Dies when warm

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trevor72

Guest
Hi all,

It's been a very long time since I've posted, but here I am again. My red micra has since past as I think I did post a long time ago, but my question is to do with my GF's 87 canadian micra.

Ok here it goes...

The car was running ok, (well pretty much like poop, even after much tuning the carb) but running anyways, then it just died one day and wouldn't pass fuel through the carb.

Today.. new carb, off another 87 canadian micra. I swapped linkage (carb was from manual, our is auto) and good to go right... WRONG! The car ran GREAT for about 5 minutes until it got slightly warm, then shut off! I've been trying to mess with this soo much because my GF really needs wheels! No success. The car is the same as before the original carb craped out! Don't get me wrong, the car runs great until warm. The warmer it gets the more throttle is needed to even get it to start again, and it wont stay runing unless you keep your foot in it! I've resorted to violence and started removing what I think is emissions junk in the hopes of finding something wrong.

Now can someone post a pic (or describe) what is NOT absolutely necessary for the micra to run. Please..pretty please :) I've removed the AB valve and the elevation something-ometer and the connecting hoses. I plan on plugging those tubes coming from the carb and see if this helps. that's another day.

Can you guys think of anything else for me to check???? My next step is to pull the head, but I really don't know why as the car has ~ 140psi cranking with the motor screeming hot (all plugs removed of course.). and It doesn't noticeably use coolant, that I can tell, and I;ve pulled all plugs a bunch of diff. times and never are they wet! Oh, the other thing, could someone post a pic of their spark plug, as is pulled from a good running micra. Again, I;m begging you guys here. My plugs are comming out all BLACK, sooty and not even a hint of brown. This to me sound very over-rich, but the hitachi carb is un-tunable! The car has good spark, fuel, and compression, what I'm I missing? BLAH! Arg, getting sick of this car, but I know it has to be something, just tired of throwing money at it!

Thanks,
trevor
 
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trevor72

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auto choke. the choke opens well before the engine wants to start to die. runs fine with it open and with it closed (functions as it should - I should say).

are there more parts than the top flap that are supposed to open?
 
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cardi

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Might seem a bit of a silly idea since I presume you have checked but is your fuel pump working OK. I had one on a Volvo that stopped working when it got hot.
 
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trevor72

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the micra uses a mechanical pump; I;ve never heard of a mechanical pump that stoped working when warm, electric yes.

I have tryed a diffent pump, off a 'known good car" My red car before it got rear-ended. Still worked the same. With plugs removed during HOT compression test, I did smell fuel escaping the cylinders while cranking.

Thanks for the responses, If anyone else has anything please don't be shy, step up, it is all very much appreciated!

Trevor
 
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cardi

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Is it an ECC system? I have a problem with my carb and after trying lots of things I am pretty sure the problem is in the carb solenoid valve, possibly the control box but they are supposed to be reliable. Sooty plugs after a short run is not unusual and it means that fuel is running well. After a good hot run the plugs should be light brown. Either the fuel is not getting through the carb or the spark is dying, the engine sounds fine. Logically the problem is not the carb itself but the feed to it or the ignition is fading when hot.
 
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trevor72

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Hmm... well I;m pretty sure that if there wasn't enough fuel getting there, then the plugs wouldn't be sooty black. You are bang on exactly the same wavelength that I was thinking about, the plugs should be light brown when runnng temp is reached. I am very curious about what this "CARB SOLENOID VALVE" is. Is there any way you could expand on this?

It seems possible that this or another valve may be staying open causing the plugs to foul when the engine warms and no longer required an enrichened mixture. Now as for ECC = not sure. My '90 red k10 had a computer under the seat, but this one doesn't seem to. This is the one year only canadian made '87 micra. It does have a small 'thing' under the driver's seet, but IIRC it is called the engine revolution control unit or something like that. I did test for contenuity there at some point a very long time ago. OK, there are 3 sets of wire leading to the carb. ( BTW this is a new carb, the original one stopped flowing fuel for some reason.) One is the anti-deiseling solenoid and the car will not run with it unpluged, that's working. the other two seem to have no effect. I remember testing the others as they didn't "click" as did the anti-dieseling solenoid, but again if I recall correctly they had power at the connection. I can check again tho.

I'm definately interested to find out what you've got on this "CARB SOLENOID VALVE", and which one you are describing as your problem. Have you got your's sorted?

Thanks.
Trevor
 
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cardi

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Not sorted yet but due to my laziness in not pulling things apart. This solenoid valve is controlled by the ECC. It opens and closes rapidly based on various sensor information fed to it. It is in the carb and has a wiring link to it from the ECC. If you have an ECC system you can see this valve working by how the revs change off and on under different loads
 
Solenoid

I have a 89 model UK micra 1.0L. It has the points ignition and no EEC system.

The carburetor has four wires going to it.
Two goto the right hand side of the carburetor. They split apart and one goes to the automatic choke (inside the circular plastic cover) and the other goes to the anti-dieseling valve which is mounted into the aluminium part of the carburetor quite near the top, this will click on and off when 12v is applied.
The other two both go to another solenoid valve on the lefthand side of the carburetor. This valve is mounted into the cast iron part if the carburetor at the bottom. It adds extra fuel when the engine is under load from the alternator. There is a small electronic box (about 80mm x50mm) under the passenger seat (drivers seat on your LHD car) that senses when the lights or heater fan are switched on. It then applys 12 volts to the solenoid which opens it and allows extra fuel to run into the inlet manifold from the float chamber. It is normaly held shut by a spring and needs power to open it.
You can apply 12 volts to the wires (earth to one, 12v to the other) and you should hear it click as well. Plus you should notice the idle speed rise slightly (about 100-200rpm). I dont think it matters which way round you connect the power to the wires.

I dont know if that helps at all?

All starting problems I've had with my car have been solved by giving it a full service. Changeing the points and setting the carburetor exactly as per the manual (there are lots of ajustments to play with).
 
Another thing worth a look is to check all the small bore vacuum hoses and the connecting rubber pieces that go from carburetor, inlet manifold and distributor. The rubber parts perish, crack and leak air into the inlet manifold. They can be replaced with small motorbike fuel hose.
 
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trevor72

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thanks guys, crogthomas that is exactly what I was interested in! Thank You very much! I have changed the coil and no difference was found. The distributor was next on my list of things to try but as this is a cost, I was waiting to see if this could be resolved without going that route, especially since it is making lots of spark will snap across ~.5-.75" gap from distributor to lead wire.

I have removed the thing that was supposed to be some kind of compensator for the elevation, but havn't replaced all the lines(rubber hoses) and blocked off the appropriate ones yet, so I'm not sure if I may be on to something or not. I'll try all that is described above and report back, it may be a while tho, as I'm out of town this weekend and into midterms next week @ school.

I do have a sneeky suspition that this is carb related.

Thanks again for all the great input.

Trevor
 
The elevation compensator that mounts into the bottom of the air filter pan can be removed without any problems. But you MUST block off the unused hoses that go to the inlet manifold. You can usually do this by rearraneging the plastic T and Y pieces. (From memory, just throw away the Y piece and use the T piece to plumb up the remaining hoses, but dont quote me on that).
Without blocking these hoses there will be extra air bleeding into the inlet manifold. At idle this will be enough to upset the mixture and cause all sorts of problems.

A common problem with the points ignition engines is the condition of the points themselves. Have you replaced or checked them recently?
 
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trevor72

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Does anyone have a pic of a points distributor? I think it is a electronic unit but it's been a while since I had it apart. IIRC it has an ICU ignition control unit that sits below the rotor and also there is a small magneto that sits in there too. I don't recall seeing poiints, I'm going to see if I can get to the car and try some stuff today.

Trevor
 
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cardi

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A fairly easy way of eliminating an ignition fault is to use a strobe light connector on each plug in turn and watch the light. If all are regular and steady the fault must be in the fuel supply.
When I had a diesel truck many years ago I had a similar problem to you and eventually found that a plastic bag was in the fuel tank and was being sucked onto the oulet pipe when it started, would run 20 mins and stop. Had to manually rebleed in those days. Water or gel in the fuel filter would do similar. Just an idea.
 
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trevor72

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Update

I've been able to spend a few hours focused working on the car. Here's what Ive found:

The will now stay running hot. The car has a new carb (the same new one). All things not essential are removed. The elevation corrector thing - removed, the "AB" valve that connects the intake pan to the manifold - removed, the lines to the carbon canister - removed, the line to the EGR valve (EGR didnt' work anyways because the thermal switch in intake manifold didn't work) - removed, and the lines on the back of the intake were 'looped' to close that connection too, where ever it when to. Now with all those connections closed and no vaccume leaks, the car ran ok, nearly the same, maybe slightly better (probably did have some small vac. leaks before.

Then I turned up the base idle a bit and kept turning the idle mixture screw left, because it seemed to be helping, although not very noticeablly. After a bunch of 'tuning' this, I was able to turn the idle down to what I beleive is approx. 1000 or just below 1000 rpm in park. The car does not "shut off" by itself anymore, starts hot and right at the hit of the key, it also stays running. But heres the bad news.... it runs like a bag of hammers falling down stairs! While taking it for a ride down the street, it would from stopped (in Drive, with the brake partially applied), run crappy, as if it was missing in one cylinder, then as the gas pedal was applied very slowly, it would at a specific point, ...just take off! Running great!

I took her back to the garage, and while running, removed each lead in turn to find that 3rd from battery side (us/canada divers side) cylinder was not fireing, or at least it didn't change the "bumpety bump bump" hopping around that the motor was doing. all other leads did. Upon lifting the revs it cleans up and runs great again. ARG!!!! Checked compression in that cylinder hot, was 150psi. I have now pulled the plugs at least 20 times and the plug is approaching acceptable, but might be lean, not sure. The plugs before had nothing but black everywhere on the porcelain, the strap the ring... the whole plug was black. NOW, the same plugs are showing me a white stap, with slight light brown just where the strap turns toward the base circle, and the top of the porcelain is not white, but red?? ya... it seems that the flame is burning off what carbon was there and there is some kind of red that was below the previous carbon layer. The plug is much cleaner, and when the new set of v-grove plugs come into the local parts store next week, (ordered yesterday) I will install and have a good base to work from in terms of judging the plug. I'll try to post some pics of the plug ASAP, so you guys can see what's going on in there.

All coments welcome, feel free to brutalize my mechanical procedures and my explainations for that matter. Oh, BTW does anyone recall which direction it is to lean/richen the idle enrichment screw?? I'm thinking that left is lean, right is rich???? not sure....

The "something valve" that lifts the idle when the lights and rear defog are on, works, (applied 12v) but not by turning on the light/defog, must the the engine rev unit under the seat, eh?

One more thing, the car will be running great hot, all good, then die/run like SH!T when the fan comes on to cool the rad. shut the car off, let the fan finish, start back up and runs decent again. hhhmmmmm... bad battery...not putting out enough... hehehe


Trev
 
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trevor72

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Running well, for the first time n 2 years!!!

Well, boys and girls, I think through the art of patients and fine tuning the ol' hitachi carb, I have been able to get my GF's micra to run good again.!! With no other changes from the day before, I did a series of test drives and adjustments. The only adjustments made were turning down the base idle. It was very high, higher than the day before. She would stay idling by herself, run great, even after a good beating, hehe, and perfomed well. She now starts hot, and on first tick over. The fan comes on and doesn't affect the motor much. I mean you can tell that it comes on but it doesn't make the car die. I left the charger on her over night, and I think the batt. was just plain low, from all the starting it was doing that day. I've checked plugs another dozen times today and get almost exactly the same result idling and shutting off after a full throtle blast down the stree, and coasting to a stop motor off. Same, plugs still look lije SH!T, but I think in a few words, my problem was a weak batter, and fouled up plugs (remember the idle was stinking rich prior to me messing with it). new plugs are still in order, and so is the stupid little box that sits under the driver seat, that won't let the "rev increasing solenoid" work when the lights are turned on.

Attached are some pics of a plug from the day before, not much change from this but they are cleaning up some more.

Thanks for all your help you guys, and I will eventually get the manuall all in.

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Cheers,
Trev
 
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