No start '92 Pontiac Trans Sport 3.1L V6 TBI

[Meridivs]

We have a '92 Pontiac Trans Sport with a 3.1L V6 TBI engine. Last Sunday evening it refused to start like someone left the transmission in Drive and the Park/Neutral switch was preventing it to start. There's the buzz sound from the fuel pump when you put the key on then nothing when you turn it to start the engine.

I checked the Park/Neutral swith by connecting an ALDL cable to the OBD port and it indicates correctly when I move the lever to Drive or Parking/Neutral. The only error code stored is "Fuel Pump Relay" but the Fuel Pump appear to be working?!

Battery is good, fuel pump fuse intact and the Park/Neutral switch appear to be working. Any idea on how we can tackle this problem?

[Tech II]

Remove the air cleaner, when someone cranks the vehicle, is fuel coming out of the injectors in the throttle body?

If no, have someone crank the vehicle while you spray carb cleaner in the throttle body......if it starts, then you have to check fuel pressure and also check the harness to the injector(s) with a noid light while cranking.....

[LMP]

...with the vertical throttle body, you can do like good old carb and pour one or two teaspoons of fuel directly ....but anyway, if fuel delivery proves OK, then pull the coil spark wire, connect a spare spark plug and start to test presence of spark....

This being said though, the error code you mention is probably indicative of your problem....

report findings...

[Jeffrv]

If I understand your post, the engine is not cranking? If so, try running a jumper wire from the positive post of the battery to the solenoid terminal on the starter, it should crank. If not, your starter is faulty. This assumes all connections are clean and tight
Jeff

[Meridivs]

Yes, it's a no crank, no start problem.

It's like when you try to start the engine with the transmission in Drive - nothing happens.

I will try to jumper the starter solenoid terminal to see if anything happens that way.

Keep you posted,

[Meridivs]

Just managed to jump-start the car with a wire from the + battery terminal to the starter terminal.

Is there any way to tell if the key is making contact when turned to start the engine?

The Brake light comes on and all dash indicators move when i turn the key all the way to start the engine but that's all it happens (headlights remain bright and the starter dead).

[maxwedge]

See if there is 12v to the wire on the solenoid when attempting top crank., pink I believe,

[Jeffrv]

I am using my manual for 95 model, but I doubt there is much difference in start circuit from earlier models.
Park/Nuetral swtch is located on LH side of engine compartment, mounted on top of transaxle. When key is turned to start, you should have 12V to yellow wire ( input of switch) as well as 12V on purple wire, which leads to starter ( output). This switch should provide continuity only in park and neutral.
If you don't have 12V on yellow wire while key in start position, power to that circuit is fed from fusible link "W" located on auxillary battery post. Manual says it is grey, as are 3 of the 4 fusible links located at that pose, all with red wires! I hope it is marked somehow.
As a note, wiring on that aux post has been problematic with my TS in the past, so take it apart, clean all coonections and make sure it is tight- losse connections have caused me grief in the past
Jeff

[Meridivs]

Thank you for all your help and ideas. Checked the voltage on the wires and relay.

The relay clicked but the voltage coming out of it was too low to get the starter solenoid moving.

Changed the relay and now everything works as it should (even better than before: started motor had some hesitation that was also related to the defective relay).

[LMP]

Indeed I had missed the point that it did not "crank" at all...

.Good troubleshooting.

I understand the starter solenoid was the culprit..as this is the only "relay" in the starter circuit..www.avigex.ca/xport/chargingstarting.jpg
right ?


..did you change it "in place" or did you have to remove the starter ?

[Meridivs]

The crazy thing is that there was one more relay between the Starter Solenoid and the rest of the electrical harness.

I don't know it's function on the 3.1 TBI engine setup but this one was faulty. At this age it's possible to be some sort of alternative solution to an electrical problem of the past.

This is the reason I plan to have a through inspection of the electrical system on this car to check if everything is in place.

[Tech II]

The only way I can think of this having a relay, is if this had a PassKey system, with a resistor on the ignition key.....then it would have a starter enable relay....

[500hpgtx]

Possible the other relay had to do with a previous owners "alarm" system. Aggravating dealing with a wiring system different than stock.
On another note, I installed my last alarm system on my grand prix. It has remote start as well. I hope to never have to install one again. I am 6'4" and getting under the dash turned my spine into a pretzel...Hope everyone has a Blessed Holiday Season!,,,KEV