W124 - 1994 E220 Starting Problem

[robinsykes]

Sometimes when I turn the ignition on and try to start the car it wont. The petrol pump has not 'whirred' and having checked, there is no spark. Eventually after many attempts the pump will 'whirr' and the car will start. I have replaced the starter relay, and following 2 weeks at Christmas when it would not start at all and had to be towed to the garage they replaced the crankshaft sensor and the car seemed to be fine. However it is still doing it though intermittantly. Once it starts it runs perfectly and will start no problem. Any suggestions? Thanks.

 

[mike65]

At the risk of sounding obvious, have you checked the contacts on the battery are clean?

Mike.

 

[robinsykes]

Thanks, but ignition comes on perfectly, i.e. all dashboard lights come on.

 

[Ramius]

Do you have an imobiliser? Had similar on an Audi, just a thought

 

[robinsykes]

Thanks, there is an approved Mercedes alarm fitted. I have had it checked out by a specialist who says it is ok.
Problem occurs even with alarm switched off with key.

What happens when th eignition key is turned on? Obviously the ignition circuit is made so that the engine spins and a spark is produced. When I have the problem the petrol pump does not pump and there is no spark. So could it be an ignition switch proble? What is strange is the fact that once started the engine runs perfectly. Are there any other parts I could change that may help?

 

[robinsykes]

Just in case anyone else has similar problem. Car sat down last week and would not start. Towed to independant Merc garage. They traced fault to faulty Power protection Relay sited on bulkhead behind battery. Hoorah!!

 

[neilairman]

opps

did your specailist charge you for a new relay ?
cause i just discovered that there is a simple fuse fitted in the top of that
relay, i think my merc dealer charged me plenty money and said it was windscreen washers ( which are electrically heated ).
a fuse was mentioned in the bill, and since she had the same trouble as you it makes me wonder

 

[Myros]

The OVP has plenty of previous on this forum

it's what brought me here all those years ago. Even though the fuse may have gone, and replacing it might fix things temporarily, the relay will eventually let you down again, as they are all from a faulty set made by Siemens, I think. The cost of replacement by the new 'washes whiter' version is worth the £50 or so it cost and the 5 mins to do it. Mine hasn't missed a beat ( barring that broken plug episode) since I put a new one in 2004.