bizarre engine behaviour

[paul w]

So, just drove from the Blue Mtns to Horsham in Victoria...great trip apart from the carby work (and subsequent overnight stay) in Cowra.

One of the jets got blocked, so the thing refused to idle...the moment the revs dropped a second, the motor stalled, so I found a mechanic.

Anyway, that was fixed and it now runs beatifully smooth...amazingly beautifully smooth, except during the drive (700km) in the first hour (and the last hour of drive), the motor suddenly died, then refired and continued on as if nothing had happened. It happened three times each time, each about 20mins of driving apart.

It did it again, this morning, on a short (25km) drive into town. The motor suddenly died, then instantly regained it's composure and continued on as it nothing happened.

So, I think dirty fuel caused the blockage in the first place, so is this some remnents? Dump the fuel?

Oh, I averaged 6.3l/100km for the trip, at 90-95km/h average.

[QkslvR83]

A similar thing happened to me once. The motor would stop at random times on the way home from the city one night, whilst still in gear as well wich was weird. Took it to the mechanic, he said there was water in my fuel tank. Changed the fuel filter, dumped the fuel/water. Filled up the tank almost full again and added a 1 litre bottle of kero or metho (cant remember) to drive out any remaing water. Done the trick.

Went to Shell the next day to complain about the water, i had to wait in a que of other people complaining about the same thing.
Apparently Shell said it was normal to have water in there main underground petrol tank and its not there fault it ended up in ours. wtf?
Have never used shell since.

[paul w]

That's a bugger.

I'll drive it some more in the vain hope it'll clear itself up. But, I will take it to the mechanic I used recently to talk about what to do.

The mechanic I visited recently? Oh yes, got a fuel leak from the line from filter to carb....old age, I'm afraid. It was cracked all along the inside. It was removed when the carb was taken apart in Cowra. Once it was removed, that was it...did not have the hose to fit myself. Got every other bloody part...

A mechanic in Horsham fixed it up quickly - so quick he didn't bother about the labor, which was a nice touch.

Thanks for the reply. Be driving back in a few days or next week, so see how it all goes then, regardless of what I do.

[Damo]

So, just drove from the Blue Mtns to Horsham in Victoria...great trip apart from the carby work (and subsequent overnight stay) in Cowra.

One of the jets got blocked, so the thing refused to idle...the moment the revs dropped a second, the motor stalled, so I found a mechanic.

Anyway, that was fixed and it now runs beatifully smooth...amazingly beautifully smooth, except during the drive (700km) in the first hour (and the last hour of drive), the motor suddenly died, then refired and continued on as if nothing had happened. It happened three times each time, each about 20mins of driving apart.

It did it again, this morning, on a short (25km) drive into town. The motor suddenly died, then instantly regained it's composure and continued on as it nothing happened.

So, I think dirty fuel caused the blockage in the first place, so is this some remnents? Dump the fuel?

Oh, I averaged 6.3l/100km for the trip, at 90-95km/h average.

Learned a priceless tip back when I was doing 'auto' at college from our very cool tech. A brilliant way to clean out the jets and idle cct of the carby while on the engine is:

First thing is to pull off the air cleaner and its shrouding. You should be able to see the threaded post which the air cleaner lid sits over in the center of the carby.
You need (don't actually need to, but will make this process far easier) remove the post. If it has never been out, it will be fair stuck in there . I use the rear grip of my decent pliers, its the only way to grip the shaft hard enough to remove.
Once you have determined that you can indeed loosen it off, re-install everything and start the car and get it to operating temp.
Once at op temp, take the cleaner and shroud off again, then take the post out.
The engine should run slighty rough with all the vac hoses off the cleaner assembly.
Get a square of cardboard which will fit over the carby inlet (I used to use my hand), now get ready as you need to be fairly quick with this!! With the peice of cardboard at the ready, apply WOT with your hand on the accelerator linkage, when the engine reaches around 4-5000rpm (it will only take a second to do so!) slam the cardboard securly over the carby inlet. With the fairly big rpm and the massive vacuum you now have applied to the carby, it will draw in a fair amount of raw fuel straight through all the jets and idle orfice's cleaning the of most of the build up of gum and crap.
Keep the throtal 100% open till it stalls, then remove your hand or cardboard.
To restart, hold the throtal fully open and crank the engine till it fires (it will take 10 secs or so as it will be flooded to buggery), once started, free rev the engine a couple of times to 4-5000rpm to clear all the unburnt fuel out of the engine. It will blow a big cloud of smoke out the exhaust, so don't do it in front of the EPA!

Repeat process once more, and she will be running sweet.

Used to do this every 6mths or so, just brilliant.



Damo

[tassuperkart]

Bwaaahahahaha. THAT is whats called an "Italian Tuneup"!!!!!!!!

Is especially effective on Holleys which are very touchy in the idle circuits to gunge.

L8r
E

[trailblazer]

I would get a carby kit for it. Pull it apart and give it a descent clean with carb cleaner and compressed air. Change the fuel filter too. At least you know it will be right then.

[paul w]

Well, still in Victoria, and have been driving it just about every day now (about 50km), and no problems at all.

Actually, since the carb clean out (and ignoring the bizarre engine behavior), it's running unbelievably smooth...not sure about using the words 'turbine smooth' for the little 1,500cc plonk, but it sure as hell feels like it. Lovely.

I'll be heading back to the blueys in a few days, so that will be a good test.

Thanks for the cardboard trick, Damo. Maybe for another time....

[Timmzy]

Great to hear its running ok.

Isn't it surprising how smooth they run even with their 'old' carbie technology, etc. And they just go forever.....

It always amazes me.

Oh and by the way that technique of 'choking' the carbie to clean out jets, etc worked well for me for over ten years on one of those old Pinto 2lt engines I had in a cortina. The original weber would require that once every 6months or so when the idle and changeover to secondary jets got rough...

Damo's been around a while .....that's a trick handed down by many a generation of mechanics that will probably die off over the years with the advent of EFI, like most things....

Darren.

[Damo]

Bwaaahahahaha. THAT is whats called an "Italian Tuneup"!!!!!!!!

Is especially effective on Holleys which are very touchy in the idle circuits to gunge.

L8r
E

My good mate Ed, used to use the 'drive it like you stole it' technique on customers (carbied) service cars, to give them a good clean. The customers would comment on how smoothly they would drive when he would return the cars after being 'serviced'.
"The Corona. Points, plugs and take it for a hard fang Ed!"



Damo

[paul w]

So, returned in one piece.

The car now features a super-clean carb, new points, and new plugs - the latter the cause of much concern.

Left the Blue Mtns for Horsham in Vic, and got as far as Cowra. The thing simply wouldn't idle, the moment the revs dropped, it stalled.

Just driving the thing was all but impossible, having to turn it over the moment one slowed. Either the battery or starter motor would be ruined.

It meant a night in Cowra, then off the next day. Motor running smoothly, apart from the odd miss. It happened three times in the morning, then three times again later that day, after many kilometres covered.

The next day, same deal: three misfires in the morning, and then later in the day, after many kilometres.

Anyway, eight days later I drove back. Just a few misfires for the two days of driving, but over the rugged Goulbern/Oberon road, missfiring often.

The next morning, outside home, the thing fired up then stalled and would not re-start. The NRMA mechanic said the carb was flooded, so a tow to my mechanic.

His verdict? Rubbish plugs. He even said where I got them from (he was correct) and said people fitted the things and complained of a miss-firing engine. Basically, the things kept miss-firing, getting fouled, which caused the build-up of fuel (this is a brief explanation).

He put in NGKs, adjusted the choke, and it runs like a swiss watch. No, really. Beautifully smooth.

So, apart from the carb blockage (bad luck) and poor choice of plugs, the car actually did quite well, covering hundreds of kays without a hiccup.

Off to Tassie in Spring. Very confident the car is now sorted.

Like to show you the photos of the trip, took some great ones for you, but I lost the camera.

Oh, also lost m,y false teeth. Don't ask.

[Panda_ET]

Personally for a nissan I never get anything but NGK my mech put bosch ones in once ran like arse until I put a decent set of NGK in Nissan manual recommends them so I just stuck with them

[tassuperkart]

hehehe, I put in a set of NGK Iridiums in everything i have and I never look at them ever again.
L8r
E

[paul w]

The car is purring. Very smooth, great gear changes (its an auto) and now I've finally got my driving lights on and wired up.

BTW, the trip to Horsham and back was 2,900km.