D1, starts immediately, won’t idle more than few secs or rev

[pibby]

Well as the title suggests, that’s what’s happening. Got a D1 with a 4.6 running 14cux. Have just put it all back together with a thor manifold, started within the first quarter of a revolution. Thought you beauty, that’s another job done. alas, not to be. The bugger just won’t idle for more than a few seconds. Using all of the 14cux sensors ie stepper/tps/fuel temp/water temp etc etc and 3.9 fuel rail.

It has injected gas and it’s hard to say whether it runs on that or not, it switched over and ran but cut out after a few seconds – out of gas. I seem to vaguely remember (geez, it was only earlier today) I could rev it.

So it was leading me to the petrol side. had a set of newly reconditioned yellow top injectors in with this change (never had them in before) so pulled them out this arvo and put the old green tops back in. nup, same issue.

checked the timing with a timing light which was fine, well it should be it starts easily. Whilst it idles for a few seconds I dash around to the exhaust to have a whiff, no petrol smell which I would have thought there would be.

I have a set of lambda indicators in the dash and when the car starts I can see them hover around lambda then as the car slowly begins to die I can see the mixture getting weaker and weaker. Revving it just makes it die instantly. I also have the software for the lpg and can see injector opening times. At startup petrol are ok then as it starts to die I can see the injectors opening up more but the engine still konks out. So it’s trying to compensate for the decreasing revs by upping the injector time but no go.

So I am starting to think petrol supply. turn the key to ignition and prime the petrol pump and hold down the schraeder valve at the same time and sure enough it’s a boy. Plenty of petrol gushing out. If I prime it then depress the schraeder valve immediately once stopped priming it still gushes out as it releases the pressure. However if I increase this period to say 5 seconds after priming and then depress the schraeder valve the pressure is all but gone and no fuel comes out.

So I am starting to think pressure regulator or not sure if there is meant to be a oneway valve at the fuel pump end. Something is letting the pressure release quickly and maybe also not allowing the pressure in the fuel rail to get to the correct pressure for the injectors to discharge fuel correctly.

If I had a pressure gauge I’d put it on the schraeder valve but even then how do you determine it’s the pump not able to get up to pressure or the regulator is not able to hold any pressure? Maybe clamp off the return line or will this damage the fuel pump? Or is this one of those things you’ve just got to replace the part (regulator) to know for sure?

Anyways, had enough thinking about it today. Time to go and walk the dogs.

(the fuel rail etc had been apart for the last 4 months with no fuel in it, maybe some rubber seal in the regulator has dried out and lost its ability to seal? 4 months is not that old for fuel i would have thought to make the car perform like this?)

appreciate any suggestions.

thanks,

brett.

[Blknight.aus]

sounds like youve lost the signal from the coil to the computer thats turning on the fuel flow.

[PhilipA]

The wire is attached to the MAF loom. have a look see.
Regards Philip A

[bee utey]

A test light wired to your pump circuit will tell you how long it runs for. In a pinch you can hot wire it, just bridge terminals 30 and 87 at the fuel pump relay.

If you don't find a wiring fault, try disconnecting the vac hose to the fuel pressure regulator. If the regulator is stuffed it may be holding just a bit of pressure.

[pibby]

Checked the fuel pump was running whilst car was idling. Just depressed schraeder valve and she was still coming out. Even hotwired fuel pump off relay as a double double check but no change in symptoms. Ran without vacuum connected to regulator but no change either. As much as I was hoping for a spare wire to plug onto the coil there isn’t one unfortunately. When car was laid up had it running on an rpi dual timing power amp but I’ve swapped between that and the standard ign module enough times in the past to be comfortable that the wires are in the right positions.

I noticed this morning that there was no tacho signal and the battery charge light is on. They weren’t on when I was checking yesterday during the day as I made a point to ensure they were working (can’t speak for the afternoon didn’t check them then). thought might have knocked wire off back of alternator but they’re still there. I thought tach signal came from coil +ve ( or was it negative), either way those two wires are still connected to the coil.

Any more places to look or sounding like pressure regulator and the alternator charge/tacho is separate issue?

[bee utey]

Mud wasps nesting in your air flow meter? Try unplugging it, should run albeit roughly.

[pibby]

Mud wasps nesting in your air flow meter? Try unplugging it, should run albeit roughly.

:)

thanks bee utey. yeah i've tried most of the obvious things. unplugged them etc as i know the 14cux will pick up some default values. done same to tps too. the bXXch just won't change her behaviour. they're all like that eh? (said in jest:eek:)

i'm going to swing by allan at british 4wd and pick up a regulator anyways as i feel the pressure should stay in the rail longer than a few seconds.

[lewy]

no nothing about fuel injection,is there enough battery power to run the fuel pump,

[bee utey]

:)

thanks bee utey. yeah i've tried most of the obvious things. unplugged them etc as i know the 14cux will pick up some default values. done same to tps too. the bXXch just won't change her behaviour. they're all like that eh? (said in jest:eek:)

i'm going to swing by allan at british 4wd and pick up a regulator anyways as i feel the pressure should stay in the rail longer than a few seconds.

OK maybe the mud wasps (serious!) have nested in a fuel pipe. Disconnect the fuel line at the filter, check for flow/pressure from the pump. Run a hose into a tin. Blow back the lines to the filter using compressed air.

[pibby]

bee utey - have used the schraeder valve to check for fuel many times in the past. the amount of flow coming out now is the same as has been in the past. what is different now is the pressure disappearing so quickly. and bugger, the shop is not open this morning though normally is saturdays so couldn't get fuel regulator.

any other ideas out there? what if i clamp off the return line or restrict it almost completely to replicate the restriction of the regulator? would this potentially cause damage to the fuel pump?

[Blknight.aus]

blocked fuel filter or the pump is out of spec?

[bee utey]

bee utey - have used the schraeder valve to check for fuel many times in the past. the amount of flow coming out now is the same as has been in the past. what is different now is the pressure disappearing so quickly. and bugger, the shop is not open this morning though normally is saturdays so couldn't get fuel regulator.

any other ideas out there? what if i clamp off the return line or restrict it almost completely to replicate the restriction of the regulator? would this potentially cause damage to the fuel pump?

Legitimate test! Start the engine, apply pliers to return hose until engine remains running. No risk so long as you are careful. As a repair you can also use a boy racer adjustable regulator in the return line, they are for those stupid turbo ricer things and have a pressure gauge. You just need to cut the return hose. Have done this before, quite logical.

[pibby]

Well, I’ll be. Was about to get dirty and pull the fuel filter out. Thought start her again and maybe it’s fixed itself? (surely I’m not the only one who thinks that?) Clamped the fuel return line, no difference. It seemed to be cutting out at about the same time interval after starting. Couldn’t think of what would be turning it off – was there a timer somewhere. So hotwired coil to the battery incase the feed to the coil was being cut?? and it still konked out.

Thought the timing of the cut out meant there was an electronic component to it (well I am only guessing here). had my old ecu in the car which was a known faulty one (it makes the air con pipes freeze up with or without the air con on and from memory there was something else wrong with it). swapped the old ecu in and the car idled and revved. So no idea what’s wrong with the supposedly good ecu but something just seems to cut out after about 5 seconds. The tacho wasn’t working and alternator charging light was still on. Put a boost charge on the battery for 20 minutes and started car again and tacho was working and alt charge light gone out. Maybe the volts were too low for the reading to register on the tacho as the battery had run down and as it couldn’t rev no charge was going back into the battery/from alt???

Anyone got a 14cux lying around I can make a donation for? The one on the car came from TRS and lasted 15 months so not keen on forking out good money for something that’s only going to last that long. I assume it’s probably not repairable at a reasonable cost.

Well, I hope that’s the end of this little story and I can go and put the yellow top injectors back in, go get a tank of lpg and see how she goes! But that’s for next week.

Thanks to peoples for their suggestions.

brett.

[pibby]

Oh well, thought I had pegged it.

Went and got another ecu and it is no better than my other good one. Bugger.

Checked once again there is a flow of petrol when depressing Schrader valve and yes there is. Disconnect fuel return line on tank side of regulator and there’s no fuel getting through. assume pump generates flow but can’t push past the resistance of the regulator. Go get a commodore pump. Now have flow going down the return line. (had the fuel filter out about 2 weeks before I pulled the manifold off and it was spotless)

So back to the symptoms. Will start. When cold it starts then stops immediately. Start like this for say 10 times till things are warm and the idle gets a bit longer as she warms up. Eventually when things are warm (for an idling car) it will start and run rough with black smoke out the exhaust, the injectors are around 7.5-9ms and rpm around 500. after about 5 seconds of this it will rev to around 900 rpm and run smoothly for say 1 or 2 seconds then die instantly (sort of like when you turn your car off and give it a slight rev). the injector pulses go to 2-3 ms which is about right. Whilst it is running rough can rev it though it is still rough but it will still cut out at the normal time interval – it’s like there’s a timer of some sort involved. Are there other relays involved which switch off/on once a car has been running for a few seconds?

Measured the resistance of the injector banks and each side is around 42.3 ohm. In the injection book for 14cux it says should be around 4-4.5 ohms. The injectors are yellow tops so not sure if this is causing the different reading. Boths sides are exactly the same resistance (well to 0.1 ohm) so
Was thinking this probably rules out a short – or maybe not?


To troubleshoot have run wires direct to battery from the coil positive, fuel pump relay terminal 87 and main relay terminal 87 but no change.

So back to scratching my head. Went to get a fuel pressure gauge but bursons and repco only sell them in kits around $350 so bit too exy for a one off test.

Checked timing with a light and spot on. Gone cross eyed checking dissy to spark plug order.

Any thoughts/other things to check?

[justinc]

Brett, come and drop by on Monday, I'll loan you the Rovacom to plug in and get some real time numbers. Are you 100% certain you have the coolant temp and fuel temp switches plugged in to the right sensor?? Try swapping them over, it won't hurt the system.

JC

[pibby]

Thanks justin. The temp and fuel sensors are in the right way and giving correct readings. I had pulled the coolant one off to check for open circuit on the relevant ecu pins and all reading fine.

Anyone else got any ideas for the meantime. Would like to keep plugging away at this. Other things/tests to do? The thing about the engine just cutting out like a timer tripping not ringing a bell with anyone?

Thanks.

Brett.

[PLR]

G`day ,

too much to take in , well to many unknowns and not questions just things to ponder .

Tach signal comes from alternator not coil .

Regulator regs down not up , vac pipe disconnect as good as it gets , smell vac pipe for fuel if none probly ok .

Ignition modules can play like this when trying to die , which are you using and could either be wired unkind or be faulty .

It has both fuels , what and where is turned off , petrol .

Does it start on petrol then switch to lpg .

Does this require a timer or is it ecu controlled , timed etc.

Is the LPG ecu stand alone or piggy back .

I`ve no idea but if it were me i`d looking at the lpg/petrol part . Make sure when it changes to lpg from petrol that this is not all that your problem is , as in its changing from petrol to nothing because the lpgs not connected but it`s still trying to switch .
Is the piggy back tying to control petrol .

If it won`t run petrol , try starting lpg , as i under stand they usually inbuild a way of starting on lpg .

peter

[pibby]

thanks plr. i'm actually out of gas. well there's such a small bit there i can force start on gas but it konks out pretty quick as can't supply the pressure. i've got injected gas and have the software and i can see on the software that it is not trying to switch to gas. but it is a good point, might try and rig something up to test this. i've got the gas system completely turned off. if there was gas it would be a good pointer to where the problem is. the switch over to lpg i've configured to be on engine temperature. you can also hear the solenoids switching on and the lpg injectors make their noise normally but none of that is occuring.

got two ignition modules one standard and one an rpi dual timing but behaves same on both.

vac line going to regulator - no smell of fuel in it or leaking fuel.



Well still checking things. The gear input (inhibitor switch) signal at the ecu is meant to read 0 volts in park and neutral and 2.5 – 5.0 volts in gear. I am getting 2.7 volts whether in gear or not. So doesn’t appear to be in spec. but will this cause my symptoms? I haven’t been able to find where it is explained what the 14cux actually does with this signal.

[bee utey]

You need a bbq bottle and a hose filler connection. Try your local gas fitter if he has one. Then all you do is invert the bottle and LPG liquid flows in to your gas tank until the pressures equalise. PM me if you need me to send you a hose assembly.

[PLR]

Well still checking things. The gear input (inhibitor switch) signal at the ecu is meant to read 0 volts in park and neutral and 2.5 – 5.0 volts in gear. I am getting 2.7 volts whether in gear or not. So doesn’t appear to be in spec. but will this cause my symptoms? I haven’t been able to find where it is explained what the 14cux actually does with this signal.[/QUOTE]


G`day ,

the wire goes to pin 34 ecu , the ecu uses it when the engine is running and in gear to maintain idle by adjusting the by pass /stepper motor .

Put it in gear when it runs and if it keeps going ?

You haven`t said how long it actually runs ?

Does it idle well , when running and at what revs ?

Is it obvious the stepper is searching ?

When it`s stopping is it slowing and is the stepper trying to adjust or does it just stop ?

Are the stepper wiring and pipe work clear and hooked up right ?

Was it running before the german manifold ?

Was it running the gas injection before the manifold or were both done at the same time and was the dual timing also fitted at teh same time ?

Was anything else done to it while not running ?

[pibby]

Well thanks to the kindness of JC he allowed me the use of his fuel pressure tester. Here’s the readings.

Motor off and prime with key – 40 psi
Motor off and prime finished – 37 psi
Motor at idle vacuum line on regulator – 50-55 psi
Motor at idle vacuum line off regulator – 50-55 psi

So fair to say a faulty fuel pressure regulator. Tried a second hand regulator from jc and voila – she works.

I’m hazarding a guess here but is this like carburetors where the orings etc dry out if they haven’t had fuel running through them for a while? the fuel pump and regulator were out of action for a few months so I’m guessing that’s it.

Btw – there was no fuel leaking from the regulator out the vacuum line and you could still suck on the vacuum line and it would hold pressure. So you don’t always get the obvious signs of a failed regulator.