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[A4RON]

i have recently put the FRST engine in my mk3 fez i have wired the ECU up as the diagram shows but when i turn the ignition on the ECU relay switches on but the FUEL PUMP relay doesnt do anything??? although if i power the FUEL PUMP up with a 12v feed from the battery the turn the ignition on the car will start and run fine apart from a little cough and splutter off boost, does anyone know where im going wrong as i would prefer the car to run as intended!!



i have used normal 12v single pole single through normaly open ford relays... i think the ECU is not working properly

[leepeet69]

I dont know alot about this subject but ive recently had a simular problem when i rebuild my FRST, behind the dash there is a fuel pump cut of switch, so wthat when you have a crash it activates and cuts the supply to the fuel pump! Could be that but im not sure! Its about 3inch's square and its a white/grey colour i think!

[A4RON]

thanks, but the fuel pump is wired as shown in the diagram which by-passes the cut out switch

[jayrs]

looks alright from ya pic.
pin 1 on your engine loom plug goes to ecu yeah?

i think your problem could be ignition relay, when pumps stop working on factory fitted RST's it can be the green ignition relay, theyn gen just need a clean on the pins, other times they need replacing

[A4RON]

hmm i cant remember off hand where pin 1 goes?? although the engine loom and ECU loom are exactly as it came out of the factory on the FRST so if thats where its supposed go then im guessing it does... and the car does run so im thinking the ECU must be working just not properly ...

as for the relay and connections... im not using the original relays just any old 12v relay should do the trick, its not green but when the ignition is on the relay IS operating properly as i can hear it and when it operates it is providing a 12v feed to the FUEL PUMP relay (switching side) and pin 5... which im guessing goes to the sensors or something (i will study the loom friday, day off work!!)

also i cant have a problem with connections as the wires are soldered directly to the pins on the relays (don't worry im perfectly capable of doing this without frying everything inside lol!) and everything that i have wired myself i have checked and tested many times to rule out every silly mistake that could possibly be made... and everything is EARTHED properly ... ive had that problem before!!

im now thinking it could be the ECU as this is controling the EARTH (ground -whatever) pin 85 on the FUEL PUMP relay (switching side) via pin 2 on the engine plug...

thankyou, i really appreciate any help or input no mater what the suggestion... im going to buy a new ECU if anyones got an OFAB going...

[jayrs]

out of interst, how come your not using ford relays? im not saying ford make them, im just asking why are you not using the fuse box set up with the relays etc?
if that makes sense

[A4RON]

i didn't want to have to mess around with the fuse box or the cars original wiring... i removed the old HCS engine and wiring including the ECU, everything up to a 'oval Grey plug' which connected everything engine related to the rest of the cars loom.

as i believe the HCS fuse box has a couple of different relays so just thought its best to do my own wiring which is in the passenger footwell next to the ECU, but at the 'oval Grey plug' i found a fused constant +12v (small red wire then used it to power pin seven) and an +12v IGN live (fat black wire -connected to pin 1 and relay pin 86 as shown in diagram also connected the oil pressure and rev counter into this plug.

they are the only connections between the car and the engine apart from the obvious battery connections but that is all that should be needed for the engine to run properly...

i still think the problem is inside the ECU....

one thing i don't know is... does the fuel pump in a FRST run constant or does it prime then come on when needed???

[~S1~]

one thing i don't know is... does the fuel pump in a FRST run constant or does it prime then come on when needed???

FRST primes when ignition is switched on.

One thing I'm not convinced about is the wiring diagram above. Dont quote me as I havent looked at a Haynes diagram for a long time, but I thought the fuel pump relay was primed by the injection relay?

[A4RON]

so.. when then ignition is switched on i should hear the pump come on then go off the i start the car and it stays on??? is this correct?? or should i hear it come on and stay on?

but I thought the fuel pump relay was primed by the injection relay?

the switching side (pin 86)of the of the fuel pump relay is supplyed with +12v by the load from the injection relay (pin 87) when the ignition is on, it must be the grounding side (pin 85) that is controled by the ECU via pin2 at the multi-plug that tells the pump when to operate...

but mine isnt?? think im going to send my ECU off for testing see if i get a result there.

[black2]

Yeah the ECU should prime for a few seconds and then stop once the engine is started it cuts in again.

Ive just wired in my zetec turbo using the above diagram and mine works perfect. I did have a problem to start with though, where by my fuel pump would not prime with the ignition but it transpired there is a earth attached to a black wire which is part of the frst loom and it goes to the battery, i had left this unattached, popped this on the battery and now it works fine. Just check all your earths.

Gareth.

[A4RON]

there is a earth attached to a black wire which is part of the frst loom and it goes to the battery

hmm, when you say a black wire do you mean two brown wires crimped into the same lug covered in a black sheath (don't know if that's how to spell it) as i think this maybe something to do with my problem...

when fitting the loom my idiot friend (although he swears blind he didn't) connected it to the +12v side of the battery!!!! this is why i think the ecu is half dead!!

its just puzzling me how it can be half working as the car does run more or lest perfect and goes like a rocket???

[black2]

I will try and get a picture of it for you chap.

Gareth.

[Excursion]

ECU should ground fuel pump, and S1 is right - FP relay should be primed from the ignition relay.

Bear in mind that pump won't prime if there is a CPS or other sensor fault, but that doesn't seem to be the case here.

[4992jk1]

are you running EEC-IV? if you are then the wires you are on about are the case ground (pin 20 of the ecu) and the other wire goes to a diagnostic plug, many of the functions of the ecu will still work with this connected to live but not all, im not sure if connecting this to live will have killed the ecu or not but i dont think it will as they are pretty tough things to break. try grounding it and see if it makes a difference.
James

[A4RON]

just to update... borght a new ecu this solved problem so it must have been something to do with those connections blowing the ECU