New Installation Problems

[pauls39chev]

Have yellow wire to tach output on distributor.
Have keyed 12V at distributor.
Tach needle bounces up and down when cranking.
Correct, spark but no fuel, can spray fuel down throat and will fire.
Have done the computer thing and manually set and it has held, now have rpm signal again on can, still no fire.
Noticed starting rpm was set at 1000, my starter would never spin that fast, have changed that to 100.

[Danny Cabral]

Correct, spark but no fuel, can spray fuel down throat and will fire.

Unplug one of the two front injectors, and using a test light, verify there's 12V at the wire connector.
There should be a constant 12V during the 5 second prime time and when cranking & engine running.
The ECU pulses the ground side of the injectors to spray fuel. (Check the fuse next to the relay.)

Have done the computer thing and manually set and it has held, now have rpm signal again on can, still no fire.

OK good, we're making progress.

Noticed starting rpm was set at 1000, my starter would never spin that fast, have changed that to 100.

If you're referring to the "Crank to Run RPM" parameter, it's usually set to 400 RPM.

[pauls39chev]

Hi Danny, good news. I sent an email to Holley tech saying we thought the ECU was faulty, he replied with a "remove injectors from pod and see if there was a greasy substance on them", which I did, and yes there was. I cleaned it off on a rag and replaced them thinking "yea right that will work" but guess what? It did! Although at first it ran quite hairy, now it idles quite smooth, will put seats back in her now and go for a drive. Thanks for your help over this and a pleasure talking to you yesterday.

[Danny Cabral]

I cleaned it off on a rag and replaced them thinking "yea right that will work" but guess what? It did!

Oh...that means you were getting the pulsed ground at the injector connector (from the ECU).
You told me that you were only getting 12V at the injector connector, but not the ECU ground.
Anyway, I've never heard of such contamination with new fuel injectors. I'm very happy you got it running!

Thanks for your help over this and a pleasure talking to you yesterday.

It was nice talking with you too, Paul. I'm glad it wasn't a faulty ECU.

[39chevy]

Just put new Ultra Street Avenger 670 cfm on on my 39 Chevy, mild 327, Turbo 350. Replaced older #80146 (4150) 600 cfm...all was good, now it's not. Motor shuts down when I accelerate, however, can full rev in neutral. Fuel psi 6, floats at 1/2 site glass. No vac leaks. I am four bolts away from going back to old carb?

[Danny Cabral]

...all was good, now it's not. Motor shuts down when I accelerate, however, can full rev in neutral.

Seems like air/fuel ratio issue (too lean or rich) or an ignition problem. I'd invest in a wideband O2 sensor kit (link).

[39chevy]

I agree, but changed back to old one and all is well?

[Danny Cabral]

The old carburetor? Agreed, that would rule out an ignition problem.