Hello, I have a '89 V-12 convertible with 53,000 miles on it. I have owned it since 2013. Shortly after purchasing it, on a small trip around town, I hit a bump in the road and the car died. Just like it was shut off with the key. It just died like a switch was thrown. I tried and tried to start it with no luck. I called a tow truck and they took it to my shop. After the car had died and wouldn't start, we got to the shop and about an hour since the beginning, it fired right up like nothing had happened and I drove it home.

I didn't think too much of it, until it did it again in a parking lot a few months later. This time I tried cranking and it would still just turn over, but not catch. I waited a while and bam, it fired right up.

I have become better at getting it going. Often if I pump the gas like a carburated engine, I can get it to sputter, and once I can get it to sputter, I can get it to catch and fire up.

Since then I have changed both crank position sensors. New cap and rotor. New ignition modules. New plug wires and plugs. New coil (when I lost the right bank), I can not find what causes it.

So it seems to be something electrical with how quickly it cuts out. But then once it cools down it will fire up on its own just just fine. But if I try and try and get a little tiny sputter or hit in a cylinder, then I can get it going by pumping the gas and revving it so it won't stall right away agtain and I'm good to get back home.

I just got stuck for a while today. I was too slow and missed the sputter and didn't get pumping the gas soon enough and I was stuck for over a half hour. I have been able to get it going in under 5 minutes for the last couple of years. But I am scratching my head here. Anybody have any thoughts? Or even better, anybody have this happen to them and what the problem was?

Thanks in advance!

 

Try to identify if its a spark or fuel problem. I'd keep a flammable in the the car so when it exhibits this no start behavior you an see if a quick spay will get it to run for a moment. If it does then you know to focus on the fuel system. You can also leave an in-line spark tester in place. The car should run fine with it in place and when left there you can quickly identify if it's a spark issue as it occurs.

 

Thanks, those are two good ideas to isolate spark or fuel. I'll throw some starting fluid in the boot for a try next time. Unless there is a better alternative to regular old starting fluid as I've only used that in diesels before?

And looks like I can order an in line spark tester cheap. That should at least move me forward down one path or another.

 

Hitting a bump and causing this is key! There's an inertia switch in a little black box on the door frame, left side, next to the hood release handle. The idea is that if you get in an accident this will trip and cut power to the fuel pump. They're a little more sensitive than they should be, potholes can set them off. There's a hole in the top of the box, you can put your finger in it to push down the button and reset the switch. It sounds like yours if faulty, not fully tripping, but cutting out power for a bit. I'd take the cover off and clean the contacts for a start.

 

Thank you icsamerica. That sounds just like the sort of thing that is causing this. Also why it would seem electrical at first since it was so quick with a bump, then fuel related when trying to start after shutting down. One more thing to try in order to eliminate suspects, but this one seems very promising.

 

Are your wiring harnesses in the engine bay original?

That would be my first suspect.

 

I went through this for 2 weeks it turned out its was the CTS . They can go bad and it will flood the engine so no start and if you get it going it will inevitably switch off at some point and wont start. The CTS controls the fuel while driving so if the resistance of the CTS is wrong it will give the wrong fuel.
Its any easy fix get a new one and replace it. I could also be wire problems going to the CTS.
Good Luck

 

I think the TPS would do this too?

 

I agree the TPS can cause fuel problems too.
Cheers

 

Yes, I am starting to lean that way - towards TPS. I may have two separate issues going on now. First it was the occasional stall if I hit a bump, which seemed likely the inertia sensor. That was the only problem for a few years. But, now I am stalling totally random. Usually after it warms up and is running fine, then when I try to give it trottle after idleing it will stall. I am going to bypass the inertia switch to rule that out. Then if I am still stalling I will have to dive into TPS and CTS. Thank you all! I will post an update when I get even 2 seconds to jump the wires together going to the inertial sensor to take that out of the equation and go from there.

 

I am afraid it is the wiring to my coolant temperature sensor. I tested the old one with engine cold it read 1.9 kohms. Brand new one was 1.7 khoms. But I also tested it at the ECU and there is the problem. At pins 5 and 19 I kept getting 7.8 kohms no matter what I did. I tested the pins with the wiring harness connected to the CTS - 7.8 kohms. Jumped the terminals on the harness and still 7.8 ohms at ECU.

I can change out parts and test, but I have not undertaken a job of re-wiring a harness like this before. I have basic knowledge, but not a lot of practical knowledge for something like this. Any tips on how to proceed? Get a new connector, if so, what is this particular one called or part number to get one. Re-use the old one, but that could be tricky too?

A new wiring harness would be easiest, I guess. I would just keep testing it further back towards the ECU to where I get a closed circuit if I jump ports 5 and 19 together on the ECU and then run new wire from there to the new connector.

Thanks,
Nick

 

Interesting. Even though the testing shows bad wiring, as the ECU pins should read pretty close to what the CTS reads it fired right up. Figuring it couldn't hurt to give it a try I fired it up cold this mornig and vroom, it fired right up. No sputtering smoking ,etc. Fired right up and idled nice. I took it for a littel test run the neighborhood to get it to operating temp and also no be too far away in case of stalling and not starting and it seemed to run great. I will take it if its running, but since the numbers aren't working out with the testing, its still a little warining light in the back of my mind. I'll try to drive it a little more to get a better idea.
I also jumped the inertia switch to rule that out. If it runs fine, I'll hook that back up and see if that has any effect.

 

If you have an intermittent loom break, then I would start by rewiring the loom of that circuit in the engine bay, up to the main connector plug near the firewall. Obviously the break could be anywhere; but far more likely to be in the engine bay.
One thing you could do is to externally wire the sensor (outside the loom) up to the plug, and see if this fixes the problem for a bit. If it does, then do it permanently.

 

I didn't see that you tested it at the ECU with the CTS disconnected. Did you do that? Still got 7.8k ohms? Should be O.L.
or test each wire individually at each end of the wire? Should be close to 0.

 

Chiming in.... your extra resistance for the CTS may be in the connector itself. One easy way to test the wiring is to pull the battery, then make a loopback and cross connect the pins of the CTS plug, then test the resistance between pin 5 & 19 at the ECU connector. You can also test each wire individually by connecting each CTS connector pin to ground. IF you need a replacment connector, this should work: https://www.efihardware.com/products...act-Bosch-Type

~Paul K.

 

Good Point, I did not try that. On a good note, it has been running fine the last few days, but in the back of my head I am still worried, as I have read the reading at the ECU should be similar to the reading at the CTS. But an OL reading would ease my mind if the harness wasn't connected to anything.

I also have the inertia sensor bypassed. If it keeps running well, I'll re-connect the inertia sensor and see if the problem returns.