M400 Not Starting

[hollowpockets]

Thought my car was having problems with fuel starvation as per the other thread, power cutting when comming on boost etc, drove to my friends last night, I tried to start the car to head home but no joy, now I have lined up the filter and pump and just used a short straight bit of braided hose to connect them but still no joy.

The pump is coming on and all seems normal, not sure where to start looking really, any ideas people?

cheers

Graham

[gadgeroonie]

first of all check you have a spark

does the fuel pump prime when you turn the key ?

does it try to fire at all ?

[hollowpockets]

Wierd

Had no joy getting it started and as it was miles away from home i just had it taken to a local garage, once off the flatbed they tried it and surprise surprise it starts first time. Suspected earthing problem then, will get some feedback tomorrow once they've looked it over.

[AMG Merc]

hollowpockets said:

"...and surprise surprise it starts first time."

Ha, and here is the formula for such occurences...
http://news.bbc.co.uk/1/hi/wales/south_east/522354...

[hollowpockets]

Time again for some problem solving guys...

Spoke to the garage today and when they tried to start it this morning it didnt work so there is deffo a problem, they checked fuel pressure and its 3 bar so pump working correctly.

Symptoms:
Now since the fuel pump was changed there has been stuttering while on boost which has got worse and now starting problems, to add to that since the pump was fitted just a few weeks ago the horn has decided to almost completely stop working, just makes a farting noise now , finally ever since I bought the car in september there has been the unresolved 'pheonomenon' of the interior lights turning themselves on while the car was on full boost.

Im now thinking they are all linked somehow and iv got electical problems, ideas?

Thanks folks

Graham

[JLSELAN]

It probably would be a good idea to trace through the wiring harness looking for compromised wires/insulation, especially in areas exposed to exhaust/turbo heat.

[caccobra]

+1. Start with the wires that are closest to the front turbo, especially the wire harness near the alternator and ac compressor. If lights are coming on by themselves you have some wires that are shorting to ground somewhere and that is most likely in the engine compartment near the front turbo. You may have to strip back the orange insulation there to actually find the probelm wires.

[gadgeroonie]

yes the wires near the front turbo are known to fail

[joust]

+2 and I'd check the battery feeds and grounding as well - not just visual, but dismantle, clean and replace.

J

[RobP]

caccobra said:

+1. Start with the wires that are closest to the front turbo, especially the wire harness near the alternator and ac compressor. If lights are coming on by themselves you have some wires that are shorting to ground somewhere and that is most likely in the engine compartment near the front turbo. You may have to strip back the orange insulation there to actually find the probelm wires.

Occasionally there is no external visible damage to the wire , but internally it is shagged and broken (technical terms). If the wire feels 'stiff' at any given point (ie around the front turbo) but flexible and compliant elsewhere, then there's a fair chance that the wire has been fried. However this is more lightly to lead to instrument failure rather than some form of shorting as described above. Happened to my fuel pump wiring, before everything was encased in heat shield and moved as far as possible from heat source.

[Adrian W]

usually the wires near the front turbo are the returns for the idiot lights, they normaly short against the exhaust giving you a false oil pressure or battery light. i would be looking at the fuse block next to the ecu, there arent that many things that would actually stop it starting at all, the ecu loom ( ignition, sensors and fuel injectors are powered from here) check the fuses, carriers and wire connections here, also worth prodding around with a voltstick if you have one.

my guess about the interior light is a dodgy pin switch (do you get false alarms?) playing up under hard acceleration and nothing to do with your problem.

Edited by Adrian W on Thursday 20th November 11:12

[rsnoble]

i had same prob found to be the 4 fues under rear clam, fues get water in them, check no corosion, worth a quick look

[rustbucket]

I THINK RSKNOB MENT FUSES

[joust]

rsnoble said:

i had same prob found to be the 4 fues under rear clam, fues get water in them, check no corosion, worth a quick look

The 2.5s were terrible with that, but not known that issue on M400s as they are better positioned and protected.

Certainly worth a check though.

J

[hollowpockets]

The main issue, not starting appeared to be water in the fuel tank, they drained, cleaned it out and fixed the fuel cap that wasn't sealing when locked.

Also a gear selector cable had been rubbing on a pulley and was through the plastic so moved it, there was also some dodgey looking wires and one of the relays for the wipers was in the wrong position according to the manual, also the daft manual boost controller wasn't working so they fitted a new one.

Still not sure whats causing the random loss of power though

Edited by hollowpockets on Thursday 27th November 15:48