ZX Volcane fueling problem?

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dave-b
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ZX Volcane fueling problem?

Post by dave-b »

Hi just found this forum and looking for some help.
I have a 1.9 Petrol Volcane non-cat it has been running fine for the past year or so but after a hectic run last week i seem to have devolped a big problem.
On tickover it has a misfire blipping the throttle doesnt help although holding the throttle down to over 3000 rpm clears it, till it ticks over again so cruising on the motorway is fine bar a slight hesitation. The car is undrivable around town as it misses constantly under 3000 rpm and will barely pull away. I checked the plugs and they seem fine. If i let it tick over and remove the plug on the 1st injector the engine note doesnt change the same with the 2nd and 3rd but on the 4th the engine will die.
I was wondering if anyone has any ideas I thought maybe the injectors are blocked and the increased fuel pressure over 3000 rpm is forcing it through. Though to have 3 blocked in 600 miles would be strange i would have thought...
Please anyone?
Dave
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AndersDK
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Post by AndersDK »

Yes - unlikely.
I'd go for a problem in the ignition cabling/distributor/coil.
Simple tests starts by checking the spark from one of those "indifferent" cylinders, while engine is running.
Insert a round screwdriver into the plug end of cable, for a spark gap testing.
You should have a reliable 12mm (at least !) spark, bluish in colour and loud ticking.
Hold down the screwdriver against any suitable chassis/engine part, to produce a 12mm gap, using a dry rag. Do'nt hold directly by hand as 30KV is very UNcomfortable [B)]
If you have weak, unreliable red/yellowish spark, you must trace the ignition problem further (engine stopped !)
On the other hand - if spark is fine (on all "indifferent" cyls) you have a fuel injection problem.
jeremy
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Post by jeremy »

If you have a simple multimeter check the resistance of the plug leads (and main king lead if you have one.) The resistances should be the same and probably about 20 K ohm. Its also worth flexing them while they are connected to the meter to see if there is a break in the conductor. (awkward I know!)
The fuel is pumped by an electric pump and the flow is controlled by a regulator - so no increase in fuel pressure with revs.
Is the engine mechanically sound? - I mean compression ok etc? A rough check is does it sound normal on the starter or uneven - as though one or more compressions are missing?
jeremy
dave-b
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Post by dave-b »

No engine seems sound its fine at motorway speeds and occasionally its ok at engine speeds under 3000 rpm just not very often i'll check out the electrics tomorrow if i can get it too work. Thanks very much for the help.
Dave
alan s
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Post by alan s »

Sounds a bit like the problem I had with my BX 16V as well as my sons TZi 1.9 petrol.
In our case it was electrical in the region of the coil. In both cases we washed the coil particularly where the low tension wires plug into the coil itself with WD40 and scrubbed that area including the plug that plugs into it thoroughly, followed by washing it out with petrol & blowing it clean & dry using compressed air.
This plug contains + as well as - terminals & grime on it can tend to become conductive through moisture contamination and seems to want to short across at low revs (possibly even as far as the HT side), such as normal around town cruising speeds. In both cases with us, our cars will now steadily pull away from idle speed without jumping. In one case however (the TZi) we had to repeat the process a couple of times before we actually fully got rid of the problem.
Alan S
dave-b
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Post by dave-b »

Thanks Alan that seems to be part of the problem after taking it off and cleaning it then putting it back on it was better for a while doing it again this morning though. On closer examination of the plug it seems that one of the terminals inside the plug isnt making a very good contact (half the terminal inside plug seems to be bent out the way). Is there any reason why i cant cut the plug off and use suitable spade connectors in its place?
jeremy
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Post by jeremy »

I would have thought that was ok as its a low tension plug. As an alternative why not simply pick up the wire in question on both sides of the plug and join them so that only that wire by-passes the plug.
Have you got a distributor on this engine - if so its well worth having a look at the inside of the cap. My Renault 21 used to eat them - they'd fill up with oil and steam and then start tracking. I could never get used to it never having had any real problem with caps before.
jeremy
dave-b
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Post by dave-b »

Well i replaced the leads and plugs (looking at them they needed replacing)last night and its still there though not as bad as it was before. The plug i was talking about is the one from the ecu to the dizzy pack so I cant bypass the one wire unfortunately. I'm going to try and rewire the plug tonight and see if it makes any difference. Fingers crossed as when i have reseated it in the past it seems to be better for a little while, if it makes little no difference i guess the next thing will be a fuel filter....
Thanks again for all the help
Dave
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