Paul17

Does any1 know where i could get hold of a fuel relay, it's the silver box that goes under the dash on the drivers side. My car is cuttin out when u accelorate the revs drop to zero it comes back in stright away course's it to bang. if this was dodge would it do this????

DazC

iTrader: (1)

Does it do it under hard acceleration (coming on boost or does it do it with gentle acceleration)?

Sounds like the overboost protection cutting indue to the rev counter (spark is being cut).

gee1599

as above sounds like its over boosting under load

Paul17

it's not that mate the cars chipped and i've tried another ecu, it's also been into motorsport development aswell it's going back in there again in 2weeks 4 them 2have another look????

SI-S1

u can still get them from ford about Ł47 but it sounds more like an overboost prob to me.

Paul17

When you chip a car do you not loose the overboost protection plus i've had the car for over 2 years, it's run fine at the amount of boost my car runs at now. i've turned it up or anything so why now would it be overboosting????

Paul17

I've not turned it up or anything that should read sorry.

gee1599

cold out side temp the chip might have a boost cut out still just higher ie 15psi or some thing turn it down slighty and test it

Paul17

My car boost's at between 10 and 11 psi i've have turned it down it's made no difference? I'm nearly positive it's not overboost protection, +is been into motorsport devlopment and there pretty sure it's not that

gee1599

if you were near i would say give my relay ago. but i dont think its that
but who nos i could be wrong

Paul17

Also the battery light has started to come on and go off when it please's thing is it hasn't worked for about a year? it doesn't even come on with the ignition. that has only just started though. this cuttin out problem happened before christmas. Got a new dizzy, Coil Tried the feed to the coil tried the green wires that run from the coil it's a proper no brainer this one

DazC

iTrader: (1)

It can only be either the distributor or the over boost protection facility, or a faulty ECU. If it does it randomly then it could be wiring.

The fuel pump relay just cuts the fuel not the ignition (which is why you lose the rev counter).

The battery light can be either the blue wire which runs from the back of the dash clocks to the alternator, the bulb in the dash or the alternator itself. The car will not charge without the battery warning light so you may break down some day if you use it without the light working.

Paul17

There's a feed from the back of the rev counter that goes to the fuel relay acording to the wiring diagrams, It's not the dizzy mines a new one plus we've tried another to that worked on other cars. I've got 2 ecu's n borrowed a series2 won off a mate n non of them worked still had the same fault. it's like something is telling the ecu that it is overboosting when it isn't is there anything that could go faultly and course this???

SafeChav

I was just about to say that aswell you beat me to it this time

As for the fuel pump relay, if u think it may be that then temporarily bridge the relay. Cheaper way especially if its not faulty which im willing to bet its not.

I suppose theres always the chance you have a low fuel pressure? Pump may be getting a bit tired and may not be coping under high fueling conditions?

davie0146

i had this problem, it turned out to be the alarm??

ripped out the alarm and bingo no more backfires/farts etc

Paul17

How do i bridge the relay mate. i found the problem with the battery light thanks , the blue wire had been cut in half must of caught on summat. so I've joined it back up, wounder why the light flickered on and off on the dash when the wire wasn't connected to anything. another thing if the blue wire wasn't connected to anything wounld it course any problems??

DazC

iTrader: (1)

It shouldn't have a wire from the clocks to the rev counter otherwise the pump relay will be getting false readings!!!!! Last RST Series 1 I had with a wire from the rev counter to the fuel pump relay had a very low rev limiter at around 4k rpm.

You should have a wire from pin 1 on the fuel pump relay to pin 20 of the ignition ECU. It's green with a red trace. This wire also connects to the fuel ECU on pin 25 and to a green yellow which is a signal from the distributor sensor.

The Series 2 RST needs the wire from the back of the rev counter to the fuel pump relay.

SafeChav

Based on that you have written and that other thread we were both posting up on a while back, i assume the series 1 relay derives a different signal direct from the sensor on the dizzy? I know my coil negative rev counter and relay are all off the same wire but ive got series 2 management on my mk3.

As for the battery light it was more than likely randomly touching something on the bodywork/engine, connecting the blue to earth illuminates the bulb.

DazC

iTrader: (1)

Yes, the relay takes a raw signal from the distributor rather than the coil pulses unlike the S2 set up. The S2 relay can be triggered by simply touching the gren wire to earth repeatedly where as the S1 relay seems to rely on the waveforms of thelow voltage the dizzy sensor actually produces.

SafeChav

Ah right, so if the relay was wired to LT side of the coil your saying this causes an early rev cut somehow? Do you actually know why they changed the relay for the Series 1??? I don't actually know why myself as everything else uses the purple items....? I suppose they are a bit shit though and always burn out.

DazC

iTrader: (1)

I have no idea why they changed to be honest. The electronics never fail in the S1 relay. The issue is that there is 1 terminal on it's own on the end and this gets a bit of a kicking from the drivers foot being over the throttle. Because of the flexing, the soldered joints crack and break. A quick soldering job and it's repaired. This may be why they changed to the pink relay, which also burn out but that is usually a printed circuit track (which again, can be fixed with a soldering iron).

The S1 relay has an inbuilt adjustable rev limiter, which is where the rev limit comes into play.

I occasionally offer to fix some of the fuel pump relays for the price of a courier to return the relay but nobody seems interested for some reason.

SafeChav

I kind of guessed the S1 relay was more reliable. To be honest i think the purple ones are vastly over rated...........16A i believe What strikes me is the connector to the fuel pump has 2 very skimpy little pins to solder onto the board, one of which not even being connected on the board, its merely there to hold it in.....i can't see that 1 pin which is about 1mm squared coping with 16A and thats the only thing that ever goes wrong with them. Out of interest have you ever measured the current flow for the fuel pump???? I'm going to use my fuel pump relay to switch a 40A relay to power the pump, ive already burnt one out and i can't be doing with keep messing around with it.

Why on earth would they build a rev limiter into the fuel pump relay aswell????? That seems like a very crap idea to me? Some people just don't have faith in repaired items, obviously i know like you a solder joint is simple to fix though...

DazC

iTrader: (1)

Repaired items are always handy to keep in the glove box incase of emergency!

From an educated guess, the fuel pump should probably draw around 15 amp. IIRC a Group A Cossie 044 pump (>220l ph at 5 bar) draws 16 amp a full chat at 5 bar pressure. RSTs run 6 bar base all the time so estimate at around that area. A 40 amp relay should be plenty good enough.

There is 2 rev limits on a Series 2 RST and there is 2 rev limits on the S1 RST.

The S2 has a limiter in the fuel ECU at 6250 rpm as well as in the ignition ECU (unless the chip removes this limit).

The S1 has a limiter in the fuel pump relay at 6500rpm (adjustable) as well as in the ignition ECU (unless the chip removes the limit).

SafeChav

Indeed they are.....although thats the first relay ive had burn out and all of my like 15 odd spares were everywhere but the glovebox, i knew that bridge wire would be handy though

Aren't the RST pumps the same as the cossie items??? I thought they had the same part number on them. Well that says it all though doesn't it. Fuel pump relay is on its limit, also heating the auxiliary air device too. Well i figured theres no point messing about and ive got more spare 40A relays than i can shake a stick at

Ah yeah i completely forgot about the rev limiter on the fuel ecu for a series 2, same end result then.

Well, i really really don't like Bosch KE Jetronic, roll on the OFAB. Have you noticed how slow things move in the FRST section thats gotta say summit

DazC

iTrader: (1)

I'd actually expet the pump to only draw 12 amps, but as they get older, they start to draw a little more current.

The Cossie and RST pumps are not the same although the Cossie pump will fit. The Cossie pump has a higher flow rating.

The S2 rev limit was slightly lower for some reason.

I think Paul has as much info on RST rev limiters as he will ever need now anyway!

Stu @ M Developments

iTrader: (12)

Morning Chaps,
Paul's S1 is a potential Nightmare for the poor chap.

He called me with teh symptoms descibed above and i thought, as you all do, its deffo either boost limiting or the distributor due to teh way the miss/cut also cuts the rev counter!!

Changed BOTH.. no change

However.... our test S2 knock activated ecu does NOT show the problem (Its just mega flat due to no knock input), but various others do, so we are now into looking at the wiring through the whole system.

KE fuel side is also dead, and its not the usual dry joint on the relay. Daz, you were here actually when this fella first came in, remember us checking the power relay in an S1? Thats this fellas.

Paul17

Any ideas which wire it could be coursing this problem? it's a proper nightmear

davie0146

Daz could you check and fix my fuel relay, its been getting a bit of a battering lately with all the wiring nightmares

pm the address and i will send it out.

ta davie

DazC

iTrader: (1)

Not a problem Davie. Is it actually giving problems?

Pop it into a jiffy bag with a Ł5 note and your address (or stick another jiffy bag in with your address on), and I'll post it back with the common failure of joint fixed.

DazC

iTrader: (1)

Stu, I remember it!!

Paul, there should be no green wire from the rev counter to the relay. Pop the dash clocks out and have a look. Then look to see if the same wire is at the fuel pump relay above the throttle pedal. If there is, remove it. This will trip the rev limiter early but I am not sure how it effects the ignition rev limiter.

Paul17

DazC
What colour wire am i looking for mate, and do u have any idea why my fule ecu mite not have any power to it????

SafeChav

Theres a fuse in the fuse which i believe is R1, (theres 2 fuses on there own, its the left one IIRC) on the fuse box lid it has a heated seat symbol. Thats the fuse for the KE Jetronic ECU.

Paul17

about the fuel ecu, were does the power go after the fuse box? does it go to a relay next to the fuel pump relay a black one? i think that this has power to it cos when you pull it out it sparks. must be live. i have a spare one of these and it doesn't seem to make any difference when i change it. i've just got a multi tester what should i be testing?

SafeChav

I believe the power supply is derived from the fuel pump relay from what i remember off the top of my head?

DazC

iTrader: (1)

Yes. The fuse for the S1 KE system is the fuel pump fuse, not the heated seats fuse like the S2. SO if the KE fuse has blown, the car won't even start (for obvious reasons).

Reasons for why there is no power to the KE box could be almost anything. I'd have to look at the diagram and compile a list of suggested possibilities.

Paul, if your car has had this extra wire fitted by someone who doesn't know the S1, it could be that in it's past, it has lost the signal to the fuel pump relay and they have run in this wire to get it going again. It will be green for the standard rev counter wire. The fuel pump relay needs the raw signal direct from the distributor which is on a green/yellow (standard wiring loom).

Use your multimeter set on Ohms (funny upside down horse shoe symbol) at the lowest setting. If the meter has a buzzer, switch it on cos it will make life easier. Touch one lead of the meter to the green/yellow (might be a green/red)) on the distributor and touch the other on the green/yellow at the fuel pump relay. The meter should either buzz, or give a reading as close to zero as possible. This means the wire is continuous and not broken. If you get a high reading or no reading at all, then there is a problem.

Paul17

i don't mean that any one has put a feed in from the rev counter to the fuel pump relay? I've got a wiring diagram in the back of haynes manual it looks like there's a green wire that goes from the coil to the rev counter then to the fuel pump relay if you've got a wiring diagram would ya have a quicklook for me i've recentley changed the clocks in the dash could this have affected something

Paul17

do ya think changing my car from mfi to efi would get rid of the problem is it worth doing and how much does it cost?

DazC

iTrader: (1)

That is an expensive way of cureing the problem!!!

I will look at the diagram for you but not tonight as I an absolutely knackered. The diagram you have sounds like a Series 2 diagram to be honest....

SafeChav

Sorry my mistake, the left fuse is the Fuel Injection fuse isn't it, and the right one is the heated seat fuse slot, without looking at the diagrams i forget because i have fuses in every slot on mine

As sugggested i would do some simple continuity checks and check the glass fuse inside the Fuel Pump relay.

Paul17

How do ya open uo the fuel pump relay? i didn't even know you could