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RCastle 12-18-2004 11:34 PM

Cranks/No Start Problem
 
Got a Ignition/starting question.1995 S-10,it has a 4.3,the bigger V-6 I think it is the 4.3 anyway.It is my neices truck,problem was that this morning it had a crank/no start problem.It just would not fire.My brother went over,said that he tried to start it,still cranks only.Pulled a plug,stuck a test plug in,and laid it across the alt. to see if he was getting fire.She cranked it,he got zapped and the truck started up,running on 5cyl.,so he puts it all back togather and now it starts every time.What could it be? I know it will fail again,and I will get called out in this cold weather to fix it for her.So if we can troubleshoot it now,it might save me some frozen fingers.Thanx all-Rcastle-



P.s.It was not getting fuel or spark.It is a stock tbi engine.

Siggy_Freud 12-19-2004 05:02 AM

Hmm. Being a TBI engine it wouldn't seem like there are many things besides the computer itself that would cause fuel and spark not to be present. Normally they are run on somewhat of a seperate circuit. If it does it again, check and see if the fuel pump still primes the engine when you turn the key to the on position. You should get about 2 seconds of priming.

If it were a later multiport system, I would guess something like the crankshaft/camshaft position sensors as they help control both fuel and spark and will elimiate both.

A faulty oil pressure sensor might cause this depending on the car. Some vehicles only wire this fail switch to the fuel source but its possible, as it runs through the computer, that it would also eliminate spark in the event that the computer wasn't reading anything from the pressure sensor.

A buggy computer can also be a culprit. If you have time, Id get a wiring diagram for this car, and look for any circuit the spark controller and fuel supply have in common. Sometimes they share a power relay or both route their power or signal source through a common sensor.

Its kind of hard to say as no engine codes were thrown correct?

Fingers crossed for now I suppose. Let me know of any other info you have.

poncho62 12-19-2004 05:53 AM

My S10 has the coil on top of the right valve cover. A couple of times the plastic slide on connector came loose, and it wouldn't start. Could he have made this connection again without realizing it, while messing around ?

RCastle 12-19-2004 07:49 AM

Siggy-No codes were thrown.
Poncho-He very well could have,stuff seems to go right for him with no reasoning available.



Here is to hoping that it does not happen any more before spring,that white crap is finally falling here and it is too cold to work on the side of the road.Next weekend I am replacing the belt tensioner on this truck. I'll check any suggestions then.

454me 12-19-2004 08:47 AM

I agree with poncho62 it sure sounds like a bad connection somewhere.

outlaw17 12-19-2004 09:48 AM

I worked on a 95 Jimmy many many times that was towed in and when it was set down we turned the key and it started , the guy would take it and a few hours later it died , sometimes it would only go 3 blocks but it started every time when at the shop , finally we just changed the fuel pump but that never did anything . One day the thing showed up and would not go and I started looking into it , I was looking for the fuel pump relay behind the glove box and when I found it and touched it I heard it click so I tried the key and whalla it started ,I shook the relay it stalled , Finally I found the problem ! Turned out to be a bad connection with one of the pins in the relay connector .

poncho62 12-19-2004 09:52 AM

Had that in my TBI Chevy van...................broken wire. However, it would start after cranking it for about 10 seconds, as the fuel pump would kick in when the engine built up enough oil pressure to bypass the pressure switch. The fuel pump relay is only for when there is no oil pressure on startup.

85 vette 12-21-2004 04:23 AM

I have a small fleet of s-10's at my shop and i had a similar problem 6 months ago. The truck would run fine then all of a sudden it wouldn't start. It would go for weeks with no problem then suddenly, no start. We had the truck towed in and i went through the usual troubleshooting. When i couldn't find anything i bypassed the fuel pump relay with a paper clip. It started right up. I figured it was in the fuel pump circuit so i went down the line and the only thing left was the pump. I pulled the tank and then the pump. When i bench tested the pump it was fine. I was ready to pull my hair out of my head when i noticed a crimped fuel line. I replaced the line and the circuit returned to normal. I replaced the fuel pump anyway considering the tank was already down. Haven't had a problem since. Now this little episode may not be anything close to what your problem is but then again....just offering another option. good luck, Rick

RCastle 12-21-2004 04:41 AM

Ill be checking all the above,plus the new guy in our shop was a Chevy Tech.He said that the A/C lines route right over the distributor cap.He suggested it may have something as far as corrosion in it.He said that what I described was not a recurring problem with the S10 so it will be hit or miss until I nail it.

red65mustang 12-21-2004 05:05 AM

amazing....
 
how many weak points they put into new cars!

gut the beast and throw in a carbed/simple motor!

it feels sooo goood while your hacking and cutting!

RCastle 12-21-2004 05:21 AM

Hey,if my neice would throw me a bone and let me do that I would!!!:thumbup:

red65mustang 12-21-2004 06:51 AM

and then....
 
ship all that #### collect to the President of GM with a friendly note of how and where to use it personally....especially the fuel pump from the tank!

lets see, spark+ atomized gas+compression=go

did I forget anything?

willowbilly3 12-22-2004 02:38 AM

Some of the troubleshooting clinics stress the fact that the first thing to do is check connections. Unplug and replug them as most are self cleaning. On the old pre obd Fords you did the wiggle test first when doing a scan. Basically it meant wiggling all the wires and connectors to check for a bad connection. The wiring on the S-10s seems to be a little more problematic than the bigger Chevy pickups. I have traced many electrical problems to a wad of ground wires that are connected to the bottom of the dash with a sheet metal screw. That is the first thing I check on one with any electrical relater problem.

RCastle 12-22-2004 04:51 AM

Will also check that ground.Thanx WB.


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