Engine will not start.

[Larry R]

The other day I took my car for a ride. It ran fine for the whole time. But when I pulled into my driveway. I let it idle for a few minutes, then the engine quit and I could not start it. I let it sit for a while and tried again, but it still wouldn't start. I winched it into the garage and started checking things. There's no power coming to the fuel pump from the ECU as well as no spark to the spark plugs. I jumped the fuel pump and I worked then, but the car would still not start. The battery is good and turns the engine over robustly. I checked the MSD 6AL and it's good. I also looked at the wiring and found no problems. The engine is a 350 SBC with a Weiand 177 blower and a Holley HP EFI on top of the blower. I'm using a Holley Dual Sync distributor. The car has been running fine for a year till now. My question is: Could this be an issue with the ECU?

[andrewb70]

Hey Larry. While a sudden bad ECU is possible, I don't believe that it's probable.
Are you able to hook up your laptop and communicate with the ECU?
I'd look over all the wiring again. Check your fuses and all relays. Andrew

[Larry R]

Thanks. I have checked the fuses, but I did not attempt to connect my laptop to it yet. Good point, I will try that.

Today I tried to connect my laptop to the ECU, but it would not connect. I tried several times, rebooted
and so forth, but no luck. I did get the "USB Link", but could not get the "Online". I'm not sure where
to go from here, perhaps send the ECU to Holley to have them look at it.

[Gaz64]

ECU is mounted on top of the blower? And no comms now? So could be ECU failure from heat. Gary

[Larry R]

The ECU is mounted under the passenger seat, the throttle body is mounted on top of the blower. Sorry for any confusion.

[Larry R]

UPDATE: I called Holley Tech and the guy was quite helpful. I double checked the power inputs to the ECU along with J12A pin 10, which is the switched power input. All showed voltage albeit lower than I would've expected. So then I checked the battery voltage, also lower than I expected, about 10 volts. I have a maintenance charger on the battery all the time when it's not being driven. I double checked the connections and found the fuse was not properly installed in the charger input to the battery. I will let it charge overnight and check everything again. Thanks for the help.

[Gaz64]

Sounds like you do have some electrical woes, and that would cause a no-start condition.
But with low volts, the cranking speed should be lower, and that should be the giveaway.
The engine running, then dying, and wouldn't restart could be alternator related. Gary

[andrewb70]

@Larry R: Keep us posted, Larry. Andrew

[Larry R]

UPDATE #2: I got the battery voltage back to where it's supposed to be. I checked the voltage at both fuses, as well as pin A10 and all were within a few tenths of the voltage at the battery. I checked the fuel pump relay and could find nothing wrong, but put in another one just to check and still no power going to the fuel pump. Is the timer for the fuel pump in the ECU? I could not find any reference to the timer in the schematic so I assume it must be buried in the ECU. Any other ideas will be gratefully accepted. Larry

[Danny Cabral]

Yes, the default 5.0 second "Fuel Pump Prime" time is a function of the ECU programming (it's software, the relay is hardware).