Is it OK to take power off the terminal on the ballast resister to fun an electric fuel pump? I tried reading up on what the resister is for, and it sounds like the voltage changes? To me I think it is not a good idea. 65 slant 225 valiant
ballast resisters
- Thread starter desy500
- Start date
-
TrailBeast
AKA Mopars4us on Youtube
If you take power for a fuel pump off the ballast without using a relay to actually power the pump you risk dropping the voltage to your ignition system.
This could result in hard or no start problems down the road if not immediately.
This could result in hard or no start problems down the road if not immediately.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,956
- Reaction score
- 12,308
Where is/will the pump be located? An electric fuel pump should be at or near the fuel tank. The fused power wire should be run inside the car in the oem conduits provided.That means the relay could be on the inside of the car, and you can pick up power for the signal side,where its warm and dry,from the accessory fusebox.Jus saying...
Thanks, the pump is on the top of the shock mount, front passenger side, done by previous owner. No issues starting up, but pump stops pumping after 10_15 min. Just starting to trouble shoot it . I don't see a relay just the 2 wires out of the pump, 1 to ballast,neg to battery. Unless relay is built in pump.
69_340_GTS
Well-Known Member
The power for any electric pump should come directly from the battery, with an in-line resettable circuit breaker. The power to the pump should be turned on/off via at least a 20 amp relay which can be activated by nearly any "ignition on" power source or an additional switch. Get a kit from a place like Painless. It will include everything you need including excellent instructions.
69_340_GTS
Well-Known Member
The problem with mounting the pump high up in the front of the car is this: How does it get primed? Liquids do not naturally flow uphill. If the pump loses it's prime, it will be sucking a lot of air, and 90% of the time that will not work! Electric pumps should be lower than the fuel pickup (bottom of gas tank). Sometimes it will work okay if mounted otherwise, but chances are it won't always.
BillGrissom
Well-Known Member
This is oft-stated, even by Holley and other EFI vendors, but doesn't make it true. I mounted an EFI pump in the lower engine bay in my 3 Mopars. My 65 Newport has run that way since ~1998. Prior to that, I tried the "mount near tank", with much fussing and it is hardly accessible for roadside repairs. If you test it, fuel just pours out of the 5/16" factory supply tube (or should), so I can't imagine it restricting the pump inlet. Re "priming", someone here asked Walbro and they said their EFI pumps can suck fuel up to 5 ft high, so no concerns there (unless climbing a 20 deg grade).
You could power the EFI pump directly off the key switch (IGN circuit), but the current draw and inductive kick-back could burn up your switch, and the extra draw could draw down your ignition voltage, as others mentioned, making for a weak spark. Always smart to power via a relay (and fuse) from BATT+. You can tap BATT+ at the big stud on your starter relay (firewall).
Re your ballast question, it is to reduce the voltage to the coil when the engine is running. That wasn't just a Mopar thing. Many here changed to a newer HEI ignition system that gives a stronger spark and runs directly off battery power, hence no more ballast.
nm9stheham
Well-Known Member
Just as a side note....the ballast resistor' purpose is to perform a crude current regulation through the coil that keeps coil heating under control over a wide range of RPM's. The electrical term 'ballast' means just that: a resistive element that varies it's resistance based on the current flowing through them. There were ballast tubes in the old vacuum tube days that did the same kind of thing: current regulation.
The voltage drop from the ballast is just a byproduct of their current regulation. It is not precise current regulation by any means like a solid state regulator, but it does keep the current flow and heating of the coil within a rough range despite wide variations in RPM.
The voltage drop from the ballast is just a byproduct of their current regulation. It is not precise current regulation by any means like a solid state regulator, but it does keep the current flow and heating of the coil within a rough range despite wide variations in RPM.
Thanks for the helpful info , it is hard to trouble shoot what previos owners have done , without sites like this one could waste a lot of time and money. So last night a put a bag of ice on the pump to see if it would still run dry , it ran about an hour , the level of fuel in the filter slowly got lower. I could see small spurts of fuel ever few seconds coming threw. I shut it off. turn the key on and the pump did not pump. waited 15 min. turn the key on pump filed the filter. started it back up put ice on the filter , let it run , it did the same thing. Any ideas before I buy the relay , and a new pump ?
moe7404
moe7404
dont forget to carry TWO new resistors in the glove box. cold and heat tend to knock them out.
nm9stheham
Well-Known Member
For the fuel situation:
- Make sure the rubber line from the tank to the fuel line is not cracked, even a little bit. A small line crack can open up and let air in erratically; I had one that did it for over a year before it was found.
- Has the tank even been dropped and cleaned? It could have crud in it slowly blocking sock filter in the tank. This is common in these cars.
- If you are willing to repeat the test, try pumping out of a fuel container instead of the tank to rule the tank being clogged in or out.
- I would consider relocating the pump lower as a matter of good practice but not sure how necessary it may be. I have raced long endurance races with 2L 4-bangers successfully with electric pumps mounted a couple of feet above the tank with no issues ever. The old electric shuttle pumps used in small aircraft DID need to be below the tanks for priming, but that does not seem to apply as much for newer pumps; so it varies with the design. You don't seem to be having priming problems with your testing.
- Make sure the rubber line from the tank to the fuel line is not cracked, even a little bit. A small line crack can open up and let air in erratically; I had one that did it for over a year before it was found.
- Has the tank even been dropped and cleaned? It could have crud in it slowly blocking sock filter in the tank. This is common in these cars.
- If you are willing to repeat the test, try pumping out of a fuel container instead of the tank to rule the tank being clogged in or out.
- I would consider relocating the pump lower as a matter of good practice but not sure how necessary it may be. I have raced long endurance races with 2L 4-bangers successfully with electric pumps mounted a couple of feet above the tank with no issues ever. The old electric shuttle pumps used in small aircraft DID need to be below the tanks for priming, but that does not seem to apply as much for newer pumps; so it varies with the design. You don't seem to be having priming problems with your testing.
thanks nm9stheham! so I first pumped into a m5 gal tank with the coil plug pulled , and key turn on pump filled the can in no time , I did squeeze the line with my fingers to see what would happen , the pump stopped pumping till I let go. next I ran the engine pumping out of the can , it did fine for 15 min at idle , but when I revved it up she ran dry again , and the pump barely put any fuel back in the clear filter. so my next test I guess is to take off the filters , and run out of the can to see if that changes anything ? what do you think?
1) can you hear the pump running?Does it get louder-quieter faster-slower while the
engine runs up to the 15 min. mark?
2) check the voltage at the ign.sw. side wire of the ballast as the engine runs, does
maintain good batt. voltage?
3) 5 Gal. in no time w/no press. load is obviously plenty,pretty much rules out a
clogged tank pick-up or collapsing fuel hose on the suction side.Only exception
is fine rust/dirt collecting on pick-up during driving w fuel slosh stirring it up.
4) EFI pumps & yours not comparable, I would mount it low & in the rear of the car
pumps ALWAYS push better than they pull,period.
5) Regardless of your findings, the factory ign. hot wire should be used to trip a
relay, not to power the pump directly. Extra current load on the factory(original?)
wiring can cause an excessive voltage drop to the regulator sense wire resulting
in your battery overcharging.
6) The ballast resistor is used to limit idle/low speed current to the coil because
actual dwell time is high at those speeds,the resistance actually goes up as
the resistor heats up during high current demands, then back down as you rev.
unfortunately it is slow to respond to quick changes........
good luck!!! :coffee2:
engine runs up to the 15 min. mark?
2) check the voltage at the ign.sw. side wire of the ballast as the engine runs, does
maintain good batt. voltage?
3) 5 Gal. in no time w/no press. load is obviously plenty,pretty much rules out a
clogged tank pick-up or collapsing fuel hose on the suction side.Only exception
is fine rust/dirt collecting on pick-up during driving w fuel slosh stirring it up.
4) EFI pumps & yours not comparable, I would mount it low & in the rear of the car
pumps ALWAYS push better than they pull,period.
5) Regardless of your findings, the factory ign. hot wire should be used to trip a
relay, not to power the pump directly. Extra current load on the factory(original?)
wiring can cause an excessive voltage drop to the regulator sense wire resulting
in your battery overcharging.
6) The ballast resistor is used to limit idle/low speed current to the coil because
actual dwell time is high at those speeds,the resistance actually goes up as
the resistor heats up during high current demands, then back down as you rev.
unfortunately it is slow to respond to quick changes........
good luck!!! :coffee2:
In all due respect I think you are wrong about "what the ballast resistor is for" I always thought it was to keep the points from burning out. And I still think that. But now that I give it a little more thought, they did still use them for electronic ignition. So maybe im incorrect? MT
67Dart273
Well-Known Member
"Regulation" is correct, but it is only PARTIALLY the story. The advantage "back then" of using a resistor / coil combo instead of a "full voltage" coil is, that when starting, the battery voltage is drug down. By using a resistor, then they could use a bypass circuit for starting and get the voltage "back up" during crank
IE what you have is
Fully charged battery, nominal 12.6
"Running" down the road, nominal 14V
But STARTING around 10.5, and on a very cold day and if the battery might be down, "less" maybe down 9V or even less
So by using a resistor and coil combo designed to run on 10-12 V nominal, you can still have good supply voltage to the coil when CRANKING
"Everybody" did this, pretty much, Ferd, GM, Ma, and AMC. All used a resistor and a start bypass setup. Fraud, AMJ, and GeeM "did" the bypass with the starter solenoid. "Ma" chose to use the ignition switch.
"Everybody" could have chosen a coil built for "straight" 12V service. Many tractors and industrial machines like welders did things this way. Most these had lower compression ratios which start easier with low voltage than do hi performnance, high compression engines.
IE what you have is
Fully charged battery, nominal 12.6
"Running" down the road, nominal 14V
But STARTING around 10.5, and on a very cold day and if the battery might be down, "less" maybe down 9V or even less
So by using a resistor and coil combo designed to run on 10-12 V nominal, you can still have good supply voltage to the coil when CRANKING
"Everybody" did this, pretty much, Ferd, GM, Ma, and AMC. All used a resistor and a start bypass setup. Fraud, AMJ, and GeeM "did" the bypass with the starter solenoid. "Ma" chose to use the ignition switch.
"Everybody" could have chosen a coil built for "straight" 12V service. Many tractors and industrial machines like welders did things this way. Most these had lower compression ratios which start easier with low voltage than do hi performnance, high compression engines.
nm9stheham
Well-Known Member
The condenser is what you may be thinking of that helps keep the points from burning up. Often when a condenser opens up, you get rapid metal transfer from one side of the point to the other and the points get all messed up.
nm9stheham
Well-Known Member
There ya go.... good explanation with the dwell change. It was hi-tech for the day!
BillGrissom
Well-Known Member
desy500 PM'd a question about "EFI pump". I answer here for everybody. Electronic Fuel Injection pumps can output high pressure (~60 psig) for MPFI, but they can also be used for carburetors (~5 psig) or TBI (~20 psig). You can find a flow curve, giving flowrate vs output pressure. For those who worry about supplying a monster carburetor, even a small EFI pump probably outputs ample flowrate at 5 psig. Downside is you must have a return line to the gas tank (or at least upstream of the pump). It may also flow much more that your carb would ever need, thus waste electricity and heat the fuel.
I have 2 cars currently using an EFI pump w/ carburetor. I measure ~10 psi return, due to returning thru the 1/4" tube of the sender, so I plumbed a "pressure-reducing" regulator in series w/ the carb (dial wheel type), to not overwhelm the float needle. I plumbed the EFI pump because I plan later TBI or MPFI, plus want a "carb in trunk" as roadside backup.
There are 3 basic external mount EFI pumps I know of - Walbro, 1990's Ford Truck, & Bosch Jetronic. Walbro type has the best fitting selection. Ford pumps have only 5/16" outlets I think. Bosch type (M-B, VW, Audi, ...) usually have a check-valve fitting that requires a banjo fitting, which I bought at a DeLorean site.
If you will only use a carb, the Holley radial vane pumps or a little rattler pump (Mr. Gasket, etc) should work. If you mount on the rear frame rail, you will hear them thru the back seat, unless you design better rubber isolation than I had.
I have 2 cars currently using an EFI pump w/ carburetor. I measure ~10 psi return, due to returning thru the 1/4" tube of the sender, so I plumbed a "pressure-reducing" regulator in series w/ the carb (dial wheel type), to not overwhelm the float needle. I plumbed the EFI pump because I plan later TBI or MPFI, plus want a "carb in trunk" as roadside backup.
There are 3 basic external mount EFI pumps I know of - Walbro, 1990's Ford Truck, & Bosch Jetronic. Walbro type has the best fitting selection. Ford pumps have only 5/16" outlets I think. Bosch type (M-B, VW, Audi, ...) usually have a check-valve fitting that requires a banjo fitting, which I bought at a DeLorean site.
If you will only use a carb, the Holley radial vane pumps or a little rattler pump (Mr. Gasket, etc) should work. If you mount on the rear frame rail, you will hear them thru the back seat, unless you design better rubber isolation than I had.
Mr Grissom is correct, My point was EFI pumps almost all have said anti drain-
back check valves in them. Most have a faster flow rate as well, thus they
hold their prime well and are more capable re-establishing one quickly.
the pump in question was not clear, but I assumed a walbro canister/bellows
or mr gasket "rattler" type was the style found on desy's car, thus the
"not comparable" reference. Hope your problem is nothing more than a
pump that cant handle the push anymore, keep us posted,:coffee2:
back check valves in them. Most have a faster flow rate as well, thus they
hold their prime well and are more capable re-establishing one quickly.
the pump in question was not clear, but I assumed a walbro canister/bellows
or mr gasket "rattler" type was the style found on desy's car, thus the
"not comparable" reference. Hope your problem is nothing more than a
pump that cant handle the push anymore, keep us posted,:coffee2:
after playing with it last night , I'm pretty sure it looses it's prime with higher rpm's , I checked the voltage at the battery , and at the pump , and they are the same , they both go higher as the rpms go up. after I ran it dry , I switched it back to pump out of the 5 gal can , but it wouldn't prime / pump . after putting it back to the tank and sitting awhile , I guess gravity helps it get primed again. Any how I'm going back to a mechanical pump for now , since the electric is too high up , and wire wrong , and mechanic pumps are cheep.
-
