Fuel Pump Relay

[Henry]

Somewhere in the fuel / electrical system on the T11 there is a relay or pressure switch of some sort. When the ignition is turned on, the pump runs for a few seconds (presume this pressurises the system) then stops. (pressure switch ?) Presume the pump starts to run again when starter is engaged and continues while motor is running with any "spare" fuel or pressure as decided by the regulator, returned to the tank. My pressure switch or relay is sticking occasionally, where do I find them. There is nothing on the fuse board, is the relay that blue box mounted on the underside of the dashboard and how the hell do you get to it without dismantling the car.   Henry

[BOOSTBOY]

Its not a pressure switch, pretty sure of that.  When you de-pressurise the efi system and then attempt to get fuel pressure again for start up, it takes a few times of on/off/on/off of the ignition to get pressure up.  Must be a timer of some sort.  The pressure is regulated by the fuel pressure regulator.  The blue box is the idle up controller which changes the idle settings when the engine is under high electrical load eg. lights, AC, fan etc..

Sorry but i have no idea where the fuel pump timer is!  Maybe trace the wires back from the pump untill you find some type of sender??

[Michael]

The computer turns the fuel pump on for a set time before start up to build up the pressure. The computer triggers the fuel pump through the main relay. If yours is staying on I would guess that the relay is sticking and should be replaced.

Michael.

[Henry]

Thanks Glen and Michael, mine sometimes doesn't turn on and sometimes does the initial run but doesn't run during attempted start-up. You then just have to sit for a few minutes then start again.  Everything else seems to be working while this is happening, instruments, starter. Seems that you have to wait a certain time with the ignition right off then you get the timed run again. So where is the main relay and what does it switch. Henry

[Michael]

That definatly sounds like the main relay. The main relay block should be located under the dash somewhere. Couldnt tell you exactly cause mine is in a civic. This should be a fairly common item and you could get one out of a fuel injected Honda or perhaps other brands at the wreckers. But before you replace it check that the earth points for the relay are ok as that may cause it to not fuction properly.


Michael.

[Henry]

Thanks Michael, the main relay is what I started out looking for, been under the dash, it's not on the fuse board, Glen says it's not the blue thing up the top, can't find anything else that looks like a relay. Anyone got anything to add to this lot?   Henry

[QikLude]

Ive had to replace that very same relay myself in one of my old ones...

The one I replaced was obvious becase it had been fixed before..
It was behind the fuse box i think.

can have a looksee if you need too, and drop a photo on the board or something.