Such problems are difficut to detect and the most likely cause I can think of is a relay that is intermittently not working. Try swapping the power hold and fuel pump relay with others to see if it makes a difference.

If you are able to test what is missing causing the non starting when it occurs, that would be the ideal solution.

Answered by KHLow2008 (expert)
39,900 answers provided

thank you for reply i will try swaping relays and test and get back to you.

"If you are able to test what is missing causing the non starting when it occurs, that would be the ideal solution."

how would you recommend doing this ?

i did forget to add also if i run fuel low so that petrol light comes on with "50 miles left" on computer if i refill with say just tenner worth of fuel even know fuel bar has move to 1/4 tank light will stay on unless i added more fuel again intermittently not everytime would this point to another problem or be connected to same problem ?

thanks
gavin

Response from nitromad
1 question asked

http://www.2carpros.com/articles/car-cranks-but-wont-start

Above link explains how to check for problems when engine fails to start but in your case, it is not going to be easy because if you crank it a few times, it works so you might not have the time and opportunity to check them out. A scan tool to monitor the condition would be easier but then it needs to be malfunctioning before you can find out wat is not working to specs.

The fuel problem might be related to the problem as problem seems to be electrically related and could be from a control unit or its circuit.

Answered by KHLow2008 (expert)
39,900 answers provided

ok thank you for that i have got usb scanner for laptop unfortually i have no idea what spec are i best find out.

i will report back after i had chance to swap the two relays as stated thank you

Response from nitromad
1 question asked

Monitor the crank and cam sensors for a start.

Answered by KHLow2008 (expert)
39,900 answers provided