Diesel lpg problem

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Porks
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Diesel lpg problem

#1 Post by Porks » Sat May 22, 2021 8:48 am

Long time problem with my 4.2td Nissan Patrol (Australia) with the Apexus fuel gauge power outage after 20 minutes running time.
Fitted in 2008 a BRC Genius 1500 Reducer mtm sequential unit ALWAyS using diesel with lpg as supplement.
Will sometimes run all day without fault OR run 20 mins (usually) or for 1 hour. Usually when it goes blank it will remain off until next day, sometimes back on in 2 mins, 30 mins.. who knows.
New kit in converter, new filters, new tank solenoid, tank retested, all earths checked constantly, hoses reversed, NOT freezing, converter TOO hot to touch.
The 20 minute thing makes me wonder if its pressure drop in line but local lpg man says NO its electrical, but how does that fit with the timing issue ?
Appreciate any comments thoughts etc Porks

I should also mention that fuel gauge was sent back to manufacture who tested same withoutfault. I then aquired a second unit to be sure and it also has the 20 min cut out thing. Plus the ECU was sent to Sydney and a thermal fuse was replaced with standard bladefuse but again no solution. Last year with the caravanconnected the cut out problem seemed to disappear (earth?) for first time, perhapsbecause of new reducer kit?

Brian_H
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Re: Diesel lpg problem

#2 Post by Brian_H » Wed May 26, 2021 5:27 pm

The usual reason for a system going to sleep is a loss of either of the live feeds, it may be worth looking into where they are both being fed from, possibly monitoring them with a multimeter when in use to see if anything it happening there. I'd say confirm where they are actually connected to might be best place to confirm. Of course as you say earth might be the cause as well, but that should be easier to work out. Again confirming where its connected to might be an idea?

Diesel systems aren't very common here but would imagine the basic wiring is somewhat similar to a petrol system without all the injectors breaks etc.

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Re: Diesel lpg problem

#3 Post by Porks » Sun May 30, 2021 4:56 am

Thanks Brian_H for your reply.
Not sure what you mean by either of the live feeds.
The only positive to the fuel gauge ( brown) disappears back into the 56 wire ECU. When the fuel Apexus PG200 fuel gauge blanks out there is no power at this brown wire. Are you referring to the Sender wire as live feed ?
There is another positive wire but not connected to gauge but it picks up the ignition from the wiper motor.
Again when the gauge blanks out I still have wipers so I cant see this as the problem.
The overall DOMINANT factor is this 20 minute running prior to cutting out.
A few days ago after installing new gearbox to chassis earth plus changing sender earth to tank flange it again ran for 20 mins EXACTLY then off for 4 mins then back on for 3 mins then off for next 15 mins till I returned home and switched off.
The gauge NEVER fails to come on (amber prior to warmup and green switch to lpg) when cold of a morning.
Thanks for your interest.

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Re: Diesel lpg problem

#4 Post by Porks » Sat Jun 05, 2021 6:00 am

Just measuring both feeds mentioned by Brian_H
When I remove the sender wire off the sender unit at the tank with motor running it measures 11.3 volts, when I measure the same wire at the connector prior to the LPG Apexus gauge it measures 2.3volts.
The 12v power wire prior to the Apexus gauge measures 14.4v. Not sure if you can actually take notice of voltage on the sender wire voltage wise ?

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Re: Diesel lpg problem

#5 Post by Brian_H » Sun Jun 06, 2021 6:56 pm

Found what there is in way of instructions for the kit, attached below

What little detail is there, suggests that the switch only really deals with showing the level in the tank - it doesn't seem theres anything there to control the solenoids (at least nothing I can see?) How are you switching them currently? Is there any ecu with this kit, or is it just your switch? If the switch is somehow wired to switch the solenoids, could you describe how its doing it? If you can provide a bit more info around this, you might get an answer from one of the installers on here.

The only possible thing I could see causing the times you describe, is if the switch is getting too hot from being asked to do something its not capable of. It should manage switching a relay for example to control the solenoids, but is probabbly not capable of switching them directly (unless you know otherwise from the manufacturer/supplier?)

As said, its not common kit to see in the UK and most of the users on here are from the UK, so as much info as you can provide should help there.

The key thing would be if you have the 12v feed dropping off when the gauge goes dead - The usual place we take our +12 switched feed from is the Petrol injector feed, you obviously don't have that option. I've found in a few cases you can find a suitable switched spare fuseway in the interior fusebox and use a spade connector to utilitse that when wanted for purposes like usb chargers etc, that may be an option if your feed from the wipers isnt suitable, though provided its switching in the right manner I can't personally see an issue with using it.

The instructions do suggest the level gauge is only used to indicate the fuel level, as is the case with petrol conversions. I wasn't getting at the voltage on the sender end, but appreciate it probabbly wasn't clear from the previous post!.

You do mention suspecting the earth connection, it may be worth checking/advising where the earth is connected to or finding somewhere better if you are in doubt of where its currently connected to is good enough?
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Re: Diesel lpg problem

#6 Post by LPGC » Sun Jun 06, 2021 8:29 pm

It seems obvious that by 'switch going blank' you mean all lights on the switch go off, but it's worth clarifying that point in case you mean something else.. Do all the lights on the switch go off?

MTM Ecu's are the same ECU's as used on BRC and Zavoli Bora sequential systems, and at least on the sequential (petrol engine) conversions the 2 main power feeds Bri mentioned should be the only aspect that can mean at least some lights on the switch on/off. I reckon Bri is on the right lines suggesting a power feed (main or more likely ignition live) issue.
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Re: Diesel lpg problem

#7 Post by Porks » Thu Jun 10, 2021 11:44 am

Thanks Guys, LPGC first.. Yes ALL lights go off, this is because the input red power wire also gives Nil voltage at the connector.
I think Brian might be onto something when he mentions the Relay. I can’t find any relay connection and have always wondered if the wire is getting too hot AFTER 20 minutes and causing the blackout. Why it sometimes runs a lot longer is a mystery but 20 minutes is the key.

So Brian when I start of a morning the fuel gauge just has an Amber light. When warmed up I press the gauge switch and 4 green lightscome on to indicate I’m using gas. When I press the switch I can hear the tank solenoid turn on. Yes there is an ECU unit 56 wire sequential which has had a replacement of its thermal fuse for a blade fuse, which made no difference. If I’m going to pick up the power wire ( joined into wiper wiring) then it sounds like I need to run it through a relay at this point ?

Having just sald that, I do occasionally get the wipers playing up, they lose the intermittent wipe or self park but some time later they correct themselves?

Thanks for the chart Brian, I have something similar. My gauge earth is attached to body not chassis. The system earths, 2 for solenoids are attached separately to battery. I have had them onto body and chassis without making any difference. I have also tried the black/ white earth of the gauge with yellow wire but that just gives a different display and so I have folded both those wires back an run the green wire. Gauge when powered on will go from single amber light to 1-4 green lights depending on lpg in tank. When I turn gas off it just goes back to single amber.
Think I might consult a local lpg guy about the relay, does this sound like a good move to you fellas ?
Thanks for your help and interest. Porks

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Re: Diesel lpg problem

#8 Post by Brian_H » Thu Jun 10, 2021 7:28 pm

I'd read it that you connect whichever of the 3 suits what you want on the display as far as the wires are concerned. Going to the body should be fine for the gauge earth.

If it is getting hot due to being asked to do too much, then I'd expect you'd notice it getting hot anyway. Think its more likely that the power is being lost for some reason.

When you swapped the switch, was it just the switch or the wiring loom as well that you swapped? I'd be tempted to check it with a multimeter when its in the dead state to see if you are getting any voltage through it. Might also be an idea to check the gauge earth in that state as well just in case its failing under load due to a bad wire or similar.

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Re: Diesel lpg problem

#9 Post by LPGC » Thu Jun 10, 2021 9:39 pm

Long shot but there is no EGT sensor reading too hot exhaust and turning power off to the system?
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Re: Diesel lpg problem

#10 Post by Porks » Sat Jun 12, 2021 8:07 am

I have a spare PG200 gauge and loom. I have tried both to no avail including switching looms. They both cutout.
There is an EGT sensor and probe at rear of turbo. This failed after about 12 months (? maybe 9 years ago) can’t remember what really happened but I think everything just went dead ??
Drove 260km yesterday, green lights (4) went off after 60 mins. Stayed off during stopping and starting for about 3 hours. Came on again for 10 mins then off again for around 2 hours. Came on again just as I arrived home.

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Re: Diesel lpg problem

#11 Post by Porks » Sun Jun 13, 2021 5:40 am

Alternator ? Just another thought comes to mind.
It has a single wire coming off the alternator to a Deutch connector which then disappears into the main 56 wire loom. The voltage at the connector with motor idling is 7 volts, is this adequate ?
I believe this wire fulfills the role of rpm sensor ?
I have found a break in this wire on a couple of occasions which completely blanks out the system.

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Re: Diesel lpg problem

#12 Post by Gilbertd » Sun Jun 13, 2021 9:25 am

I know nothing about the system you've got but it does all sound to me like a dodgy connection somewhere. If you have a bit of resistance in a power feed it will warm up as current flows. As it gets hotter the resistance rises until whatever it is powering doesn't see enough voltage to work.
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Re: Diesel lpg problem

#13 Post by Porks » Sun Jun 13, 2021 10:31 am

Thanks Gilbertd that’s about how I see it. I think I’ll put the alternator in for an overhaul, its about 10 years old although this has beengoing on for much of its life. Hopefully it may be a crook diode ?
I’ll also check out Brian’s idea of a relay on the power wire.....thanks for all your help fellows cheers Porks

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Re: Diesel lpg problem

#14 Post by LPGC » Mon Jun 14, 2021 9:55 am

Porks wrote:
Sat Jun 12, 2021 8:07 am
There is an EGT sensor and probe at rear of turbo. This failed after about 12 months (? maybe 9 years ago) can’t remember what really happened but I think everything just went dead ??
'Went dead' like it does now?

A lot of diesel LPG supplementation systems feature an aftermarket EGT sensor fitted in the exhaust, when this reads too hot or maybe if this reads disconnected the LPG system may turn off.
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Re: Diesel lpg problem

#15 Post by Porks » Tue Jun 15, 2021 12:39 pm

No lgpc, not like it does now. When it failed last time that was it nothing, no recovery.
At least now I know it will come on EVERY morning , amber then green when I switch on after warm up. Whether it lasts longer than 20 mins is always a guessing game. I suppose the egt could be faulty but expensive if not the problem, about $350 aus last time.

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