g10ens

Does anybody know whereabouts the fuel pump relay is earthed out on a 3dr? The wire I am talking about is the blue and green wire that comes off of terminal 85 on the pump relay and earths the live feed from the ignition. I can overcome the problem by running a new wire to the chassis from the relay terminal but would like to know where the other end of the blue and green wire goes to see if I can see why it's not earthing correctly, I also have no spark at the plugs at the moment so was wondering if perhaps the two problems may be linked to the same dodgy earthing point.

oldford

Normally it is switched by the ecu. See: http://bigturbo.co.uk/main6.htm

Is the ecu power there and the grounds?

g10ens

I don't know how to check for power to the actual ECU so any advice how to do that would be appreciated, there is power from the battery and the ignition getting to both the ECU relay and the fuel pump relay, I can get the pump to prime by earthing the relay out to the chassis, there is also power getting to the positive side of the coil so is it worth trying to earth the coil direct to the chassis and check for a spark?? Would this then indicate a problem with the earthing point in the ECU if there was a spark at the king lead?

martysmartie

iTrader: (1)

Pin 20 is the live, so if you can find that you can check for feed to the ECU/Scart connector.

You can't tell really by earthing the coil ground, it's actually quite the opposite, as when the coil is grounded the coil "charges" and when it's ungrounded it discharges.

It is possible to send a SPOUT via linking two pins on the ECU.

Martin

g10ens

Have just checked for power at pin 20 in the yellow plug that goes into the ECU and there was no power there, so I tried earthing the ECU relay direct to the chassis and then there was power at pin 20!!
So what does this mean, does it indicate a fault internally with the ECU?

g10ens

Also, is it safe to earth the ECU relay to the chassis and reconnect the ECU plug?? And if so should that then theoretically mean there should be a spark at the king lead or even the spark plugs and power at the Amal valve?
Obviously that wouldn't be a permanent fix but thought it might at least show that everything works when earthed out.
Sorry if these are silly questions but my electrical knowledge is very basic!!

oldford

Did you measure pin 20 with the ECU unplugged?
Then it's normal.

g10ens

Yes with it unplugged, i can't see a way of getting to the pins when it's plugged in as the casing of the plug sits slightly inside the casing of the ECU

oldford

I use a breakout box for these kind of measurements, but you could remove the top of the connector. However, you could also measure the result of an ecu getting power and ground. Main relay not only feeds the ecu, but also the injectors.
Injectors are easy to access. There you can measure with a disconnected connector.

g10ens

And I could safely check the injectors with the ECU plugged in and the relay earthed to the chassis?

oldford

You measure the supply voltage in the (disconnected) connector of an injector.
You're not checking the injectors.

Why earth the relay? You don't know it's not grounded by the ecu right now.
You can do that after you have verified there's no supply feed to the injectors.

tpaul

be careful mate as i have had a similar problem and ended up shorting out my ecu, and im now on the search for a new one before i can even rectify why my car wouldnt start in the first place

martysmartie

iTrader: (1)

What he ^^ said.

OP it sounds like your relay has a no ground, thus when you touch it to ground you have power!

This will be why the car won't run!

Martin

g10ens

Have just checked the injectors and there is definitely power getting to them (this is without the need to connect any false earths to the relays) so does that mean that everything is ok with the ECU?
There is no power getting to the Amal valve, ISCV or fuel pump under normal conditions but if I earth the fuel pump relay direct to the chassis then I get power at the Amal valve, ISCV, and the fuelpump, hopefully this will mean something to somebody!

martysmartie

iTrader: (1)

All 3 of the things you mention are powered via the fuel pump relay, which is switched via the ECU, so your ECU is not switching this relay!

It means that in theory you should have power at the ECU as well, as the injectors are powered from the ECU relay, try unplugging the ECU connector, do you still have power at the injectors after this?

If no then that is correct, after this we will move onto look at your CPS.

Martin

g10ens

Thanks, I will unplug the ECU tomorrow and check for power at the injectors.
I'm not clued up enough to understand why the CPS would effect these 3 things but if there is a problem with it then that could also explain why there is no spark I suppose?

g10ens

I've done what you said by unplugging the ECU and checking for power at the injectors and there was no power there, plugged the ECU back in and got power back to the injectors. I've also checked the gap between the CPS and pulley teeth, the gap measures 0.71mm (0.028") so is within the 0.6mm - 1.0mm tolerance specified in my workshop manual.

martysmartie

iTrader: (1)

That makes sense, no CPS input would cause your issues, the fuel pump will not prime without it's signal, nor will a SPOUT be sent, obviously things powered via the fuel pump relay won't work either.

You can check this, but first make sure it's connected properly.

Martin

g10ens

Had a look this morning and yes the crank sensor plug is correctly plugged into the loom, also checked the distributor plug and that is connected aswell.

g10ens

I also checked for power at the crank sensor, there was none there, checked for power at the distributor plug and as soon as I touched it to earth the fuel pump primed, would that indicate that the problem lies within the distributor, possibly the phase sensor?

martysmartie

iTrader: (1)

I wouldn't have thought so, as the CPS is the input used to drive the fuel pump drive and for ignition.

Although on a 2WD car, a phase sensor can cause a non starter as this is used for the sequential fueling, on 4x4 I believe it can "Substitute" this input due to having a more advanced ECU and it uses battery voltage for the reference, as part of it's "limp home" strategy.

The reason why you don't have any power at the crank sensor, is as it generates it's own AC voltage, this is seen by the ECU as a wave format, (you can check this voltage at the ECU whilst cranking the engine, I can tell you the exact pins if you want?) whereas the phase sensor has a 5V supply.

Martin

g10ens

Just to clarify mine is a 2wd car.

Any information you can give on the next step to take would be appreciated, am I right in thinking that the yellow plastic surrounding on the ECU plug can be removed whilst still plugged in to allow access to the pins?

martysmartie

iTrader: (1)

I know, I was just talking trivia re the 2 models.

Yes there is a small screw on the side of the ECU connector, once this is removed the cover comes off in two sections and there is a little plastic strip that comes out as well, once this is done you can plug the connector back in again, and the pins will be exposed.

You can measure the power at pins 3 and 4.

Martin

g10ens

I'm not getting any power at these pins, checked pin 3 to earth, pin 4 to earth aswell as checking across the two pins and none of the checks showed any power.

martysmartie

iTrader: (1)

I would say you have a bad CPS, do you have all four 'lugs' intact on the crank pulley?

Martin

g10ens

Had a look this morning and all 4 pins are definitely intact, I double checked the gap to all 4 and they're all in tolerance, checked once again for power at pins 3 and 4 but still nothing.
Would you advise me to stick a new crank sensor on or is there any other checks that should be made first?

martysmartie

iTrader: (1)

I would certainly be looking toward the crank sensor and would say it's defiantly worth trying another, it's also worth verifying the continuity of the wiring, i.e. there isn't a break between it and the ECU.

Martin

g10ens

I have ordered a new crank sensor so will hopefully be able to try it sometime this week, will let you know if it fixes the problem!

g10ens

Fitted new CPS, problem solved!! Thanks for your help, was nice learning a few basics about checking the electrical system aswell. It's only running on 2 cylinders at the moment but that's down to fuelling as all the plugs are firing and leads are set in right order so will have to look at the injectors when I get some time.

g10ens

Sticking injectors sorted, engine running fine now!

martysmartie

iTrader: (1)

No problem, please leave rep power.

Martin