Fuel System Woes (Carb? Auto-Choke?)

Hi all

Bear with me on describing the issue - I wanted to give as full a picture as possible!

This is my first venture into owning a Micra, I purchased her to commute to the local station and back and until recently she's been pretty reliable.
Over the last few weeks a problem started to appear which has now rendered the car unreliable and a complete pain!

Initially the symptoms were 'kangaroo-juice' which I put down to a 25 year old fuel tank but now we have the following list:

  1. Rough Idling
  2. Stalling
  3. Complete loss of power (stall) when putting foot on gas
  4. Engine fires up, revs once then dies

To combat this I have done the following:

  1. New Fuel Filter
  2. New Rotor Arm
  3. New Dist Cap
  4. Had electrics confirmed good by Recovery
  5. Took top of Carb off and thoroughly cleaned (made new gasket)
  6. Replaced vacuum hose attachments to Carb and Airbox
  7. Increased idle speed

Cleaning the Carb seemd to resolve the issue briefly but I was back to square one at the side of the road this morning.

My next plan was to put a fuel additive into a fresh tank of fuel and when half empty, replace the fuel filter again. I've got theories that include the Fuel Pump and Auto-Choke but I'm no mechanic

Apart from that I'm stuck and would greatly appreciated the forums knowledge on this one!

Thanks in advance
Chris
 

gtsnissanb

Official MSC Trader
It seems you've changed everything I changed apart from the one thing I left till last! Turned out to be that for me, coil had blown on mine
 

porkpie700

Buy & Sell Member
The chock wouldn't cause that amount of problems, especially not when warm. Check that the wire on the back of the anti dieseling valve has not broken off (apparently this is a common fault but is not something i have ever encountered personally). The anti dieselling valve is on the back of the carb on the driver's side, it's partially hidden by the priming pump lever.
Has the carb ever been removed or had the mixture altered for whatever reason? If the carb has been removed completely and the two gaskets below it on either side of the spacer plate have not been changed then it's possible that either one or both have a leak.
I did have this problem with my k10 because i hadn't changed the gaskets, it just sucked in air and coolant which choked out the engine. And that was a progressive thing.
Is your k10 a 1L or 1.2L dude?
 
OP
OP
C
Its a 1.0L. As far as I'm aware the carb has never been removed completely, looking at the state of the gasket that came out from me opening the top I'd say that's definite. I'll check the anti-dieseling wire but I think that was OK - I had tried disconnecting the power that goes to the auto-choke and the anti-dieseling valve but it made no difference.

Will check the wire connections and my fuel additive/carb cleaner arrived today so I'm going to get that into the tank as well...

Oh as for mixture, no idea but the plugs look a nice brownish colour so I think it's OK
 

porkpie700

Buy & Sell Member
Erm, if you disconnect the anti-dieseling valve the engine should not run, full stop. It shuts off the fuel supply when the ignition is switched off to prevent "run-on". So if the engine continues to run with the anti-dieseling valve disconnected then it's probably seized in a partially closed position in it's chamber and is the cause of your problems (Y)
If it doesn't kill the engine when you disconnect it then i would reccomend removing it for inspection and cleaning, just make sure you don't strain that wire because they are fragile little sods.
 

gtsnissanb

Official MSC Trader
Have you checked the coil? Mine would run fine once it was mid afternoon but would missfire if you were a bit throttle happy! In the morning you could not start it at all! It would get your hopes up fire up for a millisecond then die and not start again
 
OP
OP
C
OK this evening would have been a tad easier if I understood how the anti-dieseling valve worked :doh: I got it out without snapping any wires and it looks like it has a copper cylinder running through it with a silver contact looking bit at the bottom. Nothing moved within it and I couldn't tell that anything should. I checked power courtesy of a 12v bulb and there is power going to it with the ignition on. When attached to the power and looking down it again, nothing.

I would have thought there would have been a movable pin or something? Either way completely disconnecting it does not stop the engine...

(On the plus side I'm getting an expert at playing around with car bits! I'm sure that's a benefit really!)
 

porkpie700

Buy & Sell Member
There should be a little piston with a rubber tip sitting inside that cylinder, and when you turn the ignition on it should suck the piston down using the magnet contact at the bottom of the cylinder. If the piston is missing, it may be stuck inside the hole in the carb that the anti-dieseling valve was removed from. Put a small screwdriver in there and give it a wiggle, see if you can unjam the piston and get it out of there. (Y)
 
OP
OP
C
OK will take a another look. I couldn't see what was in there so I took a photo...it didn't help me much right then but you may see something...

photo.JPG
 

porkpie700

Buy & Sell Member
It looks like the piston is still in the chamber, see if you can coax it out gently. Then give it a good clean and stick a cotton bud into the chamber to give that a good clean. Make sure everything slides in and out without sticking, when it does just reassemble plug it in and it should work fine. The idle-up celonoid can do the same thing sometimes, i've had to do this to my 1.2 carb in the past.
It'll be a pig trying to clean it when you can't see what the hell you're doing but if you really stick your head up against the bulkhead it makes it easier.
 
OP
OP
C
Hi folks

Sorry for the delay in reporting back - haven't had time to look at the car recently. Anyways today I decided to get a good look at what was in the valve so I took the Carb off completely.

In the hole where the solenoid sits there is simply a brass insert which won't budge whatever (not even sure it should) and within that there doesn't appear to be a pin or anything:

DSCF0162.JPG


I noticed the other solenoid on the carb (idle) so took that off to see what that one was like - sure enough as you said porkpie700 - there was a little spring loaded piston with a rubber tip:

DSCF0163.JPG
DSCF0166.JPG


The anti-dieseling solenoid looks identical to the other one apart from it only has one connector - the inside looks the same and presumably works in the same way...

DSCF0165.JPG


All ideas very much appreciated folks - I considered that maybe the pin was missing but then surely there would be no restriction to the fuel....:down:

...or is that brass insert actually the piston and I need to be a little more forceful.....aarrgghhhhh!!!!

Cheers in advance
Cloots
 
OP
OP
C
Hi all

My confusion has been resolved. I managed to get hold of another K10 carb and checked the solenoid on that - it has a spring loaded needle. Clearly whatever has happened to mine in the past included someone removing/losing that!
Also looking at the othe carb the choke 'flap' is spring loaded closed - I expect this is correct. My carb doesn't hold it closed in fact it seems to be open all the time - I think I may have found the problem!

I'm going to swap the entire auto-choke unit over from the new carb and see how she runs!

Cheers for all the help and advice - hopefully I won't need to ask for help on this particular problem again (Y)
 

porkpie700

Buy & Sell Member
When the throttle is opened fully the choke flap should flip shut. The "idle-up" seloniod on your old carb is the wrong selonoid. The idle-up selonoid is much longer than the anti-dieseling valve and has a different type of piston inside it. I would reccomend just fitting the new carb and dicarding the old one because it looks like the old one has been messed with and not put together right.
 
OP
OP
C
About lost it with this thing now grr Carb is swapped and cleaner than a clean thing, Coil replaced (wasn't sure so what the heck) now trying to swap Fuel Pump as problem still persists...will report back

[unless I completlely lose it and scrap the damn thing!]
 
OP
OP
C
Hi Folks

To report back...the Ol' Gal is running again! Turned out after everything (and a few replacement parts) to be a blocked filter (above float needle) and lack of fuel restrictor on return line.
Thanks for all your help along the way - much appreciated.

Cloots
 
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