f/p relay driver

[500dollar744ti]

got my box hooked up, first problem is that when key is off fuel pump relay is activated at all times, it appears the injector driver is activated as well... turn key on, primes up as normal, nothing abnormal... turn key back off, fuel pump starts running again... i am new to this, any help is appreciated.

[towerymt]

With my MS "kill switch", I leave it on all the time because the ign. powers the box, not the switch. The switch breaks the power supplied by the ignition being turned on. With the ignition on, if I flip the switch off, the pump just runs constant. If I flip the switch back on, it primes and shuts off til I crank it. Somewhere in there is an answer that I'm too tired to find, so I'll get back to you tomorrow.

[MrBill]

told you it wouldnt work immediately.
does the stock FP relay work the same way as a normal relay?

[500dollar744ti]

stock fuel pump is two 15 amp relays in one box, one for pre pump, one for main... grounding both legs of the stock relay would be like grounding one leg of a single relay, i know it can be used because boris740 has a diagram of it and can testify it works... i have it connected the way he does... when ms has no power, all of the drivers are grounded, fuel pump, injectors and such.. turn on the key to give it power and everything works as it is supposed to... i am wondering can the fuel pump relay coil just not have power when the ignition is off and that is just how it works or what?

[benflynn]

this sounds too familiar to my other thread from last night, you have a pm, but the driver for the fpump and the fidle are the 2 ztx450 by the db37, there are links in the other thread to componant diagrams and such

if the ztx450 is popped it almost has to be a problem w/the stimulator, although my board was on it last night as i was trouble shooting the other


and fo mr bill, our ms install was like 20hrs on the ride i was driving to work

[benflynn]

also post your wireing for the dizzy, after having a box set in the linuxman method, it will not work w/my boxes, must be the std/rnasequence method

[Boris740]

You need to connect the power for the FP relay and every other relay that has a diode across it to the same point them MS is connected to. What is happening now is that when you kill the power to MS, the relay coil is still connected to +12V elsewhere. This feeds the current through the coil of the relay, through the diode of the relay driver and into V12 which now ends up powering MS (poorly)

[500dollar744ti]

You need to connect the power for the FP relay and every other relay that has a diode across it to the same point them MS is connected to. What is happening now is that when you kill the power to MS, the relay coil is still connected to +12V elsewhere. This feeds the current through the coil of the relay, through the diode of the relay driver and into V12 which now ends up powering MS (poorly)

ok so this is proper behavior then? and you are saying i need the +12v to all relay coils switched to be only powered in key position II instead of at all times like they are stock?

is the purpose of the diode in the relay only for stock use, as most standard relays don't have the diodes... could i just removed diodes in all relays with +12v power with ignition off instead of making coil power switched?

[Boris740]

I would not call it proper. Either power all power all relays and other inductive loads that have a commutating diode on MS board from same 12V supply or remove the commutating diode from MS board and place it directly across the relay coil. I do not know which is more hassle. I kept diode and solved this problem by using stock FP relay. Note that 12V is same 12 that powers MS. Under no circumstances you should remove the freewheeling diode. It should be either on the MS board or directly across the coil with cathode (band) on the 12V end.

http://www.viatrack.ca/Misc/FuelPump740MS.pdf

[benflynn]

nice boris, it has been so long since we put mine in i cant remeber what problem i had w/the fpump relay


how can he verify this before hacking stuff up?

[500dollar744ti]

I would not call it proper. Either power all power all relays and other inductive loads that have a commutating diode on MS board from same 12V supply or remove the commutating diode from MS board and place it directly across the relay coil. I do not know which is more hassle. I kept diode and solved this problem by using stock FP relay. Note that 12V is same 12 that powers MS. Under no circumstances you should remove the freewheeling diode. It should be either on the MS board or directly across the coil with cathode (band) on the 12V end.

http://www.viatrack.ca/Misc/FuelPump740MS.pdf

that is what i am trying to do is use the stock relay... i have it wired to do so like in your diagrams and this is when the problem occurs, i have not tried it a different way because i know that it should be able to work with the stock relay so that's what i am trying to achieve here.

[500dollar744ti]

I would not call it proper. Either power all power all relays and other inductive loads that have a commutating diode on MS board from same 12V supply

i just swapped a pin in the fusebox to put the stock fuel pump relay on a diff fuse that is switched 12v... pumps run okay now... i thought they would work the other way but **** it, this will work fine. i'll try to start it this afternoon.

thanks.

[benflynn]

yay

[MrBill]

i just swapped a pin in the fusebox to put the stock fuel pump relay on a diff fuse that is switched 12v... pumps run okay now... i thought they would work the other way but **** it, this will work fine. i'll try to start it this afternoon.

thanks.

awesome vids when you try to crank plz

[500dollar744ti]

told you it wouldnt work immediately.
does the stock FP relay work the same way as a normal relay?

i didn't say it would start immediately, i said i wouldn't be surprised and i hope it does. :-P

[Volvorules]

Get rid of the stupid ass stock volvo relay and get a Radio shack 4 pin one. Simplifies everything.

[towerymt]

Get a Bosch 4/5 post 30Amp relay from any 240 dashboard. I grab them at the JY all the time because they're great for stuff like the fuel pump, main relay, e-fan, etc.

[DecalServiceBrett]

so does it run? ;>

[500dollar744ti]

uhhscourse :-D