Help Me
 

can someone please help me? I'll try to explain my best. I just bought a 1987 GMC 350, It has dual gas tanks and the PO told me that the right one needed a new pump so i put one in and it still didn't work. So i checked the switch. That was the problem. I started and both worked an then i tried to start it again and now my truck won't start at all. I have power at the switch and back to the plug where u connect the tanks in but as soon as i plug the tanks in i lose power at the switch and tanks and the truck will not start. PLEASE HELP ME! Could this be the oil pressure safty sensor switch?

Re: Help Me
 

Theres a relay on the firewall remove & visually ck the connector & the relay too.

The relay has a 5 sec. timer in it so when you turn the key on you should hear the pump run and prime the sys.

Check both tanks for a proper ground.

Everything go's through the tank selector valve on the right frame rail so remove & visually check that connector as well.

If that all looks good then check the oil press. sw. that controles the fuel pump power.

There should be two oil press switch's one for the Insturment guage and the other one supplys pwr. to the fuel pumps once the eng. is running.

One is mounted at the rear of the intake manifold by the distributor and the other is next to the oil filter.

I cant remember witch one is what so remove the connector from one and see if the guage still works and go from there.

That should keep ya busy for a bit.

Good luck.

Re: Help Me
 

could be a fuse to. i like to check easy stuff

Re: Help Me
 

I checked to see if i was getting power to the fuel selector switch and its there and i checked all fuses the thing that has me stumped is I have power until I plug in the tanks.. Im going to change that oil pressure switch. As far as that relay i don't hear the pump at all. Where is that relay located i can't find it on the schematics. I just want to thank you very much for trying to help me. its been pissing me off for over a week now. thanks again