dkinzer

My wife bought this LS400 in late 1990 and she is now looking to buy a different car. For the most part, it has been an excellent vehicle and we have enjoyed driving it. For the first 10 years or so, all of the maintenance was done by the local Lexus dealer. Since then, I have done most of it and I have the journal entries for the significant events. For its age, it is in pretty good condition and I'm trying to decide whether to just trade it in or sell it separately. The left front fender has some minor damage but I have a replacement (same color) not yet installed. Other than that, the body is in very good condition (no salted roads in Oregon). If anyone has an interest in a relatively low mileage LS400, let's talk.

Actually, the resistance increases as the tank level falls. If you pull of the sender's connector (infinite ohms), the gauge reads empty.

That's a good suggestion. I filled the tank and disconnected the sender. There are three terminals on the sender unit and the resistance measured 4.7 ohms between the two closest to each other and about 24K ohms between each of those and the third. Based on information I've read elsewhere, I guessed that the 4.7 ohm pair was probably the variable resistance with the third possibly being a ground.At any rate, I connected a 10 ohm resistor between the closest terminals on the connector and the gauge now reads almost full. Without the resistor the gauge reads empty. Now, I'll watch for fluctuations as I'm driving around.

Over the last few months I've been having a problem with the fuel gauge on my 1991 LS400. While driving with a relatively full tank, the needle will slowly drift to a quarter or so. After a while, I'll notice that it has moved back up to what is probably the correct level. I pulled the connector on the sender at the tank and cleaned the contacts. For a few days, it seemed that that had fixed the problem but, alas, it has returned. I've read other threads here and elsewhere that talk of changing out the electrolytic capacitors on the instrument panel circuit board. I don't remember seeing what symptom or symptoms the various posters were trying to correct so I don't have any feel for whether or not that might solve my problem. I suppose it could be the sender unit itself. I did read one post that talked about cleaning the variable resistor on the sender but, again, it didn't say what symptom was being addressed. So, based on my description of the fluctuating indicator, any ideas on where the problem might lie?