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Maybe someone can explain this to me. I believe I've read here that the fuel pump relay in the main relay box (f.i. engine) operates only when the starter is engaged, and in fact the electrical schematic I have says the 12v source to the relay coil is only "hot on start." If that is the case, how does the fuel pump continue to operate after the engine starts? Obviously I'm missing something fundamental here. Thx.
The relay comes on when the ignition switch is in position 2
Its 2 relays (coils i think) in there one needs to see spark from the coil the other energizes the fuel pump. Thats about the easiest way I can explain it.
There several write ups in the EFI section.
wp
by spark from the coil, you mean it just needs a tach signal or something right? i mean, isnt it the main relay that energizes the coil?Quote:
Originally Posted by Oldblueaccord
The fuel pump has power when the key is in the "ON" position. If you turn the key to ON without starting the car you will see and hear the following.
Check engine light comes on accompanied by a "click" from the relay.
Check engine light goes off after 1-2 second self test and a second click can be heard.
When the relay is going bad you will usually fail to hear one or both of the clicks. I believe the first click is the fuel pump getting power and the second click is the fuel pump shutting off after the fuel rail is pressurized. that's why I always wait for the second click (engine light going off) before I start the car. It starts MUCH quicker when the fuel rail is pressurized.
I dont think this is going to answer your question but I think the igntion switch powers the main relay, turns the fuel pump on BUT it has about 3 seconds to see the coil signal or it goes off. Remember the relay is there as a safety feature to shut the fuel pump off if the motor is not running. I am not really sure how the 3 seconds is achieved but i have some ideas.Quote:
Originally Posted by newaccorddriver
I do think its the negative side of the coil it reads from and yes that would be considered a tachometer signal.
wp
On 1981 Accord, where is the fuel relay? I have looked thru all books, everywhere. Is it in engine compartment?
Just point me in the direction.
1981 Accord with 64,000 orginal miles...driving by little old lady till I got it..hehe.
Thanks
Frank
