Starting problem after standing with a hot engine

EA1191 · 10-05-2005, 12:22 PM

Sometimes the engine will not start if it has been standing hot for a time.
Did a test using a variable resistor to replace the temp. sensor. The pump would not run if the temp was 80deg and had to be set below 50deg. After the pump had run the temp could be increased to 100 and it would run. The next day it ran at 100deg first try. The engine was actually cold.
When it will not start I have manually closed the pump relay and had the idea of fitting a push switch in the cabin to pulse power to the pump, but not sure where to connect it, perhaps the cigaret lighter. The circuit shows a connection to the computer power lead on later models. That may activate the pump without the computer control when the starter switch is turned to accessories???
The main problem is suggested to be a leaking valve in the pump because the pressure should be maintained for hours. The pump pumps OK but there could be dirt or something affecting the valves sometimes. Perhaps the pressure regulator?. Some cars have a second pump.
Someone must have fixed this problem. And just what controls the pump relay apart from the temperature and ignition pulse? The TFI ignition module? Is there a simple test?
Just suggestions may not be confirmed because the car is not used much and the problem is intermittent.
Some time ago I had a problem with no power to the starter on the first few turns of the ignition. Others wrote with the same problem but there was no one on the system to tell us that the cause could be a corroded push-on clip on the solenoid.
The car was bought second hand with offers from Ford that if I had a problem I could ask the mechanics at the Ford sales for information. They answered questions but I now know that they knew I was off track and had no intention of making any suggestions which could fix it.

10-05-2005, 05:50 PM

dunno what car you got but have you checked the heat of the starter motor ive worked on plenty of cars that wont crank over cause the starter motor refuses to turn if its hot. and for the fuel pump connect a pressure tester to the car run-it, turn it of and see if it holds pressure and isolate the problem by clamping either the retern line the inlet line, even isolate the injectors by removing the hose from the fuel rail. if wat u are saying is the pump doesnt turn when the key is on then to make sure its not a shit pump, give the tank a bash where the pump is while ur cranking it. if i havnt helped you by this, explain in less detail what the prob is???

EA1191 · 11-05-2005, 10:44 AM

The problem is that I do not understand how the system is controled.
Where is the relay which controls the pump? The relay shown on the circuit will run the pump for 1 or 2 seconds if closed manually with the ignition off. If the ignition is on and the relay closed then the pump runs and stops but the relay stays closed with no power to the pump.
The relay has an electronic circuit which may be the short run control?
Where is the pump earth wire connected to ground? The circuit shows it connected to the chassis and that could be some of the problem. [IMG]

EA1191 · 12-05-2005, 10:40 AM

There is a new problem. The manual had an illustration of the layout of the relays but something is wrong. It indicated two relays below the top bank with one the ECU and then the Pump. Checked the cable colours and the front one looks like the pump and the next one the power. No idea where the ECU is. I have been closing the power relay. Need some way to pull the pump relay apart.
THE COMPUTER MUST CONTROL THE POWER RELAY AND IS STOPPING IT CLOSING IN SOME CONDITIONS. It always closes when the engine is cold so the ignition switch is not at fault.
I want to override the problem with another switch in the cabin, but I could do some damage if the power is connected to the wrong point.
Must read more of this site
http://www.users.bigpond.com/jack_st..._repair_1.html

NZ · 05-06-2005, 12:22 PM

by closing the power relay you are effectivly turning the ecu on which is the same as what you are doing by turning the key to the on position (without starting). whan that happens the pump will run to pressurise the fuel system.

the ecu controls the power to the fuel pump relay.

JG3282 · 06-06-2005, 08:19 AM

My XE is having the exact same problem. It has an ED starter motor and when left for even 10 minutes after it has been hot it doesn't always start. I have replaced every single wire, earth, battery terminal, three starters, two alternators, 3 batteries...

EA1191 · 06-06-2005, 11:57 AM

Five Point Slow
'The ECU controls the power to the fuel pump relay' That would seem to be the problem and when the engine is hot the ECU has disconnected the pump. Why is that necessary?
The ECU does disconnect the pump when the engine is not running and hot (from the Ford manual) and needs the fuel pressure to be maintained by the pump valves.

Au2falcons · 06-06-2005, 12:10 PM

I've had that problem with an XF EFI motor, needed a new TFI module, another thing to check is the ignition coil. Both of these items if worn can play up when hot

Cheers

Adrian

NZ · 06-06-2005, 12:16 PM

Quote:

Originally Posted by EA1191

Five Point Slow
'The ECU controls the power to the fuel pump relay' That would seem to be the problem and when the engine is hot the ECU has disconnected the pump. Why is that necessary?
The ECU does disconnect the pump when the engine is not running and hot (from the Ford manual) and needs the fuel pressure to be maintained by the pump valves.

So are you saying the car stopped when running. You may be mistaking the problem to be the fuel pump or ecu turning off the fuel pump when it could be something else that is stopping the engine. the ecu could be just doing its job by turning off the fuel pump when the engine has dropped below 350rpm as it should. you need to give more detail. the puump does have a one way valve but that is merearly to keep fuel in the rail since it is higher than the tank so the next time you start there is already fuel there and it only needs to pressurise the rail again.

EA1191 · 08-06-2005, 09:58 AM

I have fitted a light across the terminals of the pump so power to the pump can be checked. If the pump does not run when the key is turned the pump can be started by manually closing the relay and the car starts.
Had a condition where the pump did not run when the engine was cold but may have started when the ECU received a pulse from the dist. But I closed the relay to make the pump run and then the key would also make the pump run. Possibly the ECU had not returned to normal but had locked into the 'pump disable' state.
Also the FORD MANUAL states that the ECU disables the pump when the engine is hot and stopped for a time and residual pressure is needed for the injectors. For some reason that has not happened recently, but expect it will return and no idea why.

EA1191 · 08-06-2005, 10:30 AM

ONGAS,

I may have interrupted your query. It may need a new post about gas operation.
Were all those changes tried to fix that problem?

JG3282 · 08-06-2005, 11:37 AM

my belief is that it is the starter motor getting hot as I have extractors. I don't have an ECU or fuel pump.

EA1191 · 09-06-2005, 09:48 AM

The starter would have to get hotter than 75 C. Too hot to touch.
There would be a simple test to try when the problem appears. Connect a lamp from earth to the solenoid terminal - a small safety pin can be pushed into the wire or into the back of the relay plug - and check that the relay is switching. There is also a switch on the gear box to stop the starter running if the car is in gear. The other switch in the circuit is the starter leaf switch in the ignition which looks like it has been added after the switch had been designed and is not a good switch.
I have had problems with the pump not running and connected a LED lamp to the terminals of the pump with the light in the cabin. Now can see just what happens.
http://www.users.bigpond.com/jack_st..._repair_1.html