I have been slowly rescuing a Bus (could be a Champagne I based on Internet findings) that I collected last year sometime. Threads on this site have already saved me loads of headache and needless questions, but I'm really confused on this problem. To keep it brief, I got the Bus in non-running order, and someone was in the process of fitting dual ICTs. Mixed amongst piles of other junk in the Bus, I found all of the original fuel-injection components. I have most of that stuff fitted, but I have tried to ignore the EGR items as the currently fitted and sloppy exhaust has no bung for which they might connect.
The issue I'm seeing is that the Bus will start and run around my back yard wonderfully for days at a time, and then it will begin stuttering, and within minutes will be dead and basically impossible to start afterwards. I have fitted a fuel pressure gauge, and can see the pressure act sporadically while starting, jumping from 0 to ~30psi. If I use a screwdriver to reach into the airflow meter to move the gate by hand, the fuel pressure acts the same. I can disconnect the ECU harness at the ECU, or from all four injectors, and the fuel pressure will immediately achieve ~30psi and remain stable for many minutes. If I disconnected the injectors (and not the harness at the ECU) I can reconnect any one of the injectors and the pressure is lost. If I left all of the injectors connected and disconnected the harness at the ECU, I can connect the ECU and go start the Bus and drive around.
The cold start valve and the thermo time switch are both connected, and appear to be in working order. All of the idle air and bypass air control stuff has not been fitted, and the vacuum ports are plugged with silicone bungs. I've followed the the fuel-injection troubleshooting guide as best I understood it, and when the Bus is working, everything checks out (I suppose that should be obvious to me, but...) and when it isn't working, none of the injector tests work because they always have power (until I 'reset' the ECU by reconnecting its harness).
New parts: (hopefully relevant items only)
- Fuel pump
- Fuel filter (second one, first filled with rust, this one is not yet filled with rust)
- Fuel pressure regulator
- Fuel hoses
- Vacuum hoses (only using brake booster and fuel pressure regulator)
- Intake runner boots
- Intake manifold gaskets/spacers
- Fuel injector seals
Have any of y'all seen anything like this? Do I have a bad ECU or harness?