sidewz Posted May 17, 2016 Report Share Posted May 17, 2016 (edited) Hi I've got a 4k in my bitza offroader. Its an old Suzuki lj81 running a 4k and k40 box, I picked it up recently , it was running pretty rough, so I have been working through usual maintenance, and had it running fairly well up until this weekend. All of a sudden it started running rough and died. It will start and run on choke, but dies when the choke is off, even if I work the pump. Heres what I've done so far. New plugs, gapped 0.8 Cleaned & lubed dizzy. set points .45 Timing set at around 10deg with the vacuum disconnected. Dwell reports as 45Deg. New coil. 12V no ballast. Carb rebuild. Cleaned and put most of the parts from a rebuild kit into the carb. Gaskets, pump, needle valve, reset the float and stop. New intake/exhaust manifold. Released the hotbox bolts to get the intake and exhaust to makte up nicely onto the block. New vacuum hose for vac advance Blocked off other vacuum ports with new hose. New fuel filter Its been running nicely since all that, but it died suddenly. Nicely. Rough. I have checked these things.. Spark. Still got spark. Plugs are white. can't find a vacuum leak. Blocked all pipes. Took the brake booster hose off. Sprayed carb cleaner everywhere, can't hear it rev up. Disconnected the vac advance and blocked. Took the carb off, cleaned it again and checked that no jets are blocked. I've run out of ideas. can anyone tell me what else I might me missing? Thanks in advance. Dave Edited May 17, 2016 by sidewz Quote Link to comment Share on other sites More sharing options...
Banjo Posted May 17, 2016 Report Share Posted May 17, 2016 Hi Dave, Welcome aboard ! What a neat scrub basher. Listening to it, it definitely sounds like too much air, or not enough petrol. Pull out all the plugs. Disconnect the line between fuel pump & carby, and turn the engine over for 15 seconds, & see how much fuel you get out of the pump into a container, & whether it is a constant flow. Cheers Banjo. Quote Link to comment Share on other sites More sharing options...
ke70dave Posted May 17, 2016 Report Share Posted May 17, 2016 Did you replace the little capacitor thing on the distributor? I'm afraid I haven't been able to watch the video but the capacitor has given me drama before and they are cheap to replace. Quote Link to comment Share on other sites More sharing options...
styler Posted May 17, 2016 Report Share Posted May 17, 2016 Well the magic triangle says you gotta have fuel, spark and air to run so if the motor compression is good then it could be one of them... Just check each system as you go i guess... Check fuel system: fuel pump, fuel line flow, fuel filters, carby, carby shutoff solenoid, carby screw settings etc Check ignition system: look at plugs, leads, dizzy advance, dwell angle etc Check air: Compression test, air filter, vacuum leaks etc Seems you are onto this already but from your informative post I would say there could be a few things that came to mind... The vac advance is needed unless you have recurved the dizzy, it pulls much needed advance when needed You can run a ballast or non ballast system as you please but you need to wire it up correctly though as per the system intended The carb may have some sort of crap in it or a sticky part not functioning correctly after rebuild There's two types of vacuum, manifold and ported, they function slightly differently and can cause running problems if disconnected hastily The shared manifold design can be problematic with sealing due to warped faces, differences in flange thicknesses and proper tightening That crankcase breather should at least have a air filter on it rather than blocked but better with a pcv system and catch can Quote Link to comment Share on other sites More sharing options...
Banjo Posted May 17, 2016 Report Share Posted May 17, 2016 (edited) Hi Dave, I zoomed in on your photo and noticed, what appears to be a plastic fuel tank on the tray, behind the drivers seat, with an in-line hand primer. Is it possible that the pickup point inside the red tank, is not always fully covered with fuel, and it is sucking air occasionally ? It looks like the tank is fairly flat, and the pick up point might be towards the top. Just a thought. Fill the tank right up to the top, & see if the problem disappears. Does the tank have some sort of breather, so it does not create a vacuum in there, which would make the fuel pumps job very hard ? Lets know how you go. Cheers Banjo Edited May 17, 2016 by Banjo Quote Link to comment Share on other sites More sharing options...
sidewz Posted May 17, 2016 Author Report Share Posted May 17, 2016 Thanks Styler, Banjo, Dave. I think you might be onto something Styler, "carby shutoff solenoid". I didn't understand what it was, thought it was a sensor, and its currently unplugged. From what i read now, it will block the idler circuit if not powered up, which could be causing the lean condition. I'm not sure why it would have suddenly stopped, perhaps it was stuck open and has now come loose and closed? I'll pull it out tonight and clean it, see if it moves when powered up. Re the other items: Gas tank/.. It's about 1/4 full, and has a breather, so I don't think that's an issue. Gas flow. I tested that a few days ago, it half filled a jar in 10-20 seconds, so the flow looks ok, but I don't have a pressure tester. there is plenty of fuel atomising in the top venturi when I open the throttle, so fuel supply to the carb seems ok, it seems to be the mixture is bad. Compression tested up a few weeks ago, 165-170psi across all. Points & condenser. Haven't replaced those, i am hoping to get a solid state replacement, or even move to a full HEI dizzy. Plug leads. Still waiting on a new set. The current ones don't look great. PCV. I blocked that off because it seems to stick open. I just need to sort a catch can & filter as you said. Vacuum advance. I have struggled to find out which is the right place is to connect it. Last night I ran it off the #1 intake manifold port as part of my testing, but I have been running it from the lowest port on the carb, which is where the blue vac tube is connected in the photo above. If anyone can confirm if that's right or wrong that would be awesome! Here's hoping its the shutoff solenoid!! Thanks Dave Quote Link to comment Share on other sites More sharing options...
Banjo Posted May 17, 2016 Report Share Posted May 17, 2016 (edited) Hi Dave, I looked at your photo of the engine bay & saw the solenoid there, with it's lead running off to the bottom RHS, and assumed it was connected. It should be connected to the ignition switch "On" position. It is designed to cut fuel immediately that the ignition is turned off, to prevent engine over run. It could well be your issue. You seem to have covered everything else. Cheers Banjo Edited May 17, 2016 by Banjo Quote Link to comment Share on other sites More sharing options...
sidewz Posted May 18, 2016 Author Report Share Posted May 18, 2016 Sadly, no improvement. I've plugged in the solenoid, but the behaviour is the same. I can hear it click when the ignition turns on. It stinks of a vacuum leak but I don't know where from... Other than just spraying carby cleaner or ether around the carb, how should I chase down the leak? Quote Link to comment Share on other sites More sharing options...
Banjo Posted May 18, 2016 Report Share Posted May 18, 2016 Hi Dave, Does the engine run without this issue when cold, but only appears when the engine warms up. If so, that is a good indication of a leaky point on the manifold flange somewhere. Regarding the point for your vacuum advance hose to carby connection. This picture I picked up on the net, shows it very clearly. Cheers Banjo Quote Link to comment Share on other sites More sharing options...
GJM85 Posted May 18, 2016 Report Share Posted May 18, 2016 Does the engine run cleanly above idle? Like does it rev? I believe you got a blocked idle jet. Idle mixture at 2 turns out and idle speed at 1.5 turns in. If its runs when starved of air it could only be fuel starvation. Float level or idle circuit blockage. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted May 18, 2016 Report Share Posted May 18, 2016 It will start and run on choke, but dies when the choke is off, even if I work the pump. just to go back to this bit- it runs OK when driving, but just doesn't idle and is pretty flat low down?? Have you hosed out the idle drillings since it started to run bad?? A blast of compressed air or carb cleaner aerosol? Not just the jet, but the passages in the carb body. Does screwing the idle mixture in and out have any effect? Can you see a jet of fuel being sprayed down the throat when you open the throttle quickly? I reckon idle circuit blockage too. Quote Link to comment Share on other sites More sharing options...
sidewz Posted May 19, 2016 Author Report Share Posted May 19, 2016 Thanks Gavin, Banjo & Altezza. I took your advice, headed back down the fuel blockage route. I pulled the carb off again tonight, and checked the main jets again, all good. I missed the idle jet last time, other than spraying with carby cleaner. I think I cleaned the idle adjust and associated galleries. I pulled out the idle jet and checked it, couldnt see through it. cleaned it out with a mig tip cleaner, soaked it in carby cleaner, then put the tip cleaner through it again and got a bit of varnish out. Now I can see through it :) Now it runs really nicely, much smoother than before. Less hunting at idle than before, and consequently a lower idle. You guys are awesome! Thanks for helping out!!!! I can't wait to get this thing out in the mud!!!! Quote Link to comment Share on other sites More sharing options...
Banjo Posted May 19, 2016 Report Share Posted May 19, 2016 Good one Dave ! Love it ! Cheers Banjo Quote Link to comment Share on other sites More sharing options...
Clapped out Posted May 22, 2016 Report Share Posted May 22, 2016 Gotta show us all a vid, full noise, dddddddddeeeeeeeeeeeeeeeeeeeeeeepppppppppppppppppppppppp sloppy mud, ha ha! Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted May 23, 2016 Report Share Posted May 23, 2016 Have you used it enough to know if it runs hot?? Its always hard on the cooling system when you're on full power at very slow speeds. Tridon make hi-flow t'stats that flow 30% more water than the stock ones. Quote Link to comment Share on other sites More sharing options...
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