Mercedes 230TE starting problems

[pi3141]

Hi all, I had a problem with my car for a few weeks now, I wonder if I can get some help.

About a month ago the car started refusing to start, turn over ok, just not firing, when it did, it ran perfectly. Took it to a garage, Bosch fuel injection specialists.

They used diagnostics and checked all sensors were good. They checked the afm plate and lowered it a bit, checked the fuel return hose and it was only dribbling back so they suspected fuel pump or filter but they then checked the pressure and found it to be very high, 6 or 7 bar.

So we replaced regulator with a second hand part, pressure was lowered and it was starting ok.

Took the car on holiday for a week, it drove fine daily, the day we came home, after filling up petrol and unloading we went off to supermarket, it wouldn't start.

Paid for a question on website, got a bosch specialist. They suggested the fuel pump and filter or accumulator. They also did not think the pressures I posted looked right and were in fact differential pressure between upper and lower fuel distributor chambers. We bought an acumulator just in case, before we handed the car back to the garage.

The garage checked the pressure again, found it high, so we replaced the regulator again. Pressure came good, car cold started and hot started. They thought the car was ok but when we went to pick it up, it wouldn't start. They had figured out by jumpering fuel pump relay pins 7&8 and giving the pump a few minutes, then replacing relay, the car would start normally. The fuel pump was making a bit of a racket. We had noticed when we got back from holiday the fuel pump was whirring away very loudly, higher and lower when parking the car. He suggested we replace the fuel pump and run the tank low so he could check the fuel filter in the tank.

I had the car at sustained motorway speeds to run it out of fuel but I had nearly a full tank so I decided to buy a syphon hose and use my emergency fuel can repeatedly to discharge the tank into my other car.

We sourced a new fuel pump, spoke to mercedes who informed us there was two pumps, they suggested fuel pump relay, but mine looks new, I removed it and opened it for inspection and it looked clean and relatively new (very shiny) no obvious sign of damage. The car worked reliably by jumpering FPR and replacing relay and starting car.

Garage took the car, when they removed the cover to change the pump on rear drivers side (the noisy one) one of the electrical wires fell off. They saw imeadiately it was a bad connection, remade it, connected it and fired up and all seemed normal. Pumps were silent. They stopped at that point and called us, they didn't want to go any further.

We picked it up, filled up with petrol and in the morning, car wouldn't start. Eventually it got going, we decided to set off on our journey but before we got to motorway, we could hear the pumps whirring away and we decided to turn back.

This morning, I checked the fuel rate by taking feed off fuel distributor and jumpering relay. The jet of fuel was consistent. Filled a quarter of a 2 pint plastic milk bottle in about 10 seconds.

The car started first time perfectly today 3 or 4 times, I used it normally. Figure if I use it until something breaks then I may find out whats wrong.

The end answer from the internet question guy said he had replaced many a tank, fuel pump and filter for rust, but he would not suspect failing fuel pump for too high pressure.

The fuel test today suggests there is no blockage.

I've ordered an FPR from online auction site today.

I've read an exellent thread on this board that has similarities to mine.

300TE Fuel Pump Problem
Link - http://www.mbclub.co.uk/forums/engine/38414-w124-300te-fuel-pump-problem.html

Bought the car last December, previously had a head gasket replacement, drove until last month with no issues, pumps were quiet. It did have the remmanants of an alarm system installed when I bought it and I had to undo some wiring in the passenger footwell to get central locking working -wire spliced into central locking, stereo amp installed under footrest, rewired electric closure in boot.

I'm down 2 regulators an acumulator a fuel pump and a few hours labour, its been over a month and we've barely had use of the car.

Any idea's or suggestions?

 

[bolide]

Take it to a Mercedes specialist who knows the cars

Nick Froome

 

[pi3141]

Cheers Nick.

I almost decided to take it into Mercedes and get them to sort it.

See how it goes over the weekend, try the new FPR when it arrives and take it in somewhere if nothing changes is my immediate plan.

I got all the spares!

 

[Sp!ke]

Do t take it to Mercedes, they wont know these old models like an independent specialist will.

 

[Godfrey]

I used to have a 230TE that gave me some grief on starting. I too thought it was fuel related but it turned out to being tracking in the distributor cap.

 

[bolide]

The more things you change the more confusing it will get. Diagnosis is what you need

One thing I learnt from electronics & audio is that "simple" problems that are hard to diagnose and which seem illogical are often the result of more than one fault being present. The same is true with cars

Whatever you've done before a specialist will need to start at the beginning & work his way through the fuel & ignition systems. So I'd stop work now

Nick Froome

 

[pi3141]

Yeah I see the point.
I'm pretty annoyed that the garage, a bosch specialist, had the car for nearly a month and barely checked anything. Despite specifically going in to get pump changed and filter checked, it came out with neither being done. When it wouldn't start I had to think about draining the tank again, before taking it to a garage.

I would happily have paid 8 hours labour for them to have spent a day and sorted the problem. I don't know why they didn't.

If mercedes are not the best place to go and all the garages in my area send their difficult injection problems to the garage I took it too, we ourselves was referred by another garage, I don't know where to go next.

 

[grober]

Sounds like you may have a problem with the 12v supply to the fuel pumps one or both. The aftermarket alarms [ Scorpion ] ---dealer fitted--- to these cars are notorious for giving problems "later in life" . I'm not sure from your post if you have eliminated the alarm system +immobiliser completely or not. Usual immobiliser practice was to interrupt the supply or earth connections via alarm relay contacts to the fuel pump relay coil and similar on the OVP relay. Cure is to identify the 2 "foreign wires" leading to each of these relays - disconnect them and rejoin the leads to the relay thus in effect remaking the original factor wiring. Don't worry about the alarm wires they are just "contact breaking" and have no voltage on them once disconnected from the car's main wiring loom .

 

[pi3141]

Cheers Grober.

I just checked (working today/this evening) the actual alarm unit is removed (not by me) but the wiring is still there. I can see a couple of wires going into the OVP relay, not exactly sure what they are.

The wires I remade, were because the central locking would not work on the drivers door. I undone some wiring on the passenger side, in the tray under the floor and the central locking on the drivers side started working.

I also found an old Sony amp underneath the kick plate in the passenger side which I sort of ripped out. (fairly neatly)

 

[grober]

Try tracing the wires back to see where they come from. Factory wiring to the OVP usually enter the loom wrap/sleeving very close the relay base If you see 2 distinct wires with a long run that don't appear be related to the factory loom then they may be alarm associated. If the alarm is removed and they are part of its wiring they should be joined together by stripping back say an inch twisting them together and then inserted together into a screw block connector and wrapped in insulating tape. This might explain your starting problem but not the fuel pump problem

 

[pi3141]

Yeah thanks again.

I definitely need to look at this alarm wiring, I've got a thick loom leading to what was obviously the alarm unit and its not there. I don't know what the other end of the wiring is doing.

 

[pi3141]

Well the car wouldn't start leaving work last night (I didn't do anything to it!)
So today on my lunch break I removed the old alarm wiring loom. There were no direct connections to either the OVP or FPR. Some wiring went off to the fusebox where two wires were piggybacked onto some wires in there, the insulation had been removed and the wires wrapped around the exposed copper and taped over. There was a couple of connections to a fuse, power to the alarm unit presumably, I removed those. There was also a loom into the passenger footwell which was the wiring into the central locking that I previously disconnected but that was all. I took the whole loom out

I removed the spark plugs and they showed that the car has been running very weak. Barely any black soot on them at all and brown burn marks on the white ceramic. I bought new plugs and changed them.

Still won't start.

I've called recovery to drag me home, maybe they can shed some light on the problem. Otherwise I'm looking for a specialist in the West Midlands if any one has any suggestions where I can take it?

 

[pi3141]

My e300 often can not start, the reason is different from you, but the bad battery. I have not encountered this situation you said

Cheers David. I should probably charge up my battery to make sure it is fully charged.

 

[pi3141]

The recovery mechanic looked over the car and concluded it was pump. When I told him there were two he didn't believe it at first. He looked again for it but couldn't find it. He dragged me home. I wondered if the reason nobody had noticed the second pump was because it was dead. Could explain it all.

I searched the internet and found the location mentioned as back axle, jacked up the car this morning. Traced the fuel lines and eventually found the second pump behind the differential inside its plastic cover. The pump was obviously a replacement. Jumpering the fpr this second pump made less noise than the pump under the back seat with the filter and acumulator. I decided to change the older one under the back seat, making the most noise.

The connectors given by Merc on the replacement are not a straight swap so to speak and I needed to use the old pipe connections. the connection on the car pipework to the old pump were not easily budged. I undid the bracket holding the pump on and the rear pipe, removed the rear fuel pipe and used a 15mm spanner on the neck of the pump body to unscrew the pump from the union instead. I left the pipe work as it was and unscrewed the pump by hand once it had loosened. Obviously I screwed the new one back on the same way using a new copper washer. Tightened everything up and the car started first time without hesitation (using booster pack) Let it idle a while.

Took the car for a spin and broke down, engine just died, ell electrics seemed ok and no warnings, as if running out of petrol etc. Walked home, got the wires to jumper the FPR a milk bottle and some spanners. Took the air filter off and undid the fuel pipe from the bottom of the fuel distributor. It leaked a bit of petrol and I thought it may not be fuel, but when i put the pipe into the bottle and jumpered the FPR, I got no fuel, just air for a few seconds, then the fuel. Replaced the pipe, air filter, used booster pack (battery been run right down over last few days) car started second time I think.

Run it to station, filled up a bit. Ran it home. Used it twice since then, hot starting. Seems ok. Pumps are a lot quieter. Now I know what I am listening for I can hear them in the background.

I think it is sorted.

Thanks for all the suggestions!