Hi there
I've got a 1980 635csi auto right hand drive . The car has been lying in the garage for about 2 years since it was last started. I began working on it 2 weeks ago. The car cranks but doesn't start. I installed a new fuel pump. The fuel pump make a noise when the car is switched on, but no fuel flows to the engine when trying to start, also the fuel pump relay doesn't click only the main relay does.
My wiring of the main relay may be a problem because I don't have a harness and connect the wires to the relay by trial and error. The rest of the relays all have harnesses.
I also find a long black wire with 3 wires inside coming from the passenger side into the engine bay that is not connected to anything
There's is also another long wire that is attached to a pingon the inside of the engine bay infront of fuse box that doesn't connect to anything
Please help
635csi no start please help
Moderators: GRNSHRK, ron, bfons
the fuel pump normally only runs during cranking or running. You can jump the relay so that the fuel pump runs all the time (for test purposes). Past that it is simple, you need fuel pressure (as set by the regulator), injector function, and spark.
For a cold start the engine should fire on cranking; for this you need fuel pressure, spark and cold-start-injector function only. The main injectors do not have to work for a cold engine to fire and run (briefly) in 'crank'.
Look in the workshop manual (or Haynes engine management manual) for how the CSI system works.
If you crank and the engine doesn't start, poke a length of tube through the throttle butterfly and sniff (carefully) through it. There should be a strong fuel smell. If there isn't, the CSI isn't working (and/or you have no fuel pressure) and the car may never start from cold.
There is a crank sensor on the front of the engine, fitted to most motronic equipped E24s until 6/87. This is not involved in the running of the car at all, it only ever connects to the diagnostic socket. Confusingly, those built after 6/87 have a similar looking item, but it is the only crank sensor on the engine, and essential for it to run at all.
cheers
For a cold start the engine should fire on cranking; for this you need fuel pressure, spark and cold-start-injector function only. The main injectors do not have to work for a cold engine to fire and run (briefly) in 'crank'.
Look in the workshop manual (or Haynes engine management manual) for how the CSI system works.
If you crank and the engine doesn't start, poke a length of tube through the throttle butterfly and sniff (carefully) through it. There should be a strong fuel smell. If there isn't, the CSI isn't working (and/or you have no fuel pressure) and the car may never start from cold.
There is a crank sensor on the front of the engine, fitted to most motronic equipped E24s until 6/87. This is not involved in the running of the car at all, it only ever connects to the diagnostic socket. Confusingly, those built after 6/87 have a similar looking item, but it is the only crank sensor on the engine, and essential for it to run at all.
cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Chris Wright
for available electrical schematics on a 1980 car you could do worse than get the Haynes E12 manual.
BTW a 1980 built car could have either L-jet (conventional distributor) or Motronic (flat distributor). The inlet manifolds are different too.
I assumed you have Motronic but maybe you don't.
A complication with that version of L-jet is that there is a microswitch in the AFM that triggers the fuel pump to run, and (IIRC) there is a timer relay that primes the fuel system before you crank.
but in any event, you should test for fuel pressure, injector signal, CSI function, and spark. Which are you missing?
hth
cheers
BTW a 1980 built car could have either L-jet (conventional distributor) or Motronic (flat distributor). The inlet manifolds are different too.
I assumed you have Motronic but maybe you don't.
A complication with that version of L-jet is that there is a microswitch in the AFM that triggers the fuel pump to run, and (IIRC) there is a timer relay that primes the fuel system before you crank.
but in any event, you should test for fuel pressure, injector signal, CSI function, and spark. Which are you missing?
hth
cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Re: 635csi no start please help
Pics of these items would help for identification!nawaaz777 wrote:Hi there
I've got a 1980 635csi auto right hand drive . The car has been lying in the garage for about 2 years since it was last started. I began working on it 2 weeks ago. The car cranks but doesn't start. I installed a new fuel pump. The fuel pump make a noise when the car is switched on, but no fuel flows to the engine when trying to start, also the fuel pump relay doesn't click only the main relay does.
My wiring of the main relay may be a problem because I don't have a harness and connect the wires to the relay by trial and error. The rest of the relays all have harnesses.
I also find a long black wire with 3 wires inside coming from the passenger side into the engine bay that is not connected to anything
There's is also another long wire that is attached to a pingon the inside of the engine bay infront of fuse box that doesn't connect to anything
Please help
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'88 635csi, auto, black on grey
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nawaaz777
Thnks for the replies guys....the fuel pump switches on when I turn the key to on position....it makes a loud biz sound...I installed this new fuel pump myself a couple of days ago...and I'm not sure if maybe it's conneted in reverse or not. Also @brucey the fuel pump is running from on and also on start, not only on start, is this a problem. I can send pics of my wiring but from what I made out from other pictures online is that it's wired differently because of an alarm system. Yes it is a euro I think. When I swtch the car to on position the main relay clicks but the fuel pump relay doesn't. I don't smell fuel when trying to start. I think the car has a k jetronic system but I kay be mistaken.
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nawaaz777
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nawaaz777
you won't have K jet, it'll be L-jet or motronic.
The fuel pump should not run continuously unless the engine is running. If your wiring is allowing the fuel pump to run continuously this is OK for test purposes but it is not a good idea to drive the car on the road like this.
In both L-jet and motronic Bosch deliberately engineered it so that the fuel pump would quit whenever the engine stops running. Part of this idea is that in the event of a fault condition or a prang, the fuel pump doesn't just empty the fuel tank into the engine bay, where there might be a fire....
cheers
The fuel pump should not run continuously unless the engine is running. If your wiring is allowing the fuel pump to run continuously this is OK for test purposes but it is not a good idea to drive the car on the road like this.
In both L-jet and motronic Bosch deliberately engineered it so that the fuel pump would quit whenever the engine stops running. Part of this idea is that in the event of a fault condition or a prang, the fuel pump doesn't just empty the fuel tank into the engine bay, where there might be a fire....
cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~