Car not starting, Possible Fuel ECU fault.

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barringtonsteele
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Car not starting, Possible Fuel ECU fault.

Post by barringtonsteele » 07/12/17 17:26

Hi,

My MK2 97 GT died overnight. I've managed to get somewhere with diagnosing the problem, with the help of the AA, but I could do with being pointed in the right direction as far as parts go before I spend money unnecessarily.

Here is the current diagnosis:

Battery is fine and holding charge
Starter/engine is Turning over fine.
Plugs are sparking fine
Coil is fine
Will start with Quick Start sprayed into the air intake (for a second or two)
When holding the fuel line, you feel the slight pressure in the pipe then it disappears again.
Everything tested with multi-meter is reading fine.

The AA chap seems to think it was the ECU that controls the fuel pump that may be dead, which he said is the one located underneath the rear fuse box. I just don't know what this is called or where to find one if that is the case. He initially suspected it may be an inertia switch, as the symptoms pointed to the fuel system being switched off.

Has anyone had any experience of this? Any help is greatly appreciated!

Thanks!

Barry

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Re: Car not starting, Possible Fuel ECU fault.

Post by jimi » 07/12/17 17:33

Have you checked for error codes ?
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Re: Car not starting, Possible Fuel ECU fault.

Post by notroubleclubber » 07/12/17 19:29

Error code check
Then check to see if voltage is going to the fuel pump which is under the ashtray.

If it is then check to see if fuel is coming out of filter by undoing union and put in clear plastic bottle.

If it is then make sure the filter is not blocked. If its clear then it should be starting and isnt the fuel.

If no voltage to pump then put 12v to it or bridge diagnostics pins (cant remember which ones possible fp and b+) and hopefully that will start it. If it does then its either the fuel pump relay or ecu or something in that circuit such as afm

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Re: Car not starting, Possible Fuel ECU fault.

Post by benckj » 07/12/17 22:29

As above, jumper the B+ ands FP ports in diagnostic box and listen for pump running. If it doesn't run or make a variable noise this most likely the pump has died as this check by-passes the ECU control and relays. Can confirm by installing pressure gauge on fuel rail to monitor.

Having replaced a few pumps in my day it is one of the worst jobs I've done on an MR2 especially when its a turbo. Tank must be dropped along with dreaded supply line which feeds to fuel filter.

jim

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Re: Car not starting, Possible Fuel ECU fault.

Post by peteV6R5 » 07/12/17 23:58

sounds like no fuel.

as suggested bridge b+ and FP to give perm batt to fuel pump.
had similar on mine when pump croaked, got fuel flow but not enough to vaporise through injectors, would sometimes pop and bang.
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Re: Car not starting, Possible Fuel ECU fault.

Post by MR2DI4 » 09/12/17 22:45

Fuel pump, bridge the connectors in the diagnostic box and this puts 12V direct to the pump. You should be able to hear it running without the engine running put you ear to the area between the seats.

The ECU in your car is very reliable, I have 3 of them in case I ever need a spare but they don't fail.

How many miles has it done ? the fuel pump has a finite life because it has brushes on the motor that simply wear out eventually just like your alternator that does 160-180,000km. It is subject to fuel contamination however and I have heard they can simply seize up but I would have thought that is unlikely but happy to hear from anyone that had their MR2 pump seize..

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Re: Car not starting, Possible Fuel ECU fault.

Post by jimi » 10/12/17 0:39

Siezed fuel pump is not as unlikely (or uncommon) as you think. I know of several MK1's and 2's that have suffered from this.
L159333 wrote:
29/10/14 23:28
To update this thread in case others with the same problem find their way here.

I replaced the fuel pump and also reconditioned the fuel level sender, put everything back together and it all works! Pump and gauge are working as they're supposed to. I don't know if both items had actually packed up, but the pump was certainly seized up. The sender may have been fine, I simply cleaned it up and left it in a bath of Deox-C for a day, then tested it's resistance through the it's swing range - seemed ok but a little erratic at what would be low levels. I bench tested the pump in the tank but off the car prior to refit to be sure.

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Re: Car not starting, Possible Fuel ECU fault.

Post by benckj » 10/12/17 7:00

At 100km on clock mine became very erratic then died. When I removed it I dissected the internals and found one of the brushes stuck in open position so it could not make contact with armature. On closer inspection I could see that the brushes were not centralised and wore uneven due to not being shimmed correctly at factory. Can provide pics if interested.

Jim

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Re: Car not starting, Possible Fuel ECU fault.

Post by MR2DI4 » 10/12/17 8:56

Must be luck of the draw on the pump and maybe also down to replacing the fuel filter as over 90% of the fuel supplied by the pump goes round the system and back into the tank.

Mine has over 230,000Km on the clock and is still on the 1990 pump.

I would suspect fuel contaminants, fuel additives or even water in the fuel for reducing the life of the pump to only 100,000Km.

If you want to see what the fuel filter is doing, cut the old one in half, its full of brown stuff which I concluded was the worn fuel pump brushes.

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Re: Car not starting, Possible Fuel ECU fault.

Post by peteV6R5 » 10/12/17 10:57

68000 miles on mine (109000km) was still spinning but only at 9psi ---- so not enough fuel rail pressure to deliver fuel through injectors at right ratio and rate to burn.
5000 miles after V6 swap so pump had to work harder.
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Re: Car not starting, Possible Fuel ECU fault.

Post by jimi » 10/12/17 18:45

My car still has its original 29 year old fuel pump and has done 121453 miles (195460 km) with no problems (so far)
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Re: Car not starting, Possible Fuel ECU fault.

Post by benckj » 10/12/17 19:08

I would suspect fuel contaminants, fuel additives or even water in the fuel for reducing the life of the pump to only 100,000Km.
Can suspect all you like but I can tell you the pump, filters and tank are as clean as my dinner table. Brushes are all good but can see how it was not centered on the armature.

Even when new the OEM pumps don't produce great flow. Yes, they are enough for stock and slightly modified configurations but they tend to decline line at the larger flows. If interested have a look at link below which compares various pumps.

http://www.wolfkatz.com/Articles/MR2%20 ... Report.pdf
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Last edited by benckj on 10/12/17 19:29, edited 1 time in total.

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Re: Car not starting, Possible Fuel ECU fault.

Post by MR2DI4 » 10/12/17 19:22

Doesn't have to be dead center on the armature. Worked on plenty of washing machines and they are way off center by design, but I confess the lower brush lasts about 18 months before it needed replacing. How long the pump lasts is going to depend on whats going through it more than anything else. The fuel goes right through the entire pump, the brushes the armature the lot, its totally immersed in fuel 24/7 so its totally subject to whats in the fuel and basically you have no idea whats in your fuel from one tank full to the next.

My MR2 pump was dropping in pressure so now it gets smacked with 17.5Vdc when the fuel pump relay closes. Put a 5V dc-dc fully isolated converter on top of the 14.6Vdc from the alternator and adjusted the Voltage to give the maximum fuel pressure of 32psi with the vac line to the reg disconnected.

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Re: Car not starting, Possible Fuel ECU fault.

Post by benckj » 10/12/17 19:33

Managed to upload a pic to post above. I can tell you it wasn't a debris issue and one brush was stuck due to what I believe uneven wear. Was able to monitor pump problem as I have a pressure gauge on my AFPR and I noticed it was erratic before it died on a trip to town. Could not get pump to run even after jumpering B+ and later when using a DC power supply connected directly to pump terminals. Resistance readings showed an open circuit.

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