Hello. my 850 is'nt starting. I drove to a local spot for a picnic with the kids and on returning ,the car started but just did a sluttering tickover and then died. I tried to start it a couple more times and the engine would'nt even catch. There is no whine from the pump as it primes the fuel system and all the fuses are ok .Any ideas anyone

 

Turbo or non turbo?

 

If the engine is not cranking I would make sure your battery is charged. I would also take each of the cables at the battery and clean it then tighten back down. If the battery is dead it could be a dead battery or a failing alternator. Most all of the parts stores can test your batter and/or alternator for you.

 

Its a non turbo and the engine cranks over fine. It's as though the fuel pump or sensor/sender have decided not to do their thing. It did start but only ticked over and would'nt take any throttle and the engine died. I'm pretty certain its fuel supply but don't know what to do. I've consulted the trusty Haynes manual and I'm going to give the self diagnosis thing a try tomorrow. The fuses are all ok and I'm wondering if theres a sensor or solenoid that allows the fuel pump to work. What gets me is the suddeness of the breakdown because theres been no hint of a problem beforehand. Many thanks for you interest and help.

 

Well, fuel pumps give NO WARNINGS at times. That would be my best guess. when you shut the car off it was fine, likely still had pressure on the line. When you started it, it used the fuel pressure that was there to start and once the pressure died down it shut off.

I have only had an 850 for 2 days so i'm not sure if the pump primes when the key is turned. let me go check...

 

OK, I have a turbo model. when i turn the key to on, i hear some kind of hum like an air pump or something is running non stop. when i hit the starter for 1 second, like a click, i hear what I believe is the fuel pump that runs for about 5 seconds after I release the key. I did not hold the key long enough for it to start, just listening for the fuel pump.

Also, I am not sure if this car has one pump or two. On my old 740 GLE there were 2 pumps, one in the tank and one under the car. someone else will have to tell you that or look through the threads.

Good luck.

 

If I were you I would check that you are getting spark.

If you are getting spark, you could check the fuel pressure at the valve on the fuel rail. When you have the key at the II position and hit the valve it should squirt fuel. If it just dribbles out then there is a problem.

 

most likely either the pump or relay.these cars have 1 pump.

 

My 2 cents on Fuel pump relay. Its under the plastic cover that holds the fuse box under the hood. You have to take few screws off and then there is a fuelpump relay under there. Wonder what year is your car but some early 850s came with green coloured relay and later ones had an udgraded ones that are red in colour (the number onthe relay is 102 OR 103 - I dont remember). This is common problem on 850s and once you replace th relay, you should be back on road.

 

If it is the fuel pump relay would he get pressure at the fuel valve on the rail?

Just curious...

 

bad relay=no pressure

 

Hello again.
I did the self diagnostic thing and the code came up as fuel pump relay. As I did'nt have a clue where that was I decided to check out the fuel pump. Before that, I waited for a quiet time (midnight) and tried the ignition. There are three distinct clicks of relays in the engine bay when the key is turned.
To cut to the case, I took out the fuel pump, wired it to a battery and..... nothing. A phone call to a local breakers, a quick ride and I had a working pump at a cost of thirty five quid, a price I was happy to pay, although , as a Yorkshire man, twenty five quid would have been better.
An hour later we were mobile again. Yay.
Thanks very much to you all for your help, I hope I can return the Favour one day.

 

Hello again. I've just replied to your advice and I've done something daft and it's shot off into thin air.
Anyway, I've fixed my car. I did the self diagnostic thing and the code read as fuel pump relay fault. I did'nt know where that was but when I turned the ign key , there were three distinct clicks from the engine bay so thought the relay may be ok.
I took out the fuel pump, wired it o a battery and......... nothing . I phonad a local breaker, a quick ride and, for thirty five quid, I had a working pump.
An hour later we were back on the road. Yay.
Thanks very much to you all for your help and I hope I can return the favour one day.
Apologies if I've posted two threads but I'm bloody hopeless at this computer malarky.

 

Bugger

 

^^read bestharry's post for future ref. on relay location...^^