Mechanics

PICK UP

1994 Chevrolet Truck

I have a 1994 Silverado pick up, 2 wheel drive manual transmission, 350 engine. I have been having trouble with it wanting to start. By this I can get in it of a morning and turn it over and normally it starts right up. After the warm up cycle it feathers down the idle and holds and runs normal. After that it eithrer just dies or after you turn it off it fails to start. If you dribble a small amout of fuel in the TBI it fires right off and as long as I keep the idle up it runs but let ir return to a normal idle it dies and won't start again. Back to an idle and it dies again. I have checked the fuel pressure and have 8 pounds at the TBI. I have changed the fuel filter and replaced the coil. Can it be the throttle position sensor or the MAP sensor? All wires to the computer have been checked for a break but none found. Thank you for your time.
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Mark Leason
December 11, 2006.




If all of the fluid drained out, then it may not move at all. You have to try it and see if you can avoid that cost and time of a tranny rebuild.
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Tiny
Mikeybdman
Aug 7, 2006.
Hey Mark,
A faulty O2 sensor will cause this condition, Also 8 psi sounds kinda low for fuel pressure, they usually run at 14-17 psi.

Chris

Tiny
Carundell
Dec 11, 2006.
Chris,

I read from the manual the normal for this truck with TBI is 7 - 13 but it could be due to a haynes instead of OEM. Could it be due to a faulty ECM?

Tiny
Mark Leason
Dec 11, 2006.
Mark,
Faulty ECM is a possibility, but you should rule out everything else before you replace the ECM. Try this. Disconnect the O2 and see if the condition gets better, worse or no change.

Chris

Tiny
Carundell
Dec 11, 2006.
Chris,

I will give that a try this evening. Thanks

Tiny
Mark Leason
Dec 11, 2006.
Chris,

I disconnected the sensor but there was no difference in the starting of it. Once again before I did anything I turned it over and it fired right up as normal. Once the idle settled down I turned it off and tried to restart it. No luck. Dribble fuel and away she went fired instantly. What else may be blocking a signal to the TBI. I am at a loss for ideas here. Can the module in the distributor be an issue? What about the throttle position sensor. Heck there isn't much else tied into it is there. I even tried a different ECM but same results. Thanks for your time

Tiny
Mark Leason
Dec 12, 2006.
Mark,
That dribbling fuel flow and your previous psi reading have got me thinkin' fuel pump issue. Do you have the ability to attach your pressure gauge and try to run the vehicle at the same time? If you can then it should pretty much tell you if it is. If the fuel pressure is higher when you first start it and then gradually drops off till the vehicle stalls, then its a fuel issue. Also check the fuel pump relay for corrosion @ the connector, it should be on the firewall, right side of the truck. Let me know

Chris

Tiny
Carundell
Dec 12, 2006.
Chris,

The dribbling in the TBI is from an outside source say a fuel can. A small amount poured into the TBI starts the pickup immediately. I will hook a pressure gauge to the fuel line again and confirm the pressure reading but I can hear the pump start up and if it were the fuel as an issue why would keeping the idle higher allow it to run without a miss or weakness in the sound of the engine at all.

Tiny
Mark Leason
Dec 12, 2006.
Mark,
Opppppps, sorry I misunderstood ya, yeah verify good pressure at cranking then I would have to say possible distributor/pick up coil/module issue.

Chris

Tiny
Carundell
Dec 12, 2006.
Chris,

I checked the play in the distributor and there was nothing noticable in the shaft play. The pick up coil looks good but not confirmed. I am replacing the module in the distributor tonight as a buddy owns a shop and can return parts I am not able too but even he is stumped over this one. Just one of those odd things that I thought someone else may have run across and has an answer. Regardless once it is fixed I will let you know what the problem was and is currently. Thanks

Tiny
Mark Leason
Dec 12, 2006.

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