Rear gear - engine stops

[jarek_rugby]

Hi there
Today 2 times my engine stops.
It was on the parking area. I drive in, put rear gear and engine stops.
I started engine again, put rear gear and  and after few meters engine stops again.
Any ideas what it is?

[Gary Lewis]

Jarek - You may have the idle set too low, which can cause it to die.  If you don't know, there's an idle speed screw on the right of the carburetor and down close to the intake and you can turn it clockwise slightly to raise the idle speed.

Otherwise, I can't think of any reason that it would die just in reverse.

[jarek_rugby]

Gary,
i have EFI engine .

[Gary Lewis]

Oops!  My bad.

Then I'm at a loss.  Does your idle speed seem low?  Does the truck die when you first put it in reverse or when you touch the throttle?

[jarek_rugby]

it was when i touch the throttle

[Gary Lewis]

Then it probably has nothing to do with Reverse.  Instead the throttle position sensor may have a glitch in it.  

You can test the TPS to see if it gives the values shown here: http://www.garysgaragemahal.com/diagnostics.html

And the idle speed adjustment is supposed to be here, but I'm on a hospital's wifi and it is S L O O O O W and doesn't fill in, so I'm not sure it is there: http://www.garysgaragemahal.com/efi-idle-speed-adjustment.html

[jarek_rugby]

How could i do this without tachometer ? (idle speed)

[Gary Lewis]

By ear.  Get it where you like it and where it doesn't stall when going in gear, nor makes serious clunks.

But, if it is the throttle position sensor changing the idle speed won't help.

[Steve83]

Any inexpensive aftermarket tachometer can be temporarily wired in under the hood just for diagnosis.  It only takes 3 or 4 wires, and 2 of them (power & signal) connect to the truck's coil wires; the 3rd (ground) can be connected to the coil mount.  If the tach has a 4th (to select the number of cylinders), it usually just splices into the ground wire.

[jarek_rugby]

Next question. How could i  test - diagnose TPS?

[Gary Lewis]

You use a digital voltmeter and check the voltage as shown in pic below, which is from the the link above.  I believe that Vref is the orange/white wire, Signal Voltage will be the dark green/light green wire, and Ground is the black/white wire.

You will have to guestimate the angle, but if I'm right the TPS is going "open", meaning not providing an output or signal voltage just off idle.  So I wouldn't worry about making sure that the signal voltage is spot-on at all the angles.  Instead I would concentrate on what happens as you open the throttle.  Does the voltage increase smoothly or does it go to zero and then come back at some point?



This is Page 57 from the 1986 EVTM, and you can see the TPS at the top left.

[jarek_rugby]

Gary,
I checked TPS. It is OK.
Now i have to check idle :)

[Gary Lewis]

Good luck.  Has it been giving you problems any more?

[Steve83]

This caption has more detail about the TPS:



This caption explains the idle:



Read that whole caption before attempting to diagnose or adjust anything.  Note that it mentions the TPS as a cause for poor idle quality.

[jarek_rugby]

No, just this 2 times