cranks, has spark but no start?

and oh, it can also run on LPG. :)

And is it like normal that it has so many free slots?

Hi,

The black/ white wire should be a ground path from the primary side of the relay. When the key is on and the engine running, power from the green/white wire (fuel pump driver at PCM) powers the primary. That is what actuates the relay. If you are not getting power at the green/white wire, the PCM may be faulty. Keep in mind, the oil pressure switch is tied into this as well. If there is an open or no pressure, it will shut down fuel.

See the schematic below. Also, take a look at this link. You may find it of interest.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know.

Joe

See pic below. Also, I believe there should be more fuses than I see. Is that under the hood?

Thank you very much for answering.

I checked the oil pressure switch by blowing in with high pressure and measuring for resistance. It showed verry low resistance and the multimeter beeped. I was very gentle with the high-pressure gun mounted on the compressor. When i jumped the red/black and orange wire (which was hot) the fuel pump buzzed for as long as i jumped it but with a different tone, than when i jumped the fuel pump directly.

Is there any way i can test if the PCM is faulty?

And it is under the dash behind the fuse box.

Thanks for the link you sent me. I'll get a testing light tomorrow and do some more testing.

Thanks already for the help.
I saw the website is funded with a GoFundMe is there a link where i can donate? :)

Hi,

Where are you getting the red/black wire? I see the orange in the schematic, but not the red/black.

As far as testing the PCM, you could check for power out 12v driver out from the PCM for power. (Green/white wire).

Do me a favor. If you haven't already, check to see if there are diagnostic trouble codes. This had an obd1 system that doesn't require a scan tool to retrieve codes. Follow the directions in this link. All you will need is a short jumper wire or even a paper clip.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Also, the GoFundMe link is https://gofund.me/c7d318ad

Anything you offer is appreciated.

Let me know what you find with the truck.

Take care,

Joe