Hi there, brand new engine, as soon as it gets under 2000rpm is it stops dead, like there is no spark. The timing light signal is very week, have timed the car to 32 degrees total timing, revs out fine and runs well other wise. Any idea what could be causing this issue?
Has a new MSD blaster ss coil, new MSD balist resistor, this dizzy is electronic and worked fine in the old engine it was removed from,
Any ideas would be great
Cheers
jess.t.,
Feb 12, 9:19pm
Had a problem like this was the advance weights sticking and not returning giving too much timing when revs dropped off was a cheap copy of a HEI
ocean_x,
Feb 12, 9:21pm
Thanks mate, that makes a lot of sense. Will have a look at that
mechnificent,
Feb 12, 9:50pm
Er. so how do you get it to start and over 2000 ?
Tow start. haha.
When it dies, does the timing light stop flashing, or does it keep flashing right down to zero revs. If it keeps flashing then I'd say it wasn't electrical at all but a fuel problem.
If the timing light does stop flashing, then it sounds to me like it will be faulty electronics, and at a wild guess a capacitor in the electronics.
mechnificent,
Feb 12, 9:51pm
If it's what Jess says then it will show up with the timing light.
intrade,
Feb 12, 9:56pm
well i wonder from your clues if you are mixing something incompatible this clue is also the thing i would investigate but first you want to make sure the stuff is hooked up coorect and is comapible like do you have this same setup as here? http://www.dodgecharger.com/forum/index.php?topic=64295.0
or what does your system setup look like exacty consisting of what components? week timing light the first thing i was to do is mesure voltage drop with my scope on ignition module. you can use a multimeter but be awear if you have fluctuation a multimeter takes the avarage readings and desplays this on the screen it wont show lowest unless you have mid max function. scope shows it all on a graph. that would be the first thing i do checking voltage dont drops out , then alternator ripple testing you can run it with out belt on alternator for a short time for a simple test to true rool out alternator ac voltage messing with ignition module.
but we need to know exactly all components you use and if it is the system i posted a link from
mechnificent,
Feb 12, 10:08pm
The flash from a timing light doesn't get weak with a weak spark. it either flashes or it doesn't. It's fired by an internally generated high voltage of about four hundred volts and the ignition only triggers it. or not.
mechnificent,
Feb 12, 10:13pm
A ripple in the charging could stuff up the electronics Intrade. That is a good point.
Really though all he needs do is see if the spark is there right down to zero revs or if it cuts out a 2000 revs.
bjmh,
Feb 12, 11:59pm
major vacuum leak ?
mechnificent,
Feb 13, 12:28am
If he determins if the spark is dying as he suspects, by watching the timing light, and at the same time checks the timing is dropping back to ten or so degrees, then we can move on to fuel and vacuum.
ocean_x,
Feb 13, 2:27am
No vacumn leaks at all, if I hold the gas pedal abit it will fire up and just to 2500rpm, I let the gas off a bit and it goes down to 2000rpm, abit more and it completely cuts out like the key is being turned off, I'm stumped,
Fuel system consists of a edelbrock 110 gph mechanical pump, Holley fuel pressure regulator, holley street avenger 670cfm carb, all done with -AN flittings and fuel pressure guage reading 6psi, it's all new stuff
Could it be a faulty coil? Or balist resister?
Thanks for your help
ocean_x,
Feb 13, 2:28am
The alternator is a 1 wire hook up RPC, new aswel, with Gilmour belt, I have hooked the 1 wire directly to the battery. Is that correct?
ocean_x,
Feb 13, 2:33am
Have just changed the distributor to a mallary twin sparker I have lying around, what I know it a good dizzy. Seemed to idle fine to start with, now it won't fire at all, I'm sure it's something electrical.
battery is getting low now so will charge that up and see what happens
ocean_x,
Feb 13, 2:36am
Timing light stops strobing a light as soon as it cuts out at 2000rpm
bjmh,
Feb 13, 2:43am
just to humour an old bugger,check the base of your carb. it hasn't got an extra vac port that's uncapped.A lot of holleys had pcv connection and a brake booster port.
mechnificent,
Feb 13, 2:44am
Right. there is your problem then by the sound of it. When it is running down to a stop the spark should still be there if it's fuel or vacuum.
Could the motor be flexing on it's mounts and causing a wire to disconnect. You should put a light or gauge on the power at the dizzy and check it doesn't go off just as it drops to the cut off point.
mechnificent,
Feb 13, 2:50am
If the coil is mounted on the engine, check the power where it gets to the coil. Otherwise test the wire going to the dizzy.
ocean_x,
Feb 13, 3:24am
Deffinatly no vacumn leaks, pcv port is hooked up, so it brake booster,
Coil is mounted on the inner guards away from the engine heat, motor has very little flex, all the mounts are new.
Now it won't fire at all with the mallary in it, but when I first put it in it started and idled good, have a some how got a bad power feed to the coil?
I don't have a voltage reader or anything like that, just a test light
ocean_x,
Feb 13, 3:31am
By the sounds of it I need a sparky?
jason18,
Feb 13, 3:39am
Not a wire arcing out ? Sorry haven't read the entire thread. Maybe get the ign system checked by a sparky. Probably something super simple
ocean_x,
Feb 13, 3:43am
Thanks, yes it must be something super simple, I'm not that great with wiring, I'm going to get a sparky to look at it, I'm stumped
mechnificent,
Feb 13, 3:57am
Check power is getting to the coil with your test light. if it is getting power, check it's coming out the other side, to do that you will have to have the points open, otherwise the points will be earthing the power at that point. If it's coming out of the coil check it where it gets to the dizzyand points. If it gets to the dizzy check the little earth wire inside the dizzy. The vacuum might be moving the base plate when the vacuum gets up and causing a no earth situation.
If all those seem ok, there should be a spark.
mechnificent,
Feb 13, 4:01am
To test for spark you can use a screwdriver to short across the open points.
mechnificent,
Feb 13, 4:04am
Then if it starts and runs you need to go back to checking for a power loss due to the engine moving and breaking a semi broken wire or connector.
If there are no broken wires going to the dizzy and it still stops when the revs get down to 2000 revs I'd bet it's the earth wire inside the dizzy.
That's the diagnosis process for that dizzy. If that fixes that. then you need to try all the same procedure with the other dizzy.
ocean_x,
Feb 13, 4:53am
Thank you so much for your help mechnificent, found the issue. One of the wires in the mallary dizzy was in the crimp, but not crimped, fixed that and she fired right up and ran like a dream.
Thanks heap mate
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