Help Needed From A New Member!!! - Starting Issues

[gj77]

Hi all,

I'm hoping that somewhere within this pool of knowledge, there might be an answer, or at least a clue to point towards the root of my problems.

I've got a 1996 W124 E280, with 200,000 miles on the clock. I've had it for two years and in many ways it's been great, but has had some issues (mostly wear and tear), however it has now had a problem starting for a couple of months which seems to be stumping everybody, mostly because it's intermittent and because no error codes are being recorded. Most of the time it just turns over but won't fire. The fuel system and ignition system have been tested and are working, but when this issue occurs something is stopping the fuel from making the final leg of it's journey through the injectors and therefore firing the engine into life. Occasionally, the old girl forgets that she has this problem, fires into life as soon as I turn the key and runs like a dream, until she decides to let me down again. The local mechanic I've been using is very good; he's an older guy with many years of experience and a slow and methodical nature, but he can't solve it at the moment, and until she decides to fire up again, I can't even get the car back to him.

• The crank shaft sensor has been changed.
• The loom has been rebuilt around 18 months back.
• The ECU was sent for repair and reconditioning 18 months ago.

Can anybody help?

Thanks,

Glen

 

[GP801]

The two most common causes are the fuel pump or the OVP relay. I have had both on our 1995 280. Can you hear the fuel pump run when you first turn the key without cranking the engine? If not then either the fuel pump or the relay controlling it may be faulty. The OVP relay sits behind the battery under the plastic cover. This often fails and can cause non starting.
We also had a new engine ECU fitted but this caused a severe misfire rather than non starting when it gave up.

 

[gj77]

The fuel system definitely primes. I thought about the OVP, but everything I've read about that problem suggests that it causes the ABS light to stay on, and that's not an issue here (on the odd occasion when the car runs).

 

[GP801]

The OVP relay failed on ours and the only symptom was not firing. No warning lights. No other symptoms. Possibly worth trying a new or good second hand one. They were not expensive when ours failed.

 

[gj77]

Thanks, I may just try that.

 

[optimusprime]

Check all the fuses in the fuse box And same old story -- if these are white metal tips the fuses need changing for copper and ceramic type fuses . What about the fuel pump relay ?

 

[gj77]

Thanks, as the fuel pump definitely primes I think that relay is ok, it’s on my list to try though.

 

[optimusprime]

Try this,,, remove the air cleaner .Then look at the throttle plate ,now just push the plate down gently and see if its got any resistance ,,,tell us what you find .Do this without the engine running .

 

[gj77]

Thanks optimusprime. I’ve got a replacement (used) OVP coming in the next few days but I’ll definitely check out your suggestion.

 

[carat 3.6]

The next time it wont start, check to see if you have 12v at the injector plugs with the ignition on.