Sudden TLC death - turns over but won't start

[Daniel Horton]

Greetings all. I'm an original owner of a '99 TLC, now sporting about 378,000 miles. I've done most of the maintenance over the years, including the timing belt, and have been helped by the fact that it's been the most reliable and best vehicle I've ever owned. It doesn't burn oil, the heads have never been off, a set of tires lasts 90k miles, and it's pretty much in (slightly beat up) original configuration. I love this vehicle.

It's ALWAYS started when I turned the key, except for a couple of typical starter motor issues over the years. This time, it's different. It was running perfectly when I last drove/parked it about a week ago, but now will only turn over and shows NO sign of starting. Fuel is at about 5/8ths and fresh; I'm looking for good ideas where to start looking for problems that would cause such a sudden death.

One suggestion has been the crankshaft position sensor - not sure if that's a typical failure point that would case this type of problem, and if it's the first place I should investigate or if there's something more likely.

I'll take all the advice I can get, thanks.

 

[delz05]

What about the relay in the under-hood fuse box?

 

[Trunk Monkey]

Is the security light blinking or off when you put the key in?

 

[excessive]

check your EFI fuse in the fuse box under the hood, specifically look at the contacts underneath it

 

[Trapper50cal]

If the light next the clock goes out when you insert the key and the EFI relay checks out. Next up is fuel pump.

 

[Brandon Ryder]

I had a timing belt snap on me and it would crank but not start. But it also died while driving.

 

[Daniel Horton]

Security light (next to clock) goes out when I put the key in. 20A EFI fuse in underhood box is good. So, fuel pump next? Best way to check?

 

[Trapper50cal]

The problem is that the factory pump will work intermittently in the early stages of failure.
Let it sit overnight and try it again...if it fires right up, it's probably the fuel pump in early stage failure.
I just swapped mine with a cheapo to confirm then replaced with a nicer one once confirmed.
How old is the fuel filter?

 

[Daniel Horton]

Waited over 5 days (was out of town) before trying to start again, to no avail. Fuel filter is years old, but am thinking it wouldn’t cause sudden death. Fuel pump has never been replaced, and is apparently a known point of failure. Have looked at pump replacement videos on YT and it looks pretty straightforward. Short of replacing pump to see if problem is fixed, and other (simple?) way to determine if that’s really the problem, any other advice? If not, then I’ll go ahead with the replacement if for no other reason than after 25+ years it’s probably due.

 

[Trunk Monkey]

If the immobilizer is working then I would guess fuel pump next. You can test it with a test light but at your mileage, I would just replace it.

 

[medtro]

Security light (next to clock) goes out when I put the key in. 20A EFI fuse in underhood box is good. So, fuel pump next? Best way to check?

Try to start it with starting fluid, you have fuel issue if it starts with starting fluid.

 

[Daniel Horton]

Finally got around to trying the starting fluid - opened the airbox and sprayed directly into the engine air intake hose. No joy - didn't even sound like it MIGHT fire up. Maybe I need to use more SF, but I thought I gave it a pretty solid spray. I was all ready to replace the fuel pump, since it's a common problem on LCs with this many miles, but now am questioning if that should be the next logical step. So, assuming it's not fuel related, what's the consensus?

 

[John McVicker]

AIR…FUEL…SPARK

The 3 thing you MUST have in order to start. If any one is missing you will not start.

 

[Daniel Horton]

I’d add Compression to that list, but I agree all those are necessary. I guess I’ll pull a spark plug and reattach the coil while cranking to observe a spark, but is there any other way to verify ignition, or look for a common failure point? The timing belt was replaced with an Aisin kit a couple years ago - it’s not time to do it again.

The thing that has me stumped is that it was running perfectly when I last drove it and parked it in the garage.

 

[John McVicker]

I suggest you check for spark as you described on post 14…then go from there.

 

[Trapper50cal]

Yeah, if it didn't even sputter with starting fluid, that sounds like spark.