Hot start problem 1999 S70

nyckid · Post by **nyckid** » 03 Jul 2011, 16:01

This one is really getting to me. 1999 S70 GLT/Auto. 163k miles. Just picked it up 6 weeks ago. Change plugs, coolant, thermostat, tranny fluid, oil, oil filter. Replaced the ABS module from Mid-West ABS (thanks, Matt). This car starts fine 1st thing in the morning. If I drive it for 30-45 minutes, run into the store or stop for fuel, she gives me a very hard time starting again. 10-30 turns of the key. The car turns over strong (new battery), just doesn't catch. I just have to sit and wait for it to cool off. To top things off, if I let the car sit in the summer Sun before I start it, say 12 noon or after, it does the same thing just as if I drove the car, but the motor is completely cold. I am baffled. Thank to all in advance, Jason.

Post by **Ozark Lee** » 03 Jul 2011, 18:44

Is the Check Engine Light on? If so, have you pulled any codes?

Codes go a long way in helping us remote troubleshoot these problems. Post back any codes you pull by the Pxxxx numbers rather than the auto parts store's assessment of the problem which is often wrong.

One other question, how does your temperature gauge behave? After a few blocks it should be pegged at the 3:00 position.

...Lee

Post by **jblackburn** » 03 Jul 2011, 19:35

I'd check the fuel pump relay when this happens.

Remove the top fuse panel cover near the windshield next time this happens (there are some torx screws around the edges), and remove relay #103. Stick a piece of wire or something between pins 15 and 87 and see if the engine will start up.

sjbock1 · Post by **sjbock1** » 04 Jul 2011, 14:17

nyckid wrote:This one is really getting to me. 1999 S70 GLT/Auto. 163k miles. Just picked it up 6 weeks ago. Change plugs, coolant, thermostat, tranny fluid, oil, oil filter. Replaced the ABS module from Mid-West ABS (thanks, Matt). This car starts fine 1st thing in the morning. If I drive it for 30-45 minutes, run into the store or stop for fuel, she gives me a very hard time starting again. 10-30 turns of the key. The car turns over strong (new battery), just doesn't catch. I just have to sit and wait for it to cool off. To top things off, if I let the car sit in the summer Sun before I start it, say 12 noon or after, it does the same thing just as if I drove the car, but the motor is completely cold. I am baffled. Thank to all in advance, Jason.

I've been researching the exact same symptoms with my 94 850 N/A (135,000 miles, orginal owner) for the past year. This is a very common, very frustrating problem with 850s and a lot of people post about it on the internet. (google the symptoms and you will see the discussions and suggested fixes that have worked or not.)

Typically there are no codes thrown for this or check engine light. The problem is intermittent and worse in warm months so people often think they've fixed it but then the problem returns. It's not the fuel filter or expensive repairs like replacing the fuel pump or starter. The most likely problem seems to be a vacuum leak in a hose or a bad thermostat ($18) in the air box (don't know if your car has this part, mine does) or a failing fuel pump relay switch ($45-50.) I removed the air box thermostat and fixed the cold air intake hose into the open position. That cured the problem completely for the last 3 months even though the weather has been very hot here in south Texas. Recently, the problem has started occuring occasionally again but now sometimes happens within a few minutes of driving when the engine is still relatively cool or after I have just put gas in the tank. I'm going to try replacing the fuel pump relay switch and see if that helps. Good luck.

Sandra

sjbock1 · Post by **sjbock1** » 12 Feb 2012, 15:18

To update my response: A new fuel pump relay switch did fix the problem of stalling while idling. Removal of the air box thermostat and fixing the cold air intake into the open position had already fixed the dying while driving problem.