fuel pump relay
Discussion
No separate relay Mick, I think the 'pink' engine run sensor acts in that way? I think the red wire from the ignition energises the sensor and allows power to the pump.
The fuel pump does have a pressure sensitive valve inside it, once it has renewed pressure on the down side it cuts itself out. There is also a pressure accumulator down flow from the pump which is intended to balance out pressure, apparently without it the K Jetronic becomes a bit sensitive to pressure pulses from the pump. It may not be necessary to have the accumulator in your case?
The fuel pump does have a pressure sensitive valve inside it, once it has renewed pressure on the down side it cuts itself out. There is also a pressure accumulator down flow from the pump which is intended to balance out pressure, apparently without it the K Jetronic becomes a bit sensitive to pressure pulses from the pump. It may not be necessary to have the accumulator in your case?
Not familiar with that specific ECU, but others I know about all control it via the ECU on a timed basis, without any pressure feedback to the ECU - pressure while the pump is running is controlled by a simple mechanical regulator.
EDIT: apparently not in this case.
EDIT: apparently not in this case.
Edited by GreenV8S on Saturday 29th October 15:56
I had one fail on me. I had overheated but I was able to repair it and used it until I could find another one. My friendly expert came back to me with "there are none in New Zealand". I eventually got one from UK. There are two variations, one that gives the pulse when you turn the ignition on and one that doesn't. My original one didn't give the pulse so I purchased one that didn't give the pulse. The fuel system in the S1 is supposed to hold pressure so you shouldn't need the pulse. The relay is mounted on the board above the glove box. My original wasn't pink, it was purple. I haven't managed to find any details of where I got the relay from or part number, however I think the number in the S parts list, Lucas FDB 502 is correct.
The relay simple turns the fuel pump on and off. Other than the start up pulse it will only operate the pump if the engine is running. On the wiring diagram it is the pink engine run sensor.
Dave
The relay simple turns the fuel pump on and off. Other than the start up pulse it will only operate the pump if the engine is running. On the wiring diagram it is the pink engine run sensor.
Dave
magpies said:
Hi
does the S1 have a fuel pump relay?
does the S1 have a fuel pump relay?
magpies said:
not one shown on the wiring diagram.
It is on mine and in the biblemagpies said:
Another question - when turning on the ignition and the fuel pump works for a couple of seconds - what gives it that signal and is it pressure that stops it?
There is a pulse detector circuit with a 555 IC that drives the relay. Normally it checks for ignition pulses to turn the relay on but switching on the ignition has the same effect. The 555 gives a 2 second ON pulse for every input pulse it sees.Having had problems with fuel pressure at one time, switching the ignition on will activate the pump, but itv will stay activated until the pressure has built up and the pump itself switches itself off. Try disconnecting the downstream side and it will keep pumping whether the engine is turning or now.
As this is a TVR I should add the proviso that this is what it does on mine at least!!!
This is on the 2.8 of course, quite different on the 2.9 or V8.
As this is a TVR I should add the proviso that this is what it does on mine at least!!!
This is on the 2.8 of course, quite different on the 2.9 or V8.
Yeah the fuse/relay box is for the original 2.8
the Engine run sensor (PINK) is the BOSCH unit with the red stripe, I have not changed this - so could be original. It ain't pink !
The missing Engine Fan Relay had to be rewired due to burnt relay plug connections, also can see one of the 25A fuses id out of alignment and that has burnt fuse holder connections (Engine Fan)
The Dim Dip Relay is not connected for obvious reasons
the Engine run sensor (PINK) is the BOSCH unit with the red stripe, I have not changed this - so could be original. It ain't pink !
The missing Engine Fan Relay had to be rewired due to burnt relay plug connections, also can see one of the 25A fuses id out of alignment and that has burnt fuse holder connections (Engine Fan)
The Dim Dip Relay is not connected for obvious reasons
Edited by magpies on Sunday 30th October 12:22
greymrj said:
B.... hell Mick 
, that board is in a mess, lucky not to have had a fire! Mine was damaged but nowhere near as bad as that. I can see why you feel the need to do it all new. Hope it goes well.
The Engine Fan Relay and Fuse burnt on the way down to Le Mans - it was bloody hot too. Fortunately the temporary repairs worked to get us there and another day of mooching about. But other parts had failed on the board before I had the car., that board is in a mess, lucky not to have had a fire! Mine was damaged but nowhere near as bad as that. I can see why you feel the need to do it all new. Hope it goes well.Lets see if I can sort it?
I've decided to do this and see if everything works before taking the dash out.
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