fuel pump relay buzz & CEL light on instantly after battery connected

[moerhhi]

So i swapped a rebuilt engine with my old one, both 7M-GTE. Used my old harness ('91) where i did knock sensor rewire.

Now everything in and connected and this comes. CEL light comes on and fuel pump relay starts to buzz when I connect battery. Also oil pressure gauge and coolant temp. gauge rising up to the sky, dunno if that's any related.

Now, there shouldn't be any funny business with the harness, since it wasn't that bad condition, also i didn't touch any connectors around the fuel pump relay since they obviously doesn't go with the harness. Rewireing shouldn't be any issue too.

I cranked also and it did it beautifully, but not fireing up. I tried to get codes out of it but i didn't gey any, though i may have to do that again, that was quite quick test when i was pissed off, not sure if i did it correctly

Now can there be any grounding problems related that fucks up the ECU or wtf? Or is it just something to do with the relay buzz ..

 

[Nick M]

Sounds like the instrument cluster is short or grounded. I will look at the online EWD. You can too. It is unfortunately an 89, but there probably isn't much of a difference.

Are you implying that you are using a 91 harness in a different year car? The 89 has common power and individual sensors to vary the ground strength, which is very typical. I think somehow you have put ground in the combination meter. Either it is the wrong harnesss, or a bad one. There is also power from IGN fuse into the combination meter. And that could be backfeeding into the circuit opening relay, which powers the fuel pump circuit.

You should check voltage to see where you have it when you shouldn't.

 

[moerhhi]

Only thing i changed is the engine, car and harness is the same. I had no problems before engine swap.

I looked EWD, i didn't get any answer for what's with the instrument cluster like you said. It's possible that i looked wrong place or missed it ..

But anway.. I'm going with the voltmeter now, maybe something clears up or not

 

[Nick M]

Maybe you have something plugged in where it does not belong. Sometimes the plug fits more than one spot.

Do you know what an electrical back feed is?

 

[moerhhi]

Maybe you have something plugged in where it does not belong. Sometimes the plug fits more than one spot.

Yes sir, got that right! Problem was that ground wires connector that goes under a bolt to the intake manifold wasn't there. My dad put it to the starter main power stud, so the grounds got instant 12v :biglaugh: "it looked like it supposed to be there"

Foolish me, I didn't took any attention when i connected that main power line to starter.. And forgotting what belongs where. I looked grounding points from TEWD and ding! Then i realized that i didn't put anything to manifold.. so it must be somewhere else.

Thanks for trying to help Nick, it sure was mechanic fault this time, well for sure it is almost every time :nono:

Now everything works beautifully :bigthumb: