808GS3000

iTrader: (3)

Recently bought a car that wouldn't start. Narrowed it down to the efi main relay(by the passenger fender and intake), as a temporary solution/fix, The car will start if I jump the efi relay located by the passengers fender. On the relay clip, there are four wires. Two are ground and one is always reading at 11.75V. If I jump that and the wire next to it, the car will start.

On to the issue, my battery is draining overnight. I removed the 20amp fuse for fuel pump as well as the round fuel pump relay in the fuse box. When I jump the wire from the relay next to the fender (efi main relay), the car starts. Is it supposed to be able to start without the fuse and relay?? Does anyone have a diagram on the efi system? Is that one wire always live?

I ordered the relay from seawell, in the meantime I just wanted to know if that might cause the drain, as well as why would the car start when I jump those two wires.

Also is the fuel pump 20amp fuse supposed to have power with the key off? Sorry if there are so many questions...thanks!

LScowboyLS

This will answer all of your questions!

it's what the Lexus dealership or anyone serious would use, very thick & thorough!

Yamae

The best way to find the detail is to get the full manual as LScowboyLS has suggested. I happen to have a JDM manual but it is for 94 Celsior. As far as I know, this part is mostly the same with USM but I don't know the difference between 93 and 94. Attached at the bottom is from the JDM manual.

As you see, followed by a 20A FUSE, there is a Main Relay (EFI) and this directly goes to the ECU and two relays that are controlled by the ECU. The Fuel Pump is driven by the Fuel Pump Relay but the relay Opening Circuit Relay disables the current to it when needed.

What I worry about is that your car has some problem and the The Fuel Pump is disabled to work by the Opening Circuit Relay or the ECU is malfunctioning. Regarding the malfunction, the leakage is another issue to think about together. As LScowboyLS and I are writing about ECU failures in the thread of "all my crazy Lexus issues SOLVED!!", you'd better to check those capacitors too. The leaked liquid may cause a leakage and the battery draining problem since the ECU is directly connected to the B]20A FUSE[/B]. The URL of the thread is here.
https://www.clublexus.com/forums/ls4...es-solved.html

808GS3000

iTrader: (3)

Yamae I was praying it wasn't the capacitors from the start. I took out the ecu and the first thing I see is a blob of brown goo. I will try to post pictures tomorrow. Any recommendations where to buy new ones? I am fairly experienced in soldering, just need to find a place to buy the right capacitor. Also on a side note, if I were to go to the junkyard route, will there be a difference with a UL ecu vs a regular ecu? Thanks for the help and diagram by the way. I appreciate it.

Yamae

You should definitely fix the ECU ordering capacitors first. Depending on the situations it might also fix the starting problem.

Since I live in Japan and I don't know very well about the latest availability of those capacitors in Hawaii. I remembered LScowboyLS was mentioning that he bought capacitors at ebay. Also he was writing more on capacitor issues after reading my initial posts.

As you are fairly experienced in soldering, you must be also good at tracing circuits. I am also a man like that type. LScowboyLS is also like that and we are now trying to inform people who suffer ECU related problems to fix. You also had better to read the thread," (94 LS400 ECU issues/Running Rough) ".
https://www.clublexus.com/forums/ls4...g-rough-6.html

LScowboyLS

Please see my instructions on repairing your ECU capacitors

read all of the posts in that thread, particularly the ones by myself and ECU wizard yamae

it's really quite painless, I could do the ECU capacitor replacement job in less than an hour, having done them before, and the parts cost total was only $16 to my door!

808GS3000

iTrader: (3)

Yamae and LScowboyLS

I stopped by an electronics store on the way home from school. I picked up a few capacitors and a soldering iron. Got home and prepped the ecu, cleaned it, soldered it. Put the ecu back on and cranked her up. She started but had a really low idle. My tach isn't working at the moment, it comes on every once in a while. I was worried I had messed up so I took it back out and examined it. Put it back on, same low idle. I was really skeptical because the idle is usually high. I took the car around the block, the tach decides to come on. I stop on the side and I noticed the idle is at 700-750rpm. I hadn't realized this whole time it was idling way too high. It runs like a champ and the engine is literally too quiet! I have a gs300 and the 2jz is quiet but I wasn't used to the 1uz. She is idling fine and running better than before! Next up is to get the tach and speedo to work!

Also going to do maintenance plugs, valvecover gasket and all the suspension parts that need to be replaced. Thanks again!!! Whoever is having idle issues and fuel issues and whatever is mentioned on those two links above! Do this inexpensive fix! The parts was less than $30 and it would have been cheaper if I had my own soldering iron.

Yamae

So you succeeded to start and run the engine. Was the relay not related to the problem? How about the the battery draining problem? Do you still have the draining problem?

If the problems are both fixed, the capacitors are related to your problems. In the past, I haven't had this much of problems caused by the worn capacitors.

Anyway, congratulations on you success to revive the car. Hope your other maintenance projects are going well.

shoob

my first concern is "11.75v" this tells me your battery is weak, and how the hell is the car even starting. replace your battery holmes.

LScowboyLS

the only time my battery ever went to 11.75V is when my failure to fix my power steering leak in a timely fashion ended up killing my alternator!

crcuevas

I have a 94 LS400 with a similar problem. It will not start. It cranks and tries to start but will not stay on. I replaced: ECU, Fuel Pump and Fuel Pump ECU. Haven't replaced fuel pump relay. Can that cause the problem.

Also were is the open circuit relay? How do you test the fuel pump relay?

LScowboyLS

have you done the normal things, replaced plugs, plug wires, distributor caps & rotors, checked main fuse and other critical fuses such as EFI fuse as well as fuse links?

have you tried a 1-2 second shot of starting fluid in the intake opening by the battery? - if it starts with the starting fluid, that will definitely narrow down the possibilities

don't crank it for more than 7 seconds at once, and let the starter cool down for an hour between tries, I promise that you do not want to replace the starter in this car!! - a friggin nightmare!

crcuevas

Yes I have did all that with the exception of the dist caps and rotors (which I don't think that's my problem). But have not tried starting fluid. Can you send me a picture of your talking about with intake opening being by the battery? I have a 94 LS400.

LScowboyLS

apply a full 1 second spray of starting fluid to area shown in green

LScowboyLS

my favorite quick way is to find a non-essential relay of the same exact type and swap them