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Very odd starting problem.

834 Views 5 Replies 3 Participants Last post by  Rebel2345
Well, its odd to me.

This is the first Toyota I've ever owned, so I might not be able to tell you everything, but here go's.

Its been Sub Zero temps around here, and since it hit zero it hasnt been wanting to start.

I checked for spark, and my fingers agree that is has plenty. I checked for fuel, It wasnt putting out any when the key was turned over. It eventually decides to start and will start fine from then on, unless it sits for more then a couple hours. Then I have to do it all over again.

This has happened a couple times now, so I checked the wires to the fuel pump, they are good. I checked for power, and its not sending a signal to the fuel pump when the key is turned. So I decided to put power directly to the fuel pump, using gator clips and then grounded it using a jumper wire between the two original plugs. It will start that way.

Funny part is, after that, I can plug everything back in just like normal and it will start fine.

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Is this a EFI engine or carbed?

On EFI, there is a sensor that detects and acts depending on the temp. It fires off the cold start injector. If that sensor is bad, or the cold start injector is clogged(normally with a carbon buildup) you'll have the problem you describe. I'd probably start by pulling the cold start injector and inspecting it. Sometimes you can use some solvent(like a throttle body cleaner) and gentle toothbrushing to clean it.

On a carbed engine, I'm not sure.
Ahh, sorry. Yes, It's EFI, So I'll look into that.
A Chiltons or Haynes manual is a good investment for working on these trucks. Pretty good diagrams and instructions. Either will show you where the sensor and cold start injector is located.

Also, they have some good basic trouble shooting info, to boot.

These fuel systems typically have a relay that prevents the fuel pump from running unless the engine is running or cranking. If you can start the engine by jumping the pump, perhaps the fuel cut off relay has a problem.

The early pickups also had a relay linked with the oil pressure switch, might check this if applicable.

The EFI system has a cold start injection system, an additional single injector that supplies more fuel into the manifold when the engine is cold. If this system is not working at cold temps, it can make the engine difficult to start.
My guess is still the cold start system. Just because after it starts the first time, I can plug the fuel pump back in and it will start fine from then on, until it cools off again.

But I have another question.

Since I have no money to replace any parts that might need to be replace right now, would it harm anything to run a hot wire to a switch, and then splice into the fuel pump power wire to get it to start the first time?
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