GM ECM TBI Questions

[steve ravet]

Terry Martin wrote:
> 
> JET wrote:
> >
> > Hi,
> >
> > I changed a 2.8L to a 4.3L both TBI in an 1988 S10 4X4, but I can't
> > make it run.
> >
> > There is no check engine light at all.
> >
> > I have spark, but no fuel. Can anyone give me a hint on where to
> > start.

No check engine light at all?  Or no codes stored?  The light should
come on for a second or so when you turn the key on, then go back off. 
If you short pins A&B on the ALDL, you should see it flash the 12
trouble code at least.  If you don't get a check engine light, make sure
the ECM is powered correctly, and isn't dead.

I can't recall the fuel pump circuit exactly, but it's pretty simple.  A
relay controlled by the ECM switches either power or ground to the fuel
pump.  When you first turn the key, you should hear the relay click on
for two seconds, then turn back off.  There is usually a connector hear
the fuel pump relay that you can apply battery voltage to to force the
pump on.

You'll just have to get the schematic and follow the circuit through to
see what the problem is.

--steve