bzmirich

I'm desparate. For 2 years now, my 1990 LS400 (170k miles) will stall while driving. I've noticed it only happens on warm and humid days (lets say above 80 outside temp) and if the gas tank is low. In fact the lower the fuel level, the lower the outside temperature to cause the stall.

On days where it's 90 or higher, I can only stop the stall if the tank is totally full. I can get down to a half tank or so before the problem occurs on days in the 80's. More importantly, the problem doesn't happen in winter/cool temperatures.

It also doesn't seem to happen during the first miles driving for day. For example, I can start it up in the morning of a very hot day with a 3/4 tank and drive the 10 miles to work no problem. But if I stop somewhere after a few miles to get the paper, when I get back in and start the car, I'll go a half mile or so before it stalls.

I can put the car in neutral and usually restart it without stopping, however it will usually stall again quickly. It also seems to happen mostly with the RPMS around 1k-2k. If I quickly accelerate past that, I can usually get the car to not stall intil the next time I get down to 2k RPM.

Now that the warm weather is returning (I'm in NJ), I know it's going to start up again. The dealer's response is to bring it in, but they won't acknowledge that they have a clue what it is. I can't afford to have them play around and charge hundreds to say they couldn't find anything (that's exactly what happened last year when I brought it in).

Any help or comments would be greatly appreciated.

JAndersson

This is a long shot, but have you tried to change fuel filter? Can be clogged. But it seems to be a to easy fix.

EUBT

Sounds like a fuel delivery issue. Check your fuel pressure and the system components: filter, pressure regulator, efi relay, pump-sending unit, etc. Also could be a vac prob. Could check induction sys.

bzmirich

yes, thank you, I tried that last year, no luck. It's almost exactly like vapor lock but I'm told that can't happen nowadays.

tiguy99

Did u ever find out the problem?

dicer

The problem is very likely the fuel pump resistor.

bruceb58

The OP hasn't been active on the forum in over 6 years.