TBI

[Shannen Durphey]

Martin Powlette wrote:
> 
> I was hoping to get more discusion on the subject but anyways here is an
> update.  I tried Bruce"s test for the IAV and it did not move in or out when in
> diagnostic mode ign. on and or off. Fuel pressure ,relay and fuse is ok  I also
> noticed that when cranking there was no fuel at the injector.  Almost like the
> ECU didn't know the engine was trying to start.   I back probed the TPS and
> noticed that the same 5V in was going right back out throttle in idle position
> or otherwise, as if it kept on reading full throttle. Toyota has a default
> fuction that stops the fuel pump from pumping in wide open throttle when
> cranking it also prevents flooding when cranking.   I disconected the TPS and
> the hard start was gone, instant fuel at the injector.  I guess the ECU was
> substituting the TPS signal.  I will replace the TPS but can someone tell me
> what is the exact rtelationship between cranking and TPS reading or have I got
> it figured out already.  Thanks for the reply Bruce.
> 
Just like carburetors, if the manifold gets soaked during
cranking there needs to be a way to dry it out.  GM systems
go into "clear flood" mode if tps during crank >~80%.  5v 
indicates full throttle to ecm, hence the attempt to
introduce more air and less fuel.

Shannen