Stalls after acceleration when dropping to idle

Quote:

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Originally Posted by mudnut

Have you gone over
the above list?
Mine has started
to backfire on start up
but intermittently.
Intermittent faults are
the worst!!!!!
I replaced the leads
and fixed a lot of
problems a few
months ago.

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RB30 carby can be pretty weather sensitive when it's on dual fuel.
I had been having misfiring and occasional backfiring.
I basically put in a second dizzy which I opened up and cleaned before I put it in.
No backfiring or misfiring now, but it idles pretty low when cold(about 400ish) on LPG.
Petrol idling is slightly higher(about 650ish).
I think the problem is in the carby idle circuit.
I haven't bothered to tune the carby yet, 'cos the problem isn't urgent.
Open up the dizzy and give it a good clean and lube the mechanical parts.
I would also try advancing the timing a little bit as well.
RB30 Patrol dizzy is electronic, but there're vacuum advance & mechanical(centrifugal I think) advance, which are both mechanical. They need lubing and service after a long time use.

In mine, ignition lead no-2 was showing 5200 ohm resistance, which was fair bit higher than the rest(twice as much).
But, I still haven't replaced the leads.

As for the OPs issue, I think it's the carby, according to my similar experiences.
Having said that, it's worth checking the fuel filter, gauz filter and fuel pressure, before opening up the carby and trying to tune it.

Quote:

---

Originally Posted by mudnut

Have you gone over
the above list?
Mine has started
to backfire on start up
but intermittently.
Intermittent faults are
the worst!!!!!
I replaced the leads
and fixed a lot of
problems a few
months ago.

---

Yes, intermittent problems are definitely on my list of least favourite things, I've checked some of the things on the above list already, spark plugs were replaced at last service, I replaced the ignition leads a few weeks back, the sight glass is not too dirty and the fuel level is about right, the earths and electrical connections seem pretty good, linkages are all moving smoothly and I've put a bottle of the injector cleaner in the tank.

I'll try and get a new fuel filter this arvo, and I'll also spray some cleaner down the throats of the carb to see if that helps and I'll spray some WD40 around the manifold to check that and have a look in the dizzy. See if I can find anything.

By the time I was halfway through the track yesterday it had returned to a normal idle, and is now running sweetly, so if none of those items are the cause then I guess I'll have to wait and see.

Quote:

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Originally Posted by Patrol'n

Yes, intermittent problems are definitely on my list of least favourite things, I've checked some of the things on the above list already, spark plugs were replaced at last service, I replaced the ignition leads a few weeks back, the sight glass is not too dirty and the fuel level is about right, the earths and electrical connections seem pretty good, linkages are all moving smoothly and I've put a bottle of the injector cleaner in the tank.

I'll try and get a new fuel filter this arvo, and I'll also spray some cleaner down the throats of the carb to see if that helps and I'll spray some WD40 around the manifold to check that and have a look in the dizzy. See if I can find anything.

By the time I was halfway through the track yesterday it had returned to a normal idle, and is now running sweetly, so if none of those items are the cause then I guess I'll have to wait and see.

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Open up the dizzy and give a good clean with a soft brush and some contact cleaner.
Then spray some lube or use few drops of machine oil or similar.
RB30 Nikki carbys are definitely temperamental after few hundred thousand kms on them.
Even if they are in mint condition, they still need seasonal tuning.
Summer tuning isn't quite right for the winter.

In my case, even though I got new leads, I didn't change them, 'cos I kinda had a gut feeling that a single ignition lead with slightly higher resistance couldn't cause all the hiccups.
Another solution would've been to get the dizzy reconditioned by a pro.
I opted for a second used dizzy instead, as I tend to believe in having backup units when it comes to electrical stuff in car engines.

If you haven't rebuilt the carby in the past, it might be a good thing to do it now. When I did mine, I installed a brand new plunger boot from the rebuild kit. After just over a year, the plunger boot failed(cracked). Most likely from not being careful when I inserted it during the rebuild.
As I didn't wanna buy another kit($78) juts for the plunger, I fixed it up with superglue.
If you're rebuilding the carby, take all the time and do it slowly if it's your first carby rebuild job.
Doing things in hurry without enough hands on experience is not ideal.

Quote:

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Originally Posted by dom14

RB30 carby can be pretty weather sensitive when it's on dual fuel.
I had been having misfiring and occasional backfiring.
I basically put in a second dizzy which I opened up and cleaned before I put it in.
No backfiring or misfiring now, but it idles pretty low when cold(about 400ish) on LPG.
Petrol idling is slightly higher(about 650ish).
I think the problem is in the carby idle circuit.
I haven't bothered to tune the carby yet, 'cos the problem isn't urgent.
Open up the dizzy and give it a good clean and lube the mechanical parts.
I would also try advancing the timing a little bit as well.
RB30 Patrol dizzy is electronic, but there're vacuum advance & mechanical(centrifugal I think) advance, which are both mechanical. They need lubing and service after a long time use.

In mine, ignition lead no-2 was showing 5200 ohm resistance, which was fair bit higher than the rest(twice as much).
But, I still haven't replaced the leads.

As for the OPs issue, I think it's the carby, according to my similar experiences.
Having said that, it's worth checking the fuel filter, gauz filter and fuel pressure, before opening up the carby and trying to tune it.

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Mine isn't dual fuel so at least I don't have the complication of LPG to deal with, it is weird as it is intermittent, but I'm going to have a look at the rest of the items on the list on the previous page, and that will include replacing the fuel filter and having a look at the dizzy, so I'll see if that shows anything.

I've found a an old school carby bloke that will rebuild the carby for $380, I'm considering it just to eliminate that as the cause, but I might do all the other things first as I'd rather not spend the best part of $400 if I don't have to just for a carby freshen up, but if the other things don't show up any problems, I reckon I'll be doing the carb, having to constantly maintain revs on rock and clay descents and climbs can be a brown pants experience. (Yes a sensible person might ask why I would even go on the hill in the first place when it wouldn't idle, but it was working fine when we started the track)...

Quote:

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Originally Posted by Patrol'n

Mine isn't dual fuel so at least I don't have the complication of LPG to deal with, it is weird as it is intermittent, but I'm going to have a look at the rest of the items on the list on the previous page, and that will include replacing the fuel filter and having a look at the dizzy, so I'll see if that shows anything.

I've found a an old school carby bloke that will rebuild the carby for $380, I'm considering it just to eliminate that as the cause, but I might do all the other things first as I'd rather not spend the best part of $400 if I don't have to just for a carby freshen up, but if the other things don't show up any problems, I reckon I'll be doing the carb, having to constantly maintain revs on rock and clay descents and climbs can be a brown pants experience. (Yes a sensible person might ask why I would even go on the hill in the first place when it wouldn't idle, but it was working fine when we started the track)...

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For $380, you can buy a brand new carby. It's on ebay.
To rebuild your existing carby using a carby specialist, it shouldn't cost more than $200 or so.

http://www.ebay.com.au/itm/CARBURETT...item2ecdbd766b

Or get the rebuild kit,

http://www.ebay.com.au/itm/CARBURETT...item2c99f241f8

From the description, I reckon it's the carby. dual fuel causes extra dramas with carbys when it comes to tuning it for both fuels as well as LPG causes slightly extra wear due to LPG being a gas on ambient temperature. But, the normal mechanical wear and tear of the carby still happens with petrol, as well as the blockage of fuel lines from residue over time.
Best way to isolate the issue is to get a second used carby and fit it in. I keep a second carby all the time just in case.
As you may know, both RB30 and TB42 carbys are essentially the same with minor differences inside(main jet size etc).
You can bolt in a TB42 carby onto an RB30 and still run it. It probably run bit rich, but shouldn't have any major dramas.
I'm pretty sure the second carby that was sold to me by a wrecker as an RB30 carby is from a TB42.
The only issue I'm having with it atm, is that it's idling rpm is bit too high. Even with that problem, I think it's due to the butterfly shaft getting stuck inside.(not an issue from jet size or other TB42 carby specific issues)
I just need to dismantle it and polish it a bit.
So, I reckon you should get a second carby and test it. If that's the issue, then get a rebuild kit and fix your original carby and sell the second one.
I'm keeping my second one, 'cos I need it for long trips.

So, in a nutshell, dual fuel or not, carbys need rebuilding after 100k of kms or so.
Running a carby on LPG is fine, as long as you run it on petrol for few kms every week.
I put the carby through couple of kms on petrol everyday.

have a look at the above few pages of the Nikky carby manual(previous post). That will guide you how to do the rebuild job.

See if you can borrow a second carby from a mate. Happy to lend you mine, but you're way too far away.

More diagrams here.

http://www.patrol4x4.com/forum/nissa...-needed-75406/

That's some good info mate thanks heaps! I reckon I'll definitely rebuild the carb, I have no way of knowing how many k's are on it, so probably good insurance anyway.

Not my first go at rebuilding a carb, done a few webbers some years back, but will be my first Nikki carb. I like the idea of a spare too, maybe a worthwhile spare for a couple of longer trips in the pipeline.

Quote:

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Originally Posted by dom14

See if you can borrow a second carby from a mate. Happy to lend you mine, but you're way too far away.

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You're not in Perth then?

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Originally Posted by Patrol'n

You're not in Perth then?

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Melbourne. can't seem to find a way to edit my profile.