no spark in start

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67barracuda

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Well after removing the ground from the frame to in stall the new electric fuel pump, I'm not getting any spark at the plugs when trying to start. The motor cranks and I seam to have power everywhere, I just can't figure it out
I did test the system with a spare distributor plug into the FBO electrical ecu and spinning it with my finger with the ignition in run, I have spark at plugs. The gaps in the distributors look to be the same, I can't really check the one in the motor no space.
So, when cranking no spark with same system, only difference is the draw from starter and a different distributor. Could it still be a ground problem? What do I try next.
 
Check for voltage on both sides of the ballast resistor during cranking.

During cranking voltage to ignition comes from another source.
I assume you reattached the ground you removed
 
If it cranks then the block is grounded, and the ignition is fine...... except the ECU is mounted on the apron, so the ECU has to be grounded to it, and the apron back to the battery. If the coil is firing with the spare D spinning it which is still controlled by the apron mounted ECU, then the ECU is working so is also grounded. The only thing not addressed is the ballast resistor during cranking, and
Dana67Dart is on the trail.
 
If it cranks then the block is grounded, and the ignition is fine...... except the ECU is mounted on the apron, so the ECU has to be grounded to it, and the apron back to the battery. If the coil is firing with the spare D spinning it which is still controlled by the apron mounted ECU, then the ECU is working so is also grounded. The only thing not addressed is the ballast resistor during cranking, and
Dana67Dart is on the trail.
I check the voltage on ballast when cranking and it drops to 7.5volts. I do have the FBO set up with the jumper wire across the ballast. Also have extra ground with from the ecu to the motor and from the motor to the frame. Battery is mounted in trunk and grounded to frame.

E94E90F7-BB82-477E-A9CA-C1BF2C1488E4.jpeg
 
Did some more checking.
checked + side of coil with key in run got 12 volts
checked + side of coil when cranking got 7.5volts
checked battery post on starter "large lug" when cranking drops to 7.5volts
check battery- to inside trunk cable disconnect 12.25 volts = checks battery to ground on frame is ok problem before
 
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Had the same issue with a friends car @zkx14 Ended up being the ecu. Can be the voltage drop is just enough. Try and swap it out if you can. Still think his was temp change though.
 
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Had the same issue with a friends car, needed a new ecu for some reason. Weird issue for sure. Prob the voltage drop is just enough for that ecu. At least swap it out.
swapped it out with an orange one, same problem.

just check the battery 12.34 volt and then drops to 9.8 volts when cranking. Bad battery?
 
Go into the FSM see what the drop should be. If that's a mini starter prob the battery. Have it load tested at the parts store.
 
You've got a wire missing/not connected.. The ballast is bypassed/overrides during starting so that you get battery voltage to the Ignition in the key start position.
The key has an ignition start and run position and you should have a wire in the harness that will have battery voltage in the start position only. that's the one you want.
 
if you have a 4 wire ECU run a jumper wire from battery + to the wires on the side of the ballast resistor that provides voltage to the ECU and Coil, that will bypass the wiring from battery thru firewall to ignition switch back thru fire wall and thru the ballast resistor. If it starts and runs you know where to start backtracking from. (I would disconnect the same lead from the ballast resistor while testing as a precaution)
 
just check the battery 12.34 volt and then drops to 9.8 volts when cranking. Bad battery?
What is the battery voltage at the battery while cranking?
What is the battery voltage at the starter relay while cranking? if there is a large difference the loss might be from the long run from the trunk and might be or contributing to the issue.

Well after removing the ground from the frame to in stall the new electric fuel pump,
  • I assume it worked properly before adding the electric fuel pump?
  • how and where did you tie in the electric fuel pump (FP)?
  • did you have an electric FP before and it worked?
 
If you have the OE starter, those things pull a lot of amps when they're going out.. could be a contributor.. if so, replace it with a late model lightweight. They draw a lot less amperage and you won't run into this kind of thing so much.
 
This may be stupid, but is your ignition wired through your tach? I had a car at work that would have spark while cranking, but the coil + side was wired through the tach so it would go dead once the key was in the 'run' position.

Then again, it was a Ferd, and that car was all kinds of screwed up!
 
The ballast is for FBO and has the jumper wire running to both side of the ballast. If the battery is dropping when cranking, wont running a wire to coil drop also.
yes I have mini starter.
 
What is the battery voltage at the battery while cranking?
What is the battery voltage at the starter relay while cranking? if there is a large difference the loss might be from the long run from the trunk and might be or contributing to the issue.


  • I assume it worked properly before adding the electric fuel pump?
  • how and where did you tie in the electric fuel pump (FP)?
  • did you have an electric FP before and it worked?
The has was running fine a month ago. I change out the fuel tank and pump. I didn't wire the pump up fully just yet. running wiring straight to battery and switch to check leaks. I did have to remove the ground and exhaust to get the tank out, but I think that is fine.
The battery voltage when cranking is 9.8 about.
 
sorry just reread the posts and you had already answered my questions:

Did some more checking.
checked + side of coil with key in run got 12 volts
checked + side of coil when cranking got 7.5volts
checked battery post on starter "large lug" when cranking drops to 7.5volts
check battery- to inside trunk cable disconnect 12.25 volts = checks battery to ground on frame is ok problem before

That is a lot of voltage drop though.

Found this in a another forum:

"I am a far cry from being an auto-electric expert. I can tell you the service procedure for testing the pick-up coil in the distributor. Connect an ohmmeter to the pigtail leads of the distributor, resistance reading should be 150-900 ohms. Another test is to connect one lead from the ohmmeter to ground and the other to either of the pigtail leads. If the meter shows a reading the pick-up coil is bad. I got this information from my blue Motor's manual. In my experience Motor has always been the gold standard of repair manuals."

I always lean back to... It worked... I did something... now it doesn't work. bo back to what I did and start from there.


Simple test.... pour some fuel into the carb. leave fuel pump off, see if it starts. if it does then the added drain on the battery of the fuel pump might be reason for no spark / start
 
My battery is in trunk also, and grounded to frame back there, and block is grounded to frame up front.

The voltage in run, at the coil+, should be stepped down by the Ballast to about 7.5 volts or a bit more. During cranking that same post should be getting about same as what the starter is getting, about same as what the battery is reading. 10.5v is plenty for most coils. The Ecu could be getting a similar 10.5v during cranking. Obviously nothing can get more than battery voltage, but all those components will work, down to about 9.5 volts..... in my experience. Occasionally even lower.
To test the pick-up coil, I hook up an analog voltmeter at the pigtail, set to A/C volts and the smallest scale you have, then with pick-up still in the D ,I just spin the mainshaft and watch the needle swing back and forth, indicating it is pulsing. With pick-up on the bench, I just wave a screwdriver over the magnet and again look for the needle swing. No needle swing is bad. It doesn't matter if the screwdriver or whatever wand you are using gets stuck on the magnet, just keep your eye on the needle when they separate.
 
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My battery is in trunk also, and grounded to frame back there, and block is grounded to frame up front.

The voltage in run, at the coil+, should be stepped down by the Ballast to about 7.5 volts or a bit more. During cranking that same post should be getting about same as what the starter is getting, about same as what the battery is reading. 10.5v is plenty for most coils. The Ecu could be getting a similar 10.5v during cranking. Obviously nothing can get more than battery voltage, but all those components will work, down to about 9.5 volts..... in my experience. Occasionally even lower.
To test the pick-up coil, I hook up an analog voltmeter at the pigtail, set to A/C volts and the smallest scale you have, then with pick-up still in D ,I just spin the mainshaft and watch the needle swing back and forth, indicating it is pulsing. With pick-up on the bench, I just wave a screwdriver over the magnet and again look for the needle swing. No needle swing is bad. It doesn't matter if the screwdriver or whatever wand you are using gets stuck on the magnet, just keep your eye on the needle when they separate.
Had the battery test, which was good just a little low so charge it for me. 12.46 volts 760cca
I pulled the D and bench tested it worked fine. I put in my spare D anyway which also bench test good. I still have no spark.
Voltage in run at the Coil + 12volts, my ballast has the jumper wire on it.
During cranking the same post has 8volts now, after battery was recharged. I still not getting enough voltage to the coil during cranking.
I going to pull the ground off again and clean the frame again. I also have a ground strap from the engine to the K member.
I have 12 volts everywhere in run, it just that is drops considerable in start.
 
You can run a jumper wire directly from the battery positive to the ballast resistor. That should bypass the ignition switch and wiring.
 
Voltage in run at the Coil + 12volts, my ballast has the jumper wire on it.
During cranking the same post has 8volts now, after battery was recharged. I still not getting enough voltage to the coil during cranking.
Yur ballast seems to be hooked up wrong
Take a look at the drawing in post 16. See the little U-cutouts on the dual-ballast resistor? your plug connectors are supposed to have pins on them that orient them correctly on the ballast. Make sure yours are on there correctly.

Follow the circuits.
Ignition 2 is crank mode; notice how battery voltage comes thru the ig Sw and feeds the top right terminal of the DB resistor, then carries on to feed the coil battery voltage during cranking. Simultaneously battery voltage from the ig sw passes down thru the right side resistor and exits to feed A) the ECU a reduced voltage at the top-of-the-pentastar pin.and B) that same reduced voltage is fed to the ECU bottom left pin via the second resistor now in series with the first. So if either resistor is crapped out, it breaks the circuit in crank mode and you get no spark. Either nothing gets power, or the coil does but the switcher is dead, depending on which resistor is bad.
 
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Yur ballast seems to be hooked up wrong
Take a look at the drawing in post 16. See the little U-cutouts on the dual-ballast resistor? your plug connectors are supposed to have pins on them that orient them correctly on the ballast. Make sure yours are on there correctly.

Follow the circuits.
Ignition 2 is crank mode; notice how battery voltage comes thru the ig Sw and feeds the top right terminal of the DB resistor, then carries on to feed the coil battery voltage during cranking. Simultaneously battery voltage from the ig sw passes down thru the right side resistor and exits to feed A) the ECU a reduced voltage at the top-of-the-pentastar pin.and B) that same reduced voltage is fed to the ECU bottom left pin via the second resistor now in series with the first. So if either resistor is crapped out, it breaks the circuit in crank mode and you get no spark. Either nothing gets power, or the coil does but the switcher is dead, depending on which resistor is bad.

My ballast is only a 2 pin with jumper not 4 like the drawing. Which the jumper eliminates the ballast as I understand it from FBO system.

ballast%20bypass.jpg
 
Oh that explains your wonky voltages.

But it doesn't explain the voltage differences between run and crank; with a jumpered ballast they should all be the same. Furthermore, why jumper the ballast? just splice everything together.

Waitaminute I think I get it.
In run; the coil voltage is battery; it cannot be otherwise
While cranking, the coil gets whatever is left over at the battery, say 10.5 or thereabouts.So then your wonky coil readings are correct.
So now the question moves to the trigger and FBO unit.
The trigger you have already proved.
So what is the FBO unit doing? There's the 64-million dollar question. Is it recognizing the pick-up signal, and if yes, why is it not firing.
Ima thinking it's time for an FBO wiring diagram
Are you looking for spark on a specific wire (not good) or near grounding the coil tower wire (best).
Here is your coil test;
Turn the key off and , and near-ground the tower-wire. Then run a jumper from the battery to the Coil plus. Next, go find a 10inch or longer flat coarse file and lay it on a fender cover with one end grounded. Grab another jumper and hook one end to the coil minus. Now drag the free end of this jumper along the file disconnecting when you run out of file. This simulates a point set trigger. You should see a stream of sparks at the coil wire. Near-ground is a gap about 1/4 to 3/8 inch. If yur welding, the coil is good. If it sparks over 1/2 inch, it's very good.
If it passes this, then remove the jumper from battery to coil plus, and instead turn on the key to run. Then repeat the dragging wire.
You shouldn't have to do any of this, cuz IIRC you have already proved the coil with another distributor subed in.
Don't forget; in crank mode that blue wire goes dead and the FBO needs a different power feed. IIRC this is a brown wire. You did connect it to the blue one didn't you? This was sorta mentioned in posts #2 and #9. Hyup I checked, it's the brown wire.
During cranking voltage to ignition comes from another source.
I assume you reattached the ground you removed
You've got a wire missing/not connected.. The ballast is bypassed/overrides during starting so that you get battery voltage to the Ignition in the key start position.
The key has an ignition start and run position and you should have a wire in the harness that will have battery voltage in the start position only. that's the one you want.
 
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Bypass resister.
See what happens.
I'm thinking coil situation.
Or ecu no good
 
Oh that explains your wonky voltages.

But it doesn't explain the voltage differences between run and crank; with a jumpered ballast they should all be the same.
not sure this tells me anything but was trying to check ignition switch. I remove the start wires connector from the ballast and removed the wire off the coil +. then check voltage at the start wire connector of the harness and it was still only 8 volts when cranking. now there are 2 other wires tied with the start wire, not sure what they are for. I didn't really want to take the three wire apart to check power from the ignition switch. what the best way to check the ignition switch. I was told that I needed at least 9.5 volts at the coil when cranking to get spark. I also tried my backup ecu no luck. But with the ignition in run and the distributor out spinning it my hand I have spark.
 
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