12v+ FP ECU mod will keep the fuel pump running when you turn the key to acc.

If you run anything direct to the acc it could drain the battery when the FP is running too.

Stock ECU's with the 12v+ mod WILL NOT hold the injectors open and hydrolock the engine with fuel.

Other then that, it keeps the voltage up on thirsty Walbro's and such.

 

More great detailed info on this thread about the 12 volt mod. I want to be clear, I ran a separate relay to mine to keep the voltage up, not having anything to do with the soldering the green and red wires together from the factory harness in the driver side rear compartment. I bypassed it completely. One wire of 10 gauge to the power side of the relay from the battery, one wire to a switched output so it turns on when I hit the key to ACC, then a ground wire, then the other to the hot side of the relay. Wolla it comes on every time I turn the key. I did this after the extensive research on the voltage drop and the power loss from the stock wiring in the SC.


In the end, I think I did the right thing, only time will tell, to see if works accordingly. If for some reason this doesn't work, all I have to do is pull the separate fuse, and rewire the factory wires back together separate. I really dont think I will have a problem with mine doing any vapor locking.


ok, just read this whole thread. man there is alot of good info in this thread. i look forward to your progress. thanks for the detailed thread. i would like to know why not to do the 12v mod. i don't think you ever got a reply from quick on that one.

Thanks man, I appreciate it. trying to get everything done right in time for the IA in April. There is also a local show toward the end of March, I also would like to attend.

 

It hasnt been built or come in yet. As of matter of fact, I need to call DM first thing this morning and see why my clutch hasnt come in yet.. Been a few weeks, and she told me that they were in stock. Maybe they are combine shipping or something...

 

Yeah, DM is starting to slip.

I had an issue, never got resolved. Small, but it's the principal.

If I want to buy Chinese stuff, I'll stick to Ebay and not get middled.

 

I dont blame you there... I had a small issue to about DM, they told me the couplings were in stock two weeks ago, but never got an email. I did call back, and she got it out the next day after they had their order had come in. No biggie, got it resolved, all is happy. I like their products and their pricing. It seems they have all the goodies! In the end, I will continue to buy from them, when in need of hard to find parts. Aaron has been alot of help and his team members.

 

They do have great prices on OEM stuff, which matters!

Everything else is generic, and can be found elsewhere if one is so inclined.

Let's hope they help you out before that show, huh!?

 

ugh i would of thought these guys keep at least 1 or 2 of these AEM kits ready to ship.

 

Well maybe they do keep them in stock ,but they just sold out , or maybe they are made to order.

Sometimes they drop ship, from canada.

Good guy to deal , i have dealt with him a couple times , and remember they can't keep everything in stock.

My only issue with them is the shipping , it's too expensive..

 

that sounds like an injector control issue, not a fuel pump issue.
it sounds like your priming map was turned up way too high (initial pulse of fuel shot in on the first RPM). i have had a few cars do this exact same thing and want to "kick back" when the "cranking fuel" is turned up too high. too much fuel gets in, and the piston tries to compress the fuel instead of the fuel/air mix... i am curious as to how the fuel pump mod blew your engine though

 

Lex, you need to have your AEM trigger that fuel pump relay (i think you can even have it do different voltage or pull-down to ground) so your fuel pump isnt running while they key is ON. most EMSs will prime the pump for 2-3 seconds when you turn the key on, then shut it off. they technically just shut the pump off after 2-3 seconds when there is no RPM signal, so the pump doesn't keep running if you're in a crash or something.

 

i am pretty sure they just drop-ship everything (unless they have a few parts of which they sell huge quantities). i bet 98% of their parts are drop ship.
i work in product management at a distribution company, and we drop ship parts for on-line retailers all the time.
i know for a fact that rx7store and suprastore do mostly drop-ship.

 

Cartmill ,
My engine kept locking up , i have to pull the plugs out cover the turbo and other stuff , pull the efi relay and crank it till i get all the fuel out.
i did this more than 15 times , i went to replace my crank seal and the crank pulley will not come of everything got stuck on the crank .Even the crank pulley bolt wouldn't come off .

In the end i swapped the engine with the same setup in the same car everything went perfect after i undid the 12v mod.
I had the same setup in my SC300 before i sold , and i never had that issue.

You don't have to crank the car, just stick the key in the ignition and turn it one click the fuel pump came on.
Like i said at the end i didn't care to find out what was the issue because i got my car running like a champ!!

 

interesting.
well, what i was saying was that your injectors are fired by the EMS. otherwise, they're closed. at rest, they're closed. fuel pump running or not, they're closed. the fuel lines can be pressurized to like 200psi, and the injectors are closed, not open and filling your combustion chambers up.

 

It was weird as hell, i don't know why it was doing that , like i said i had the same setup in 2 different SCs and the only time i had the issue was with the SC400 with 12V mod lol.

 

your injectors would have had to be wired open, so if the fuel pump was priming, it was just shooting fuel straight onto the pistons. lol