Strange noise from injectors

[DanPrice]

Hi, I’m hoping someone might be able to help with a bit of an issue I’ve got. I’ve just replaced my head gasket and now I’m getting a buzzing noise from my injectors that I’ve never heard before. I can’t see any damage to any wires and I’m pretty sure I’ve got everything connected back up properly but was wondering if anyone has had this happen before and knows what’s causing it. OPCOM says there are no error codes logged and looks like all the sensors are working ok. But don’t really want to try and start it with the injectors making this noise in case something bad happens.

Thanks in advance.

 

[KevinH]

Hi, it may be worth checking the two purple relays located in the rectangular black box that sits on top of the ABS unit. They are identical, one is the fuel pump relay and the other nearest the front of the car is the engine management control relay, which controls the injectors. Ensure the ignition is switched off to ensure no EML light appears, take them out one at a time and clean the terminals with some emery paper then lightly smear some vaseline on the terminals and replace them.

If either of the relays look brown or are bulging then best to replace it.

The GM part # for both relays is: 90494959

 

[DanPrice]

Hi Kevin, thanks for your help, turned out one of the relays wasn’t seated properly, I’d taken them out so I could turn the ignition on to close the windows and not have the fuel pump kick in and mustn’t have pushed them in properly when I put them back in. It’s all working again now. Although I’m still getting water in my oil after changing the head gasket and rebuilding the water pump so I think I might have a cracked head

 

[KevinH]

Hi Dan, glad you got it working again.

The cylinder heads are prone to cracking around the spark plug threads which is due to overtightening of the spark plugs especially on cylinder No. 4 (gearbox end) due to a coolant gallery that runs very close to it.
The spark plugs should only be tightened to 20Nm (dry, no lubricant on thread).