99 LC dies randomly. Pls help. (1 Viewer)

[KBDave]

Hey all

I bought a 99 LC with 208k on it last Saturday. I drove it home (about three hours) with absolutely no issues, and about three blocks from home, it randomly died. I was basically just idling down the street at 25 mph and RPMs went to 0. All the dash lights came on as they do when the key is turned to ON (CEL, battery, etc). The radio power cycled but the clock didn't reset. I pulled to the side of the street, stopped, put the shifter in N, and it fired right up. Drove the last few blocks to home just fine.

Two days later (and about 80-ish miles of trouble-free highway and city driving), it died about two minutes after leaving work in the evening. This time I was giving it throttle and felt it stutter and stumble before it died. Once again, coasted to the side of the street, shifter to N, fired up immediately.

This morning, three days after the last incident (about another 70-ish miles), it died on my way to work this morning. This time I also felt the stutter/stumble before it died. It took maybe a couple extra cranks to start but not excessive.

All three times were around the same 25-30 mph, engine warm for the 1st and 3rd, not fully warm for the 2nd. Just driving on city streets, no bumps or anything.

My fuses look good and there's no corrosion. My thought was maybe the EFI relay or the fuel pump. I talked to my mechanic today and he said it almost certainly isn't the fuel pump because it almost certainly wouldn't have fired up right away. He said the relay could be the problem. He plugged in and scanned for codes and there was nothing at all.

PO said this never happened to him (I texted him after the second time). I know that it has a fairly new throttle body (unsure on how new, he gave me some receipts but that wasn't one of them, but it looks very clean and new).

The truck also has an intermittent issue where when you unlock it, the alarm goes off until you insert the key into the ignition and turn it to on. I do not *think* that this is in any way related, but I suppose it could be. I don't know.

I've searched and searched and I can't find a solid answer other than fuses, relay, or fuel filter/pump. I know there are people on here with tons of knowledge, and I would greatly appreciate any help or info that anyone can provide.

 

[nissanh]

No chek engine codes could be an indication of a bad/failing fuel pump. How much gas you have in the tank? Generally don't let it fall below 1/4 mark if you want to have a healthy fuel pump.

How old is the fuel filter? If no sign of replacement, replace it WITH an OEM UNIT.

 

[KBDave]

No chek engine codes could be an indication of a bad/failing fuel pump. How much gas you have in the tank? Generally don't let it fall below 1/4 mark if you want to have a healthy fuel pump.

How old is the fuel filter? If no sign of replacement, replace it WITH an OEM UNIT.

Re: fuel pump and lack of CEL: That's what I was thinking. Gas has been over a half tank every time. I have no idea on fuel filter.

 

[Hokie99]

When you put your key into the ignition does the red immobilizer keep blinking, and the car doesn’t start?

I bet you a dollar to a donut you need the Efi relay bypass from Medtro.

Same exact issue happened to me last week.

Look up crank no start efi relay

 

[KBDave]

When you put your key into the ignition does the red immobilizer keep blinking, and the car doesn’t start?

I bet you a dollar to a donut you need the Efi relay bypass from Medtro.

Same exact issue happened to me last week.

Look up crank no start efi relay

It always starts. That's what I don't get and that's why I don't want to take it to the shop. It's hard to troubleshoot something so random. No CEL, no stored codes, always starts right back up.

 

[Hokie99]

It always starts. That's what I don't get and that's why I don't want to take it to the shop. It's hard to troubleshoot something so random. No CEL, no stored codes, always starts right back up.

Mine did that as well for about a month and then it didn’t. The bypass from Medtro is 85 bucks and at some point all these rigs will need it.

there’s an issue with the fuse box and the efi fuse as they age. The fuse box is 450 bucks and about 2 hours labor to change or the above bypass.

 

[87warrior]

My 100 would randomly die at low speeds when I first bought it. No CEL, no drive-ability problems, nothing obvious. One day I was driving down a dirt road with Torque running and the Cruiser died. I looked at the Torque display and noticed my MAF sensor reading was pegged to the high end. When I restarted the cruiser the MAF sensor reading went back to normal and it was running fine. I started running Torque when ever I would drive the Cruiser and also noticed some random rich conditions on the fuel trim readouts. Incidentally, those rich conditions corresponded to the MAF sensor reading pegging out to the high end. Replaced the MAF sensor a few years ago and haven't had another problem with stalling.

Pickup an OBD bluetooth dongle and observe some of the engine sensors with your favorite OBD app. I wouldn't suggest throwing parts at the problem until you have some reasoning behind it.

 

[KBDave]

Mine did that as well for about a month and then it didn’t. The bypass from Medtro is 85 bucks and at some point all these rigs will need it.

there’s an issue with the fuse box and the efi fuse as they age. The fuse box is 450 bucks and about 2 hours labor to change or the above bypass.

But mine isn't doing the immobilizer flash, so I'm not sure we have the same problem. I've read about the fuse box problems but it seems that they're fairly rare, not something that's happening to every 100 series. Add in the fact that my fuse box is clean and there's no corrosion that I can find at all, and it leads me to believe that this is not my issue. Again, I could be totally wrong.

My 100 would randomly die at low speeds when I first bought it. No CEL, no drive-ability problems, nothing obvious. One day I was driving down a dirt road with Torque running and the Cruiser died. I looked at the Torque display and noticed my MAF sensor reading was pegged to the high end. When I restarted the cruiser the MAF sensor reading went back to normal and it was running fine. I started running Torque when ever I would drive the Cruiser and also noticed some random rich conditions on the fuel trim readouts. Incidentally, those rich conditions corresponded to the MAF sensor reading pegging out to the high end. Replaced the MAF sensor a few years ago and haven't had another problem with stalling.

Pickup an OBD bluetooth dongle and observe some of the engine sensors with your favorite OBD app. I wouldn't suggest throwing parts at the problem until you have some reasoning behind it.

This sounds like what my Cruiser is doing. Just random RPM degradation and it dies with no warning. Totally perfect driving other than that. I suppose I'll have to get some OBD stuff. Thanks for the input!

 

[Hokie99]

But mine isn't doing the immobilizer flash, so I'm not sure we have the same problem. I've read about the fuse box problems but it seems that they're fairly rare, not something that's happening to every 100 series. Add in the fact that my fuse box is clean and there's no corrosion that I can find at all, and it leads me to believe that this is not my issue. Again, I could be totally wrong.



This sounds like what my Cruiser is doing. Just random RPM degradation and it dies with no warning. Totally perfect driving other than that. I suppose I'll have to get some OBD stuff. Thanks for the input!

So if your immobilizer is not flashing it’s probably not your issue.

But just to be clear my fuse box has absolutely 0 corrosion,the relay issue is not related to corrosion typically.

 

[KBDave]

So if your immobilizer is not flashing it’s probably not your issue.

But just to be clear my fuse box has absolutely 0 corrosion,the relay issue is not related to corrosion typically.

Hmm. Well maybe I'll pick up one of those bypasses just to have for potential future use. I appreciate the info for sure.

 

[KBDave]

After it died yesterday afternoon (4th time overall), I cleaned up the MAF sensor today and replaced the EFI fuse just because fuses are cheap. I drove it around for about an hour and a half through town and on some dirt roads, trying to see if it would die again and it didn't. Going to take it camping tomorrow since it's a much better ride than my 2000 Tundra. Hopefully it doesn't give me any problems, but at least I've got USAA Roadside Assistance if it does.

 

[Eicca]

Other people have had similar symptoms after a wire for the cam or crank position sensors has gotten worn by the serpentine belt. Check those two for wiring damage.

Beyond that I’d suspect the fuel pump.

 

[KBDave]

Other people have had similar symptoms after a wire for the cam or crank position sensors has gotten worn by the serpentine belt. Check those two for wiring damage.

Beyond that I’d suspect the fuel pump.

I had read some posts on that and looked around for anything that looked rubbed, I didn't see anything obvious though.

 

[abuck99]

Sounds fuel pump related to me. 200k is common interval for FP- especially in warm climates and if its been run low on gas regularly- that will shorten pump motor life. If you're not the original owner- then assume it was run low frequently.

As fuel gets low in the tank the pump runs hotter as there's less fuel (hotter fuel) to cool the pump motor. As the pump heats up or overheats-repeatedly, inside the sealed motor gets bits of burnt carbon from the brushes built up on the commutator bars- this creates higher electrical resistance and reduces the motors torque. So when its cool, its fine but after it heats up, resistance increases and the pump stops working or slows to the point it can keep up with engine demand.

Changing the FP is pretty easy job; just under the second row seat. The Denso pump is the one you want. While you're in there, if you have budget consider replacing the fuel level sender at the same time- these get a corrosion build up on the potentiometer and start to give false readings commonly after 200k-250k.

Pic of a failed level sender @ 190k:

 

[KBDave]

Sounds fuel pump related to me. 200k is common interval for FP

This was my original thought as well, but my mechanic talked me out of it. He's been around for a long time, and while he is not a "Toyota guy" specifically, he knows his stuff and I trust him. He said that if it was the fuel pump, it would most likely not start up again right away, it would take some time to cool down and then it would start back up. I think the EFI relay or fuel filter will be my next attempt, followed by fuel pump. I'll do that sender also, thanks for the heads up on that. My Tundra must have some corrosion on that part also, as it's not always accurate. Do you happen to know if this is the part I want for the LC? Link: Fuel sender

I'm going to see how this camping trip goes, hopefully no more issues but I'm not terribly optimistic that the MAF sensor was the issue as it was not terribly dirty.

I really appreciate all the help so far, guys.

 

[abuck99]

This was my original thought as well, but my mechanic talked me out of it. He's been around for a long time, and while he is not a "Toyota guy" specifically, he knows his stuff and I trust him. He said that if it was the fuel pump, it would most likely not start up again right away, it would take some time to cool down and then it would start back up. I think the EFI relay or fuel filter will be my next attempt, followed by fuel pump. I'll do that sender also, thanks for the heads up on that. My Tundra must have some corrosion on that part also, as it's not always accurate. Do you happen to know if this is the part I want for the LC? Link: Fuel sender

I'm going to see how this camping trip goes, hopefully no more issues but I'm not terribly optimistic that the MAF sensor was the issue as it was not terribly dirty.

I really appreciate all the help so far, guys.

I think there are different pumps for different years dont recall the cut off years. Yeah the sender I bought was 83320-60340; fyi it was half that price when I bought from PS last May. (around $75). The logic your mechanic provided about the FP is sound; (but Id bet its still the FP). Mine hadn't failed when I replaced it, the level sender did so I preventively changed out the FP @195k (. FWIW I noticed an immediate improvement in engine response).

 

[Hokie99]

This was my original thought as well, but my mechanic talked me out of it. He's been around for a long time, and while he is not a "Toyota guy" specifically, he knows his stuff and I trust him. He said that if it was the fuel pump, it would most likely not start up again right away, it would take some time to cool down and then it would start back up. I think the EFI relay or fuel filter will be my next attempt, followed by fuel pump. I'll do that sender also, thanks for the heads up on that. My Tundra must have some corrosion on that part also, as it's not always accurate. Do you happen to know if this is the part I want for the LC? Link: Fuel sender

I'm going to see how this camping trip goes, hopefully no more issues but I'm not terribly optimistic that the MAF sensor was the issue as it was not terribly dirty.

I really appreciate all the help so far, guys.

I would bring a foot of wire with you just in case your efi relay does go down so you can do a temporary bypass to get you home

 

[KBDave]

No problems on the way out to the camping spot or on the Forest Service roads taking the kids fishing (about 160 trouble-free miles). It died yesterday on the way back, while doing about 50 mph. This time the RPMs dropped to around 1200 or so as I was driving, I was pumping the gas pedal trying to get it to stay alive but it was unresponsive and died after a few seconds. I put it into N and restarted it while it was coasting, and drove the rest of the way home without issue.

 

[Hokie99]

No problems on the way out to the camping spot or on the Forest Service roads taking the kids fishing (about 160 trouble-free miles). It died yesterday on the way back, while doing about 50 mph. This time the RPMs dropped to around 1200 or so as I was driving, I was pumping the gas pedal trying to get it to stay alive but it was unresponsive and died after a few seconds. I put it into N and restarted it while it was coasting, and drove the rest of the way home without issue.

Glad you got home safely! I’m not sure what the problem is, typically if it’s the EFI fuse/relay the car cuts off completely, but maybe not always?

 

[ramangain]

When you get your OBD2 app connected and monitoring, include the throttle position sensor.

Also, when the engine RPM slowed down to 1200RPM while driving at 50mph, did the truck violently slow down to match engine speed to driveline speed through the tranny? Or did the driveline disengage from the engine during this event?