V6 VN running rough [LPG Problem?]

[KrazyKazza1]

G'day fellow commodore lovers.

I seem to have a problem; My 89 VN Commodore Berlina is a Dual Fuel..

Unfortunately it's running rough on petty (LPG might be broken, lack the funds to risk paying for gas i wont use to test if it is broken)

It's got an All or nothing attitude Where if you're not accelerating, it's dead.

My Dad's speculation is that when you run a car on Gas for a long period of time (Years), it will effect how the car runs on basic Unleaded Fuel and as a result will "Run like a woolly goat".. He says this will require it to be re-tuned to Petrol. (He isnt a mechanic or anything so he's pretty much just guessing from what i can tell :P )

Is this true? And if so, how can i fix it all?

Speedy help very much appreciated.

~Kazza

[vn_wagon90]

I had an ef tha did the same thing ... i changed Plugs, leads, O2 sensor and cleaned the throttle body up (throttle body cleaner (not cheap crap) and it was good after that, i rekon
O2 Sensor first, only because it has had gas going past it and now the computer doesnt know what to do when on petrol, therefor the car isnt running right.. Just some things to look at


Yes if a car has been running on gas for way to long the car will lose tune of the petty side of things .. O2 sensor has a different reading that it hasnt had in a whle and doesnt know what it is suppose to do.
In saying this, im thinking fuel filter and stale fuel maybe the cause of the reason it is running like crap, Even a fuel pump. When was the fuel filter last changed ??

[KrazyKazza1]

No idea when things have been changed. I cleaned the TB, have got new High Tension Leads to go in, going to get a new fuel filter this weekend (was planning on it before reading your reply) and i just found my Fuel Pump fuse was stuffed.

Unfortunately, hit another hurdle.. after reinstalling my TB, my car doesnt get any electrics. No dash lights, central locking or anything. The battery shouldnt be dead, as i unplugged the + before working on it, and it's a new battery anyway.

HELP! :S

[BadDad62]

Hey Krazy have you kept much petrol in the tank? as without it most fuel pumps will die from lack of cooling/Lubrication, Maybe the cause of Fuel Pump fuse being stuffed.

[KrazyKazza1]

Pretty sure there's always been fuel in the tank since before it started running like Crap.

Changed the fuse for the F/Pump last night.

Electrical problem has been fixed.

Here's what i've done (Or am doing today)
-New high tension leads
-New DFI
-New Coil Pack
-New Battery
-Cleaned Throttle Body
-New Spark Plugs
-Injectors Cleaned
-Trans Service
-Regular Service

Also hoping to go out and get a Fuel Filter

[KrazyKazza1]

Bump!

New TPS in car, gas high tension leads [trans service hasnt been done yet but it's not a problem with the trans so im in no rush to do it]

got an O2 sensor at the post office waiting to go in..

[Gosling1]

Kazza - I have been having a similiar problem with my Series 1 VN as well......

I had an LPG system fitted back in '05, and for the most part of the last 6 years, it has worked fine - dual-fuel system, you can change it over manually whenever you like. It always starts on fuel, and then at 1650rpm, it will change over to LPG. This engine has now done > 340,000km...

A few months ago, the cook started having issues with the car stalling-out, as she slowed down at traffic lights or give-way signs etc. Not every time, it seemed a bit intermittent......and occassionally, she could not get the car started after leaving it parked for a few hours....

This problem has slowly been getting worse - to the point that on some occassions after I drive it to work, it simply would not start for *ages*, and when it did, it coughed and farted like a bitch, clouds of white smoke pouring out the exhaust for a couple of minutes.....and really bad stalling basically as soon as you lifted your foot off the throttle when approaching a corner at any speed under about 40kmh.......a right pain in the arse.

Got the local LPG bloke who did the install to check it out - when I described the problem to him, his immediate diagnosis was a dud inlet manifold. He said that LPG conversions must not have any vacuum leaks at all, and if the manifold gaskets had a leak - then it will stall out and run rough. Also - the rough, lumpy idle on morning startup (which was also random - does it sometimes and not others) - was probably due to water leakage into the cylinders from the cracked inlet manifold......

Anyway, the inspection of the motor found that all cylinders are between 80-100psi, the inlet manifold gasket is shot, and 5 of 6 injector o-rings are also shot. He told me to not waste any money on the old motor - tired and worn-out he said - and just replace it with a later V6.............which I probably will.

So it may be worth getting a compression test done, and also replace all your injector seals and both inlet manifolds........

[delcowizzid]

check the fuel pressure regulator vacum hose for petrol pull the hose off the manifold and prime the pump a few times if fuel comes out or it smells of fuel its dead

[KrazyKazza1]

@Gosling1, i may look into getting a compression test done some time soon.

@Delcowizzid, i wouldnt know where im looking or how to prime the pump.

The black cylinder between the fan & the battery, with 2 vac hoses from the tb manifold going into it, what is this? and this being broken at the end where one hose is supposed to be put on- can that be causing my problem? .. is it even worth getting a replacement or is it going to cost an arm and a leg?