87 silverado 350 tbi only runs with map disconnected

[shufflekidd]

Hi guys, newbie here. I recently inherited an 87 silverado,350,heavy duty,manual tranny that would crank but not start. 57k original farm miles. Checked the fuel tanks, both were loaded with red varnish, as well as the fuel lines. After reading up a bit, I decided to go ahead and install a completely new fuel system. Installed in bed of truck new jegs 17 gallon fuel cell, disconnected the old fuel lines and return lines and relays and pumps,pulled out old tanks,installed a new inline fuel pump (9-13 psi) with relay,new fuel filter,new tbi and injectors. Also, while i was pulling, went ahead put in new ecm with old chip,new chip in distributor,new coil pickup,new tps,new iac,new antiknock and map sensor. When I finished all that, new battery and cables.I disconnected the vacuum lines to canister. I can start and run the truck, but only when the map sensor vacuum line is either pinched off or disconnected from sensor harness. As soon as I hook up the map sensor, with the truck running, it immediately shuts off. Ideas? And thanks to any who may take the time to answer a noob's questions. 

[VileZambonie]

Do you have access to a scan tool? Plug the MAP back in and unplug the TPS and see if it starts and runs.

[jaredts]

Does he have to have a scan tool?  I thought on an '87 he could jump a and b connectors on the aldl and turn the switch to on to read trouble codes?

[VileZambonie]

Does he have to have a scan tool?  I thought on an '87 he could jump a and b connectors on the aldl and turn the switch to on to read trouble codes?

That's fine if all he want to do is read codes but jumping the DLC is going to give him data we need to determine what the ecm is seeing for MAP voltage.

[shufflekidd]

Thanks guys for responding! I will perform the test plugging in map and unplugging tps wednesday. I have built an aldl cable rs232 for an old laptop tonight and will try and get some readings tomorrow also with winaldl. 'Preciate your time!

[VileZambonie]

Clear the DTC's before you scan it. Take a screen shot and post it.

[shufflekidd]

Ok, cleared trouble codes, checked map sensor,tps calibrated and checked, engine starts and runs fine for a few minutes then appears to be starving on fuel. Checked aldl codes and have zero error messages stored, did this twice. apparently the new sensors and ecm are fine, probably a bad fuel pump from auto parts store, will check that tonite with fuel pressure gauge. Again, thanks! i can't wait to get the old girl on the road again.