TheGickel

Just bought a 96 LS400 with 200k miles. Car has been well taken care of and serviced and I needed some cheap dependable transportation for a little while. I had always heard how bulletproof these cars are and so I went with it. The very next day we are driving down the road and it just dies. No warnings no rough running no nothing. to make a long story short had it towed in and he found when you moved the relay in the fuse box it would start back up. So replaced relay and it would not act up for the mechanic while there. We picked up the car and the very next day my wife is driving it to the store and it dies again and won't restart. I go get her and move the relays around again under the hood and it fires back up. Car is running smooth it appears when it is running but has died on us 3 more times in the past 2 days. Wife is scared to drive anywhere. It seems to be a connection or something in the fuse/relay box unless the computer is heating up the relays and shutting the car down. Any thoughts or help on this would be great. Thanks in advance.

Dtwillis5

Which one of the relays?

deanshark

I've heard of this happening a few times. There has to be a loose connection where the relay plugs into the box. I think I read somewhere that someone sqeezed the terminals together a little so it fits in tighter and doesn't wiggle.

Dtwillis5

I have a no start problem too! Its getting gas so its spark or air flow . Im think a bad ecu, ignition module or clogged cat converter. Sound like im on track? It dont have codes stored but when it used to start it had cel and trac thats y i list ecu as a problem

MicahBerry

TheGickel,

Can you clean any connecting points that the relays touch? Then, per deanshark's recommendation, tighten the terminals so that the relay fits tighter.

Micah

cj44

COULD SOMEONE PLEASE HELP ME. I am new to ls400 and to this forum. I just changed the starter on a car I just bought and now it won't start. I've checked vac. lines and plug conn. and it will try to start for a split second but won't continue, but if I spray starting fluid it will run, so it seems that its not getting fuel. So I changed the filter and I think I can hear the pump running so I don't know why it would'nt be getting gas. I took apart the ECU ( after reading on here to check that) and it looked fine. It won't run at all unless I keep spraying starting fluid and then runs pretty decent for a few seconds( thats all the spraying I want to do). I am stumped! Is there any way to check the fuel pump or related relays to be sure thats not the problem? I've already checked all the fuses and like I said I hear a buzzing sound in the trunk, where I assume the pump is in the tank, when I turn the key to start. I'm out of Ideas.

MicahBerry

Does the starter continue to turn and the engine doesn't "catch" or fire? Or does the starter begin to turn and then quit? My car requires about a full second (may be a little less) of the starter turning before the engine runs.

If it's fuel:
Can you check the fuel pressure (possibly borrow a gauge tool from Autozone) to make sure you're getting proper fuel pressure? I don't have the proper pressure number here at my desk at work.

I had my starter replaced by a shop a few weeks ago, and they had to remove the intake a second time. They said they had to replace the seals that I gave them (which I purchased from Sewell). They didn't charge me for the newer ones they supplied, saying that they messed up the seals, and it wouldn't run right.

cj44

The Starter will turn as long as you turn the key to start pos. and the engine initially sounds like it has started but then just stops. its like it tries to start and then something stops it, but when I had my wife turn the key and I sprayed starting fluid into the intake it would run fine as long as I kept spraying the fluid. Thats why I think its fuel related but I guess it could be something electronic thats keeping the fuel from being passed on to the intake. I also changed the coolant temp. sensor ( lg. plug) with one from autozone, and cleaned the afm with afm cleaner, I used all new gaskets and I used copper gasket adheasive on the upper intake gaskets. Most if not all of the plug connectors broke when dissconnecting them but I used zip ties to secure any that felt even the tiniest bit loose. One more thing, although I don't see how this could be an issue, the main fuel supply line going to the fuel rail leaked into the open valve chamber while I had it apart. I went to the parts store and when I came back it was streaming down into the top of the head, I had a latex glove twisted up in the banjo hole but it wasn't tight enough. I did have shop towels stuffed into the ports so it didn't all go in but anyway whats pretty much everything thats happened up to this point. I really appreciate your reply Micahberry I can use all the help I can get.

deanshark

cj44; First thing, you need to put the year of your LS when asking a question about it b/c they changed over the years. But, over by the coolant sensor that you changed there is another sensor which sometimes some people either leave loose or don't connect it. I can't remember what it's called (I'll try to look it up) but it works with the fuel injectors. I know it's burried under wires and stuff to where ya can't see it good. If the intake was taken off then that sensor was unplugged. Take a look on the passenger side of the engine near or behind the ECT to make sure all the sensors are connected. I'll try and find the thread I read that in but it was a while ago.

cj44

Ya, oops Its a '93. and I know the sensor your talking about because thats the one they gave at the parts store first and I had to return it for the larger one. I think I pluged that back but I will check for sure.

While messing with it today I went ahead and changed a couple of EFI fuses that did'nt look bad but just to be sure and I changed a vac. line (the small one that goes on the side of the intake ducting from the airfilter) that was a little dry and loose and gave it another try. This time it actually ran for about 30-40 sec. but would'nt repeat. I also noticed a "fuel pump control unit" in the trunk Is there any way to know if its good?
Thanks for the input Deanshark

cj44

Well apparently that little plug on the lower part of the coil pack is very important. When I went to double check the sensor connection, that Deanshark mentioned, I discovered I had forgotten to reconnect the little plug on the coil pack. After that was corrected it started right up! Thanks again everyone

deanshark

Oh yeah, power to the coil is very important. Without that you might as well buy yourself some new shoes b/c you're gonna be walkin'. Seems like it should have started and ran like crap with one coil though. But, this is why you should always check your work a couple times after ya finish and then check it again. Glad ya found it. I still can't remember what that sensor is I was thinking about, that bugs the hell out of me.