Petrol Pump W126 series

[shayes]

My Car won't start after two weeks standing idle. It hiccuped just once on 21st November. (about to take the family to a Pub for my Birthday lunch. It just died as I went round a corner a qtr miles from the house. Got some petrol and put it in just in case. No change. Two hours later when I had called the AA I returned to the car to find it started and has been going merrily ever since. That is, until I gave it a brief two week holiday.

I've just replaced the Kickdown Relay with one I possibly took out of the Car a couple of years ago and whereas previously on switching on the ignition I had no ticking sound from the pump area, now I get a continual low whining sound, but no clicking. If this is diaphram based, presumeably clicking is what I am hoping for? Car did not start. The OVR I replaced with a new one back in 05 and the Fuse looks fine.

What does this tell me, other than the Relay may have become a little damp and the replacement is doing the job. But what of the pump? Is it knackered.

I had the pump replaced a couple of years ago with a s/h one. Found the old one in the Garage and just briefly attached a battery to the terminals. A Whir and a squeek, and a bit of a jump. Not sure if I should have done this or if the pump may be OK. It was only replaced as one of many things to try to sort a similar problem of dying in 2005.

Any thoughts, other than bout time I got a newer Car?

 

[television]

These relays do get dry joints, and the fuel pump relay is known to go open circuit on one of the tracks. Blanket soldering often cures them.

 

[shayes]

These relays do get dry joints, and the fuel pump relay is known to go open circuit on one of the tracks. Blanket soldering often cures them.

Update on events. Got the mechanic over to give a tap to the petrol pump whilst turning over and after about two minutes cranking I couldn't beleive it but the engine started to splutter. Got it running, went out in the evening and drove about sixty miles. Three days later, same problem, car will not start.

Now I have said that there is a sound from the pump just with the igniton switched on, and according to the Manual the pump is only energised when the starter is actuated, or engine running.
I'm wondering if the problem is the pressure regulator (damper) which keeps the back pressure constant and supposedly sends excess fuel back to the tank. If this damper is malfunctioning and sending all fuel back to the tank instead of to the engine it may explain the problem starting. Anyone experienced problems with a pressure regulator?

 

[television]

Why not slacken the gland nut where the fuel pipe comes from the tank into the injection system at 17 in the link

http://www.detali.ru/cat/oem_mb2.as...&L=765.706&CT=F&cat=568&SID=47&SGR=045&SGN=03

 

[type49]

The pump should activate for a second or two when first switching on ignition. It should run all the time when cranking or engine running. Easiest way to check is to get a bit of 30 amp ish wire. Remove fuel pump/kickdown relay. You will see the relay has 2 banks of pins on it. One bank is full, the other goes half way accross.
Bridge the end of one bank with the one opposite. This should be roughly in the middle. (Does this make sense ??) You may see terminal numbers on the relay, if so the bridging numbers are 30 & 87. This should run the pump all the time regardless of key position. Obviously not recommended to drive like this, just for diagnosis purposes only.

 

[shayes]

Why not slacken the gland nut where the fuel pipe comes from the tank into the injection system at 17 in the link

http://www.detali.ru/cat/oem_mb2.as...&L=765.706&CT=F&cat=568&SID=47&SGR=045&SGN=03

Yes I guess thats the answer to at least determine what flow is happening. If none then I guess simplest to replace all parts at the pump end.

The wire straddle in the Relay I don't think is necessary as I can hear a noise from the pump which suggests the electricity is definately getting to it, plus the car started and ran the other day. Could be a damper problem, could be filter blockage or the pump itself. When my sudden oncome of sciatica eases I'll have to get out in the wind and give it a look. Not feeling much like doing anything at the moment.

Stuart
(ps any remedies for sciatica? Cold peas on the back, warm baths, not even Nuerofen seems to take away the severe pain.Hobbling around like a man of ninety unable to walk more than ten yards. Had it some years ago and had forgotten that trying to push a Merc might not be a good idea!)

 

[television]

Tell yourself that you do not have time for all of these Winter problems, mind over matter and get well soon