GMC no start ; anyone help ?

[olds443]

Does anyone know any links to troubleshoot an 1988 GMC 1/2 ton with 5.0 tbi? I have a manual but it is almost useless.
I was driving up I80 when it just shut off. It was at this time that I noticed the temp gauge was very hot. At first I thought I blew a head gasket. There is no water on the oil and no oil in the radiator so should be good there. I checked and seem to have no spark. I am getting fuel into the throttle body. I replaced the coil, coil module, cap and rotor but still no spark.
So what am I missing? Suggestions welcome.

Thanks,
Jason

 

[dr_frankenstein]

OK.... there is the Cap, Coil, and Coil module right......... now what about the electronic spark control unit?

what codes is it throwing?

A.j.

 

[wagon]

Check your fuses. I believe that you have one labeled inj and one inj2, or something like that. I don't have my 1988tbi handy or else I'd run out and look. Also check to make sure that you have power at the coil when the ignition is on.
Also, a good site for those trucks is fullsizechevy.com. Good luck.

 

[olds443]

I have power to the coil with ignition on. Fuses looked good and I did switch out with good ones, just in case. Not sure how to check codes without a scanner. As for the electronic spark control... do you mean this?
Thanks for the help this far.

 

[SFITurbo]

Thats it....keep a good one in the glove box. There is a voltage check for it but it went with the Blazer when I sold it:frown:

 

[olds443]

yep, changed that too and the part that goes under the rotor on the distributor

 

[468Chevelle]

On the data link connector under the dash, there is like 12 holes in it. There are two terminals in the corner of the connector that are right next to each other. Put a paper clip to jump those two together. turn the key on, the check engine light will flashes in a series. For instance four flashes, a quick pause, and three more flashes is a code 43.

 

[steve hughes]

Take the distributor cap off and make sure the rotor turns when cranking the engine. When you check for codes with the paper clip trick it will first flash code 12 3 times unless the ecm has a problem. After it flashes code 12 3 times it will flash any additional codes 3 times each.

 

[dr_frankenstein]

I have power to the coil with ignition on. Fuses looked good and I did switch out with good ones, just in case. Not sure how to check codes without a scanner. As for the electronic spark control... do you mean this?
Thanks for the help this far.

nope thats not it.

it looks alot like this

A.j.

 

[SFITurbo]

If I recall there is a "brain box" on the firewall to the p side of the distributor that controlls timing and dist. inputs.

 

[olds443]

After replacing all that crap above and still not getting spark or fuel (plus it taking me a couple of weeks as it was all in spare time) I ended up taking it to a local shop who was stumped as well. Then they checked and found no spark or pulse to the injectors and determined it was a bad distributor. Changed that out and it started right up. I brought it home and set the timing and now she purrs again, 180k miles and all.
Thanks guys for all the help.