I think I might of experienced vapor lock on friday and again today. On friday while commuting home on the interstate, the 740GL began to stutter as if starved of gasoline or air. It then died so I pulled over on the shoulder. This happened after about an hour on the road. I walked to a gas station and called a friend, about an hour later we arrived back at the car. I tried turning over the car and it popped right off! The air temp was about 95, and the tank was about 30%.
Tday the same thing happened after driving about an hour. The air temp is 100, the tank was about 75% full. This time I let the car sit for about a half an hour and it popped right off. It then ran fine all the way home (approx. 15 miles).
I made a couple of shorter trips over the weekend without any problems. My hunch is that it is a vapor lock problem, any comments?
Oh yeah the service light has been coming onn lately with no apparent problems until this, if they are related. Thanks, Scott

 

Service Light is an oil change reminder light.

I would check the Fuel pump relay in the fuse box.

Vapor Lock is very RARE on these cars.

I would look at that Last.

It could also be a bad Fuel Pump.

 

I second the tech suggestion. No vapor lock on fuel injection because the pressure of the fuel makes boiling point much higher temperature. Your problem sounds very much like the fuel pump relay. You can flick the relay with your thumb and middle finger the next time this happens if it fires right up I would drive to the closest volvo dealer for relay. I keep a spare in the boot.

 

Hey, thanks for the replies. I did a quick check on the diagnostic computer. All I came up with for the electrical was an oxygen sensor. For the fuel scan I came up with nothing. I plan on replacing the fuel filter on friday. I did a quick check in the fuse box for the pump relay. I noticed that it's way in the back. It looks like the front tray of smaller fuses pops out and then it looks like you can do the same to the rear tray. Has anyone ever done this? I thought I'd ask before I tried to. The rear of the fuse boxx is where the fuel pump relay is located, right? Thanks , Scott

 

on my 88 740 fuel pump relay in behind the ashtray second row near the drivers knee. Big white relay. If yours is a different year.......