Caddy won't start - sometimes


#1

95 Caddy with 4.8 engine fails to start every so often and leaves one stranded. Engine cranks fine, but no spark. Two Caddy garages have worked on it, changed a few parts, but found nothing as a cause. After towing to the garage, it starts, and its been left at the garage a total of a couple of weeks and they run it all over and it starts every time. After the last time, with the security system bypassed, the car started OK. Problem fixed I thought. I sold the car; the next day the purcharer calls and says the car won’t start. Money refunded, and it’ll be towed back to the garage (100 miles). Once there it will probably start (hasn’t got there yet). WHAT THE HELL’S THE MATTER WITH THIS CAR?


#2

Intermitant problems such as this are the hardest to diagnose. Because the problem has to occur while trying to figure out what’s wrong. If it doesn’t occur, there’s nothing wrong. And because of this, it’s you that must figure out what’s wrong.

There’s only two things that can be happening. Either engine is getting no fuel or no spark. And you can quickly determine which isn’t occuring. Purchase a can of starting ether. The next time the engine won’t start, remove the air filter cover and filter. Give a quick spray of the starting ether into the intake duct. Now try starting the engine. If the engine starts but then stalls out, it’s a fuel problem. If the engine just cranks over without starting, it’s an ignition problem.

Tester


#3

Thank you, Tester. I did hold a spark plug wire near a ground while cranking and there was no spark. I can try the ether, but the garages agree that it’s no spark. I’m going to leave it at the garage until they can find out why there’s no fire. In posting this hope to find someone that may have had this problem and perhaps would know a fix. Maybe a new distributor’s next, then a harness, etc. Again, thank for your input. Care to add anything?


#4

Why did you take the car back and refund the money? You sold the car in good faith and the new owner drove it away. After that all problems belong to the new owner. There was NO reason to take the car back.

Sell it again, and this time do it right. Once it’s sold, it’s sold.


#5

Yeah! There is!

Just for yucks and giggles, remove both side mount connectors from the battery. On the positive connector with the red rubber cover, peel back that red rubber cover to expose the connector. Sometimes corrosion can form under this red rubber cover and cause a voltage drop to the power distribution center. When this happens, all sorts of weird electrical problems can occur. Such an intermintant starting problem.

If there is a lot corrosion under the cover, don’t bother trying to clean it. Just replace it with a new battery cable.

Tester


#6

I like that possibility. For what it’s worth, if the battery connection looks okay, you might work your way back through the harness to the PCM main connector and see that it’s in good shape. When it won’t start, try just turning the key to the On position, and listen for the fuel pump to run. If it doesn’t run AND you’re getting no spark, I’m willing to bet you have a PCM problem, either at a connector or in the computer itself.


#7

I’m going up to where the car is stranded today and I’ll check the battery connection. During one stint when it wouldn’t start in my garage the local Caddy dealer’s best Caddy mechanic came up with some instruments to check various items. He checked items like the Hall Effect switch, etc. and during several attempts it still didn’t start. However, during one attempt it did start but he wasn’t checking a specfic item at the time. So he didn’t nail down the cause of the problem. He took the car for about 10 days and drove it around town, back and forth to work, on errands, etc and it started every time. He did bypass the security system in case a wire was intermittent in the steering column. Back home it started OK too. So I sold it, and the next day the car wouldn’t start again, and that’s where it stands now. The problem is still there, and I couldn’t in good faith stick the purchaser. So I’ll get it back by tow or, if the car feels like it, it’ll start. Then I’ll give it back to Caddy dealer and just tell them to keep it till they find the problem, even if it takes the rest of the year. I don’t need the vehicle, but it really must be fixed before I’ll sell it again.


#8

The fuel pump is audible when the key is turned on.


#9

That was real good of you to take the car back. Though not many folks may have done what you did, it is nice to hear about the honest care for the buyer.

Along with others, I suspect the culprit is caused by an intermittent electrical connection in the ignition area. If I was working on this I would find key test points to check by looking over the wiring diagram and then find the spots on the car. Then when the trouble happens you are ready to hunt the gremlin down. Hopefully then one of the test point areas will show up the trouble spot. Problems like this are commonly caused by bad terminal connections, relays, and ignition switches.