87 740 GLE stalls and restarts while driving

yosef7 · Post by **yosef7** » 28 Oct 2012, 06:54

Hello. I have an 87 740 GLE that has been giving me intermitant problems for two months. The car will not run at this time. Until the last two months it has been a champ. I have changed the fuel filter, both pumps, relay as well. At first this seemed to help but not anylonger. While driving it will stall and the tack will drop out. Sometimes to zero sometimes not. But then it suddenly starts up on its own and I continue to drive. Sometimes it just is dead in the water and I pull over. Wait or try to start and it has always restarted. I have the car home and it now will start but will not idle very long before stopping. I read all that I can on the forum. I have not seen when a solution has been reached, finalized and the person said this suggestion has worked. I am thinking ign and the hall sensor or modual. If I am headed in the correct direction which should I try?
Thank you all for your help.

Post by **billofdurham** » 28 Oct 2012, 12:35

If the tach drops to 0 before the engine winds down that indicates a loss of ignition pulses to the coil negative terminal. Suspects would be the power stage or the crank position sensor.

If the tach tracks the engine speed as it winds down that indicates a fuel injection problem. Suspect the radio suppression relay or loss of fuel pressure due to relay or pump. As you have replaced the relay and both pumps you can probably disregard them, apart from checking connections. The radio suppression relay on the '87 740 is on the coolant reservoir strap.

Bill.

mar cos · Post by **mar cos** » 10 Nov 2012, 00:12

hello i know what the problem is without a doubt.It is the ignition amplifier located on the driver side fenderwell.It is bolted to the fender next to the air box.What happens is they are bolted to a heat sink over the years they get so hot that the heatsink grease dries up thus allowing the electronics to burn u.Replace it and your problem will be solved.I also have a 87 740 that had the exact problem.Good luck and let us know what happens.the part is about 90.00 only available from volvo dealer

yosef7 · Post by **yosef7** » 14 Nov 2012, 13:46

Bill and Mar cos,
Thank you for the feedback. I believe we have an ignition problem. Bill , your wisdom is taking me in that direction. Due to the tach situation. It does not wind down. Mar, I changed the amplifier out previous. But I got to thinking that the distributor,hall sensor may be involved. So, I went to take off the dist cap and felt a loose connection at the base. Not the coil wire. something else. I think the plactic housing is broken away from the dist base. But I tried taping / straping it tight in place that helped for a short time. I think I have to replace this piece or the whold distributor. This one is tough to get to though. Any suggestions? I can not even get the cap off. The dist sits in the back of the engine compartment. Fits sideways into the engine. Can not get any tools back there to unscrew the cap. If I have to take the dist out what is the suggestion. I hope I do not have to lift the engine.

Post by **billofdurham** » 14 Nov 2012, 15:32

Why Mr. Volvo had to put the distributor in that place beats me, but the cap can be removed. Three screws hold the cap in place. Two are easy to find - one at each side of the cap. The screw on the driver's side of a left hand drive vehicle is slightly higher than that on the passenger side. The third screw is harder because it sits between the outlets for the plug leads. If you feel the cap you will find two plug outlets nearest the bulkhead (firewall). The screw sits between them. The screws are captive so you can't lose them but don't try to remove them from the cap. I use an offset screwdriver to get at the screws.

One tip when you come to remove the cap - mark the plug leads and pull them from the cap before you start. Do NOT remove the coil lead so you can see which hole it goes into for re-assembly.

If the cap is broken then that could be the whole of the problem.

Bill.

yosef7 · Post by **yosef7** » 15 Nov 2012, 08:09

Thanks Bill, Yes, Mr. Volvo sure put this in a dificult spot. I had marked the wire leads. Made that mistake many years ago. I still cannot get the off set to fit between fire wall and cap. When I get this I will let you know. What do you know about that wire set at the base of dist. I cannot see anything because of the location. It is no longer tight to the base. I believe this is my problem. The intermitant short. I thought I would need to take the distr out to even fix this part. So any special tips on taking this dist out would be appreciated. I am towing it to a place to work on the vehicle Friday. Plan to just replace the dist out. Any idea of the difficulty with the o rings. I hear mixed thoughts on that difficulty. My manual does not have details for this particular dist set up.
You have been and are a real stand up kind of guy. A good man. Thanks

Yosef

Post by **billofdurham** » 15 Nov 2012, 11:54

Two bolts hold the distributor in place. You should be able to see them with the cap in place but they are easier to remove when the cap is off. Use a small mirror to look down the back of the engine.

The wire at the base of the distributor will be for the Hall sensor. It should run to a plastic wiring connector on the side of the distributor plate.

If the problem is being caused by a broken distributor cap why replace the distributor? A new cap is a lot cheaper and you won't need to worry about the O rings. If you do pull the distributor you will need to replace the O rings.

Bill.

yosef7 · Post by **yosef7** » 20 Nov 2012, 12:40

Bill you are correct about the cap being less expensive. It took a lot of work to get the cap off. Each screw (3) took a different tool. Cap looks great. The dist came off fine as well. My problem may be in the hall sensor connector. It was broken and just hangs off of the dist. I thought I could reattach this but that did not work. I will now look for one to replace it and then try again. Hope this was the problem. Any thoughts? Would this part have caused the hall sensor to go bad? Let me know. I will work on it next week when I tow it to a friends garage.

Post by **billofdurham** » 20 Nov 2012, 12:49

If the Hall sensor connector is broken the sensor won't be able to do its job which is, very basically, adjusting the ignition timing.

If you can repair this by putting in a new connector you will have an easy task in front of you. If you need to replace the Hall sensor it is more complicated.

Keep us updated, please.

Bill.