAA. An hour into my wait for a tow I tried starting it again, and it starts no problem at all! After about 20 seconds, it sputters then dies.
My first thought is a fuel pressure problem, so I turn the key to see if I can hear the fuel pump, and its humming away for a second or so then turns off, just like it should. I then try to start it again, really hard to start and runs really rough for a few seconds, then putters to its death. Seems to only start when I either let it sit a while or let the fuel pump run its course and shut off before cranking. Haven't had a chance to try and pull codes or really look under the hood, just wanted some suggestions where to start.
A little background on the vehicle, in the last 3 years the alternator, water pump, cap and rotor, plugs and wires, and fuel filter have all been changed at least once. Last year I had a no-start problem in which every part in the ignition system and fuel delivery system was tested and was in working order. Compression test done then also, don't remember exact numbers but they were within range of a new engine. Cap, rotor, plugs, wires, and fuel filter were all replaced less than a year ago.
Not sure if this helps, but this happened when it was snowing fairly hard with gusty winds, and the temp was around 10F.

5 Replies

PEAR69

MECHANIC
1,482 POSTS

Start with the fuel pressure--what is the fuel pressure? Test before start up - and after start up. Also, pinch off the return line to the fuel pump and turn the key on and engine off - what is the fuel pressure then. Then test the TPS (throttle position sensor) and the IAC (idle air control sensor) for proper function. What is the quality of the spark? What brand of ignition system components did you use when you replaced them?

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Tuesday, December 29th, 2009 AT 1:26 AM

PALATZO

MEMBER
3 POSTS

Alright, called my mechanic, who of course is on vacation right now. Had to go through a list of things to test. Tried starting with starting fluid, no go. Was about to test for spark when I noticed a wire arching at the coil. Ran out and get a new set of wires and installed them. Lucky for me I hadn't yet put the air intake back on the throttle body, because it probably would have sustained some damage when flame started shooting out as I was trying to start it. My mechanic is going to stop by tomorrow to check it out on his way back from Florida, but he is fairly certain there's a problem with the timing. I know my truck has a timing chain, and it is quite a hassle to get to, but I imagine chances are slim the chain broke. What are the chances it could slip? I suppose he will know how to readjust the timing and tighten the chain back up, but about how much do you think this would cost?
Also, if the engine were flooded and there was excess starting fluid in the throttle body, could that cause the flame? I'm hoping it's not really a misfire, and I have no idea it my engine is an interface engine or not, and I'm afraid to discover some bent valves if the timing really is off.

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Tuesday, December 29th, 2009 AT 7:28 PM

PEAR69

MECHANIC
1,482 POSTS

Pouring excess gas or starting fluid into the throttle body can easily cause a valve to bend - especially if there is not enough spark to ignite all of the fluid. Simply put - liquids do not compress.
Once again I ask -- what brand name ignition components did you install? As you said, the wires were basically new (3 years old). If you installed anything other than A/C Delco brand ignition system parts, then you are wasting your time.
Your timing chain can most definately stretch and cause this issue. A simple degree of rotation test will confirm this. If it were broken, your engine would not even back fire.
Unplug the fuel pump relay to disable the fuel pump. Then crank the engine. It will not start but you will get all the excess fuel out of the system. Then reinstall the relay and try to start - without starting fluid. Hopefully your issue was just a coil wire issue.

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Wednesday, December 30th, 2009 AT 7:40 AM

PALATZO

MEMBER
3 POSTS

I don't know what brand the wires and plugs the guy who put them on last time were. The wires I installed are Duralast. The cap and rotor I installed and they are ac delco. Can you describe this degree of rotation test? I've got a general idea what you mean, but have never done it so I'm not sure how hard it should be and what an acceptable degree of rotation would be.
I won't be able to do anything to it until new years day, but I will be sure to try all the steps you have mentioned.

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Wednesday, December 30th, 2009 AT 10:23 PM

PEAR69

MECHANIC
1,482 POSTS

I only care about the brand of wires that were on the engine at the time the engine started running bad. Duralast are junk.A/C Delco are the only ignition parts that should be used.
Yes I can explain the degree of rotation test but you have not answered all of my questions. Read my questions and post back with the answers. We will go from there.