RRC Starting Problem
Discussion
I tried running the pump from a separate battery, otherwise unpluggeed from the car, and the car wouldn't start at all,not even reluctantly. That was what prompted my earlier pondering about whether the car knows whether the fuel pump is present or not, ie, an open circuit back to the ECU stops something else from functioning? I don't want to power the pump up withthe harness connected as I suspect that might fry something else.
Additional earth I can try. I just looked back through the hiostory with the car and it had a new fuel pump fitted 6 months ago.....so, someone else has been on this track but didn't solve it.
Additional earth I can try. I just looked back through the hiostory with the car and it had a new fuel pump fitted 6 months ago.....so, someone else has been on this track but didn't solve it.
Fuel pump will probably be switched through the inertia switch, the fuel pump relay and the main relay. My understanding is that the fuel pump relay and the main relay are controlled by the ECU. If you want to try "scatter gun" then suggest change those 2 relays. You could monitor the voltages at the inertia switch, you could shunt (bridge) the inertia switch (for testing only).
When it finally starts, does it continue to run reliably?
Edit to add: Does your fuel pump run for a couple of seconds to pressurise the fuel rail when you switch the ignition on? No cranking of the engine required, so should be easier to hear.
When it finally starts, does it continue to run reliably?
Edit to add: Does your fuel pump run for a couple of seconds to pressurise the fuel rail when you switch the ignition on? No cranking of the engine required, so should be easier to hear.
Edited by V8 Fettler on Tuesday 24th February 16:59
No wading from me, although I've only had it a couple of months; who knows what happened in the past. It doesn't LOOK like a car which has seen much other than tarmac.
I also keep erring towards the fuel pump relay, my only hesitation being that this relay drives the fuel pump regardless of where the signal to do so is coming from - correct?? In which case how come it runs fine? If it's not the relay then I am starting to wonder whether the ECU is not feeding the relay/pump correctly during cranking. I believe you can get the ECU tested? Or maybe it would be easier to try and borrow a known-working one and try that.
I also keep erring towards the fuel pump relay, my only hesitation being that this relay drives the fuel pump regardless of where the signal to do so is coming from - correct?? In which case how come it runs fine? If it's not the relay then I am starting to wonder whether the ECU is not feeding the relay/pump correctly during cranking. I believe you can get the ECU tested? Or maybe it would be easier to try and borrow a known-working one and try that.
Well the mystery thickens a little more.
Took the cover off the fuel pump relay and managed to monkey-arm the key from the back seat
So, when I turn the ignition on, sure enough the relay closes for a second or two as expected, then releases. Then when I crank, the relay closes again. Which suggests that the relay, the ECU and the coil pulse are all doing their thing correctly. Somebody may have been in there before, the relay is a brown plastic Bosch and not the tin-can one I expected??
If you recall from a post of mine above though, the voltage at the pump blipped up to 10+ for the ignition-on priming sequence (I guess it made 12v although the DMM didn't catch up quickly enough) but it was much lower, 7v I think, during cranking. Candidates for that, well, maybe the starter is dragging the voltage down, although it's a new battery (perhaps could do with a charge now) and the engine turns over happily enough. A bad earth? A bad connection somewhere between the relay and the pump? Maybe I need to jumper from the relay to the pump and see what that does. Or maybe a new relay anyway, perhaps the contacts are not allowing full current to flow?
I. Am. Almost. There.
(I think…..)
ETA - I did indeed jumper 12v onto the relay output, and for the first time ever, I heard the pump run, although clearly it has run before as I have driven the car 50 miles or so. Sooooo, now I am thinking there is an issue with the power supply going onto the relay (contacts, not the switch side). The brown cable feeding power to the relay comes from the ECU - and that ECU pin also feeds the ignition switch, according to my wiring diag. So maybe I am full-circle back around to the switch itself. If not then I need to check the power output at the ECU, pin 15.
Just rambling away here, I guess I'm either hoping that writing it down will give me a eureka moment, or that someone will recognise the symptoms and advise what they did to cure it themselves!
Took the cover off the fuel pump relay and managed to monkey-arm the key from the back seat
So, when I turn the ignition on, sure enough the relay closes for a second or two as expected, then releases. Then when I crank, the relay closes again. Which suggests that the relay, the ECU and the coil pulse are all doing their thing correctly. Somebody may have been in there before, the relay is a brown plastic Bosch and not the tin-can one I expected??If you recall from a post of mine above though, the voltage at the pump blipped up to 10+ for the ignition-on priming sequence (I guess it made 12v although the DMM didn't catch up quickly enough) but it was much lower, 7v I think, during cranking. Candidates for that, well, maybe the starter is dragging the voltage down, although it's a new battery (perhaps could do with a charge now) and the engine turns over happily enough. A bad earth? A bad connection somewhere between the relay and the pump? Maybe I need to jumper from the relay to the pump and see what that does. Or maybe a new relay anyway, perhaps the contacts are not allowing full current to flow?
I. Am. Almost. There.
(I think…..)
ETA - I did indeed jumper 12v onto the relay output, and for the first time ever, I heard the pump run, although clearly it has run before as I have driven the car 50 miles or so. Sooooo, now I am thinking there is an issue with the power supply going onto the relay (contacts, not the switch side). The brown cable feeding power to the relay comes from the ECU - and that ECU pin also feeds the ignition switch, according to my wiring diag. So maybe I am full-circle back around to the switch itself. If not then I need to check the power output at the ECU, pin 15.
Just rambling away here, I guess I'm either hoping that writing it down will give me a eureka moment, or that someone will recognise the symptoms and advise what they did to cure it themselves!
Edited by CAPP0 on Thursday 26th February 17:55
Does the pump run permanently with your shunt/bridge/jumper in place? Does the Rangie now start almost instantly with the shunt in place? This will close off the possibility of other issues.
What happens if you shunt 12v to the relay input? Don't forget, the supply (without the shunt) will run through various devices, eg main relay
What happens if you shunt 12v to the relay input? Don't forget, the supply (without the shunt) will run through various devices, eg main relay
I know you're all waiting for today's episode, so here goes!
Yes, if I shunt straight onto the white/purple off the relay, the pump runs continuously. But, the Rangie still demonstrates the same (failure of) starting issue.
I haven't shunted 12v to the relay input for fear of back-frying the ECU? However, I have monitored the voltage there, and this is where it gets interesting. Ignition on, engine not running, not cranking, I have 12v (or thereabouts, 12.8 earlier) at the brown relay power input. But if I crank it, bearing in mind that the brown power feed is fed direct from the ECU, the voltage drops to around 8-9v. I tested the battery voltage during cranking and it "only" drops to around 11.5. which I'd probably expect.
So, something is dragging the ECU output volts down when the engine is cranking. And given that the car still didn't start when I shunted the pump direct, I wonder what else is having it's voltage dragged down when the car is cranking. I have already tried flying an earth lead (jump lead) from the battery to the engine, to give a stronger earth. Am I back to whether the ign switch is the root of all this? It still only ever seems to fire the millisecond I release the key. Round and round in circles….
Yes, if I shunt straight onto the white/purple off the relay, the pump runs continuously. But, the Rangie still demonstrates the same (failure of) starting issue.
I haven't shunted 12v to the relay input for fear of back-frying the ECU? However, I have monitored the voltage there, and this is where it gets interesting. Ignition on, engine not running, not cranking, I have 12v (or thereabouts, 12.8 earlier) at the brown relay power input. But if I crank it, bearing in mind that the brown power feed is fed direct from the ECU, the voltage drops to around 8-9v. I tested the battery voltage during cranking and it "only" drops to around 11.5. which I'd probably expect.
So, something is dragging the ECU output volts down when the engine is cranking. And given that the car still didn't start when I shunted the pump direct, I wonder what else is having it's voltage dragged down when the car is cranking. I have already tried flying an earth lead (jump lead) from the battery to the engine, to give a stronger earth. Am I back to whether the ign switch is the root of all this? It still only ever seems to fire the millisecond I release the key. Round and round in circles….
If the pump is running continuously, you probably have pressure in the fuel rail, but cannot be certain without a fuel pressure gauge. You could crack open the fuel line and see if fuel sprays out, but this is a potentially dangerous exercise!
If you try and crank for 15 seconds with the pump running continuously, are the spark plugs soaking with petrol?
What year is the car? Do you have catalytic converters? Don't want to fill them with unburnt fuel.
Are all service items "in date" eg fuel filter?
Spark, fuel.
If you try and crank for 15 seconds with the pump running continuously, are the spark plugs soaking with petrol?
What year is the car? Do you have catalytic converters? Don't want to fill them with unburnt fuel.
Are all service items "in date" eg fuel filter?
Spark, fuel.
Well once it starts (which it did 5 mins ago) it runs fine, sounds nice, not missing anywhere. There's definitely fuel and spark once it's running. I just think something is dragging voltages down somewhere during the cranking phase and that's stopping it from having enough grunt to start.
It's a 91 3.9EFI VSE. I think some had a schrader valve on the fuel rail to check the pressure with but this one doesn't seem to have.
It's a 91 3.9EFI VSE. I think some had a schrader valve on the fuel rail to check the pressure with but this one doesn't seem to have.
Well, I'm losing the will to live with this one! After all the above, I have now cleaned the battery posts, the starter motor live, and the live post which is on the bulkhead fed from the starter, which puts power inside the car. Problem still exists.
I shaved back some insulation from the brown (pin 15) cable to the ECU and took some readings. It sits at 12v+ with the ignition on, but drops to approx 8v when cranking. However, the battery voltage itself, and the voltage up to and including the bulkhead live post, only drops to 11-point-something. Once the engine has started, this immediately goes back up to 13.8v as would be expected. So, something is dragging the voltage to the ECU down when cranking, and I believe that will be affecting both the fuel pump voltage and the injectors? Just looking at the wiring diag and that same power feed to the ECU also looks like it feeds the main relay and the fuel pump relay - so that bears that out, the pump and injectors are not getting 12v when cranking. I don't know whether they would operate at 8v - guess not.
The wiring is not in good condition on the car, someone/someones has been at it in several places and there is indication of previous overheating under the lower dash panel (melted plastic) although what that was, or when, or what was repaired, I'll never know.
One other point, the heavy black cable to the ECU should be earth but it isn't. I'm getting no continuity from that cable (again, insulation shaved) to the body. Even if I short that cable to earth, the car still doesn't start properly. Can/does the ECU get it's earth from elsewhere?
I'm still at the point where the engine only really starts once you have cranked it for a while and when you back the key off. I now don't think it is the ign switch itself, I have jumped that and it still doesn't start.
I have also used jump leads to put an earth straight from the battery to the alternator, and then another to go onto the water pump for the block, to make sure I have a decent earth. Thinking about it I may put one to the body and see whether that helps; perhaps I have either missed an earth to clean, or there is one not present somewhere?
Last thing I can find in the wiring diag is something called the "main connector" which looks, amongst other things, to supply that brown ECU/relay power. Item 12 in the Haynes manual on the dedicated fuel injection wiring diag. Does anyone know where that lives - I'd check it for cleanliness etc.
Other than that, over to you guys for any ideas where/how to look next?
I shaved back some insulation from the brown (pin 15) cable to the ECU and took some readings. It sits at 12v+ with the ignition on, but drops to approx 8v when cranking. However, the battery voltage itself, and the voltage up to and including the bulkhead live post, only drops to 11-point-something. Once the engine has started, this immediately goes back up to 13.8v as would be expected. So, something is dragging the voltage to the ECU down when cranking, and I believe that will be affecting both the fuel pump voltage and the injectors? Just looking at the wiring diag and that same power feed to the ECU also looks like it feeds the main relay and the fuel pump relay - so that bears that out, the pump and injectors are not getting 12v when cranking. I don't know whether they would operate at 8v - guess not.
The wiring is not in good condition on the car, someone/someones has been at it in several places and there is indication of previous overheating under the lower dash panel (melted plastic) although what that was, or when, or what was repaired, I'll never know.
One other point, the heavy black cable to the ECU should be earth but it isn't. I'm getting no continuity from that cable (again, insulation shaved) to the body. Even if I short that cable to earth, the car still doesn't start properly. Can/does the ECU get it's earth from elsewhere?
I'm still at the point where the engine only really starts once you have cranked it for a while and when you back the key off. I now don't think it is the ign switch itself, I have jumped that and it still doesn't start.
I have also used jump leads to put an earth straight from the battery to the alternator, and then another to go onto the water pump for the block, to make sure I have a decent earth. Thinking about it I may put one to the body and see whether that helps; perhaps I have either missed an earth to clean, or there is one not present somewhere?
Last thing I can find in the wiring diag is something called the "main connector" which looks, amongst other things, to supply that brown ECU/relay power. Item 12 in the Haynes manual on the dedicated fuel injection wiring diag. Does anyone know where that lives - I'd check it for cleanliness etc.
Other than that, over to you guys for any ideas where/how to look next?
Does appear to be voltage related. As reality check, when you have "no start", is there a spark? Are the plugs wet with petrol?
Do you have access to a fault code reader, eg Rovergauge or ECUmate?
The wiring diagram shows lambda sensors and fuel system purge control valve, do you have these on your 1991 Rangie? It's pre-92 but my understanding is that these would/could have been fitted 1989 onwards,
Do you have access to a fault code reader, eg Rovergauge or ECUmate?
The wiring diagram shows lambda sensors and fuel system purge control valve, do you have these on your 1991 Rangie? It's pre-92 but my understanding is that these would/could have been fitted 1989 onwards,
Thanks for the suggestions above. Answers in sequence…
There's a spark when cranking, I haven't checked a plug for wetness though, that'll have to be next.
I don't have access to any fault readers which would work with this. I guess Rovergauge is the cheaper option although would have to work out the "make your own cable" task. Mind you at this rate I imagine an investment in ECUMate might save a lot more hair-tearing.
Is the diag connector the blue 3-pin under the steering column?
Unfortunately I don't know anyone locally with the same car to test another ECU. However there is a good indy not too far from me, who has worked on my L322, so I might have a chat with him.
Mine doesn't have lambda sensors fitted (although it does have the plugs on the harness). I did check with the previous owner and he said they were never there when he had the car,
Never mind scattergun, flame gun is starting to sound like an option!
Thanks again for sticking with me on this lengthy saga and offering suggestions chaps, I do genuinely appreciate this. Looking forward to nailing it now.
There's a spark when cranking, I haven't checked a plug for wetness though, that'll have to be next.
I don't have access to any fault readers which would work with this. I guess Rovergauge is the cheaper option although would have to work out the "make your own cable" task. Mind you at this rate I imagine an investment in ECUMate might save a lot more hair-tearing.
Is the diag connector the blue 3-pin under the steering column?
Unfortunately I don't know anyone locally with the same car to test another ECU. However there is a good indy not too far from me, who has worked on my L322, so I might have a chat with him.
Mine doesn't have lambda sensors fitted (although it does have the plugs on the harness). I did check with the previous owner and he said they were never there when he had the car,
Never mind scattergun, flame gun is starting to sound like an option!
Thanks again for sticking with me on this lengthy saga and offering suggestions chaps, I do genuinely appreciate this. Looking forward to nailing it now.
I bought a cable from the Rovergauge man as I couldn't be bothered to make my own.
It plugs in under the driver's seat into a white three pronged connector.
At the moment it should be plugged into an earthing connector, so you split it to plug Rovergauge in.
Hope that makes sense!
Found this image:
http://www.paulslore.com/aulro/IMG_3804.JPG
In normal use those two white halves should be connected.
It plugs in under the driver's seat into a white three pronged connector.
At the moment it should be plugged into an earthing connector, so you split it to plug Rovergauge in.
Hope that makes sense!
Found this image:
http://www.paulslore.com/aulro/IMG_3804.JPG
In normal use those two white halves should be connected.
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