baz walton

Hi troops
Had a fun day today trying to solve a fueling issuse on a cossie.
The fault showed up after the re-fitted engine was fired up for the first time.
The car ran smoothly but was throwing fuel out of the exhaust.
Not a bit of fuel, a lot of fuel.
After various investigations into the pumps, the filter, the regulator. it was finally noticed that it was only running on 3 cylinders.
None of us had noticed as it was running beautifully.
After eliminating the injectors from the problem it was found to be that there was a constant 12v at the injector electrical cap of number one cylinder.
Once it was isolated the motor carried on running like a clock, but with out the empty cylinder thowing massive amounts of unburnt fuel through the motor.

So question: The car has had a lot of work on the electrics this year
(the rebulid thread is here: https://passionford.com/forum/restor...-some-tlc.html )

Does anyone have any Idea what may be the electrical fault that could cause number one injector to recieve a constant 12v?

Many thanks for any input.
Cheers
Baz

James @ M Developments.

iTrader: (2)

all the injectors should have a constant 12v, they are earth controlled by the ecu.

baz walton

Hmm, now that's put the cat in amongst the pigeons.
If the voltage is right on number one, then the 0.2/3 (ish) on the others isn't.

We thought it was the injector, so swapped the injectors around. Each time, whichever inj was in number one flowed out continuiously whilst the others were off. (this is just ing and pump on)

baz walton

Cheers Tony, should I be looking then in the engine loom, as this is seperate from the car loom and only has a wire to the ign and rev counter I think?

baz walton

I probably have, (I have the big blue books)

I have just been asking James if the wasted spark might have anything to do with it as I had to snip and solder the two wires to pin 21 and 26 to get them routed properly into the cab. I have had the ecu connector apart when doing this so a fault there could be possible.

baz walton

No it was done at motorsport dev, a few years back, all I did was snip move and resolder two wires.

baz walton

Thanks for that digram. According to that 21 was the air con on my L8 and 26 unsed. So m/sport dev must have used the empty pins for the wasted spark.

botters

iTrader: (2)

are you sure you havnt put the idle speed control valve plug on number one injector, its easily done, i did it myself and it caused a miss and fuel to spray out of the exhaust!

baz walton

Hi Botters, I don't think so, but I will be checking

baz walton

@Tony,
You said the test for the injector cap is a probe on the cap and one on the battery. ( I assume you mean the power side of the batt, as the body could be used if it was an earth required?)

With the probe on, and the engine running I will see a constant 12v, because of the fault. When the fault is detected and fixed then I should see the 12v pulsing at the cap?

martysmartie

iTrader: (1)

The injectors are constant live, and pulsed by the ECU, I doubt you can check via a multimeter, as it will be to fast for most of them to capture, ideally you would use NOID lights.

Check the injector grounds to see if one has shorted.

What Tony means is check the power at the connector, using the battery for the ground connection, i.e. so only your positive probe should on the injector LIVE wire at the connector.

Martin

baz walton

Cheers Martin.

baz walton

You know that feeling when you're in two minds about whether to say nothing and get away with it, or 'man up' and admit to it.


I thought, I'll just check to see if there is an earth problem on the wiring to the injector. I took off all the new tape I had covered everything in and couldn't see anything wrong with it. Except that the earth wire was brown/yellow where the other three were brown/black.
I thought, 'no, couldn't be. I looked at the idle valve wires. You guessed it. brown/black. I swapped the plugs and turned the key. PPPPPuuuurrrrrrr.

Then I noticed the dripping from the exhaust under the car at one of the exhaust joins. I thought Oh, here we go again. I switched off and was about to wade in again, when I decided to clean the fuel of the floor first. There wasn't anywhere near as much. And it didnt seem to feel like fuel between my fingers. I bit the bullet and did a tongue test. It was dirty water. The exhaust blows it out the back like all cars, but at tickover it drips out of the joins.

So the key got turned again and I sat back and watched her purring along happily.

So thanks to Martin, James and tony for adding a lot more info to my limited knowlage.
And a special thanks to Botters for saving me the embarrassment and cost of paying an auto electrician.
Who would have spent ages trying to trace a fault that was standing next to him in ill fitting overalls.

You sir, are a star. And I, gentlemen am a TiT.

James @ M Developments.

iTrader: (2)

thats actually pretty common, ive seen it a few times.

botters

iTrader: (2)

no problem mate, i only knew because ive done it myself , had me scratching my head for a while lol