Starting Problems

[softedave]

I have a 2008 Roadsport that I built myself. I have never had any problems before but now gave an intermittent starting problem. When I click the start button sometimes the starter fails to turn and the immobiliser re-activates. It sounds and feels like the problem you get if a battery lead is a bit loose. However, all connections appear to be good. Also, when the problem occurred today I kept my finger on the button and it made a humming noise for a few seconds before starting to turn the starter again. Any ideas?

[radical78]

check battery voltage. battery earth. starter relay .starter motor

[rotorwings]

Also check the battery voltage under load (while starting). In some cases the rest voltage can be fine, but the battery is still dead because it cannot cope with the load.

The voltage might drop to 9-10V momentarily, but really should not go lower during starting, and should recover quickly.