diagnostic connector under the hood.

Key off - jumper FP to +B w/ a paperclip then try to start. "Quick check for fuses, wiring
& pump operation."

 

This is COPY from www.clubna-t.com wrote by BEAN:

Walbro GS341 install for Lexus SC300

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The back seats come in two pieces... first you have to pop the bottom seat loose... it is held by clips and is pretty easy to pull up... its only two clips as far as i could tell.

Once you remove the bottom piece; you must unbolt the top piece... there are 3 12mm bolts holding metal clips down to the chassis... once these are unbolted you can pry the bottom part of the seat up; then push the whole seat up (there are 3 hinges holding it in and this method after working with it a bit will get it removed). Careful not to snap anything.

After you remove the back seats then you need to relieve the fuel pressure... crank the car and pull the fuel pump relay. Its under a black box with large plastic screwheads on the driver side of the car. Its the big round fuse and is labelled 'EFI Fuse' on the relay map on the box top... do this while the car is running.
The car should die; after the engine dies; open your gas tank and unscrew the cap to relieve tank pressure.

Disconnect the negative battery cable after you have the front seats slid forward enough so you can fit back there; you'll be sitting there for a little while


Pulling the pump
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There is a circular panel in the middle of the back seat area... get a thin flathead screw driver and pry it off, careful not to scratch it; its got some sticky stuff on it and will come off easily.

There are 9 or 10 phillips head screws holding the tank in; unscrew all of them; and don't be alarmed if it makes a weird howling/unsealing sound. Freaked me out at first lol.

You should be able to pull the cover off now, if you want to take the whole pump assembly OUT of the car, then you'll need to clip wires... Honestly, I'd recommend taking the stock pump off and placing the new hardware with the GS341 pump in its place (with the NEW insulator and sock) while inside the car.

There are 3 10mm bolts holding the fuel pump assembly in place; along with a small rubber fuel hose with two brass clamps on it...
The EASIEST way to get it off is to unbolt the 3 bolts and then slide the bottom brass clamp down and off and onto the fuel pump assembly fuel line... After this wiggle the brass line off of the rubber hose slowly; letting the excess fuel dribble into the fuel tank.
Have a rag handy just in case!

After the fuel has dribbled out and you've got the brass fuel line disconnected from the fuel hose, unplug the fuel pump itself from the harness. The stock harness plug should plug RIGHT into the new pump. Make sure you use the new insulator and new hoses if yours arent in good shape. You'll see how to take it off, it has a hose connecting to the hardline and the harness and thats it. Make sure you put on the new insulator and new sock!

Place the fuel pump assembly back into the tank (make sure you have the brass fitting from before so you can reconnect the assembly to the stock brass lines

Once these are done; remount the fuel line hose with the fuel pump assembly fuel line and reconnect the brass clamp to hold it in...

Bolt the 3 10mm bolts back onto the fuel pump assembly and make sure everything is good and tight...
Take the fuel tank cover and place it over the tank and get all 9-10 phillips head screws and screw it back down....

Reconnect the negative cable on the battery; and then reconnect the EFI relay and close your gas cap and tank

Give the car a test start... the first start will prolly be boggy and rough... lots of smoke for me. Lines are getting repressurized and the ECU was just reset... I had to give mine about 3 or 4 good revs... and it settled at about a 400-500rpm idle and slowly idled up to 800 or so...

If your car runs great; sweet... if not, make sure you hooked the fuel lines back up since the stock harness was used. (the kit comes with an extra harness, that some people use but I've found the stock harness fits fine)

Get the circular panel and place it back over the hole and make sure the sticky stuff stays stuck to it... Then reinstall the seats opposite of removal... i have to get my seat tops restitched so i left em out for a while...

The walbro GS341 is kinda loud; so don't get nervous.

After you let the car idle for a while give it a test drive around the neighborhood; get on it and everything; gotta test that hoe out.

Congrats, you just installed a fuel pump.

 

This probably doesn't help, but this is the only picture I have as my wiring is insulated..Good luck, the Walbo's are great fuel pumps but they do make some buzzing noise....

 

Hey everyone,
I finally got it to start today.
A poor connection was the problem , I redid all the old connection posts and wires.
Also the battery is just about gone too , so i will be replacing it later on today also.
thanks again for all the feedback , its very much appreciated.

 

allright guys, for future reference, i truely believe we need to get the gss 342 like cantseeme did. I just installed the gss341 and it does not fit the same way as the stock of gss342.

 

Im curious, what was different?
On mine the connector was different. It would have been much easier if they were the same.

 

yeah the connector was different for me as well but the gss341 makes it so the harness sits on the opposite side as the stock fuel pump and gss342 like yours. This caused my gss 341 to sit at sort of an angle and I had to clamp it as a precaution to hold it in place. I really believe the gss342 would be more of a direct fit as suggested by the sellers on ebay. Plus, the gss342 are cheaper

 

sorry to revive an old thread but was just wondering if on the gss342 the connectors are different as opposed to the gss341 where the connectors are the same.

 

The connectors WERE definately different on mine. I may be wrong , but I believe thats the only difference between the 2?
It sure would have been alot easier if the connectors would have been the same though.

 

so if you could do it over again would you go with the gss341

 

Without a doubt. But i will say that since i finally got the 342 in. Its been fine.