Stalls after acceleration when dropping to idle

[Pearly]

Can anyone help - garage can't find solution. I have a 3 l rb30 petrol motor. It stalls when I come to a stop if I take out of gear. It's intermittent and appears to happen when hot. The hand throttle pulled to spin it over at about 2000 rpm appears to be the only way I can stop her from stalling. I'm guessing its probable a needle in carby issue or a diaphragm ?? Can anyone help? It's driving me mad as when she stalls I lose power steering - no fun at all !

[93patrol]

sounds like you need a carbie kit through it mate they are about $80-100 or you can hand it over to a mechanic and get them to do it, I just ordered a 330 holley from ebay and whacked it on still needed a final tune though from someone more experienced than me on this sort of caper

[lucus30]

Don't have LPG and a snorkel do you?

[mudnut]

The second stage of the carby can stick in various positions and cause problems too. Does it flood, (black smoke) or starve for fuel?

[Pearly]

Thanks guys. Interesting it starts ok after stall but you have to put your foot to the floor like trying to start a flooded engine .... Also along those lines and something that makes scense now, when you take foot off the gas and just let it idle going down hill after she's worked hard getting up it, she occasionally backfires - so maybe it is a flooding problem ?. If so where should I look first? And no I don't have snorkel yet or LPG - thanks all what a great forum!!

[mudnut]

Could be a bit of foreign material in the needle and seat, or the float is split.

The Haynes manual list: Idle speed incorrect, clogged fuel filter, or water in the fuel, choke not operating correctly, damaged distributor, faulty emission system, incorrect spark plug gap, vacuum leak and also incorrect valve clearance, (but RB30 has overhead cam, so not relevant unless lifters or camshaft are worn).

Easy to do stuff : Try a cup of metho in the fuel tank or put some injector/carby cleaner in the fuel.

Check the distributor, for eroded or burnt metal and that there is no signs of moisture or cracks. Check the rotor button, making sure the overspeed spring is working and that the outer edge isn't eroded or deformed.

Take the top off the air filter housing and make sure all the linkages and choke are working. Change fuel filter.

Clean the sight glass in the front of the carby, and see that the fuel level isn't too high or too low.

Move all the linkages and make sure that the second stage butterfly is able to move easily throughout its range.

Tape up the unconnected hose connections. With the engine idling, spray wd40 or crc around the inlet manifold, (especially the gasket). If the spray is sucked in anywhere the revs will increase.

Check all of the electrical connections (especially earths and battery terminals).

Check all the High tension leads.

Check the spark plug gaps (.8 to.9 mm).

Have a look at this thread: http://www.nissanpatrol.com.au/forums/showthread.php?28517-RB30-Facts-Figures-and-Helpful-Hints

[GQ TANK]

My tb42 has a simalar issue when I first got ir - then it stoped working on petrol.

I ut a kit though the carby.

The rb30s and tb42s carbys are basically the same - they even use the same kit.

[huardlc]

hi mate seems like your engine timing is completely out of wack...

[Patrol'n]

I have an RB30 patrol and this weekend I have experienced similar issues as you described, where the engine would drop revs and stall if I put the clutch in and let the revs fall and wouldn't idle. It also did the backfire when going down the hill as you described, what did the problem turn out to be?

Any help would be greatly appreciated, right now it's running fine again, it just seemed to happen for a while then go away again, then come back at random.

Thanks, I was ready to park it in the lake yesterday it was winding me up that badly...

[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.

[dom14]

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.

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.

[Patrol'n]

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.

[dom14]

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.

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.

[Patrol'n]

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.

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)...

[dom14]

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)...

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/CARBURETTOR-CARBY-CARBIE-VERY-RARE-SUIT-NISSAN-PATROL-GQ-Y60-TB42-4-2L-RB-3-0L-/201020241515?hash=item2ecdbd766b

Or get the rebuild kit,

http://www.ebay.com.au/itm/CARBURETTOR-CARBY-REPAIR-SUIT-NISSAN-PATROL-GQ-Y60-TB42-4-2L-RB30-FORD-MAVERICK-/191561351672?hash=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.

[dom14]

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

[dom14]

More diagrams here.

http://www.patrol4x4.com/forum/nissan-patrol-gq-y60-ford-maverick-11/carb-diagram-tb42-needed-75406/

[Patrol'n]

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.

[Patrol'n]

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

You're not in Perth then?

[dom14]

You're not in Perth then?

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

[dom14]

Your second carby doesn't has to be a Nikki.
If you are going for a second new carby, I would go for a Webber or a Holly.
Both available on fleabay, even cheaper than Nikki I reckon,& can yield lot more power with proper tuning.
Check bumtree. I saw a guy selling a Holley 600 for an RB30 for $100 or so. He also has an RB30 carby with a manifold.
Guy's in Perth. I wanted them, but he apparently won't post or separate the manifold & the carby.

http://www.gumtree.com.au/s-ad/perth-region/engine-engine-parts-transmission/holley-600-carby/1083863545

http://www.gumtree.com.au/s-ad/perth-region/engine-engine-parts-transmission/gq-patrol-rb30-carby-and-manifold/1083862226

[garett]

from what i hear holley's arnt great for 4wd ing, on steep hills the tend to lean out too much. (just what i hear) if any one can tell me i'm wrong let me know, cos i will probably end up fixing up a couple land rovers (brother is a land rover fan) :(
i'm a webber fan got one coming for my laser, v-tec is not going to save you :tease:

[dom14]

from what i hear holley's arnt great for 4wd ing, on steep hills the tend to lean out too much. (just what i hear) if any one can tell me i'm wrong let me know, cos i will probably end up fixing up a couple land rovers (brother is a land rover fan) :(
i'm a webber fan got one coming for my laser, v-tec is not going to save you :tease:

Hey Garett,
We poor bums can't afford Webbers. So, if you are ok with donating a one, I'm happy to help with your charity by taking it. :D :harhar:
BTW, by the looks of it, Webbers are hard to come by comparing to Holleys( I meant secondhands).
If you find a one suitable for RB30, on fleabay or bumtree, pls let me know.
Can't afford brand news atm, 'cos I've been spending too much on other mods. :)

[dom14]

I've been advised, the below bumtree Holley carby is not suitable for RB30(too big)

http://www.gumtree.com.au/s-ad/perth-region/engine-engine-parts-transmission/holley-600-carby/1083863545

[Patrol'n]

Yep, from what I can find out, the 330 Holley designed for 4wds are good, (company in Queensland do them), but they are not cheap... I've also been warned they have mechanical secondaries and don't mind a sip of fuel or two, although that's just the usual blokes drinking beer round the fire talk.

I have rebuilt and put webber 34ADM's from the 4.1 cross flow XE / XF falcon on a couple of different motors before, I put one on an old hard revving gemini, fuel usage was high but it made a TONNE of power!

I'm still also toying with a fuel injection transplant from an R31 skyline or VL commodore, just dunno, I do like carb simplicity, but I would also like extra power for highway, even with removing the heater element thing, a bit more would be nice.

I still think I'll go the rebuilt carb route, just want to make sure it's 100%, I hate reliability issues....

[dom14]

You are not likely to get extra power by converting to EFI, but fuel economy will improve.
Check with the link I gave you. $50 or less for a carby+ manifold+air snorkel pipe is a good deal if you can pick it up.

[taslucas]

This may seem simple but have you checked to see all the linkages are working free and smoothly? I'd suggest a good going over with wd40 and check to see if there's any detached springs.

[Patrol'n]

This may seem simple but have you checked to see all the linkages are working free and smoothly? I'd suggest a good going over with wd40 and check to see if there's any detached springs.

Thanks mate, I've found it is often the simple things that get you! I've had the air cleaner assembly off and all the linkages are working perfectly. All the springs are attached and the electrical connections all seem ok :-)

[taslucas]

All good then. Any vacuum lines off or split?

[Patrol'n]

All good then. Any vacuum lines off or split?

They all seem ok so far but a couple have hardened up with age so they'll be getting replaced this weekend, along with a few other maintenance things, and a couple of little improvements to my cargo area set up