how to check lem fuel pump relay wire is working?

[Paulio]

hey i tried to install a new relay for the fuel pump the other day but for the life of me, i couldn't get the link switching the relay.

is there a fail-safe way of checking that the link is even trying to switch the relay on?

must be missing something..

paul

[matt dunn]

Make sure it is wired to the correct output.

You can test them,
but how depends on what version of link you have
and if you are using a laptop or a hand remote.

[Paulio]

99% it is the right output. it is an old lemv5, using a laptop to tune. have tried testing with a multimeter but couldnt get any results.

[matt dunn]

99% it is the right output. it is an old lemv5, using a laptop to tune. have tried testing with a multimeter but couldnt get any results.

Ok,

Probably the purple wire then on a V5 from memory,
if they used the link loom.

I would just unplug the ECU and earth out the wire with a test light and that should run the pump.

With a multi meter, Test the wire at the ecu plug with the ecu unplugged,
and you should get 12V,
then put another wire from the there to earth
and the multi meter voltage should drop to zero volts, and the pump relay should go.
If all ok then plug the ECU back in.

I know with the hand remote you can hold one of the buttons down on the test screen to run the fuel pump,
but I dont remember how with the laptop.

[tsoob]

yeah what he said.

[mjrstar]

i think the problem you may have is that the link will provide an earth swith so... you will need to find a constant source of 12 volts to run the relay then use the link to switch the relay on and off. you are probably thinking the link provides 12 volts which they don't. i hope this helps.

[IH8TEC]

i've got the problem when i switch the earth on the relay, but when i turn the car off the pump keeps going. but when in the "on" the link turns it on, primes it for abotu 3sec then turns it off.

do you need to put the link wire onto a 12v source or the earth?

[mjrstar]

Hey brendan, i had the same problem with mine, it's a shortfall in the switching system on the ecu, there does not seem to be a lot you can do about it. i have ended up running a new relay off the ignition to the pumps. sure it's not ideal but seems to do the job.
link should provide the earth swithing.
it sounds like it is wired up correctly.

[RedMist]

The link pump trigger is dependant on RPM. So if you stall the engine, or if you sever a fuel line the pump switches off after a few seconds. Rather than have a flame thrower ensure that you use said trigger or a factory fuel cut, don't just wire it to the ignition.
I've owned a LEM3, LEM4, LEM5, a EvoLink and never had a problem with any of the pump triggers. Note that they are earth soursing and can be damaged if you supply them 12v.

[IH8TEC]

it is switching the earth. but when i turn the car OFF from running or in the ON position, the thing just keeps going. now the only wire i've changed is put the green one to the link.

[piw]

That's a bastard of a problem and occours only on the G3 series ECU's.

The problem is that with no power on the ign to the ECU, the ECU brain is not working as it's turned off and does not know to turn the internal transistor off.

PITA,

as I found out after I had wired most of the car that weird things happen,
in my case when you turned the ign off the whole car kept running,
lol.

To fix it,

Every input that goes to the ECU, must come from a switched ign source,
so you ned to change the battery feed to the FP relay, to and ign feed,
only on the relay winding side, not the main Bat side.

[mjrstar]

link plus ecu has the same problem... but i do like the way you have solved it. i think i'll be stealing this idea to make my system work better. now.. where did i put those wire cutters....

That's a b**tard of a problem and occours only on the G3 series ECU's.

The problem is that with no power on the ign to the ECU, the ECU brain is not working as it's turned off and does not know to turn the internal transistor off.

PITA,

as I found out after I had wired most of the car that weird things happen,
in my case when you turned the ign off the whole car kept running,
lol.

To fix it,

Every input that goes to the ECU, must come from a switched ign source,
so you ned to change the battery feed to the FP relay, to and ign feed,
only on the relay winding side, not the main Bat side.

[IH8TEC]

cool, will try that tomorrow and hope it works.

[Paulio]

thanks to matt dunns comments, found that the ecu isn't switching off properly so it never actually went through its off-to-on 3 second prime stage (hence, the relay not switching on and off with the key).

as I found out after I had wired most of the car that weird things happen,
in my case when you turned the ign off the whole car kept running,
lol.

haha that happened to me last week, $&#$% weird when your car doesn't turn off!

To fix it,

Every input that goes to the ECU, must come from a switched ign source,
so you ned to change the battery feed to the FP relay, to and ign feed,
only on the relay winding side, not the main Bat side.

sounds like what i'll be doing tomorrow, cheers!

paul

[IH8TEC]

well, i just sorted my problem, i ended up ditching the std fuel pump relay as it was being a c##t.

used a spare horn relay i had, and wired that in as follows for anyone interested, excuse the awesome paint skills

there were two wires left over from the standard relay

big black and white wire - only had +ve 12v in the start position
little white and black wire - think it's an earth, but didn't need it.

[matt dunn]

there were two wires left over from the standard relay

big black and white wire - only had +ve 12v in the start position
little white and black wire - think it's an earth, but didn't need it.

Yeah the standard relay uses those two wires as a second switch,
so the relay will click in as soon as you go to crank, reguardless of if the ECU triggers it or not.

[IH8TEC]

so why does the std relay not have a constant 12v source like i needed on the new relay?

thats what i couldn't figure out when trying to sort the thing.

also is it worth hooking that earth wire up to an earth? cause it's still earthed at the pump, or do i not need to bother