M635csi running but cutting out under throttle.(need help)

Post Mon Jun 22, 2009 12:40 am

Guys I have recently bought a 1985 resto M635csi project M88 block, this has been standing for a number of years.She would turn over well but so far a non runner. I have replaced the plugs,dissy cap rotor arm still a non runner. then bridged the relevent pins on the fuel pump relay nothing. Put a direct feed to the fuel pump under the car and nothing (Fuel pumps Knackered).
So now I have changed the fuel pump under the car and the swirlpot inside the tank as well as draining the old rotten fuel out (there is a good bit of thick sludge in the bottom of the tank, will change the tank in time as I have a clean one but the filter should stop the shit getting threw right?).
So new dissy cap, rotor arm, plugs (not set though), fuel pumps, fuel filter, quater of tank of new fuel and a direct feed to the pump under the car, both pumps spinning (I know the one under the car is but sure the swirl pot is as well) and hey presto she's running starting on the button. Give her a bit of throttle and the poor M88 Knocks herself off.
Any ideas guys much appreciated.
Cheers Sean.

Post Mon Jun 22, 2009 12:46 am

sounds like it could be either fuel pressure or AFM related. i found out a while back that my M30 sill start and idle with the AFM disconnected but die if i applied throttle. maybe it's stuck or the wiring is damaged somewhere?
also, is the vacuum feed to the fuel pressure regulator ok? it also sounds like a possible fuel starvation issue so maybe the fuel pumps are not working correctly, or the new filter is full of slime?
if you whipe the fuel feed line off and crank it over, does it give a healthy squirt of fuel? (usual caution to be applied during this test!)

Post Mon Jun 22, 2009 2:46 pm

off topic but is the ///m635i silver and half restored paint wise (polaris silver)

Post Thu Jun 25, 2009 11:34 am

No its been sitting for a long while few bits missing off engine but now nearly there.
Clour combination its alpine white with cardinal red sport leather interior.
Will have to get a few piccies up.
Cheers Sean

Post Thu Jun 25, 2009 1:38 pm

seanboy wrote:No its been sitting for a long while few bits missing off engine but now nearly there.
Clour combination its alpine white with cardinal red sport leather interior.
Will have to get a few piccies up.
Cheers Sean

we want some pics! white with red leather

Post Thu Jun 25, 2009 1:45 pm

Sounds like it may be something to do with the throttle position switch (TPS); worth checking it clicks as the throttle is opened and test the continuity with a multimeter.

Post Tue Jun 30, 2009 11:55 pm

Hi there i had a bmw 635csi with the same problem after 3 hours we find out the problem mine was parked for 3 year. it was the air mass meter or have a look at the ECU hope that work regards

Post Wed Jul 01, 2009 9:54 am

Don-king how did yo know it was the ecu? Is it a case, if the ECU is no good then your best bet is to find a replacment?
Cheers Sean.

Post Wed Jul 01, 2009 5:09 pm

you find out the ecu is no good if there is no current coming through the HD leads. ECU's and other major parts of these cars are very hard to find, as I found out with mine. Thankfully got lucky and found ecu and car was sorted. Good luck anyway.

Post Fri Jul 03, 2009 12:59 pm

Is the swirl pot in the E30 tank the same as in the E24 tank?
Cheers Sean.

Post Fri Jul 03, 2009 6:42 pm

Right Guys, I did what Gareth mentioned, which could be the problem so disconnected the fuel filter and see if was full of slime from the tank, just a dark coloured petrol as if its been contaminated with the shit at the bottom of the tank.

Right guys I have not been getting the pumps to work on the key or even by bridging the fuel pump relay, what I have been doing is puttin a direct feed to the pump underneath and was sure the pump in the tank was running also. To make sure it was running (swirl pot)I ran the pipe from the tank into a bucket then put the feed to the pump underneath and no fuel.
I'm thinking the fuel pump (swirl pot) in the tank could be the cause?
Also the fuel pump(brand new Bosch Pump) under the car used to make a lot of noise at first when engine run for anbout ten minutes at first but is now very quiet?
Any Ideas guys as im

Cheers Sean.

Post Sun Jul 05, 2009 11:40 pm

Guys I need help, realised that the pump in the tank was not getting a power when I was putting a direct feed to the pump underneath the car (What I thought was it would pass threw the circuit and liven up the pump in the fuel tank, it didnt).
Pumps dont work on the key, when you bridge the relay, fuse is ok, Tried a different ECU.

Any Ideas?
Any Auto Sparky's?
Cheers Sean

Post Wed Jul 08, 2009 9:12 pm

firstly, have you tried a direct feed to both pumps to be sure they're getting power? and when a direct feed is applied, do they both run? if so, will it pump fuel then start?

once that's ok, then it's time to trace through the loom and look for breakages and duff relays etc where applicable.

I'm not familiar with the setup you have but it'll be a lot easier to diagnose once you know the engine will fire and the pumps themselves are ok.

Post Thu Jul 09, 2009 12:12 am

Sean, why did you buy a dead one ? I hope it was CHEAP ? These cars will start and run OK without the in tank pump so don't worry about that for now. Give me a ring if you want and I will try and help / not laugh !

Post Thu Jul 09, 2009 7:03 am

Pete, two for the price of one. Got a pump coming from Fritz's. Will let you know how im getting on!

Post Thu Jul 09, 2009 3:37 pm

Right guys the car will start then knock itself off, If I keep the key on the ignition she will stay running?
Where is a ballast resistance wire connection kept on these?
Cheers Sean.