1994 S-10 starts and immediately stalls.

Tiny
JAGFIX
  • MEMBER
  • 1994 CHEVROLET S-10
  • 79,000 MILES
It is a 1994 S-10 TBI 4.3L.4x4. The engine will start and idle a couple seconds then immediately stalls. It will start right back up and idle for a few more seconds and stall again. After numerous attempts, it will start and stay running without stalling and I can drive on like normal with no problems and it might be normal for a few days then start acting up again. I replaced the ignition module but that didn't fix it. I tried spraying starting fluid into the throttle body just as it was about to stall and it appears to stay running until I stop spraying indicating a fueling issue. I swapped out the fuel pump relay and that didn't help either. Walking to and from work in the cold weather is starting to suck. Any help will be greatly appreciated as I am at a loss.
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Sunday, November 20th, 2011 AT 9:27 PM

22 Replies

Tiny
RIVERMIKERAT
  • MEMBER
Check the fuel pump itself when the problem occurs. Key on, engine off, check fuel pressure. Check the injector relay also. One or the other is suffering an intermittent failure.
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Sunday, November 20th, 2011 AT 9:35 PM
Tiny
RASMATAZ
  • MEMBER
Clean out the idle air control valve and EGR valve to include checking the fuel pressure if its within specs
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Sunday, November 20th, 2011 AT 9:37 PM
Tiny
JAGFIX
  • MEMBER
I visually inspected the EGR valve and didn't notice any faults. I need to check it with a vacuum tester I suppose. Not sure where the injector relay is located.
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Sunday, November 20th, 2011 AT 9:46 PM
Tiny
RIVERMIKERAT
  • MEMBER
Should be in the underhood relay box just aft of the battery.
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Sunday, November 20th, 2011 AT 10:02 PM
Tiny
JAGFIX
  • MEMBER
I do not have a relay box under the hood. There are 2 relays located on the firewall and a relay box that houses the fuel pump relay in the cabin below the center console. My manual doesn't show a injector relay. Any suggestions?
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Sunday, November 20th, 2011 AT 10:12 PM
Tiny
RIVERMIKERAT
  • MEMBER
Check to see if the injector is pulsing. I have attached a schematic that shows where the injector receives its signal from. Upper right corner.
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Sunday, November 20th, 2011 AT 10:49 PM
Tiny
JAGFIX
  • MEMBER
Thank you for the schematic. It is hard to view and it appears to be different than my vehicle wires. I noticed the schematic is for a VIN W. I have the TBI VIN Z.
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Sunday, November 20th, 2011 AT 11:00 PM
Tiny
RIVERMIKERAT
  • MEMBER
VIN Z schematic. Slightly different. Click the thumbnail. Then right click the image and select "Save Image As". Then you can view it with any image viewing software you may have, or print it.
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Sunday, November 20th, 2011 AT 11:33 PM
Tiny
JAGFIX
  • MEMBER
Ok guys. The abouve diagram was too blurry once printed, but thank you anyway. I spent the majority of Sunday messing with this thing with no success. Here it is Monday morning, and it starts right up and stays running. What the heck is going on? Brought it to work so no walking today. I'll see what happens around 5 when I go home. I might do some more checks at lunch time. Any more suggestions please? The IAC was removed and appears to be clean and not stcking. The PCM was removed and no visual problems noticed. There is a red pig tail under the hood to apply battery voltage to, to power up the fuel pump. I hear the pump running with battery voltage being applied to the pig tail. Is it safe to try that while the engine is running and apply the voltage just about when you can tell it's going to stall?
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Monday, November 21st, 2011 AT 1:08 PM
Tiny
RASMATAZ
  • MEMBER
You were told to check fuel pressure 2x and I don't see you performing it-the fuel pressure is critical we need to know what it is before we can continue to help you-
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Monday, November 21st, 2011 AT 5:59 PM
Tiny
JAGFIX
  • MEMBER
The fuel pressure was about 13psi.
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Monday, November 21st, 2011 AT 6:29 PM
Tiny
RASMATAZ
  • MEMBER
How did the EGR valve and ports looks when you open it up? The IACV is clean try replacing it and see what happens
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Monday, November 21st, 2011 AT 7:01 PM
Tiny
JAGFIX
  • MEMBER
EGR valve looked good and with vacuum applied the diaphram moves and holds steady so I assume it is good. I guess I can try a IAC valve but I don't like the idea of throwing parts on it like the ignition module which didn't fix it but I guess I don't have a choice at this point. Thanks for the info. I'll keep you posted. At lunch it started right up with no faults again. I bet it won't run when it's time to go home though.
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Monday, November 21st, 2011 AT 7:10 PM
Tiny
RASMATAZ
  • MEMBER
Think! Positively were trying our damnest to help you out-Did you clean out the IACV port? Were not here to tell people to throw parts at it till its fixed, if we do we don't belong here-Remember were not there with the vehicle-Good Luck
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Monday, November 21st, 2011 AT 7:18 PM
Tiny
JAGFIX
  • MEMBER
I understand. I thank you guys for the help and advice. Just gets very frustrating as you probably understand. Would an IAC valve cause these issues only at start up? Trying to understand what exactly is happening during start up and idle that would cause this mystery to occur. Never stalls when driving it. Reliable while it's actually running, just getting it to that point is difficult sometimes. Really weird how it acts up sometimes for a few starts, then somehow fixes itself, then will drive fine for 3 - 5 days with no problems then all of a sudden the next morning it won't start again. Freaky?
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Monday, November 21st, 2011 AT 7:46 PM
Tiny
RIVERMIKERAT
  • MEMBER
That 13PSI fuel pressure reading concerns me. It should be much higher, like between 30 and 50PSI. Try checking the fuel pressure over a period of time. When it's acting up and when it's driving nicely. See if it varies and by how much.
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Tuesday, November 22nd, 2011 AT 3:30 AM
Tiny
JAGFIX
  • MEMBER
Well, it wouldn't start yesterday after work. Does the same thing as before. Actually it does start but stalls about 5 - 10 seconds later. This is a TBI Z VIN engine. I think the pressure is suppose to be around 13psi.
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Tuesday, November 22nd, 2011 AT 12:51 PM
Tiny
RIVERMIKERAT
  • MEMBER
See attached image of fuel pressure specs.
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Wednesday, November 23rd, 2011 AT 12:13 AM
Tiny
JAGFIX
  • MEMBER
Ok. Thanks again. I checked the fuel filter, a little dirty but not bad. With a listening device on the fuel tank, you can hear the pump start making weird noises right before it quits running and stalls out the engine. The battery power to the pump remains constant as does the ground, so it's looking like a fuel pump is needed. Do you guys recommend a fuel pump only or the whole drop in assembly? The parts stores are asking about a harness code? Where do I locate it? I examined the harness but no tags could be found? There are a few different ones for this truck, not sure which one to get.
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Wednesday, November 23rd, 2011 AT 1:23 PM
Tiny
RIVERMIKERAT
  • MEMBER
The whole drop in assembly usually includes the fuel level sending unit and float, along with the filter sock. If the gauge isn't acting up, I would go with just the pump. I couldn't find anything about a harness code, so either take a picture of the connector, or take the old pump in.
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Thursday, November 24th, 2011 AT 1:32 AM

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