bus dies after 5 secs

[dingo]

75 Bus with F.I.: Bus starts and runs for 5 secs then dies very sharply. No splutter. Plenty of fuel in tank. Pump tested and works.

this is not a vac. leak..i.e. cannot be feathered to keep it running. This starts and runs perfectly for 5 secs then dies.

I dissassembled double relay and the contacts looked good. With ignition on, i have power to injectors.

The last attempt late at night, fuel pump came on with Ignition ON, and then kept running after engine died (after 4 secs) and KEPT running after i pulled the key out. I had to disconnect batt. to get it to stop.

[dingo]

ok that last symptom was probably lingering WD-40..it doesnt do that anymore

OK ive scanned colin's copywrighted diagrams of dual-relay and now understand the three phases and what voltages need to appear at what time and locations..so now its a matter of training the dog to hold the meter probes in place while i crank from the cockpit

[drober23]

Hmmm, I don't think lingering WD-40 would keep your engine running so long that you would have time to disconnect the battery.

Anyway, the running on is a clue. It tells me that if you have fuel, you keep running. I would look to see if you are still getting fuel after those 5 seconds. Any chance you can get a helper? You could pull a fuel injector and see if it stops spraying when the engine dies. Maybe you're only firing off the cold start valve?

[Amskeptic]

so now its a matter of training the dog to hold the meter probes in place while i crank from the cockpit

Just turn on the ignition and move the wiper inside the AFM counter-clockwise a bit. Listen for the fuel pump. If it runs, then the pump is likely getting a signal. If it does not run, check the little copper contacts inside the AFM that close upon movement of the wiper (terminals 36 and 39 on the connector) for cleanliness, and as importantly, inspect the plug for any loose contact fingers and pull back the boot to see if any wires have broken or frayed near the plug.
Colin

[dingo]

It was the ECU wire that picks up pulse from the hall effect...it had come loose. meanwhile i rewired the whole shebang and conquered my fear of double-relay..actually a dead simple and beautiful FI system

[ruckman101]

I love a good success story. Still learning to brave a carb.


neal

[Sylvester]

I love a good success story. Still learning to brave a carb.


neal

Me too!

[dingo]

carbs can be conquered..just take a spare one and dive in like a hungry hyena

[Amskeptic]

actually a dead simple and beautiful FI system

=D>

[Kubelwagen]

I just have to say that I replaced the "cs" at the end of the thread topic with an "x" when I read it and momentarily thought I was on a different troubleshooting forum.

[dingo]

...especially if you have trouble shooting