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NF Fairlane + Sprint Gas, losing power and surging 

 

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 Post subject: NF Fairlane + Sprint Gas, losing power and surging
Posted: Thu Jan 15, 2009 10:04 pm 
Oompa Loompa
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Age: 49

Posts: 30

Joined: 4th Nov 2007

Ride: Fairlane

Location: Brisbane, Northside
QLD, Australia

A little while ago I noticed a moaning noise from the converter when I put my foot down a little, this later developed in to intermittant/momentary power loss. It has now gotten so bad that at times when you cruise at 60klm the car dies for a moment and kicks back in surging for a moment and dieing again.

If you put your foot down the power slowly comes back and suddenly there is a huge burst of power, then sometimes it dies off again.

I recently took it in for a checkup, the place tuned it and it come back with heaps of power and ran sweet for 2 days. Once it started playing up I switched back to petrol and noticed the idle on petrol was terrible. My nephew gave me instructions how to retrain the idle and I done that, petrol now idles fine, but on LPG it surges on idle and runs like crap.

After checking all plugs, wires, hose clamps and so on I figured I do a backyard test on the converter with a lump of wood, tapping it lightly at first then a little harder to see if maybe some junk might get disloged from it, I know this sounds silly, but what happened was each time i tapped it the idle dropped and the car almost stalled, not sure if this indicates anything.

I removed the gas hose from the converter to the inlet and put my finger over it to test for pressure, there was enough to make it impossible to keep my finger on it.

Between the Converter and the Inlet is a type of valve that has a 4 wire plug and is has a stepper motor and a type of ball vavle on it. When you turn the ignition on it closes and then opens to half way and stay there, it does this on LPG or Petrol. I disconnected the plug, opened the valve to max open and tried running the car on lpg, it barely idled at all. So I reconnected the plug and had to turn off then on the car to get it to reset back in to the half way position. (Not sure what this is called or what it's used for).

Today I also replaced the coil as it showed signs of cracks in the casing, after replacing it there was no change to how the car ran.

So now I am stumped. What might be going on. This system was install 1 yr and 8 months ago.

I would also like to know how to get hold of the technical docs that show the wiring and setup so i can double check everything, if someone know where/how/who to get it from and how to tune it at home enough to get it running so I can get it dyno'd.

I also heard that there has been problems with wax buildup or other contaminants that can foul up the system, how do i remove it ?, I don't mind pulling the converter apart, this system is new to me, the only one I ever pulled apart before was my old Datsun 200B LPG model back in 1980, but I also had full tech docs with it back then.

The place I took it too recently said I should just replace the converter, but at a cost $500 I rather attempt something at home, if all goes south then it won't hurt cause I'm possibly up for a new converter anyhow.

Last edited by skozzy_ak on Thu Jan 22, 2009 4:56 pm, edited 2 times in total.

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Posted: Sat Jan 17, 2009 2:41 pm 
Oompa Loompa
Offline

Age: 49

Posts: 30

Joined: 4th Nov 2007

Ride: Fairlane

Location: Brisbane, Northside
QLD, Australia

Today I removed the converter and filter (2 seperate parts).

Dismantled the converter and it was fairly grubby inside, around the point where the gas enters the converter was stained dark red and sticky as hell, I scrubbed it with terps and washed it with degreeser. At the point of the converter where the gas enters is a lever on a kunckle that is operated from one diaphram, the kuckle point was sticky and the valve end is a rubber stopper that was coated black ( read later ) and etched away, I was able to flip the stopper around and use the good side.

The two adjusters on the side of the converter operate a 2 finger lever which limits another diaphrams movement, these had junk on them so that is also cleaned. The rest of the converter was mostly clean, just a little broken rubber fragments from the diaphams, probably from assembly.

I had an idea from reading other posts here and there the redish gunk was wax buildup from poor quality gas, but I couldn't understand what the black gunk was till I pulled apart the filter.

The filter has 3 parts, a solinoid, a paper filter and magnet. When I pulled it apart heaps ( and I mean heaps ) of black magnetic dust come out, the small 3mm diameter magnet had about 10mm of black dust stuck to it and the rest just fell out. So that was cleaned, as for the paper filter, it was small enough to put over my mouth and blow through it, but it was ( and still is ) badly blocked with the black dust and it was impossible to clean out, when I try blow through it I nearly pass out it was so hard.

So i am guessing that it was the main source of my problem, and the other may have been the worn out rubber stopper on the gas inlet side of the converter.

At present, the car idles better then it ever did ( since I owned it ), accelerates smoother then it ever did. Befor the problems the converter or filter used to make a moaning noise, it does it again but only under full throttle, but this time there is no power loss like there was before. So I guess again that the noise is from the filter.

So in the end a few slow and carefull hours worked for me, the car runs well once again. It will need to be re-tuned I guess as now the mixture/idle settings are tampered with and to be safe it will need a gas leak test done to make sure I didn't F anything up. It doesn't leak water, it doesn't smell of gas but to be safe I will have it checked.

If guess next time I come across this I will attack the filter first, it's smaller and easier to pull apart.
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Posted: Thu Jan 22, 2009 5:00 pm 
Oompa Loompa
Offline

Age: 49

Posts: 30

Joined: 4th Nov 2007

Ride: Fairlane

Location: Brisbane, Northside
QLD, Australia

Well I got a new filter installed and now the car is running like a dog again, increasing speed a little to fast stalls the motor but it does handle big rpms ok once you get it there.

There was no leak found after begin tested at the shop from when I pulled it apart last time, so i will have to do it again to check if more junk made it to the converter or maybe a pin hole in a diaphram.

Does anyone know if there is another filter inline from the tank to the converter like maybe at the tank. Something is restricting the gas flow and I can't pinpoint it just yet.
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