So I totally screwed up doing my fuel pump hardwire. I'm such a fool.

87 t2 with megasquirt 1

So my ecu is actually unplugged, that's a good thing. I suck with ecu's and I don't know if the previous owner had the ecu supply power to the pump.

I checked the relay plug and decided to use the blk/wht with yellow dots for my power to coil, and brn for the ground. I got 12 gauge wire for my fuel pump from the battery with 30 amp fuse, 12 gauge wire for ground for fuel pump.

I was confident which plugs were coil and switch for my 4 prong relay, but I reversed it. I had my hardwired 12gauge wire on the coil and the factory blk/wht yellow dots and brown for pump.

As soon as I hooked up the battery ground, I heard fuel running through my lines, but like a dumbass I still went to my car and turned ignition on. I noticed it and turned off my power.

So checked my relay for which side was coil and switch and realized I had it backwords.

Anyways, so now I do not have any power ignition on or off from any of the wires that went to my original fuel pump relay. I have ground on the pin with double black wires ( which after looking at the diagram is the ground)I didn't touch , I have ground on the blue/red wire I didn't touch. I also have ground on my blk/wht yellow dots until I turn on the ignition then I get nothing.

I don't have the original cover for the fuses on left kick panel, but I checked all the fuses that went there and none are blown.

WTF did I do?
Worst case I can tap ignition on power from somewhere and ground from the chasis for my coil, but I am wondering what happened to the power I thought I had at that blk/wht with yellow dots

I really shouldn't have rushed it, Any help would be appreciated

 

You want to make sure the engine fuse (15 amps) is good. If it were good the B/W wire in the two wire main relay plug would have power w/key to on and the B/W wire (not White/Black) at the alternator's two wire plug would also have 12 volts w/key to on.

 

I'vebeen using the diagram from Foxed.ca. I didn't see any info on white/black vs black/ white. I looked at my fuel relay plug and there was a big fat black wire with white stripe. I never had power to that with key on. I don't know if it has to do with the megasquirt and not having a MAF anymore.

The wire I origionally used was the black wire with a white stripe and with yellow dots every inch or so. I swear before I was getting power with key on before. My fuse isn't blown, and I'm stumped. I'm not an electrical guru.

Worst case I can use another source of key on power and ground, but I'm worried something else could have gotten damaged.

 

There are two B/W wires at the circuit opening relay. One has power w/key to on and the other w/key to start only, so there's a difference between the two. Secondly, I'm trying to state that if you wanted to prove the engine fuse was good, since it powers the B/W wire at the relay mentioned w/key to on, you could also check the B/W wire at the alternator. That plug has two wires where one is B/W and the other is W/B, so I made mention of the W/B so you would not get confused and check the wrong wire. Make sense?

 

If your car has a Megasquirt, then you should abandon all the factory fuel pump wring and instead wire it up with nice new 12 gauge wires to be run from the Megasquirt.

How To Megasquirt Your 2nd Gen RX-7

 

ok, I distinguished the 2 b/w wires. The one I am using for my relay coil is the correct one. The weird thing is that I only get power to it sometimes. I just got it to have solid power for one second, and the next second I cant get any power from it. I remember before doing this whole wiring thing, the fuel pump would only prime occasionally. I believe when the fuel pressure was very low.

Stupid question: I checked power and ground at the plug behind the alternator, I see power(B/W wire) but not seeing ground, the W/B wire.

Keep in mind my ecu is not plugged in and my engine is not running.

btw, is there an exact location on that fuse panel where I can check the fuel pump fuse? I don't have the cover that would normally tell me which one it is. I looked at foxed.ca, and it just tells the general location

I bought the car used with a ms1. I'm trying to get someone to help me with it, even posted about paying someone money to help. I really need to spend some time and sit down and read your tutorial more in depth. It would help if I had a teacher there to help and answer questions too. I'll get my ecu and see if that is the reason im not getting power.

This really makes me realize how handicapped I am when it comes to auto electrical. It's so frustrating because the last steps to completing my car is ecu tuning

Anyways, thanks for the help guys, your input is greatly appreciated.

 

In the FAQ section is a pic of the fuse panel cover (fuel relay is powered by the engine fuse).

The W/B wire at the alternator has a ground w/key to on and engine not running only when the plug is connected to the alternator, so when it is unplugged there would be 12 volts w/key to on and not a ground.

The B/W wire at the alternator, main relay and circuit opening relay are all powered by the same engine fuse. If it's spotty at one location it should be spotty at all of these locations w/the caveat being a faulty crimp. And the center position top row of the circuit relay is the B/W wire powered by the engine fuse.

 

Once you've ready my tutorial, you should be primed to replace the pump wiring. It's fairly complete including the relay terminal numbering. If there are any questions, all of us in the Megasquirt forum would be happy to help.

 

Thanks guys, I'll do my homework

 

hey guys, I just wanted to update you guys and make myself sound even dumber.

So the relay I bought from Mcmaster Carr under their "long life" relays was a solid state relay made by Hella. I should have checked the relay itself to see which side was switch and power, but I didn't. Ends up the solid state relay was completely different than the normal relay. Its completely flipped, and not only that, the power and ground was one way. I guess there is a diode in there.
So I screwed up the solid state relay I had, and finally wired up a normal relay and everything is fine. I really killed the life out of that relay

 

Solid state relays are basically an optocoupler feeding a TRIAC, IGBT or MOSFET (depending on the purpose of the relay). Semiconductors don't take kindly to reverse polarities and such. Lets the magic smoke which powers them out, and it is very difficult to get the smoke back in.

Meh, I did the same thing to an 57LO5 regulator two weeks ago. Connected the damn thing backwards, little puff of smoke, circuit didn't work.