ELECTIC FUEL PUMP POWER

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WAYNE0

WAYNE0

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For those of you that have an electric fuel pump & have hooked up to the ignition switch where at the switch are you getting your power ?
 
What are you working on exactly? It's best to go from key power to ignition/voltage regulator to a relay and use battery terminal on the starter relay to power a fuel pump.
 
THERE IS ONLY ONE. The key output you want is the IGN1 or "ignition run." Go out into the engine bay. You did not tell us what you are working on

Generally ON A MOPAR the "run" line comes out of the bulkhead connector in the engine bay, at some point branches off, and feeds the VR IGN terminal, the ballast resistor, on some cars has or had an electric choke, maybe an AC idle solenoid, and on 70 / later cars fed the blue wire to the alternator field. On many years, but not all, this is dark blue

NONE OF THIS IS FUSED, and is only protected (poorly) by the fuse link.

Run over to MyMopar.com, and download a service manual for whatever you have.

PLEASE POST what you are working on, make model and year. It's also helpful if we know whethter the vehicle was rewired with a "universal" harness, or factory stock wiring
 
I always wire the FP relay thru the oil pressure switch. That way if the engine quits (Due to accident, or fuel line rupture), the fuel pump will shut off. In certail applications I add a pushbutton switch in parrellel to the pressure switch, to prime the fuel system, and prevent extended crank times.
 
if your car doesn't have aircon you may find that you have a spare fuse bay on the fuse box,in the "switched by the Ignition switch area". in which case a fuse in that bay and a wire from it to a relay that you can use to switch a properly fused power supply from battery to the pump would work. you then just load up the fuse box and ignition switch with the current needed to trigger the relay.

you put a suitable fuse, rated for your pump, in the wire you run from battery to your pump via the switched part of the relay

ideally either the wire from fuse box to relay or wire from battery to pump circuit would include a roll over/ impact/inertia switch, probably the pump feed if your inertia switch can take the current needed to run the pump, but either would work.

https://www.moss-europe.co.uk/en-gb/switch-inertia-fuel-pump-c41220ax

you will find them in the US this just happens to be the first i found

what you do for a race car will depend on where you race but ideally on a street car you use the inertia switch to stop the pump on impact to avoid it emptying the fuel tank into the damage caused by an accident. in most cases a race car has an external cut off switch and track staff to switch it to OFF, should the worst happen. you don't have that on the highway


just seen the post above from charrlie_s oil pressure switch idea provides very similar protection

Dave
 
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If running a stock ammeter, never draw power directly form the battery, or anywhere on the battery, side of the ammeter for any add on loads.
fuel pump.png
 
or do you trust aliexpress $5 for something that look exactly like the summit one for $100
https://www.aliexpress.com/item/1005006698555274.html?src=google&pdp_npi=4@dis!GBP!15.24!4.99!!!!!@!12000038038289592!ppc!!!&src=google&albch=shopping&acnt=494-037-6276&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&gclsrc=aw.ds&&albagn=888888&&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005006698555274&ds_e_product_merchant_id=705499124&ds_e_product_country=GB&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=17859500389&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gad_campaignid=17190468917&gbraid=0AAAAADznYb8AabVGyZqxsZFL4lTihJMQ0&gclid=Cj0KCQjw0LDBBhCnARIsAMpYlAosD7WzquO9hXWQEjec41GWLSVY14_y-W92l4f6Dvk5FlsFuWopXU8aAiGOEALw_wcB

Mmm
i think summit racing would get my cash....
 
67 barracuda MSD box MSD dist. intank holley fuel pump it has a inline fuse small block with paxton supercharger all aftermarket gauges
 
Dave999 said:
if your car doesn't have aircon you may find that you have a spare fuse bay on the fuse box,in the "switched by the Ignition switch area". in which case a fuse in that bay and a wire from it to a relay that you can use to switch a properly fused power supply from battery to the pump would work. you then just load up the fuse box and ignition switch with the current needed to trigger the relay.

you put a suitable fuse, rated for your pump, in the wire you run from battery to your pump via the switched part of the relay

ideally either the wire from fuse box to relay or wire from battery to pump circuit would include a roll over/ impact/inertia switch, probably the pump feed if your inertia switch can take the current needed to run the pump, but either would work.

https://www.moss-europe.co.uk/en-gb/switch-inertia-fuel-pump-c41220ax

you will find them in the US this just happens to be the first i found

what you do for a race car will depend on where you race but ideally on a street car you use the inertia switch to stop the pump on impact to avoid it emptying the fuel tank into the damage caused by an accident. in most cases a race car has an external cut off switch and track staff to switch it to OFF, should the worst happen. you don't have that on the highway


just seen the post above from charrlie_s oil pressure switch idea provides very similar protection

Dave
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No. I already said this. There is ONLY ONE, it is "ignition run" coming from the key switch and IT IS NOT FUSED

You certainly don't want the pump run off the ACC buss

On the oil switch idea, You will need to use a special oil switch. OEM grounds with no pressure. Not the type switching you want
 

67Dart273 said:
On the oil switch idea, You will need to use a special oil switch. OEM grounds with no pressure. Not the type switching you want
Click to expand...
A switch like is used on my 88 D-150 It has the contacts for a gauge and another set for the electric boost for the choke. Use the contacts for the choke to trigger the pump relay.
With idiot light> More Information for STANDARD MOTOR PRODUCTS PS133
With gauge> Use a "T" and the factory style sender, and the above switch for the fuel pump.
 
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Charrlie_S said:
A switch like is used on my 88 D-150 It has the contacts for a gauge and another set for the electric boost for the choke. Use the contacts for the choke to trigger the pump relay.
With idiot light> More Information for STANDARD MOTOR PRODUCTS PS133
With gauge> Use a "T" and the factory style sender, and the above switch for the fuel pump.
Click to expand...
Yep, and I think maybe the Vegas and other GM's used similar, as well as Toyota, back in the day. Of course the Toy ones are a little bit smaller thread and may not seal
 
Just something to consider. I am not a fan of the inertia switch. Granted it will trip and shut down the fuel pump in the case of an accident, but I will play devels advocate here. What if the fuel system developes a leak or the float sticks in the carb? the fuel pump will keep runing, adding fuel to the fire (so to speak). The oil pressure switch will shut down the FP as soon as the carb runs out of fuel, or the engine stalls. Remember we are adding an electric pump to a system that was never designed for one, and there are no safety systems on the vehicle.
 
Every car ever made with an electric pump has some sort of an inertia switch , maybe the engineers are wrong .
 
jimjimjimmy said:
Every car ever made with an electric pump has some sort of an inertia switch , maybe the engineers are wrong .
Click to expand...
I'm really not up on the "new" cars, but the only American car I have seen with an "inertia" switch are Ford products. And we are talking about "Retrofitting" an electric pump to a carburated vehicle. The vehicles you are talking about were "engineered" for use with the electric pump. I don't have a problem with the inertia switch, but it only solve half the problem. Actually wouldn't hurt to use both safety devices.
 
my thinking was, if you take it from "run" on the switch you are taking it from the power source for the coil which is subjected to the back emf from the coil with every spark... i didn't think a relay would like that, could imagine it chattering. if it can mess with an electric choke it can mess with a relay....
and obviously running the pump straight off RUN is a no,no if the key switch is standard... BUT have no experience of doing it so am happy to be wrong...
ie if my suggestion was daft there was some logic to my daftness even if i had not considered everything. :)

but noted. I agree extra load on the ammeter if hooked to battery side, if you still have ammeter hooked up. but if its a small pump on a no aircon car you'd be ok... you are only using about 20 of your 36 amps normally might get close with heater wipers lights on.... even then you probably got a good couple hours driving to notice the drain and switch something off

must admit i prefer the simplicity of a nicely specified mechanical pump... if you have a rebuilder you can change the valves (flow) and the strength of the diaphragm spring (pressure). to adjust to what you need if you need to, and can find carter parts.
But am sure electric is king for full on race engine that sees 99% of the time WOT max rpm

inertia or roll over switches common on euro cars with EFI pumps seems to make sense to take advantage, especially if you get one with a warning light, mount it within reach of the driver, solid mount to A pillar next to "under-dash" with the light in line of sight, can be easily reset if you happen to leave the ground, Bo and luke style, when you take that railway crossing way too fast, running a carb you won't just stop dead....


Dave
 
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Charrlie_S said:
I'm really not up on the "new" cars, but the only American car I have seen with an "inertia" switch are Ford products. And we are talking about "Retrofitting" an electric pump to a carburated vehicle. The vehicles you are talking about were "engineered" for use with the electric pump. I don't have a problem with the inertia switch, but it only solve half the problem. Actually wouldn't hurt to use both safety devices.
Click to expand...
Yep, I've only seen innertial cutoff switches on Fords. It's more common to have an engine RPM based cutoff to turn the pumps off if the engine stops
 
The fuel pump control is in the ECM software on modern cars. They use a timer that counts down and shuts off the pump when it reaches 0. It only resets if the controller sees engine rotation. So it's constantly counting down from 2 sec. When the engine stops, no rotation is observed, the timer decrements to 0, and the pump is shut off.

The timer was historically always 2 seconds but there may be other manufacturers that used other values as well.
 
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