|
|
Feb 13, 2017 23:24:00 GMT
|
Hi all, Got some questions regarding carbs and adjusting the autochoke and idle speeds. The car is a 1988 Nissan Sunny with the E16s 4-cyl SOHC engine. Carb has an electric autochoke. The car doesn't warm up too quickly and is prone to stalling for the first 10-15 minutes when I'm breaking to approach a junction and take my foot off the throttle/disengage the clutch. Local mechanic suggested the autochoke might not be working right. I think it is as it high idles when first started and then drops the revs down after 2-3 minutes. Is that standard time for the car to warm up. i notice that the high idle is only 15-1600 rpm when the Haynes spec says it should be more like 2200. Any thoughts on why it might be so low? The normal idle is about 600rpm. Again, that's lower than the spec - apparently should be more like 800rpm. i found these two articles, www.hemmings.com/magazine/mus/2009/10/The-Lost-Art-of-Choke-Adjustment/2144991.html - not sure if that just applies to larger US cars www.vw-resource.com/choke2.html - seemed to make sense despite it being specifically aimed at VWs. i adjusted the position of the autochoke OK but didn't seem to make much difference in the warm-up. I was going to adjust the normal idle but noticed the screw t the back of the carb is really easy to turn - like no resistance to me adjusting it. Is that right? I want to dig into this and try and fix myself. All advice really appreciated and can provide photos if neccessary. This is a diagram of the carb in question, repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/1c/e6/0a/large/0900c152801ce60a.gifOh, and I notice that the spring that connects to the accelerating pump lever had come out of it's hole on the side of the carb. I can reposition it but it dislodges everytime. Would that have a significant affect on the carb function? Cheers for reading
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
|
foxy99
Posted a lot
Posts: 1,370
|
|
Feb 14, 2017 23:06:19 GMT
|
This is a tricky one as your car does idle but cuts out approaching junctions. Mk2 Polos were plagued with this problem as were very hard to get to idle and as soon as you came to junction and fut was off gas carb was effectively going back to idle mode and cut out but you seem to be able to get it to idle so sounds like a different issue.
Believe it or not with the Polo the problem was often down to the 'dwell' on points ignition not being long enough. I take it your car has electronic ignition.
|
|
1974 Daimler Double-Six VDP 1965/67 Hillman Imp pick-up 1984 VW Polo breadvan 1970s Yamaha Twins (4) 1976 Honda SS50ZK1
|
|
djefk
Part of things
Posts: 844
|
|
|
Start with the cheapest / most simple faults to fix and check for induction air leaks first before disturbing the carb or any other settings - do a quick check of all the vacuum hoses for splits and renew any you deem to be compromised or just past their best.
Then check all manifold / carb sealing surfaces by spraying WD40 / plusgas etc. on them when the engine is running. Leaks will be obvious from the liquid bubbling and / or the engine note changing.
Whenever I've experienced similar symptoms to you, doing the above has provided a cheap fix in at least 50% of cases.
Moving to your accelerator pump, that will cause hesitation when you accelerate (if it doesn't then that suggests an overly rich mixture) - Annoying so you definitely want to getvit fixed once youve identified the source of your idling problem
Also, give the thing a full service and at the same time and check the thermostat is the correct one / opening when it should, as it should warm up fairly quickly regardless of any vacuum leak or other carb fault - You don't say whether you've done this? If not then given the situation you're faced with this is a good idea anyway.
Good luck and report back! We will need detailed pictures of your carb and specifically the parts in question to help further.
|
|
Last Edit: Feb 15, 2017 4:35:31 GMT by djefk
|
|
|
|
Feb 15, 2017 16:36:43 GMT
|
This is a tricky one as your car does idle but cuts out approaching junctions. Mk2 Polos were plagued with this problem as were very hard to get to idle and as soon as you came to junction and fut was off gas carb was effectively going back to idle mode and cut out but you seem to be able to get it to idle so sounds like a different issue. Believe it or not with the Polo the problem was often down to the 'dwell' on points ignition not being long enough. I take it your car has electronic ignition. Thanks for the feedback!
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
|
|
Feb 15, 2017 19:33:01 GMT
|
Good luck and report back! We will need detailed pictures of your carb and specifically the parts in question to help further. First off, thanks a lot for the response! I'll try and provide feedback as best I can. I'm totally green to this, so do point out the obvious if I don't mention it Start with the cheapest / most simple faults to fix and check for induction air leaks first before disturbing the carb or any other settings - do a quick check of all the vacuum hoses for splits and renew any you deem to be compromised or just past their best. All the hoses seem intact bar one on the left hand side of the rocker cover. Could be replaced, so I'll get on that - it's only a short length from the rocker cover to to air filter casing. Then check all manifold / carb sealing surfaces by spraying WD40 / plusgas etc. on them when the engine is running. Leaks will be obvious from the liquid bubbling and / or the engine note changing. OK, I'll get on to that this weekend. Seems pretty easy. If there is a leak, would I need to remount the carb/replace the gasket? Also, I did get some carb cleaner - would it be worth having a shot with that? Moving to your accelerator pump, that will cause hesitation when you accelerate (if it doesn't then that suggests an overly rich mixture) - Annoying so you definitely want to getvit fixed once youve identified the source of your idling problem
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
foxy99
Posted a lot
Posts: 1,370
|
|
Feb 15, 2017 20:42:20 GMT
|
The devices in the pan will be heat or vacuum controlled things for operating things such as choke pull-down flap or to cut off hot air supply from exhaust manifold.
I know your car isn't a VW but similar era and the things look remarkable similar to those on my Polos.
iirc the small one is for when you accelerate rapidly the vacuum collapses in the manifold and the device opens the flap as it doesn't need to be closed if you are accelerating.
The large one afaik gets warm then sucks through a small tube to shut a flap in the intake nozzle on the air cleaner so that hot air from exhaust manifold stops coming thru.
|
|
Last Edit: Feb 16, 2017 18:35:10 GMT by foxy99
1974 Daimler Double-Six VDP 1965/67 Hillman Imp pick-up 1984 VW Polo breadvan 1970s Yamaha Twins (4) 1976 Honda SS50ZK1
|
|
djefk
Part of things
Posts: 844
|
|
Feb 15, 2017 23:34:45 GMT
|
That rocker cover to air filter hose sounds like a good first job to tackle as that could be causing your idling problem.
If you replace the hose and no change then yes finding leaks with carb cleaner would work, it will evaporate very quickly due to the very high solvent content, however because of that it's very flammable and hence even a tiny vacuum leak will suck enough in to change the engine note as it burns it. Just take your time in squirting each mounting surface of the carb to the manifold and the manifold to the engine itself.
Focus on these first easy couple of steps and a service (if needed) and then report back. You need to start with the basics before disturbing anything else.
While you're doing that - Take another close look at that spring (but don't worry about it yet as that isnt he cause of your idling issue I don't think) - can it be bent so that it stays in its mount or does it appear to be in need of replacement?
|
|
Last Edit: Feb 16, 2017 0:27:53 GMT by djefk
|
|
|
|
Feb 16, 2017 10:34:41 GMT
|
The devices in the pan will be heat or vacuum controlled things for operating things such as check pull-down flap or to cut off hot air supply from exhaust manifold. I know your car isn't a VW but similar era and the things look remarkable similar to those on my Polos. iirc the small one is for when you accelerate rapidly the vacuum collapses in the manifold and the device opens the flap as it doesn't need to be closed if you are accelerating. The large one afaik gets warm then sucks through a small tube to shut a flap in the intake nozzle on the air cleaner so that hot air from exhaust manifold stops coming thru. Yeah, it suprised me how similar the description in the article I posted was to my engine even though it's aimed at VWs. Thanks a lot for the info.
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 16, 2017 12:15:48 GMT
|
It's because a carb is a carb, doesn't matter what badge is on the car, they are all off the shelf products by and large. Same carbs on different engines and operate the same.
|
|
|
|
|
|
Feb 17, 2017 15:22:08 GMT
|
Focus on these first easy couple of steps and a service (if needed) and then report back. You need to start with the basics before disturbing anything else. Well, I wonder if I did disturb something. I replaced the hose as mentioned. Straight forward enough although I think the internal diameter of the hose might be a bit too small as getting it on to the air cleaner and rocker cover pipes was a bit of a mission and then refitting the air cleaner involved a bit of effort to keep it in place while I put the retaining bolts back in. That was yesterday lunchtime. After work as I drove home (short drive across town) the accelerator started to become intermittantly unresponsive - thought the engine was losing power but it just seemed the pressing the accelerator didn't do anything and the engine dropped down to idle speed. This started just as I was pulling away on a roundabout and going downhill. Managed to half-coast/half-power the car back home the rest of the way. One thing - it didn't seemed to affect reversing. Managed to parallel reverse park the car fine. So this morning I checked the seating of the air cleaner and all the pipes around it and all seemed fine. Took the air cleaner off and checked the carb and that seemed OK - throttle linkages and all seemed as they were (to my untrained eye, I should say). I had to reseat the spring on the accelerator pump arm again but that hadn't been a problem for a week or so before, so not sure that had caused the problems. Anyway, got the car up to temperature (it's a bit more spluttery on starting up I noticed) and drove it to work - all seemed fine - accelerated fine and didn't drop the revs more than usual. Seems I've opened pandora's box.
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 17, 2017 17:14:46 GMT
|
What part s it you think is the accelerator pump arm?
|
|
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 17, 2017 17:16:15 GMT
|
Iask because I cant tell from your pics. However your symptoms suggest either no advance or no accelerator pump operation.
|
|
|
|
foxy99
Posted a lot
Posts: 1,370
|
|
|
There's so many things it could be but sometimes you can find the cause visually.
Sounds like it could be a vacuum problem or even fuel supply.
I once drove a car from Edinburgh to Glasgow in 2nd gear (at 2am after getting off a plane from Amsterdam). It was torture. Basically as soon as you put it any gear above 2nd it would die. Turns out there was a pinhole in the fuel-line from the tank before the (mechanical) fuel pump. Therefore the higher revs in 1st or 2nd gear kept the engine spinning fast enough for enough action on the pump to compensate for the fuel it was losing thru the pinhole.
So looking at your situation it seems that the carb is working in low throttle-opening situations. IE when your foot isn't on pedal much. This means there is a high vacuum, under the throttle plate, sufficient to pull fuel from the float-bowl thru the tiny idle-circuit hole(s) under the throttle-plate into the manifold.
When you press the accelerator the high vacuum at the part of the carb collapsed and the idle circuit is cancelled out and the next stage of the carb should kick in. That's when the increased speed of the engine should draw fuel from the drillings higher up the venturi and also the squirt that gets sprayed in by the accelerator pump adds fuel to the fire. Something could be wrong here.
However it might be something as simple as a dirty or disintegrated fuel filter. Could be a faulty fuel pump. Have a look at them before doing more to the carb. If your fuel pump is mechanical it should just unbolt from the head and you should be able to press the plunger in and out with your finger. You'll be able to tell if it's weak or worn.
The fuel filter is even easier to change (usually).
|
|
Last Edit: Feb 18, 2017 2:09:16 GMT by foxy99
1974 Daimler Double-Six VDP 1965/67 Hillman Imp pick-up 1984 VW Polo breadvan 1970s Yamaha Twins (4) 1976 Honda SS50ZK1
|
|
|
|
Feb 18, 2017 17:46:04 GMT
|
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
|
|
Feb 18, 2017 17:47:37 GMT
|
There's so many things it could be but sometimes you can find the cause visually. Sounds like it could be a vacuum problem or even fuel supply. I once drove a car from Edinburgh to Glasgow in 2nd gear (at 2am after getting off a plane from Amsterdam). It was torture. Basically as soon as you put it any gear above 2nd it would die. Turns out there was a pinhole in the fuel-line from the tank before the (mechanical) fuel pump. Therefore the higher revs in 1st or 2nd gear kept the engine spinning fast enough for enough action on the pump to compensate for the fuel it was losing thru the pinhole. So looking at your situation it seems that the carb is working in low throttle-opening situations. IE when your foot isn't on pedal much. This means there is a high vacuum, under the throttle plate, sufficient to pull fuel from the float-bowl thru the tiny idle-circuit hole(s) under the throttle-plate into the manifold. When you press the accelerator the high vacuum at the part of the carb collapsed and the idle circuit is cancelled out and the next stage of the carb should kick in. That's when the increased speed of the engine should draw fuel from the drillings higher up the venturi and also the squirt that gets sprayed in by the accelerator pump adds fuel to the fire. Something could be wrong here. However it might be something as simple as a dirty or disintegrated fuel filter. Could be a faulty fuel pump. Have a look at them before doing more to the carb. If your fuel pump is mechanical it should just unbolt from the head and you should be able to press the plunger in and out with your finger. You'll be able to tell if it's weak or worn. The fuel filter is even easier to change (usually). Thanks for the full replies. Really helpful! I'll do more digging. Was out in the car for a while today and didn't experience the same problem.
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 18, 2017 18:09:05 GMT
|
Ah I see now thats the pump arm the pump is down the back of that there carb.
Without being with the car its very hard to diagnose.
|
|
|
|
foxy99
Posted a lot
Posts: 1,370
|
|
Feb 18, 2017 18:09:27 GMT
|
That's probably good news as it means it's an intermittent problem. I'm thinking fuel-filter. Occasional bits of debris getting thru...
|
|
1974 Daimler Double-Six VDP 1965/67 Hillman Imp pick-up 1984 VW Polo breadvan 1970s Yamaha Twins (4) 1976 Honda SS50ZK1
|
|
|
|
Feb 19, 2017 15:48:24 GMT
|
I had the same problem on the same car - really random accelerating issues. The carb is an Hitachi, I had similar problems with my Justy, which also had an Hitachi. Buy a vacuum pump on Amazon and check the diaphragms are intact, but nothing seems to be obvious on these, they just don't seem to work. Incidentally, never had problems on Micra K10 carbs. I sold the Sunny in the end.
|
|
|
|
|
|
Feb 21, 2017 14:19:29 GMT
|
I had the same problem on the same car - really random accelerating issues. The carb is an Hitachi, I had similar problems with my Justy, which also had an Hitachi. Buy a vacuum pump on Amazon and check the diaphragms are intact, but nothing seems to be obvious on these, they just don't seem to work. Incidentally, never had problems on Micra K10 carbs. I sold the Sunny in the end. Thanks for the feedback - I was wondering what I'd need to check the diaphragms. Ordered! I hope this is something that can be fixed as a learning process is never great if it turns out the thing you're learning about isn't actual functional in the first place. As a longer term aim, I've started looking at a Weber as a replacement somwhere down the road. Not sure if I can justify the cost of that. Feel free to offer opinions. Elsewhere someone suggested even putting twin DCOEs on it..
|
|
Nissan N13 owner | Mechanical neonate since 2016 (Give me all the info)
|
|
foxy99
Posted a lot
Posts: 1,370
|
|
Feb 21, 2017 19:02:28 GMT
|
My opinion is that if you aren't bothered about high (or better than standard) performance stick with the unit on it. You hear ppl saying 'this unit was c**p and that unit was c**p' but thousands of ppl would have used cars like these with no problems.
It can be a major frustration trying to get to bottom of some problems but once cured at least you know the standard unit is matched to the car.
What about buying a used one and swapping them over? You can them strip/service your original.
I did this with my Polos and one of the used units transformed the car. I couldn't believe have perfectly it idled. But then it wouldn't accelerate as it was a slightly different model of carb which didn't have a 'load switch' attached to it.
The amount of stuff on carbs is bewildering sometimes
|
|
1974 Daimler Double-Six VDP 1965/67 Hillman Imp pick-up 1984 VW Polo breadvan 1970s Yamaha Twins (4) 1976 Honda SS50ZK1
|
|
|