TBI Engine won't start, no fuel

[Mastiff]

A new mystery today. The truck started last weekend, but today there is no sign of life. It cranks like crazy. I notice no fuel smell like is typical when cranking. I pulled off the air cleaner and after cranking it for a while jumped right out and looked/felt in the throttle body bores and under the pods and there is zero sign of fuel. When I turn the key before cranking, I can hear the pump running (pressurizing the system, right?). So why no fuel? My only hypotheses: (1) pump is running but not actually making pressure, or (2) module is shot and not opening the injectors. Ideas?

 

[Blue85]

Check the ECMA and ECMB fuses - one of them powers the injectors, I think. Also, IIRC the ECM needs pulses from the distributor to fire the injectors, so it could also be an ignition related issue.

 

[Mastiff]

If my ancient timing light is telling the truth, I have no spark. So, likely something related to that. Maybe bad module...

 

[dyeager535]

Concur with above.

You won't have injector pulse without the ECM getting feedback from the ignition module that the engine is rotating/firing the plugs.

Pickup coil is a possible suspect too, if it's old and you don't have a spare distributor already, my personal thought is to buy the ~$100 parts store complete cheapies. It should work at least long enough to fire up. And since you have to pull the distributor to replace the coil, IMO it's better to be able to just pull the distributor than guess at module, put it back together, be wrong, then have to pull it completely out, to get at the coil. Replacing both the coil and module that are more expensive individual components, and still chinese junk. lol

 

[Mastiff]

Well, I pulled off the cap and rotor and all the connections to get a look in there. Nothing looked suspect, but when I put it back together it fired up. Maybe a corroded connection just needed to be shined up.

One thing that was strange to me is that when the +12 connection to the cap (coil in cap) was removed, the computer didn't run the pump. I wouldn't have expected that. I also was unable to measure 12V at that connection with the key turned to "on", which I thought I should be able to.

I've had on my list to replace the distributor, but it's going to be a painful job. My TBI conversion was kind of a hack and retained my coil-in-cap setup, so I'm going to have to do a bunch of rewiring to get it to go. The mapping of wires for my setup to a normal external coil setup is not the least bit obvious to me. I think I have some other threads on this forum where I was trying to unravel the mystery.

I was looking at the DUI distributor:

GM EFI DUI Distributors – Performance Distributors

performancedistributors.com

Maybe more reliable than a Chinese parts store item? Any other quality choices available?