Bump starting problem - David Horn
In a car park yesterday I came across a father and daughter pushing a car along, and struggling. They were pushing it right across the car park to where they had an extension lead and battery charger, and being a generous soul I offered to help push it for a bump start.

The battery wasn't completely dead (dash lights came on etc), but the engine would only run for a second or two and then stopped. It was a newish Clio with a petrol engine, and I was stumped as to why the engine kept stopping as my assumption is that the alternator easily provides enough juice at tickover to charge the battery and generate enough power to deliver regular sparks.

The only thing I didn't try was starting it and revving it, all this happened without touching the accelerator. I assume they got it going in the end, since someone else stopped and offered jump leads. I'd left my car blocking the exit ramp so had to go any fetch it.
Bump starting problem - Screwloose
David

Not enough battery power to complete the security process at key-on?

If the immob hadn't managed to read the key, then you would get the 2-second-and-cut symptom as the ECU would be in locked mode.
Bump starting problem - Bill Payer
Could have had a 'deeper' fault - perhaps one of those common Clio sensor faults (IIRC water temp and cam - or crank - shaft) sensors fail. Or some kind of idel control problem.
So the car might start, but not run.

Just guessing.
Bump starting problem - Cliff Pope
Modern petrol cars have devices to prevent re-starting if the engine is stopped before it has warmed up. So after one fire it would shut itself down to prevent raw fuel getting into the cat. I thought bump-starting was potentially very damaging, and futile, with modern cars?
Bump starting problem - jc2
If what you say is true,how can you ever start the car again?
Bump starting problem - normd2
the shutting down after one start attempt is incorrect but failed bump start attempts or continually trying the starter without it firing up can lead to unburnt fuel damaging the cat. IMHO one or two bump starts that get it going won't do much, if any, damage.
Bump starting problem - jc2
Modern catalyst equipped cars can be bump,jump or tow started but only if they fire up right away;the reason manufacturers tell you not to is because,if they do not fire up immediately,they will fill the catalyst with unburnt fuel.
Bump starting problem - Cliff Pope
If what you say is true how can you ever start the car again?


I am only quoting previous threads here, which warned that cars have devices to prevent damaging re-starts. I imagined that after time had elapsed the unburnt fuel would have evaporated and dispersed.
Bump starting problem - Cliff Pope

See previous thread on restarting problems:



www.honestjohn.co.uk/forum/post/index.htm?t=18294&...e
Bump starting problem - henry k
The AA guy who came to get our Yaris restarted said.

"Its the car washing problem !!!!"
Customer quickly backs the car out of the garage, washes it and then it will not start.
Customer thinks it is water in the bits but it is not.
I.E you should leave the car to warm up for a couple of minutes before switching it off.

To sort it he said you need to turn the engine over without the fuel pump operating.
This will blow out the fuel and reset the situation.
So he was looking to disable the pump ( a fuse or connector) and then turn the engine over.
Bump starting problem - jc2
The plugs are wet and do not spark or spark well;you do not normally need to disable the pump-most modern calibrations will disable the pump if you crank with the throttle wide open.Running the car round the block after washing it not only dries out the plugs,catalyst and exhaust but also shakes water out of the various crevices in the body.
Bump starting problem - kithmo
If what you say is true how can you ever start the car again?


My old Mk1 petrol Ford Mondeo could be started with WOT when overfuelled, pressing the pedal fully down whilst cranking cuts off the fuel injection allowing fresh air to be pumped in until the engine starts.
Bump starting problem - Tornadorot
If the immob hadn't managed to read the key then you would get the 2-second-and-cut
symptom as the ECU would be in locked mode.


Yes, on my car, if the immobiliser isn't happy, the engine will actually run very briefly before the immobiliser kills it. But you should get the appropriate dash warning light as well.
Bump starting problem - Screwloose
But you should get the appropriate dash warning light
as well.


Yes indeed; but would anyone notice it while they were pushing?
Bump starting problem - gsb
I expect this is a dumb question but do the above comments about the cat apply to diesels as well.
Bump starting problem - jc2
Pre Euro III & IV,no effect but later cats are much closer to the engine but should not suffer any harm.
Bump starting problem - kithmo
If the immob hadn't managed to read the key then you would get the 2-second-and-cut
symptom as the ECU would be in locked mode.


The car wouldn't start at all if the immobiliser hadn't read the key, it disables the starter motor circuit.
All I can theorise is that the battery voltage was so low that it couldn't keep the fuel pump running and the 2 second burst were from the residual pressure in the system.
Bump starting problem - Screwloose
The car wouldn't start at all if the immobiliser hadn't read the key it disables
the starter motor circuit.


Err.... They were bump starting it?
Bump starting problem - kithmo
Err.... They were bump starting it?

Doh!..... I'll get me coat........
 

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