W201 / 190E Temporary Fuel Supply Problem

[rjsdavis]

Thanks for all those that have assisted me with the other little problems that I have had with my 190!

At the moment, whenever I start my 190E, she starts first time, however, she does suffer from a brief fuel supply problem - this is particularly prevalent after she has been parked up overnight.

She will start first time, but I need to dap the throttle to prevent her from cutting out. Immediately after starting, she needs me to keep my foot on the throttle for about 10 secs, whilst she appears to be cleaning out a blockage in the fuel line. The rev counter and engine noise indicates that the fuel is not getting into the engine as it should, and she will not go above about 2,000 rpm for the first few secs...

After about 5-10 secs - this is cleared and she will rev and appears to tick over normally.

However, as you are driving her - for the first ten minutes or so of driving, she is still suffering some slight fuel problem. As you pull away from stationary, she has not got full power available to her (not that I am looking for quick starts), and you can feel her struggling to get the fuel into the engine.

After about 7-10 minutes of driving - the problem disappears (when she is running at normal engine temperature). If she is parked up for a few hours during the day - the problem will return, but again only until she is back up to normal operating temperture.

Can someone please help me identify what problems to check for as I am no expert mechanic, and could really do with a little guidance with this.

Thanks alot.

Richard

 

[Stevie A]

I don't think it will solve your problem entirely but it might - change the fuel filter. It is under the car at the back between the two wheels under a plastic cover. If it is clogged then this will cause fuel supply problems and you will notice the difference when a new filter is put on. About £10 for a fuel filter from GSF car parts and a mechanic could change it in half an hour.

Other things that might cause problem you mention is the cold start valve. Do some searching for "hard start 190E" and you will get ideas.

If the car sometimes stalls also then the fuel pump relay could be on the way out.

 

[rjsdavis]

Steve

Thanks alot for the reply. Much appreciated.

Firstly - with the fuel filter - is this a particularly complex job? Would I not be able to do this myself, or do I need specialist equipment?

Also - the car has never stalled. Sometimes she won't run immediately from the first start, but a dab on the throttle as she starts sorts this out, so she always ends up starting first time.

Thanks again

 

[Stevie A]

You could do fuel filter yourself. Buy the Haynes manual for the car. It is a straight forward job. It means crawling under the car though. You can get a fuel filter from GSF car parts or eurocarparts. The Merc fuel filter is huge compared to normal cars. I couldn't believe it when I saw the size of the fuel filter for my car. I noticed better accelaration and a lot less noise from the fuel pump when it had been changed.

If you are competent to do fuel filter you should change your spark plugs too. About £1 each from sparkplugs.co.uk or a dealer and an easy job that will also improve starting. You'll need a socket set with spark plug tool and spanners for fuel filter. Argos sell decent spanner sets and sockets cheap.

Do as many jobs as you can yourself to save money and your car will run better too. Learn by doing and you'll be more empowered for it too.

 

[rjsdavis]

Here's an embarrassing question!

I've got the new filter - and it's ****** enormous! Anyway - got the car up on the ramps to start fitting it, following the Haynes manual advice that says that it is in the "fuel-line, adjacent to the fuel tank"!

Got underneath the rear axle, and could I find what I saw in the picture in the manual?? NO :-( Spent half an hour, looking all around - could see the three fixed pipes that run along the passenger side of the floorpan, but these didn't lead anywhere that I could see.

Haynes manual tells me that the access to the fuel filter is from underneath and the jack the rear of the car up - but where is it?? I can't find it anywhere.....

No smug answers please.......

 

[Parrot of Doom]

The next time you start the car of a morning, open the bonnet beforehand and have a careful look around at any fuel pipes you can see. Look for trapped air pockets.

If you see any, or when the engine is running you see air moving around (you can keep the engine revving by finding the throttle pot and pulling it with your finger), then you have an air leak somewhere.

 

[Stevie A]

Fuel filter is under a plastic cover around rear axle area. I think the cover sticks out a bit so should be obvious if you look for screws / nuts that need taken out to remove fuel filter / pump cover.

 

[mike65]

The fuel filter and pump/relay sits just inside the rear passenger wheel area behind a large flap.

However I don't think changing will cure the problem (though it won't hurt), it sounds to be like the check valve is at fault if its not working you can get vapor locks in the lines (can someone back me up on this?!) Has the rough running coincided with the summer weather?

Mike.

 

[Stevie A]

The fuel filter and pump/relay sits just inside the rear passenger wheel area behind a large flap.

However I don't think changing will cure the problem (though it won't hurt), it sounds to be like the check valve is at fault if its not working you can get vapor locks in the lines (can someone back me up on this?!) Has the rough running coincided with the summer weather?

Mike.

Mike, what's the check valve? And where is it? What happened to your bigger car in the picture with RIP?

New fuel filter will help a bit and new spark plugs too is a cheap way to better running.

 

[mike65]

The check valve is the non-return valve so the line does'nt drain empty (I think I have that right, check valve seems to be an American term).

I bought an old Audi A6 as I wanted a largish auto barge so the 190e is gone (but in the ownership of someone else, should still be on the road for a few years yet).

Mike.

 

[rjsdavis]

Thank you so much for all that have replied. I am really grateful. HOWEVER - I have to start again!

I spent 30 mins on my back looking for the poxy fuel filter - getting more angry that I couldn't find something so straightforward. In anger, went round to the local MB dealership for location assistance. They spotted straightaway that my car was not a 190E, it is in fact a carb'd 190. Even though the badging on the back (AND ON MY V5), say it's a 190E. I've always assumed that it was, as I've never really had to tinker around in the engine. You can imagine how ****ed off I was to discover that I had wasted so much time.

Anyway - now that I've established that this is a carburettor and not DI 190, I suppose my original question remains as to trying to identify why my car might be running hesitantly until warm.

I should point out that she was laid up from December 2004, until Jan 2006 in the garage. She was turned over regularly but not used. She still runs perfectly fine when warm, but it is just that initial period for the first five minutes where she runs as though there is an intermittent fuel supply problem. Any ideas - on what I can check to resolve?

By the way - does anyone need a fuel filter for a 1989 (ish) 190E? Brand new - Unipart part

I will still be installing a new air filter and four new spark plugs to see if that helps, but I know that it is something else that is really at the heart of this.....

Thanks again for all submissions so far.

Richard

 

[mike65]

Dear God! Someone clearly could'nt bear the idea of not being fuel injected! Either that or its had an engine swap and they did'nt notify the DVLA.

Mike.

 

[Stevie A]

Richard - Take the fuel filter back and swap it for your air filter and / or a fuel filter that fits your car. Partco takes stuff back no probs if you have receipt.

Find the non-return valve that Mike mentioned and have it checked out. New plugs will help loads I think. I helped someone once who had a low mileage 190E that had been laid up for ages and it would not start. Turns out it just needed a set of new plugs.

Maybe something on the carb is acting up until the engine is warm.

 

[Stevie A]

Richard - I could remember something from MB Manual for my 190E car specifically about 190 model only on start. On cold engine start it says: "Briefly depress accelerator once (only on type 190). Turn key....and release only after the engine is firing regulary. Do not depress the accelerator during the starting process." This is for 190 and not 190E models. This must be to set the choke or something.

This is for all models 190/190E:
On engine at operating temp it says do not depress accelerator on starting but if the engine fails to start after approximately 4 seconds then fully depress the accelerator and continue to crank until the engine fires regularly.

Hope this helps.

 

[rjsdavis]

Thanks Stevie A - much appreciated, unfortunately, this doesn't cure the problem..... thankfully she starts IMMEDIATELY, first time, every time - come rain or shine.

The problem is only with the hesitant running immediately after starting from cold. For her to start easily, you need to "catch" the ignition, immediately after she has started and fired. If you don't - she will run for a few secs and then stall. However, if you catch her as she fires by pressing the throttle, you can feel that there is a fuel supply issue as she hesitant for a few secs, with very hesitant revving, and then after about 4/5 secs (with the throttle) partially down feeding her some extra fuel, she breathes properly.

When you pull away (cold), she is still hesitant. If you pull away from stationary whilst cold, you get those few seconds whilst she is trying to get enough fuel in to provide the power - and then it's as if the "blockage" clears and she is back to normal. Once she has reached just under 80 degrees operating temp, the problem disappears. If you leave her parked up all day whilst at work, you will get the same problem again when you get to go home.

My guess is that there is a problem in or around either the fuel filter or carburettor. I am not experienced enough to be able to diagnose it, but if I am told what to do - can usually do it pretty easily. I'm just trying to work out what to check or replace.....

Richard

 

[Stevie A]

Richard, I still think spend £8 and put in new spark plugs first then run some carb cleaner through the system and find location of fuel filter on your model and change that.

See Haynes Manual for fault finding but here's what I had quick look at:

Engine hesitates on acceleration - worn spark plugs / Vacuum leak at carb or throttle body etc / blocked carb.

Engine hard to start when cold - worn plugs / choke mechanism incorrectly adjusted or faulty.

Try new plugs asap and see what happens.
Hope this helps.