I have a 86 740 GLE(non-turbo) that goes for 15 minutes (hihgway and or neigborhood) and then goes dead. I sit wait read a book for 30 minutes and it starts back up and goes for another 15 minutes. I've replaced the FP relay and that helped for two days. Now she's back to her old tricks. Please help. It takes to two hours to drive to church which is ten miles away.

Brian

I agree with David - hall sensor. It is a semiconductor device which breaks down over a short period of time and gradually its voltage difference reduces until you have no spark. It's worth checking the connection to the sensor first on side of distributor - it can disintegrate causing intermittent spark.
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BillB

Sounds like a classic case of a bad Hall sensor in the distributor. It generates the pulses that are uded to trigger the coil and provide spark. An easy check is to carefully observe the tach during cranking in the no start condition. It should knudge up ever so slightly as you attempt to start. If it does not you have no spark and the Hall is the prime suspect, secondary suspect would be the power stage.
If tach does nudge up then you almost certainly have spark and problem is fuel related.
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David Hunter

If it were me, I wouldn't throw a bunch of costly parts at it without trying to narrow done the possibilities a little.

If you have an extra spark plug (known to be a good one) carry it with you so that when it dies you can check to see if it's getting spark. Also, when it dies and you try to start it, can you here the fuel pump(s) running momentarily when you turn the key?

I realize you may need a second person to help with these observations. Take along a friend/spouse/kid/whoever. Besides, they can keep you company while you wait for it to start up again.

You can do it alone... just get an extra spark plug and ground it to the top of the intake manifold... If you sit in the car and crank, you can look through the windshield under the hood and see the spark plug...it does work.

Mike


ditto with Chris on NOT buying a ton of $$$ parts to fix a simple problem... diagnose first, spend later.

If you pick up the volvo factory fuel manual, (go to www.volvotechinfo.com) it has a whole range of diagnostic procedures to see exactly which components are working. AND it is extremely reasonable to buy ~$25.

Basically, from the factory ignition manual, it says that if you have spark, then the ignition is fine... and the fuel may be a problem. Depending on how old your rig is, the main pump may be dying or dead... and ditto for the in-tank pump. There is a way to test and see if both pumps are working... and this is by removing the FP relay and jumpering two terminals... 87/2 and 30 with some kind of wire.... THis will turn on BOTH fuel pumps... you can easily hear the main pump from the drivers seat, but the in-tank pump you will have to open the gas cap and stick your ear in the hole to hear it.

... these should get you started.

Brian, I would put my money into an FP regulator, new fuel pump(s), & new fuel filter. Good aftmkt is fine despite what you will hear from others who will describe aftermarket parts as akin to putting diesel fuel in a Ferrari. I have had great performance with aftmkt. Just my 2 cents worth. It's really about what you feel comfortable doing. I also believe that the 740 line is probably not one of the better series. I am stuck with one also.
On the bright side, I do applaud you for expending so much effort to get to church!
Good Luck!

Have you resoldered the fuel pump relay. Rarely do relays go bad. They do however get solder joint problems. I would also remove and resolder the radio suppression relay. this will eliminate two common problem areas and not cost you anything. (solder & cheap iron)