Huw Posted July 1, 2006 Share Posted July 1, 2006 got a bit of a quandry.... went to fire my zed over the last couple of days....it had been a bit reluctant to fire and keep idling (even with choke on)...now it won't fire at all...it turns and there is spark at all plugs... (there is petrol too!) However it seems to come closer to firing when you play with the leads and plugs (take lead out force it to jump from lead to plug, strange) The plugs and leads are basically brand new...engine fully rebuilt...carbs rebuilt (but have had trouble with them before, believe it to be all sorted tho) AS some background I did rewire under the dash prior to this, to fir the radio in, but i believe everything went back where it should and everything else works...... any help would be great... Huw Quote Link to comment Share on other sites More sharing options...
pauly_adams Posted July 1, 2006 Share Posted July 1, 2006 i was looking through my haynes manual and i could be your ignition coil u may have the + and - arount the wrong way it says u can loose upto 60% of your spark may cause misfireing and if that doesnt work check the points in the dizzy that might also be the prob pauly Quote Link to comment Share on other sites More sharing options...
Zeddophile Posted July 1, 2006 Share Posted July 1, 2006 Sounds like a spark or timing issue..... Holding the leads a short distance away from the plug tends to amplify the spark (don't ask me how, it makes no sense to me). Check that your timing is correct (will probably have to static check it, since its not running!), check the coil connections. Maybe try temporarily bypassing the ballast resistor, see if that improves things..... As Paul said, points could be an issue, as could the coil.... You've rebuilt much of the engine, by the sound of it, but you haven't mentioned any work done to the ignition system, other than leads and plugs. I'd probably start by lifting the dizzy cap off, have a good look at the rotor button. Crank it over while holding the coil lead about a centimetre away from the rotor button (obviously after removing it out of the dizzy cap, and holding it in a well insulated manner - they can give you a nasty kick). If its okay, you should only get a small yellow spark at best, if you get a bright spark your rotor button is probably tracking to earth. Make sure the contacts in the cap aren't all corroded, and that there is no moisture inside the cap. Then check your points gap while you have the cap off, and adjust if necessary. If you find nothing there, then the next thing to examine is coil/ballast resistor. If you don't yet have a workshop manual of some description, now would be the time to buy or borrow one, I would say, as you are probably going to need various specs, depending on exactly which equipment you have. The only thing that I can think of under the dash which may affect the ignition system is if you have interfered with the tacho wiring. From memory, the 240s are inductive pickup tachos, and I think they require the tacho to be in the circuit for the coil to work properly.... Quote Link to comment Share on other sites More sharing options...
luke_mcmahon85 Posted July 2, 2006 Share Posted July 2, 2006 i just did the 280zx coil and distributor swap on my car, so i have a spare 260z coil and distributor laying around that work perfectly if you want to test it out to make sure that's not your problem Quote Link to comment Share on other sites More sharing options...
Huw Posted July 2, 2006 Author Share Posted July 2, 2006 tomorrow will tell :-) spent all day at work today but charged battery whilst gone...so shouldn't be a problem with that.... Will check to make sure didn't knock anything out of tacho cause have had that coil prob before..... thanks for the offer on the coil and stuff but I've got the 280zx coil etc sitting on my bookshelf in my room waiting as well....so if the coil etc ends up being the problem I'll just do that swap :-) anyway...we'll see tomorrow Huw Quote Link to comment Share on other sites More sharing options...
Huw Posted July 3, 2006 Author Share Posted July 3, 2006 well here we go..... 1) there is spark at the plugs 2) there is also healthy spark at the coil/dist 2) just corrected the gap at the points (but still not firinng (was a bit too close) 3) all timing seems correct both at dizzy and the engine. 4) checked all tacho connections, they good.... anyway...still not firing, recharging the battery now and checking fuel pump and carbies.....although aerostart didn't fire it either (through the carby mouth)..... Stumped... :?: Huw Quote Link to comment Share on other sites More sharing options...
luke_mcmahon85 Posted July 3, 2006 Share Posted July 3, 2006 when i put the zx dizzy in, i tried to use the 260 coil, and had the exact same symptoms...had spark, and it looked good, but still wouldn't start...swapped the zx coil in and it fired straight up if i were you, i'd put that zx coil and dizzy that you have in (only takes 10 minutes) and see if that works Quote Link to comment Share on other sites More sharing options...
Huw Posted July 3, 2006 Author Share Posted July 3, 2006 only problem is then i need to rewire the tacho don't i? cause the 240 tacho's don't run with the 280 tacho's do they? might try that tomorrow before work. Quote Link to comment Share on other sites More sharing options...
Huw Posted July 3, 2006 Author Share Posted July 3, 2006 only problem is then i need to rewire the tacho don't i? cause the 240 tacho's don't run with the 280 tacho's do they? might try that tomorrow before work. although, it was running very well last week, which is why I'm confused... Quote Link to comment Share on other sites More sharing options...
warrenz Posted July 3, 2006 Share Posted July 3, 2006 How about fuel, are you getting fuel to the cylinders. After all that trying I would expect the plugs to be wet when you pulled them out. The 260 has the electric fuel pump, can you hear it pumping. Are all the fuses ok ? I guess the wires for that start in the dash or ignition somewhere Pull the fuel lead to the carbies off and see if petrol is coming through. Warren Quote Link to comment Share on other sites More sharing options...
Huw Posted July 3, 2006 Author Share Posted July 3, 2006 Mine's a mechanical fuel pump, have a 71' 240.... pulled the hose off both carbies and cranked engine (disconnected so no spark!!) and squirted petrol into a jar....so unless it's a problem within the carbies (rebuilt) i should have petrol.... The petrol was a bit....lethargic in its splurts but then I've never looked at a healthy one so..... Plugs were wet initially bu in the last couple of checks no...so I really stumped.... Huw Quote Link to comment Share on other sites More sharing options...
Zeddophile Posted July 4, 2006 Share Posted July 4, 2006 i would expect the fuel to be quite lazy on a mechanical fuel pump - after all, it drives off the camshaft, so at cranking speed its not going to flow much (since a electric fuel pump for carbies run around 4-5psi). Carbies run mostly off the fuel bowl inside them, which is controled by the float - which is why people recommend to change the fuel tank when you do an EFI conversion, as carby fuel tanks generally aren't baffled (any fuel surge is supposed to be soaked up by the fuel bowl). You shouldn't need to rewire the tacho for a 280zx coil (i don't believe), just make sure its wired correctly. If it was running well last week, and isn't now, to me that would be even more of a pointer for an electrical fault of some description, and coupled with the fact that aerostart won't fire it.... However, its looking to be a bit of an odd one... You should (i think) be able to see fuel squirt in the body of the carburettor if you operate the throttle linkage with the airbox off, which will tell you whether or not fuel is definitely making it to the cylinders. Although, if aerostart didn't make any difference, I'd say the problem isn't fuel. How was the spark at the plugs? It should be a fairly bright blue spark. Are you sure you got the points adjustment spot on? even a few thou out can make the car not run, on some vehicles. Basically, if you have good spark, fuel and compression (hopefully a given with a rebuilt motor!), and the timing is right, there should NOT be any reason for it not to fire on the average carbie car. And I can't think of anything on a zed that would stop it, it has no ecu or no other electrical inputs it relies on..... I'd suggest possibly cranking it over with the plugs removed a few times (disconnect the low tension wire from the coil to prevent spark), in case its well and truly flooded, in which case hopefully that would clear it. Only thing I'm not sure about is whether that would suck more fuel out of the carbs, but its worth a try I guess.... The one other thing that comes to mind is the fusible link that gave Sulio trouble a while ago, but I'm not sure if it would have this effect... Quote Link to comment Share on other sites More sharing options...
Huw Posted July 4, 2006 Author Share Posted July 4, 2006 what fusible link? running on empty now....new battery, plugs have sprk, fuel directly put in.....may be well and truly flooded but even if cleared don't think I'm any closer..... Huw Quote Link to comment Share on other sites More sharing options...
Huw Posted July 5, 2006 Author Share Posted July 5, 2006 Well.....got new plugs....regapped the dizzy and cleared the bores.... cleaned carbies quickly....AND... zed fired first shot...now idling happily in the driveway...damn i wish i had permit/rego so i could go for a spin!! So could have been: -points -plugs -Battery (brand new bosch battery sitting in there now) -carbie? (unlikely) -?? but running very nicely now. Thanks for all the suggestions Huw Quote Link to comment Share on other sites More sharing options...
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