Eek! My W202 won't start

[Nasco12]

Starter motor does its stuff (turns over?) but the engine doesn't fire.

I tried this four or five times. The last time I tried the fuel gauge went up to full and then slowly declined to empty.

Any ideas?

 

[Uncle Fester]

Lack of fuel, or lack of spark?

 

[Nasco12]

Any way to tell?

 

[up2u]

pressuer

hi there is a valve on the fuel rail at the front of the engine looks like a tyre valve ! first open the fuel tank filler cap, then remove the black valve cap then with a small flat screw driver and a rag release the pressure !!
if no pressure it`s the pump or pump relay or fuse
cheers hope this is of help

up2u

 

[Nasco12]

Thanks for that. Unfortunately, the story's moved on. Yesterday, I had the car trailered to a garage. And guess what? It started .

Which in some ways is worse because I am half expecting this to happen again.

 

[Stratman]

Get the fault codes read. Yates in Tudor Road, Hampton is a Mercedes specialist and will be able to read them.

 

[Nasco12]

It was trailered to TM Motors in West Molesey. I only got a brief chance to speak to them on Friday so I am not quite sure if they put it on Star or not. They should have done but either way, the mechanic couldn't find anything out of the ordinary.

Perhaps he had magic fingers.

 

[vijilants]

hi there is a valve on the fuel rail at the front of the engine looks like a tyre valve ! first open the fuel tank filler cap, then remove the black valve cap then with a small flat screw driver and a rag release the pressure !!
if no pressure it`s the pump or pump relay or fuse
cheers hope this is of help

up2u

It could also be the fuel sender units that are causing a lack of fuel if it does appear to be a fuel issue so don't be too hasty to change the pump until you have tested the pump.

The w202 uses a saddle type of fuel tank. The sender units and the pipe in between balance the fuel between both sides of the tank.

A common problem is the guage shows you have fuel in the car but no fuel getting to the engine but the pump works. This is due to the fact that the senders go faulty and there is fuel on one side of the tank but none on the other.

 

[Nasco12]

The car's travelled about 80 miles or so since the last fill up, so I would guess there's plenty of fuel on both sides.

Thanks for the suggestion. I wonder, would that explain why the reading often seems lower (not massively) when you start than it was when you stopped?

 

[cazyp]

Are you sure it's a fuel problem?
Sounds like it's an immobiliser problem to me.

Immobiliser problems can also give dodgy dashboard readings/lights etc.

 

[Nasco12]

I've just got back from the garage. The only thing logged on Star (or whatever they use) is a fuel gauge sensor fault. All I can say is that it doesn't seem to be faulty now.

Otherwise, the car starts and goes fine. All very mysterious.

 

[big_amg]

i had a similar problem with one of my 202s, it would start and drive as normal, and then one day it wouldnt start, it would turn over but nothing. keep trying, but nothing. and then i would wait a while and guess what? it would start like normal. My one was cured by replacing the crankshaft position sensor. i think it cost about 40-60 quid from eurocarparts and 20-30 quids worth of labour iirc.

good luck

 

[Nasco12]

I wonder if what happened is to do with the previous journey in which I started the engine, moved forward 3 feet (to get the car nearer the hose should you ask) and switched off.

Could I have flooded the engine?

 

[Smiley]

Yes that is your problem. You should not start a car from cold, run it only for a couple of minutes and then turn it off. There will be unburnt fuel in the exhaust and the ECU will think there has been a failure in the fuellling and prevent it starting. The only way to get it started then is to hold the accelerator pedal to the floor and crank - gets air through the exhaust and clears the unburnt fuel. You will shorten the life of the engine and the cats if you keep doing this!
If you start the car from cold then run it until it is off the cold start cycle - about 5 mins min and preferably not on idle.