I have a 92 isuzu mu which when I bought several months ago would sometimes wait several seconds with the key on crank before it would turn over, then run fine. After a few weeks it stopped doing this and started first pop every time. The other morning after driving it down the road and parking. It wouldn't start for half an hour, and did the same thing today.
I have checked the terminals, tried jump started it and made no difference. Also ran a second set of jumper leads from the battery terminal to the block incase of a bad earth which did nothing.
When I try crank the motor, the voltage needle will drop ever so slightly below 12v then straight back up to about 12.5, and the stereo will turn off, and the dash lights will all stay lit. Once off crank, the stereo turns back on and the dash lights all stay lit as they have been the whole time.There is also no click noise of a relay or solenoid from either in the cab, or engine bay.
Another interesting thing to note is the tail gate release will not work if the car is not starting. Once the car has started and been turned off again, it then works fine. Or if the car is running it will function correctly.
The starter motor also works first pop once the engine is up to heat.
Has anybody got any suggestions as to what it may be?
Thanks,
Andrew