Fuel pump runs as soon as the battery cable is hooked up! PLEASE HELP

ttocs · May 31, 2016

ok I thought it was just turning on when the battery is connected but not with the key. I wish I had my mustang bibles wiring section but I do not have access to it.

lwarrior1016 · May 31, 2016

98 has a separate relay behind the glove box, Im not sure if the 94-95 cars do. There should be 2 relays in the system, an external and the one inside the ccrm.

BigSkySN95 · May 31, 2016

mcglsr2 said:
Assuming you did nothing else to the wiring, and the previous fuel pump was working fine, then something awfully strange is going on. You are all of a sudden getting battery voltage on a wire that is supposed to be on in the IGN position. This happens now with your replacement CCRM, yes?

Have you confirmed that your ignition switch is off? Not in ACC? If yours is like mine, you can turn the key clockwise to ACC, RUN and START (IIRC) and also you can turn it counter-clockwise to ACC. ACC will prime the fuel pump. Some older, worn ignitions might let you put it in the ACC state and still remove the key. Double check that your ignition is the OFF position. If it is, then there might be something wrong with the switch itself. Disconnect the fuel pump so you don't burn anything out. Then see if your radio will come on.

Lastly, I'm not sure why your CCRM burned out. I assume the pump was pulling too many amps through the relay, but somehow still under the fuse threshold. Not sure. You might have a separate issue not related to the pump. Could be coincidence. Did you do any other wiring? Did you move the CCRM around, modify an wires/connections?

Edit: I think the fuel pump relay is inside the CCRM. Not sure how you test it other than probing the correct pins on the harness that connects to the CCRM.

Yes, happening the replacement CCRM. Keys are on the passenger seat and the ignition was new 20,000 miles ago.

ttocs · May 31, 2016

did you wire an external relay like is recomended from aeromotive?

BigSkySN95 · May 31, 2016

ttocs said:
did you wire an external relay like is recomended from aeromotive?

No, everything I read on the forums had people just using it with factory wiring

ttocs · May 31, 2016

what kind of HP are you pushing? How fast the pump runs depends on how much gas it needs to feed and the faster it runs the more current it takes. It could be just above the threshold of what is safe on the CCRM and causing problems. But honestly ignoring the manf suggestions because of what you read on the net is just possibly setting yourself up for failure. A relay costs way too much don't get me wrong but when you take into account in the case it is a safety device it just pure lazy that it isn't put on. I would start there and see what happens but you might need another CCRM after installing it.

mcglsr2 · May 31, 2016

I'm not sure he's gotten as far as flooring the car and making max HP. From what I understand, he did the install, connected the battery, and poof - fried CCRM and running pump. I'm not sure he's even driven the car yet.

OP, how handy are you with a multimeter? I suspect you'll have to start probing to see where the short is...

ttocs · Jun 1, 2016

I would still start with the relay since it was recomended.

JerZeyStangz · Jun 1, 2016

Any update on this? My aeromotive 340lph should be arriving in a few days from summit. It does make sense what TTOCS said about him passing threshold of being safe, it must be drawing more power for a reason.

mcglsr2 · Jun 1, 2016

JerZeyStangz said:
Any update on this? My aeromotive 340lph should be arriving in a few days from summit. It does make sense what TTOCS said about him passing threshold of being safe, it must be drawing more power for a reason.

Except that the Aeromotive stealth units are designed to be dropped in using OEM wiring. Wouldn't be very stealth otherwise. Having said that, if one *wants* to run heavier gauge wire and separate relays, etc. then go for it. Certainly won't hurt. However, I don't think that's a requirement for these specific pumps. But I'm not sure. I will do some research.

Also, and again could be wrong, but I'm not convinced that this is the OP's problem. If the pump was under-amped, then it wouldn't push enough fuel (fuel pressure might be low). It wouldn't turn on just because the batt is connected. For that, it means, to me, that the power feed to the fuel pump is getting BATT voltage, and not IGN voltage.

BigSkySN95 · Jun 1, 2016

mcglsr2 said:
Except that the Aeromotive stealth units are designed to be dropped in using OEM wiring. Wouldn't be very stealth otherwise. Having said that, if one *wants* to run heavier gauge wire and separate relays, etc. then go for it. Certainly won't hurt. However, I don't think that's a requirement for these specific pumps. But I'm not sure. I will do some research.

Also, and again could be wrong, but I'm not convinced that this is the OP's problem. If the pump was under-amped, then it wouldn't push enough fuel (fuel pressure might be low). It wouldn't turn on just because the batt is connected. For that, it means, to me, that the power feed to the fuel pump is getting BATT voltage, and not IGN voltage.

Well my first plan is to drop the tank and hope a visual inspection yields a obvious answer. I'm only running a V3 Si trim blower on stock heads, I just wanted the 340 so I would be ready for heads and cam in the future

ttocs · Jun 1, 2016

this is a direct quote from their page.pretty sure the stealth name just means it fits in the tank, not that the stock wiring is good enough. Sorry if your on the dark mode highlight the page and you can read it.

http://www.aeromotiveinc.com/tech-help/faqs/faq-340-stealth-fuel-pumps/

"10.) Q: I heard that to use the 340 Stealth Pump you have to upgrade the OEM factory fuel pump wiring, and possibly the relay and fuse/breaker, is this true and why?A: The wiring used to power the fuel pump plays a key role in supporting the electric motor that runs the pumping mechanism. It’s the combination of motor torque and the pumping mechanism speed it produces that enable the incredible flow the Stealth 340 is known for. The factory fuel pump wiring and electrical components were engineered for a fuel pump drawing Â¼ to Â½ the current. Failure to upgrade this wiring, including the relay and breaker/fuse assembly, may result in a substantial reduction in performance of the new 340 Stealth.
The 340 Stealth Fuel Pump is a break-through in OEM replacement fuel pump technology. It is capable of flowing 33% more than conventional, performance replacement fuel pumps, and as much as 100%-300% more than the vehicles original pump. For proper installation and to ensure the optimum performance and service life, please see the installation instructions on page 2 to view the flow and current draw at pressure chart, and the bottom of page 3 for wiring recommendations. Ensure proper wiring, your new 340 Pump, and your engine, depend on it!
NOTE: For specific wiring kit recommendations, see FAQ #16."

mcglsr2 · Jun 1, 2016

^ Hmm, going to flip through the installation directions here shortly. I stand corrected, though - it looks like they will want you to upgrade your wiring.

That being said, it still doesn't explain why the pump gets power when the battery is connected. It just means the pump wouldn't push it's full volume using the OEM wires...

JerZeyStangz · Jun 1, 2016

We just got to wait for the OP to drop his tank and go from there. Ttocs I would love to see how you would upgrade the wiring on our cars like mentioned in the other thread.

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BigSkySN95 · Jun 2, 2016

If I have to upgrade the wiring, I'll have a barely used Stealth 340 pump for sale. 255 Walbro will fit the bill just fine for now.

BigSkySN95 · Jun 2, 2016

I'm out of town but next week the tank comes out and I'm concentrating completely on getting this car running.

BigSkySN95 · Jun 7, 2016

**UPDATE** My tuner thinks my Quarterhorse may be bad and causing this problem, chip is coming out tonight so I'll have answers tomorrow.

JerZeyStangz · Jun 7, 2016

My pump is getting installed today by a shop, I will let you know how it goes.

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ttocs · Jun 7, 2016

BigSkySN95 said:
If I have to upgrade the wiring, I'll have a barely used Stealth 340 pump for sale. 255 Walbro will fit the bill just fine for now.

if you read the recomendations then you will have a fuel pump for sale then. That sucks for you since your lucky to get %50 of the retail value on used parts even if it was used over night. Now for someone like me who likes to have a spare part waiting as I know I will keep the car long enough to have one waiting, I got $50 for you.

mcglsr2 · Jun 7, 2016

I wouldn't be so quick to ditch that pump. All that will happen, if your wires are too small, is deliver less amps to the pump. This means your pump won't reach max capacity, so it may end up acting like a 255 rather than a 340. Which is no big deal, if you want to keep your stock wires you are going to use a 255 anyway. I would send Aeromotive an email and ask them what would happen if the stock OEM wires aren't quite enough to deliver full amps. If the answer is "the pump won't flow rated capacity" then maybe who cares. As long as you have the correct fuel pressure through the rev range and under load, who cares?