TB42 LPG misfire loss of power above 3000 rpm

[Baalsgate]

Hi I am new this forum and New to owning a FWD , I got the Nissan Patrol LWB 1990 with a cracked head and got a new head machined up, fitted it myself new gaskets, new head bolts all torqued to speck in order.

Now its been running a few weeks and not perfectly had a bit of a miss when at idle on gas and petrol so after new points, leads, I modified the rotor to have an extra couple of mm, misfire seems gone err well sorta .

I had a spare gas carby and expander and changed them over being that I was suspect about the operation of them.

I think its getting very close to running right but now i have found that put it in first gear it will rev out to 6k rpm the first time (intermittently) then will not go over 3000 3200 rpm , foot on the floor it seems to be missing and spluttering, I thought it may be the rev limiter on the rotor so I locked it off with a bit of wire , and still does the same thing.

strange but it seems to do it when the "power" light comes on , while I first thought the power setting just changed where the transmission changes gears but maybe its connected to more than that ?

I am in knoxfield VIC and while I am pretty good with engines , and electronics I am looking at this and scratching my head .

Would be good to meet some other Nissan Patrol people in my area if they are so inclined.

Any suggestions ?

[killalux]

does it have this prob on both petrol and gas?
is it worse under load?

could be either running lean, or ignition missfire on all cylinders, which would suggest coil, coil lead or track in the rotor button.

[ShaneGQ]

mine did the same. took it to a gas place and they knew straight away to put a new dizzy cap and points, then reset the cardy idle.

[Baalsgate]

ok here is an update :

I replaced the gas expander ( I had a spare one ) and cut off gas relay thinking that it was not operating properly.

Petrol now seems to be running fine with out any problem so it suggests that its in the gas system.

On Gas its running fantastic up until it hits this problem .

I have my suspicions about the tank tap not opening enough , here is why
when we did the roadworthy the gas tank tap was hard to shut off completely when we took the tank out and I suspect its not a great tap.
It seems to have a post for a magnetic gas cut off but there is no coil on it I wonder if its not open fully because there is no solenoid thing, I might try adding one and seeing if theres any difference, running out of ideas.

It feels like im out of gas but sit at idle and it will rev out accelerate no problems at all, until its used a bit of fuel then the spluttering begins as it hits 3000 rpm and seems to persist until I have lower revs for a few seconds then it will rev out again with out a problem .

I will try a couple of other ideas tomorrow , may see if i can get a pressure gauge on the gas line to be able to monitor pressure.

keep the suggestions comming and thanks for the comments

[blownba]

Well it isn't RWC without the electric lock off on the tank if it has the provision for one.
You shouldn't be getting any gas flow at all if the lock off is not powered up!!!!
There is something up there.
I hate to be mean but judging by the knowlege you have and what you are calling the CONVERTOR, you really should not be stuffing with what you are.
High pressure lines should only be touched by qualified personel.
Me thinks you need to spend the dosh and get it to a good gas joint.

[Baalsgate]

Well it isn't RWC without the electric lock off on the tank if it has the provision for one.
You shouldn't be getting any gas flow at all if the lock off is not powered up!!!!
There is something up there.
I hate to be mean but judging by the knowlege you have and what you are calling the CONVERTOR, you really should not be stuffing with what you are.
High pressure lines should only be touched by qualified personel.
Me thinks you need to spend the dosh and get it to a good gas joint.

Yes the Electronic lock off on that tap seems that It may have been modified maybe the valve body removed but its non functional even when adding the magnetic coil, I will not know until I disassemble that mechanism as to how it is open.

As for you personal opinion on what qualifications I have with regards to working on high pressure systems, you don't know me or my qualifications so you can not make these assumptions, while I agree that people that have not the necessary abilities or qualifications should well leave these systems alone, I do not fall into this category.

As for what I call it that makes no difference it "converts" and regulates high presure to low pressure so I refer to it as a converter.

With regards to LPG system regulations in Victoria the electronic lock off at the tank is only necessary on systems installed after a certain date of installation ( I dont know what that date is but my system was installed in 1990 ) preexisting systems installed before prior to that date where the regulations changed which were compliant at the time of installation do not need to be compliant with new regulations as long as they were compliant to the old ones even for a RWC, which is what I was told by APA when the tank was tested and a LPG certified installer that checked the system for the RWC.

I cant be certain but I think the tap was damaged by the mechanic tring to shut it off the tap with a wrench, when we were making up new brackets, so I will be replacing the tap on the tank when I have time to eliminate that as a possibility and also make it easier to shut off.

Anyways thanks for your comments .

[blownba]

The reason why I said that is because usally when a lock off is there the tank is newer than Jan 94 and requires it to be functional.
I will keep my comments to myself than shall I ???
Good luck anyway.

[Baalsgate]

Fixed at last Yay !, Swapped over the LPG Tank on the weekend and it was the tank Valve obviously not opening properly but just enough to fill the line but under load or heavy acceleration it would run out of gas.