fuel pump primes 17 times then stops, engine won't run

[Toilet Duck]

Penelope Stopit said:

Ok my speakers are back on and I've viewed your video

Some of what I'm posting here may have already been advised but I don't think so, the topic is getting too big for me to read all the way through right now



I'm posting the following assuming that the pin numbers in the above image are for your cars MFRU and ECU's pin-outs

The first thing to do is connect a multimeter between the battery positive (not any positive....it must be the battery positive) and the cable going to or the terminal in the MFRU 6 way plug (6/3) White/Pink or Pink/White, the MFRU must be fully connected

Is that ECU Switched Negative switching on and off 17 times?

Many thanks, I will check this when I get my car back next week

[Penelope Stopit]

Toilet Duck said:

Penelope Stopit said:

Ok my speakers are back on and I've viewed your video

Some of what I'm posting here may have already been advised but I don't think so, the topic is getting too big for me to read all the way through right now



I'm posting the following assuming that the pin numbers in the above image are for your cars MFRU and ECU's pin-outs

The first thing to do is connect a multimeter between the battery positive (not any positive....it must be the battery positive) and the cable going to or the terminal in the MFRU 6 way plug (6/3) White/Pink or Pink/White, the MFRU must be fully connected

Is that ECU Switched Negative switching on and off 17 times?

Many thanks, I will check this when I get my car back next week

I could do with a diagram. What Honda model/year car is the engine fitted to, is it K20 or K20a or??? Is the ECU Standard to look at for correct pin-outs???

[Kccv23highliftcam]

I was suggesting [in an ofhand way I guess] going back to stage one and re examining, checking and recording everything from the beginning.

"[b]We can't access the ecu at binary level, however swapping the ecu should
have eliminated the possibility of the ecu being at fault.[/b]

Well as long as the test ecu is in fact serviceable, NOW..

...EG there was a little know/remembered danger of swapping Tornado aircraft mecu/ DECU's from side to side as a diagnostic aid...[apart from the part where it needed two independent tradesmen/supervisors to put them back round again...apologies for the thread diversion]

Edited by Kccv23highliftcam on Thursday 1st November 16:35

[Toilet Duck]

Penelope Stopit said:

I could do with a diagram. What Honda model/year car is the engine fitted to, is it K20 or K20a or??? Is the ECU Standard to look at for correct pin-outs???

It's a K20z. I understand the ECU is standard but with the Hondata add on to allow reflashing/changing parameters etc, and therefore the "Atom specific map."

It would seem that the ECU is supposed to just prime the fuel pump for a set period as opposed to continuously/repeatedly or until another signal is received:

[Penelope Stopit]

Toilet Duck said:

Penelope Stopit said:

I could do with a diagram. What Honda model/year car is the engine fitted to, is it K20 or K20a or??? Is the ECU Standard to look at for correct pin-outs???

It's a K20z. I understand the ECU is standard but with the Hondata add on to allow reflashing/changing parameters etc, and therefore the "Atom specific map."

It would seem that the ECU is supposed to just prime the fuel pump for a set period as opposed to continuously/repeatedly or until another signal is received:

This is good, I'll take a look around the web later for more info
Yes the timed 2 second or whatever priming sounds good to me

[Toilet Duck]

Just for clarification, that screenshot is courtesy of another Atom owner with a Hondata Flashpro adapter. That plugs into the ECU and talks to it via the Hondata add on installed on the ECU board. You need to purchase the Flashpro in order to map the ECU or to make any adjustments etc. I don't currently have one although I will be purchasing one when my car is ready to be remapped. The Flashpro is "locked" to the ECU it's plugged into so won't work with others. I also believe that once it's locked/plugged in then the vehicle has to be dynoed in order to give it the required settings

[jeremyc]

Toilet Duck said:

It's a K20z. I understand the ECU is standard but with the Hondata add on to allow reflashing/changing parameters etc, and therefore the "Atom specific map."

It would seem that the ECU is supposed to just prime the fuel pump for a set period as opposed to continuously/repeatedly or until another signal is received:

There are some interesting sensors in that list on the left that might be worth learning more about: Fuel Status, PTANK (which is a pressure reading).

It might also be instructive to understand what data is available on the 'Analog Inputs', 'Digital Inputs' and 'Multiplexer/Digital Output' tabs, as well as the 'Onboard Datalogging' of course.

Edited by jeremyc on Thursday 1st November 18:18

[stevieturbo]

Penelope Stopit said:

You asked the person that is attempting to fix the fault -

Is the ECU constantly powered up during the "17 cycle"? If it
was losing power for some reason would that cause it to cycle the fuel pump
etc. each time?

The reply you got was -

I did not check this, I only checked the fuel pump output from the ecu
which was cycling with the relay clicking. I would have thought that if
it was the main power supply that was switching on and off that the dash
would also switch on and off too and I didn't notice that happening
_______________________________________________________

I don't wish to sound bhy but......Whoever is attempting to fix your car is not a good automotive electrician, it is obvious that the instrument cluster isn't powered by the ECU supply fuse

I have witnessed many a fault multiply into several man made faults due to a testers lack of knowledge
Be carefull

Just a thought

Edited by Penelope Stopit on Thursday 1st November 14:58

Neither are you.

If the ecu is not alive, then the CEL will not be lit. Plain and simple. If the CEL is lit, then it is safe to assume the ecu is powered up and alive.

So their response is quite reasonable. Although it is a proper basic check they should have done ages ago when faced with this problem.

They're wasting their time until they can isolate where the source of the switching is coming from...so they need to do some testing to try and do that.

[GreenV8S]

stevieturbo said:

They're wasting their time until they can isolate where the source of the switching is coming from...so they need to do some testing to try and do that.

The recent quote from the mechanic said:

mechanic said:

I only checked the fuel pump output from the ecu which was cycling with the relay clicking.

I think that indicates that the ECU control line to the FPR is pulsing. That might be a driver hardware issue but IMO more likely that the ECU was deliberately triggering this. However, I can't think of any situation where this would be a reasonable thing for the ECU to do when it was functioning well enough to drive the dashboard and run the engine.

mechanic said:

I would have thought that if it was the main power supply that was switching on and off that the dash would also switch on and off too

I agree - I would expect it to be apparent from the digital dash if the ECU was losing power.

[Penelope Stopit]

stevieturbo said:

Penelope Stopit said:

You asked the person that is attempting to fix the fault -

Is the ECU constantly powered up during the "17 cycle"? If it
was losing power for some reason would that cause it to cycle the fuel pump
etc. each time?

The reply you got was -

I did not check this, I only checked the fuel pump output from the ecu
which was cycling with the relay clicking. I would have thought that if
it was the main power supply that was switching on and off that the dash
would also switch on and off too and I didn't notice that happening
_______________________________________________________

I don't wish to sound bhy but......Whoever is attempting to fix your car is not a good automotive electrician, it is obvious that the instrument cluster isn't powered by the ECU supply fuse

I have witnessed many a fault multiply into several man made faults due to a testers lack of knowledge
Be carefull

Just a thought

Edited by Penelope Stopit on Thursday 1st November 14:58

Neither are you.

If the ecu is not alive, then the CEL will not be lit. Plain and simple. If the CEL is lit, then it is safe to assume the ecu is powered up and alive.

So their response is quite reasonable. Although it is a proper basic check they should have done ages ago when faced with this problem.

They're wasting their time until they can isolate where the source of the switching is coming from...so they need to do some testing to try and do that.

Mmmm having a bad day are we? I didn't read anything about CEL

Anyway if you're one of the masses that relies on a bulb in a dash to.....................

Edited by Penelope Stopit on Thursday 1st November 21:00

[Penelope Stopit]

FAO Toilet Duck

Here are a couple of things that could be causing the problem but bear in mind I am still searching for a diagram

There is a possibility that a fault with the Oxygen sensor heater could drag the ECU's ignition supply voltage down which in turn would switch off the main relay, fuel pump relay and Oxygen sensor relay

Once the Oxygen sensor relay switches off, the ignition supply voltage to the ECU will rise and the whole cycle begin again

The thing is that the same fault could occur if there is a short circuit on or in the wiring harness somewhere

The techies that have posted here attempting to solve the "17 times and out" mystery are far more knowledgeable than myself when it comes to ECU internal electronics and they could very well be correct as they have done the maths and the figures add up.......But??????

There is a possibility that a wiring fault will be causing strange things to happen

Get someone to take a look at the Oxygen sensor and its wiring plus have a good look around the wiring harness especially in the engine bay or close to the exhaust

There are other wiring faults that will cause this cycling but I really do need a diagram to point you in a good direction for testing

Let's see if the above helps

Edited by Penelope Stopit on Thursday 1st November 20:59

[GreenV8S]

Penelope Stopit said:

drag the ECU's ignition supply voltage down

I wouldn't rule anything out until the cause is found, but the precise repeatability of the seventeen cycles doesn't suggest an analog electrical problem.

[Penelope Stopit]

FAO Toilet Duck

There is also the possibility that the main ECU fused supply is playing up or the main ECU return (Earth)

If no fault is found with what I've mentioned in my previous above post you could ask someone to take a look at the main ECU supply fuse and the cables to and from it

I can't remember if you have unplugged the ECU and checked its terminals and the ECU plug terminals
Have you opened the ECU case to check for water getting in?

[Penelope Stopit]

FAO Toilet Duck "Toilet Duck" I chuckle every time I type Toilet Duck, it's a great user name, anyway moving on

I've now installed Hondata K Manager to my Desktop (You owe me a few Mb of SSD Chips)

K Manager shows me the below ECU Pin-outs that match up with the diagram I previously posted and have posted again below the pin-outs image

At present we are interested in ECU E Connector

You will notice that the Ignition supply to ECU pin 9 splices off to the Oxygen sensor relay Terminal 30 and when that relay is energised it continues onwards from relay terminal 87 to the Oxygen sensor element, a momentary short, open circuit or voltage drop due to something else on this ignition supply could cause the problem and this is why I mention take a close look at the Oxygen sensor and its wiring plus other wiring around the engine

What do you think? It's bed time for me now, I'll be back





Edit

I forgot to mention that what Atom have done is to do away with the 3 relays that are shown in the above diagram and used 4 relays in a plastic box from JLR which you know is named a Multi Function Relay Unit or the likes of, the 4th relay being the starter relay that isn't shown

I would never ever wire the Oxygen sensor in the way that Honda have, perhaps Atom have altered it but that's doubtfull

Edited by Penelope Stopit on Thursday 1st November 22:52

[stevieturbo]

GreenV8S said:

I think that indicates that the ECU control line to the FPR is pulsing. .

There is no control line from ecu to FPR...that's silly.

Penelope Stopit said:

Mmmm having a bad day are we? I didn't read anything about CEL

Anyway if you're one of the masses that relies on a bulb in a dash to.....................

Edited by Penelope Stopit on Thursday 1st November 21:00

Like...DUH. Stop before you really make a fool of yourself.

[GreenV8S]

stevieturbo said:

There is no control line from ecu to FPR...that's silly.

How is the fuel pump relay controlled, in your experience?

[eliot]

GreenV8S said:

stevieturbo said:

There is no control line from ecu to FPR...that's silly.

How is the fuel pump relay controlled, in your experience?

Allow me to uncross those wires for you two:
Fuel Pressure Relay
Fuel Pressure Regulator




And yes, taking the live for the o2 heater from the ignition seems an odd choice instead of the main fused 12v supply. Again easy to eliminate; pull the o2 relay out.

[Kccv23highliftcam]

Ok. As I intimated earlier the fault finding needs to back to stage 1 and thoroughly recorded step by step.
There are differences in relay panel and harness that need to be physically discounted for a start. Once this is done then the relay panel has to be checked for both continuity and insulation resistance.
This problem will only be solved by taking a logical approach and carefully eliminating items piece by piece.
It is disappointing that you appear to have been left holding the baby by the ecu vendor and vehicle manufacturer.

Btw has anyone checked from the ignition switch down to the relay box (power supplies) ?

Edited by Kccv23highliftcam on Friday 2nd November 10:48

[Toilet Duck]

Thank you very much for the continued help, really appreciated

jeremyc said:

here are some interesting sensors in that list on the left that might be worth learning more about: Fuel Status, PTANK (which is a pressure reading).

It might also be instructive to understand what data is available on the 'Analog Inputs', 'Digital Inputs' and 'Multiplexer/Digital Output' tabs, as well as the 'Onboard Datalogging' of course.

I suspect a lot of the fields are "generic" and do not necessarily mean that a particular sensor/input etc is therefore present/available, but don't know for sure. The other thing is I don't own a Flashpro to connect to the Hondata ECU so I can't check myself. I plan to buy one, but don't want to connect/lock it to my ECU as that will cause it to loose its existing map etc and require dynoing. My plan was to do some other changes before getting it dynoed/mapped, but this current fault has thrown a spanner in the works.

Kccv23highliftcam said:

Ok. As I intimated earlier the fault finding needs to back to stage 1 and thoroughly recorded step by step.
There are differences in relay panel and harness that need to be physically discounted for a start. Once this is done then the relay panel has to be checked for both continuity and insulation resistance.
This problem will only be solved by taking a logical approach and carefully eliminating items piece by piece.
It is disappointing that you appear to have been left holding the baby by the ecu vendor and vehicle manufacturer.

I agree, i think this probably needs to be looked at from the beginning again

Kccv23highliftcam said:

Btw has anyone checked from the ignition switch down to the relay box (power supplies) ?

Not that I'm aware from (I haven't)

eliot said:

And yes, taking the live for the o2 heater from the ignition seems an odd choice instead of the main fused 12v supply. Again easy to eliminate; pull the o2 relay out.

Will try disconnecting the O2 sensor once I have the car back. I can't pull the relay as its soldered inside the MFRU

Penelope Stopit said:

FAO Toilet Duck

Many thanks for all the info/pics etc, I will have to wait until I get my car back to check this out

Edited by Toilet Duck on Friday 2nd November 12:33

[eliot]

were are you in the uk ? (profile is /dev/null)