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Discussion Starter · #1 ·
Long story short, new motor, new trans, new trans brake, new line lock, new Sniper EFI w/ hyperspark distributor and coil, new fuel pumps, new rad fan, new meth injection kit, new trans cooler w/ fan, new starter, and NEW ELECTRIC WATER PUMP. Everything is wired and the the motor runs w/ everything functioning as it should except the EWP. It’ll blow a fuse as soon as the ignition is in the “on”position.

Tested the EWP motor with a with a 20 amp fuse on a spare battery and it works as it should.

Here’s the different wiring setups I’ve tried:
1: relay w/ ignition switch to activate, power from alternator, grounded to block
2: relay w/ ignition switch to activate, power from alternator, grounded to chassis
3: relay w/ ignition switch to activate, power from battery, grounded to block (& switched to chassis also)
4: power straight from battery, grounded chassis and block with a manual switch
5: ONLY WAY IT’LL NOT BLOW FUSES - hard wired to 2nd battery (power and ground separate from the rest of the vehicle’s electrical system) with a switch to turn on/off. Car runs and will sit and idle at 185-190 for as long as I want.

Here’s what’s weird and has me confused, as soon as I connect the positive to any part of the cars 12v “hot” and try and start or manually switch on the pump it’ll blow the fuse.
Last thing I haven’t tried is a new alternator which I needed to upgrade to anyways and will be installing tomorrow. But I don’t see how that’ll magically fix the problem.

Any help or ideas would be appreciated
 

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I would start by looking really hard at all your grounds.

Try grounding the pump straight to the battery with the other wiring configurations.

Although that doesn't entirely make sense as it's blowing a positive fuse but it's worth a try.
 

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Discussion Starter · #3 ·
So I checked , rechecked, and then re-rechecked all my grounds but I’ll give it another go. Can’t hurt. I have grounds from the battery to starter, chassis & block, block to chassis, heads to chassis, and alt to block.

I have run the pump ground straight to the battery. With the 12v+ connected to the vehicle’s battery and all the other components connected (+/- terminals connected) it’ll blow the fuse. If I disconnect the +/- terminals and run just the pump off the battery it’ll run the pump with no issues.

That’s why I’m confused, no other components are blowing fuses and all electric pumps, relays, triggers, etc work as they should. Car runs great minus the pump which is kinda vital to being able to drive it 😂
 

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It sounds like you have plenty of ground.

Walking into it as here is what I think I'd start with.

1. Battery terminals, make sure they are tight and all connections good.
2. Battery voltage, both engine on and off. Is the battery low causing the pump to draw more current to run?
3. What is the rated draw on the water pump? Is it real close to 20 amps? Id guess it should be closer to 10-15, if so disregard.
4. When running the relay what gauge wiring are you using for the pump, what kind and how many connectors are between the pump and power source?
5. Have you checked voltage at the pump?
 

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Make sure you're not grounding positive wire at your relay due to wiring error. Since it blows fuse when key is turned on, I think it's a direct short to ground on positive wire. Double check the relay wiring. Take just the positive wire from the load side of the relay off, the + wire to the pump, and try that. If fuse blows, you can now find cause. If it doesn't blow, there's a ground in wire from relay to pump, or a direct short in pump itself. That's why it'll run on a separate battery that is not connected to the frame ground. Just my first blush thoughts.
Where is the fuse located that is blowing out?
 

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Discussion Starter · #6 ·
It sounds like you have plenty of ground.

Walking into it as here is what I think I'd start with.

1. Battery terminals, make sure they are tight and all connections good.
2. Battery voltage, both engine on and off. Is the battery low causing the pump to draw more current to run?
3. What is the rated draw on the water pump? Is it real close to 20 amps? Id guess it should be closer to 10-15, if so disregard.
4. When running the relay what gauge wiring are you using for the pump, what kind and how many connectors are between the pump and power source?
5. Have you checked voltage at the pump?
Appreciate you taking the time to help me out. So here’s responses to your steps:

1. Battery Terminals are tight
2. Brand new battery sits @ 12.5 volts. I replaced during all this cause I thought maybe the voltage was a little low (12.2 @ battery) was causing more current too be pulled and blowing the fuse.
3. Rated draw 6-10 amps according to manufacturer
4. Running 12 awg brand new wiring. No splices or connectors
5. I’ll check voltage drop at the pump and see if there’s anything strange.
 

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Discussion Starter · #7 ·
Make sure you're not grounding positive wire at your relay due to wiring error. Since it blows fuse when key is turned on, I think it's a direct short to ground on positive wire. Double check the relay wiring. Take just the positive wire from the load side of the relay off, the + wire to the pump, and try that. If fuse blows, you can now find cause. If it doesn't blow, there's a ground in wire from relay to pump, or a direct short in pump itself. That's why it'll run on a separate battery that is not connected to the frame ground. Just my first blush thoughts.
Where is the fuse located that is blowing out?
Thanks for your response. So I rewired and rechecked the wiring using new wire and a new relay. Same results.

I don’t think it’s a short to ground directly in the EWPs chain of wiring cause when I wire it directly to the battery without the rest of the cars electrical system connected to the battery it’ll work fine. It’s only when the rest of the vehicle is connected to the battery and the pump is part of the same system that it blows a fuse. Now I can disconnect the pump and run it on a separate battery with the vehicle running and it’ll work. As soon as I take the same wire setup from the 2nd battery and touch the +/- to the battery the rest of the system is on while the car is running it’ll blow the fuse. Everything else electrically in the vehicle works as it should (that I’m aware of at this time).

Again, thanks for your time and help.
 

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Thanks for your response. So I rewired and rechecked the wiring using new wire and a new relay. Same results.

I don’t think it’s a short to ground directly in the EWPs chain of wiring cause when I wire it directly to the battery without the rest of the cars electrical system connected to the battery it’ll work fine. It’s only when the rest of the vehicle is connected to the battery and the pump is part of the same system that it blows a fuse. Now I can disconnect the pump and run it on a separate battery with the vehicle running and it’ll work. As soon as I take the same wire setup from the 2nd battery and touch the +/- to the battery the rest of the system is on while the car is running it’ll blow the fuse. Everything else electrically in the vehicle works as it should (that I’m aware of at this time).

Again, thanks for your time and help.
I will be looking forward to your resolution. It seems you've tried about everything. Good luck friend!
 

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What is your alternator putting out in VDC & amps to your system with the engine running? Internal or external regulator? Leaning towards the alternator personally... Can you reverse wire the relay so the EWP has constant positive battery terminal connection and then wire the ground through the relay for just that circuit? There's a reason it works with the engine off but then it fails when you have the car running and it would likely be the voltage regulator not providing steady-state volts and amps the system... Just my $0.02
 

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Does it blow the fuse key on engine off or only when the engine is running?
I don’t think it’s a short to ground directly in the EWPs chain of wiring cause when I wire it directly to the battery without the rest of the cars electrical system connected to the battery it’ll work fine. It’s only when the rest of the vehicle is connected to the battery and the pump is part of the same system that it blows a fuse
 

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One thought short of my following suggestions: Do you have another vehicle to try this on? Just to see if you can duplicate the blown fuse? IF the fuse blows on another vehicle (it's okay to run it for a second without water), then it's the water pump motor switching sensing a surge in power from the starter voltage drop then amp spike as the solenoid releases from the key switchback to run from start. One more thing to test...

What ignition system are you running? Does your ignition box and Sniper system connect directly to the battery? Where does your coil get power from? Signal from the ignition box is from the dist, then to the Sniper since it's batch pulse EFI so there's a signal to the EFI but... You need to disconnect everything, plug in the EWP then you need to systematically connect each component... Fuel pump, ignition box, coil, EFI, fan(s), any relays controlling anything. Even a stereo amp, one at a time, adding a new one in each time and see what happens. OR Disconnect them all then plug in the EWP and try adding them in one at a time, then disconnect that one and move to the next one, then disconnect that one too, so forth and so on until you find the circuit that's causing the flare. That may at least narrow the circuit down... Don't know what else to say on this... I'm leaning towards a bad voltage regulator though. You never mentioned whether you have a internal or external regulator or what year this car is...
 

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via @Custom Jim re: Relay swap:


https://electronics.stackexchange.c...ck-diode-with-an-automotive-relay/56323#56323 (this one explains the diode)

Excerpt:

The diode is a really good idea. It's called a freewheeling diode. This answer covers the details (and that's why I put this as a comment only): electronics.stackexchange.com/a/56323/930 Scroll to where it says "Some Background Info". In short, the diode takes the energy stored in the relay's coil when you switch the current off. Without the diode, the energy has no place to go and will cause a large and probably destructive voltage spike
 

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Wasn't there recently a rather lengthy discussion regarding relays wire gauge and fan controllers here? About a month or so ago... @Custom Jim
There might have been.

It was stated in reply #6 that the water pump draws 6-10 Amps

With the pump positive going through a 20A fuse and then to the battery positive post and then the negative wire off of the pump going to the same battery ground, the fuse never blows.

If then the pumps positive wire were to be wired through a relay and the activation coil is wired with one side going through a 5A fuse and then this connected to the battery positive post, then when the activation coils other wire is then touched to the same battery ground, then the relay will click, then power get's pulled through the 20A fuse to the pump and with it grounded will allow the pump to pump or spin.

If when touching the activations wire to ground causes the 5A fuse to blow, then there is a short or too low of a resistance in the activation coil, If the 20A fuse were to blow, then the relay has to be connecting the supply of power to a ground and the only ground would be on the one end of the coils activation wire.

If a fuse blows very quickly and pops hard, to me this indicates a real good direct short. If it glows a bit and then blows, on let's say a 20A fuse, then the current draw might actually be 30A. Remember that a 20A fuse willpass 20A all day long and probably pass 25A also all day but then if asked to pass 30A it doesn't happen right away but there is a time delay and if the current is increased to 35A, the time delay s shorter and then if asked to pass 100A, then in a split second it pops.

Jim
 

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Discussion Starter · #19 ·
Well installed the new 140amp alternator (internal regulator) and it’s holding at 14.3-14.5 at idle. Still same issue with it blowing the fuse when hooked to the cars electrical system. As of right now I have the EWP wired to a spare battery in the trunk I can turn on and off with a switch. It’s a temporary fix for now, Think I’ll try the reverse wire relay so a ground activates the relay this weekend as Ace suggested.

Ordered a spare pump motor (on back order til October) and going to give CVR a call in the morning to see if they have any ideas.

I guess I’ll have to go through all the cars wiring at some point for peace of mind. I’ll probably do it this winter.
 

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Damn, sorry that didn't work out. As Custom Jim mentioned, the relay may well be the culprit. The guys talking about a short in the body of the pump itself made sense too... If the wiring in the pump is shorting to ground, then the ungrounded second battery works because it's direct-wired and not grounded touching the water inlets on the front of the engine, grounding that way through the body and block grounds then to the negative terminal on the main batt. Good suggestion above there... May check that out too... Can't hurt and maybe the pump motor or wiring is roached. Check that relay though ... Check ohms resistance from + to ground on body of pump and then from - to body of pump... See if there's a short to ground. It should be an isolated circuit for the pump motor and not use the body for ground ... That would at least tell you if you have an internal short in the pump itself.
 
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