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Fuel pump wiring and also opinions on dead head fuel rail

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Hi guys,

Firstly my car is a celica gt4 st205 running link g4+ plug in ecu.

I'm sorting out a few bits on my celica gt4 st205 and would like some opinions and peoples experiences on what I'm looking to do.

On the celica they have a complex wiring setup for the fuel pump with a resistor pack and relay in the engine bay. From what I understand this setup is to vary the speed of the fuel pump on idle, I'm running a walbro 225 pump and was thinking of running the output from the ecu to a new relay in the boot meaning I can delete the resistor and relay in the engine bay. Doest anyone see any negative to this setup?

Also what's people's opinion on dead heading the fuel rail, I have set up my fuel rail this way to reduce the amount of heat that is in the cycle and a friend of mine says it comes with its downsides so thought id ask for opinions on here.

Adz ill kick you off with my experiences, i own a 185 with a 205 engine running a haltech and gtx2867. made about 240awkw at 17psi. this was on a dynodynamics rolling road dyno.

the toyota wiring is old, lets face it even the 205's are over 20yr old. if you plan to upgrade the pump its worth upgrading the wiring. if ethanol is available near you it worth makign sure your components are ethanol safe.

delete the resistor or by pass them, imo its a complication thats not needed. i run stock fuel lines to the fire wall, then a stainless filter and turbo smart reg with teflon lines. i havnt had an issue to date with this setup and its running a walbro 460lph pump.

i just got done running a new alternator feed wire to the old fuse box and added a standalone relay and fuse box for the ECU/pumps/fans etc. i noticed about a 0.5v increase at the ecu and the car cranks better too. same battery, starter motor even same cable from the battery in the boot. so keep that in mind as the voltage drop to the pump would likely be more due to load.

i am sure there are hp gains from cooler fuel, but we seldom see fuel coolers. so i feel the gains are negligible and you need to focus on the low hanging fruit first. such as exhaust and intake restrictions.

Will chime in on the fuel pump wiring. I just did this on a GTR in the shop here, and we now see a solid 13.5V at the fuel pump under all conditions Definitely worth it, as it was dropping to ~10.5V previous to this.

I tapped a 12AWG wire into the main power feed in the engine bay fuse box, ran this to another fuse I installed in the box, and then all the way to the back of the car. 12AWG was a little overkill, but its all I had on hand. This feeds a relay mounted in the boot, which is triggered by the original fuel pump wiring. I left the OEM relay and speed adjust resistor in place, but now that system only provides the trigger signal for the new relay, so its redundant.

Thanks for the input.

Supporting mods wise I'm quite covered and will soon be fitting a forged block.

My battery is in the boot already and my thinking is run the fuel pump output from the ecu to a relay in in the boot meaning 8 can binall the resistor and stuff in the engine bay.

In an ideal world I'd love to make a new engine loom as my car is far from the standard st205 setup now running a caldina intake and coil on plug and I've now got alot of redundant plugs in the bay

Attached Files

"In an ideal world I'd love to make a new engine loom as my car is far from the standard st205 setup now running a caldina intake and coil on plug and I've now got alot of redundant plugs in the bay"

Do it, we'll help, it's fun :-).

On the next few weeks I'm going to pull the stock engine loom out then when i have the big pile of confusion in front of me I'll probably need all the help I can get.

I've only just started to scratch the surface of wiring hence buying the wiring course yo go with the tuning courses

Resistor delete like you describe is a pretty standard mod for old cars. I'm not sure what you mean by dead heading. Are you talking about keeping a manifold pressure referenced regulator under the hood? Most of the newer cars have returnless fuel systems with regulators in the tank and software compensation according to fuel pressure.

Return systems with conventional fuel pressure regulators are a lot easier to deal with for a performance application. The main reason you want the cooler fuel of a returnless system is for evaporative emissions.

Dead heading the fuel rail is where he Feed from the pump is T'd between the rail and fpr and not fed in one side of the rail through the rail then to the fpr

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