Petrol Pump fails when warm starting

Hi, I have a 1990 124 200TE. When the engine is warm and I try to start the car, the petrol pump sometimes doesn't kick in. I'll wait a few minutes and then try again and it will start. When I hear the
'whirring' of the petrol pump as I turn the ignition switch I know it will start. When I don't hear the pump I know it won't start. I also cuts out occasionally when driving along.
I've had a new Petrol Pump Relay fitted (the one with 'kickdown' written on it) and a new overload protection relay. The car always starts from cold?
Any ideas would be appreciated.
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Bender Boy wrote:

It could be a relay but first i would turn the fuses or replace the due to corrosion. Then I would replace the ignition switch, not the tumbler(lock) just the switch in back.
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Thanks for the reply
I have turned the fuses in the past but this didn't work. I hadn't thought of the switch part of the ignition. Have you known of this problem before and is the switch difficult to get to?
Thanks again
macdrone wrote:

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Fuel Pumps get power directly from the fuel pump relay, which will switch on as follows: - for 1 second when you put ignition key to "run" position - when you put ignition key to "start" position - when ignition key is in "run" position, and when rpm is above 500
The fuel pump relay also has coolant temperature signal input from the ECU. I don't know what it does, but it is likely that it will shut down the fuel pumps if temperature is too high (I don't see what else it should be there for).
So, you may get a wrong temperature signal, or the fuel pump relay reacts wrongly to the input. That could explain your situation.
Bender Boy skrev:

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It can be the ignition switch that is bad. What happens when you starts the car? Does it run rough for a while? If yes, then you got hot start problem... vapor lock... which requires you to replace a few seals in the fuel distributor.
If not, then it is probably ignition switch or fuel pump.
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Tiger wrote:

The switch is up under the dash (2 screws and remove plastic) then reach up and there it is.
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