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

Originally Posted by 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?

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.

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.

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?

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

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.

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

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.

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.