Josh NZ Posted June 23, 2012 Share Posted June 23, 2012 Ok, so the big day arrived today, and i finally finished the electrics on the S2A. I tightened the last bolt on the alternator and put the bonnet back on. I then put 10L in the fuel tank (91 octane) and primed the fuel pump with a few squirts. She fired up after a few turns on the starter motor which was really exciting, until some funny business began to happen. It began by idling extremely high for around 10 seconds, and after that, the revs slowly dropped until (at a guess) it was sitting around 300-400rpm. The body was shaking and it sounded a little like a bridgeported rotary engine whilst blowing thick black smoke. Then i tried revving it. It then proceeded to sputter and fart which sounded like a machine gun (also blowing VERY thick black smoke) until the revs went sky high again and the process repeated. When it revs high, theres no smoke at all. Once i got it revving low again i tried adjusting the mixture screw which seemed to do nothing. Does anyone know whats going on here? I know that black smoke is a bad combustion or over-fuelling in some cases.. can the ignition timing also produce these symptoms? It could be a bad miss but i wouldnt know as im not very good with these things.. So far ive (in the engine bay) replaced Fuel pump spark plugs and leads Brand new carb (pattern, reputable) All fuel lines with an inline filter just before the carb water pump alternator (17ACR) New engine oil (Castrol 20w 50) Im very stuck on this one.. is it as simple as a good tune up (how do you even do that??) or is it more? Looking forward to your suggestions.. Sincerely, F.N.G Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted June 23, 2012 Author Share Posted June 23, 2012 Ok, so the big day arrived today, and i finally finished the electrics on the S2A. I tightened the last bolt on the alternator and put the bonnet back on. I then put 10L in the fuel tank (91 octane) and primed the fuel pump with a few squirts. She fired up after a few turns on the starter motor which was really exciting, until some funny business began to happen. It began by idling extremely high for around 10 seconds, and after that, the revs slowly dropped until (at a guess) it was sitting around 300-400rpm. The body was shaking and it sounded a little like a bridgeported rotary engine whilst blowing thick black smoke. Then i tried revving it. It then proceeded to sputter and fart which sounded like a machine gun (also blowing VERY thick black smoke) until the revs went sky high again and the process repeated. When it revs high, theres no smoke at all. Once i got it revving low again i tried adjusting the mixture screw which seemed to do nothing. Does anyone know whats going on here? I know that black smoke is a bad combustion or over-fuelling in some cases.. can the ignition timing also produce these symptoms? It could be a bad miss but i wouldnt know as im not very good with these things.. So far ive (in the engine bay) replaced Fuel pump spark plugs and leads Brand new carb (pattern, reputable) All fuel lines with an inline filter just before the carb water pump alternator (17ACR) New engine oil (Castrol 20w 50) Im very stuck on this one.. is it as simple as a good tune up (how do you even do that??) or is it more? Looking forward to your suggestions.. Sincerely, F.N.G Quote Link to comment Share on other sites More sharing options...
Burnsinbarnsley Posted June 23, 2012 Share Posted June 23, 2012 Timing.... Carb settings....???? Just guessing!! Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted June 23, 2012 Author Share Posted June 23, 2012 Same! Haha I wish I knew the extent of the carb settings, what bit does what and how much you tweak it etc. Plus a how-to on ignition timing (and what people did with theirs) would be so very helpful Quote Link to comment Share on other sites More sharing options...
Gremlin Posted June 24, 2012 Share Posted June 24, 2012 I would investigate the carb further. I am no petrol guru but i guess it points to carburation problems. Close all the set screws and start off form there maybe? Are you sure the pattern carb is jetted correctly?? G Quote Link to comment Share on other sites More sharing options...
Julian Posted June 24, 2012 Share Posted June 24, 2012 Sounds like the float chamber is flooding. Check the float for leaks (if it's brass) and the needle valve for gumming/sticking/foreign bodies. Julian. Quote Link to comment Share on other sites More sharing options...
Briarston Posted June 24, 2012 Share Posted June 24, 2012 It's quite a while since I worked on a carb. engined vehicle, but it sounds to me also that the problem is fuel/carb. related. The black smoke and rough running suggests over rich mixture/carb .flooding, while the build up of revs. and dying seem like running out of fuel symptoms. The mixture screw on the carb. only adjusts the slow running mixture, the other the idle speed. I suggest you check the carb. particularly that the main jet and internal ports are clear, also the float level and needle valve Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted June 25, 2012 Author Share Posted June 25, 2012 Fantastic, thanks for all your swift replies. I will break out the Haynes manual and get cracking this weekend Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 16, 2012 Author Share Posted July 16, 2012 Hey folks, I haven't had a chance to get at the carb as of yet but I managed to get a video of the old girl playing silly buggers with me. Hopefully someone out there can help me diagnose if my problem is what's listed above or if it's something else. Quote Link to comment Share on other sites More sharing options...
ian_s Posted July 16, 2012 Share Posted July 16, 2012 i wouldn't run it for too long like that, if it is running very rich it will wash all the lubrication off the bores quite quickly! Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 16, 2012 Share Posted July 16, 2012 I had dreadful trouble with our Lightweight (the others I own are Tdis, so don't have carbs or ignitions). It had similar symptoms to yours initially, and as I worked through the list (follows), it gradually improved to merely being down on power, poppling on the over-run and backfiring and running on when switching off the ignition. I started by adjusting the tappets, checking the timing and stripping and checking the ignition, replacing the coil, cendenser and points. There were a few issues in there and a small improvement was made. Next came the fuel system - partially cloggd lift pipes in the tanks, a leaky lift pump, carb clean and rebuild (no fault found in there) and new exhaust manifold (corroded at the inlet manifold joint below the carb, allowing air to leak into the inlet manifold, bypassing the carb) helped, as did rebuilding the emcon system (diaphragm was perforated, allowing excess air to bypass carb), but still no cure. I also replaced the exhaust. In the end, I found the biggest problem was that the factory timing figures and the timing markers just don't work with modern unleaded fuels - they're 3-5 degrees out. Setting the timing by ear, adjustingt he distributor until the highest idling rpm was found, and then adjusting the carb to set the correct idle speed cured all the trouble. The engine now runs sweetly and quietly with plenty of "go", no over-running or missing and starts instantly regardless of how many weeks or months go by without a start up. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 16, 2012 Author Share Posted July 16, 2012 Snagger- I agree with your thoughts on timing. Can you elaborate on how to adjust the distributor? I'm assuming that after the distributor adjustment I am to just lower the idle speed screw and then adjust the mixture screw last? This is the last issue that is standing in my way engine wise so I'm chomping at the bit to get her running nicely! Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 16, 2012 Share Posted July 16, 2012 It's just as simple as it sounds, or even easier - just loosen the securing clamp at the base of the distributor and intially set the timing to TDC. Then start the engine, and keeping clear of the fan and belts, rotate the dstributor slowly one way and the other until the engine reaches its highest idling rpm. Once you find that peak, stop the engine and tighten the clamp (stopping the engine is just to protect you while you use the tools). Then restart the engine and adjust the carb to get a nice, steady idle (and on carbs other than the Zenith, adjust the enrichment screw for throttle response). I'm pretty inexperienced with petrol engines, so can't give much advice on setting up the carb, but the timing is really that simple. It just seems alien to completely disregard the factory timings and manuals, but they were all set for 2 and 4 star leaded petrol with very different burn characteristics from modern unleaded. Quote Link to comment Share on other sites More sharing options...
alfmech Posted July 16, 2012 Share Posted July 16, 2012 for what its worth i had similar issues with mine years ago and ended up a combination of sticky valves and diabolical timing setup by a moron (me ) valves freed up themselves luckily after a bit running and timing setup by ear rather than timing marks, worked fine afterwards so might be the same for you, my engine had been unused for about 10 years when i had the issue though so cant guarantee it applies Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 16, 2012 Author Share Posted July 16, 2012 Mines been sitting for 20 plus haha so it certainly applies! I would like to replace the points, coil and condenser. Plus I will adjust the tappets as I have no idea what they're like. Are we sure it's not a serious miss? I don't know what one sounds like so I wouldn't know Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 19, 2012 Author Share Posted July 19, 2012 Righto, so I had a crack at the carb tonight. Pulled it off and stripped it down. Prior to stripping it, I noted that pulling the linkage made the tiny wee jet which is driven by the accelerator pump (assuming its the accel jet) squirt petrol quite happily which would explain why it was able to rev up. It got me thinking that my slow-running jet is blocked but I don't know which one that is! After stripping the carb, cleaning it and resetting the float level to 33mm (I think), I replaced it on the engine and tried the starter. The difference was noticeable, but in a bad way. It's now running worse than before!! It downright refuses to rev now, even with my foot flat to the floor it just does the sputter and fart thing constantly. When left to idle, it does the same thing but just slower. Prior to this I tried the dizzy twisting motion. Worked in a way.. The dizzy is now hard twisted to the right (I guess that means its advanced a lot) which I didn't think was a good thing.. Ah and also, when the motor is doing its fart and sputter thing, twisting the dizzy has no effect at all... So its a real peeve!! Any one got any bright ideas? Im all ears on this one. I'm inching ever so closer to sending it to a reconditioner and being done with it > Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 19, 2012 Share Posted July 19, 2012 Have you made sure you have clean, new fuel? Old fuel is useless as only the heavy molecular chains remain - the lighter, more volatile molecules evaporate off and after a few months petrol becomes difficult to use in engines. Have you cleaned the spark plugs? They might be coked up now with the poor running. HT leads also degrade with age, causing ignition issues (don't buy cheap replacements as these are invariably of such low quality that they're worse than old ones). Have you cleaned out the air cleaner with (the old) petrol and replaced its oil? It could be gunked up, stangling the intake... Setting the distributor that far off doesn't sound right. I seem to recall mine was set about 3/4 around its total available arc, so still had plenty of movement left. It could be that the timing chain has become stretched with use prior to laying up, or that the sprockets or cam shaft skew gear (which drives the distributor) have worn, allowing slop in the timing. I hate to say it, but I think you'll have to systematically work through the fuel, air and ignition systems just like I did, looking for leaks, blockages and defective parts as you go. Hopefully, you won't need to pull the head off, but it is possible that after 10 years of laying up, the bores have rusted, creating low compression and blow-by. Quote Link to comment Share on other sites More sharing options...
discomikey Posted July 19, 2012 Share Posted July 19, 2012 have you had a look at the choke system, id also suggest it might be the idle screw on the carb, although the low revving points to the air passage being blocked off, which is why i suggested choke. Quote Link to comment Share on other sites More sharing options...
Julian Posted July 19, 2012 Share Posted July 19, 2012 The fault here is with the carb, as simple as that. Take the air filter ducting off and run it, look down the top, I bet you'll see it flooding, or maybe the choke flap has stuck... Julian. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 23, 2012 Author Share Posted July 23, 2012 I have cleaned the air filter previously with kero, and changed its oil. I also blew it through with compressed air so I know the filters not blocked, chokes not blocked either, it works perfectly. I now that it's over fueling because the spark plugs are caked with black soot. I have a feeling that the timing is way out as well but I need to stop its sputtering episode first because when it's sputtering, twisting the carb, idle speed screw etc has NO effect. I will however disconnect the fuel line before the pump and run the line out of a fresh can of petrol to see if the petrol is to blame Quote Link to comment Share on other sites More sharing options...
Julian Posted July 23, 2012 Share Posted July 23, 2012 Petrol is not to blame and the timing is certainly not way out. Look towards the carb, chances are the float valve is sticking or you've got a puntured float etc - this one really is a basic fault and you don't need to think beyond the basics! I notice you've got an in-line filter in the fuel pipe fitted, I just wondered if you've done any other mods to the fuel delivery system as I know some of the Facet electric fuel pumps produce too much pressure for some carb float valves to cope with..... Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 23, 2012 Author Share Posted July 23, 2012 Ok, I'm focused on the carb now haha! Inline fuel filter-correct! The fuel system is entirely standard spec, just with new-old-stock parts. Fuel pump is replaced but with the same brand and model part. I agree with your thoughts on the needle valve/float. I have no idea how to check or repair them. I thought I had repaired as the Haynes manual directed me, but I only made it worse Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 23, 2012 Share Posted July 23, 2012 Float needle, or as I had, a faulty carb from factory, it leaked straight through the o-ring from the float bowl into the throat. At the very least, take the bottom off the carb, (leave it attached to the truck is easiest actually) and remove the float (push the brass bar out holding it in place) and the needle valve will drop out, blow all this through with compressed air, and check the needle valve for a nice un-stepped taper and refit needle, float and retaining bar. Get a new o-ring of the same size for the middle of the carb (do NOT go thicker), dry the carb THOROUGHLY of petrol, and smear o-ring with instant gasket/silicone gasket/whatever you call it, and refit. Put the carb back on the truck and then leave for at the very least 24 hours to let the silicon go off (it won't go off soaked in petrol). Then try again. 95% of Zenith running problems can be cured by the above, and adjusting linkages. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted July 24, 2012 Author Share Posted July 24, 2012 Brilliant, I'll crack open the little bugger and try again! How does one raise or lower the float level?? Explanations in land-rover-for-dummies language please Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 24, 2012 Share Posted July 24, 2012 You bend the tab on the float arm gently with a pair of pliers If you have a haynes or a workshop manual it is all in there, including the float height. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.