So I drove a 94 GT4 jdm model today and upon going into gear, it made a slight humming noise. What could this be? the owner had no clue and I was guessing maybe Fuel Pump? It turns off once car is in neutral for a bit.

Also what are some common problems with the GT4 that I should look out for? This specific car has about 160k on it. It's all stock.

And how easy is it to upgrade it to 300hp?

I have no idea what the humming noise could be. Do you have any idea where it could be coming from? Anywho, getting the GT4 up to 300hp is pretty simple. Most ppl have gotten 300+ with just a 3in exhaust system (from the downpipe all the way back), aftermarket intake system, and a Boost controller (electric is best IMHO).

Anywho, before you even buy the car, i suggest becoming a memeber of this site
gt4oc.com
Its a specific GT4 website with tons of info and how too's!!
Most specifically a "how to guide" on what to look for when buying your GT4!!
look ill even provide a link straight too their how too section, although youll have to be a member to veiw it all.
GT4OC.COM How to guides!!

And here is another site, with tons, upon tons of info that you can use to modify and repair your gt4 as well!! (if you ever get of course) and the great thing about it, is that i dont have to quote all these sites that have the info already there!

Good Reading

another good article you should read about effectively and reliably adding more power to your stock 3sgte:

original source
thread by manphibian

Damn, thanks aloooooot 3WayStunna, what a great website that is. Pretty much exactly what I was looking for. And thanks azian.

the humming is prob the intercooler water pump if it shuts off

Yep, me geuss would be the charge cooler water pump bearings being noisey. The pump switches off after approx 30 seconds of the throttle being at idle and restarts once the throttle is actuated.

300bhp is doable if done right

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So would it be normal to make that sound or would it have to be replaced soon?

i've never heard it... when do u get it and where do u hear it from? the exhaust hums....

the intercooler water pump is effectivly infront of the passenger side wheel in behind the plastics and ****, roughly infront of the resonator box

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yea its def coming from the left side passenger side. Gonna test drive it again tomorrow and also take it to mechanic for inspection.

oh ok. well i dont have that sound as far as i know, i've got 140,000. perhaps it needs new toyota long life in the IC

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You only really hear the noise when the bearings inside the pump wear and become noisey, the bearings can be replaced seperately if you are good with a tool kit The bearings are available on ebay for a couple of quid.

I don't hear anything like that on either of my GT4's. Could be chargecooler pump, hard to say - have your mechanic look at it. If you are shopping around, Sean @ zenautoworks.ca has an ST205 in stock in Calgary also. That is who I got mine from.

-Chris

Additionally if you want some really good information about how incredibly easy it is to make 300+HP on a mostly stock ST205 Engine - see Jim's threads in our FI section. He and Batman both made ~340 WHP on stock ST-205 engines/ECU with only MBC, WI, Intake and Full 3" exhaust.