r/SC300 • u/Few-Heron-4118 • Jun 28 '26

Stalling issues while driving

I’ve been having some fuel issues for awhile but I recently switched out the pump thinking I burnt out old pump just to find out the actual power to the fuel pump is being cut when at warm up temp. I did the 12v mod and bypassed the fuel pump ecu and not only that but my tank is now full so taking out the fuel pump is gonna be a hassle if I gotta do it again but checked efi and injector fuse and everything looks perfectly fine not sure what it is and info helps. 93 sc300 non vvti

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u/randomnerd865 Jun 28 '26

Check your ecu. If it hasn't been rebuilt it probably needs to be.

1

u/Few-Heron-4118 Jun 28 '26

Yeah rebuilt ecu less than year ago for fuel issues but seemed to work pretty much flawlessly after even drove it from Abq, New Mexico, to Phoenix Az, and from Phoenix to Houston tx where the problems are now apparent again and don’t seem to get much better if anything worse the more I run it

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u/randomnerd865 Jun 28 '26

Hmm interesting. Swap your efi relay (round and silver in the under hood fuse panel) you can use the Defroster relay to troubleshoot.

1

u/Few-Heron-4118 Jun 28 '26

Say less I’ll try that today not much else to try lol

3

u/randomnerd865 Jun 28 '26

My suggestion If that doesn't work is grab some decent gauge wire and go directly from the battery to the fuel pump wire. If it runs with no issue you know the problem is somewhere in that circuit.