740 stalling out while driving, cranks/won't turn over

abbeyforbes · Post by **abbeyforbes** » 07 Apr 2012, 11:30

Hi guys, hope you are all having a beautiful Easter weekend!
My 740 has had some issues lately. I've owned it about 4 months, have changed oil, flsuhed coolant system, and got new tires, that's about it. New battery was put in at time of purchase, car has roughly around 220,000 miles on it. I took it on a long 3 hour drive two weeks ago, it made the trip fine, stalled out at one red light near the destination, but started right back up again. THe next day, I drove it to a friends house, it was raining pretty hard and as I slowed to go around a tight curve, the car stalled and would not restart. The engine cranked but would not turn over. A guy that stopped to help sprayed some ether in it and it started. Stalled again on the next trip and couldn't be re-started for two days, we check the battery terminals, the pump relays, all check out fine, no smell of gas in the regulator, strong smell of gas when cranking the car though. The plugs were saturated, and the spark was weak, yellow. Two days later when the weather cleared, the car started and drove fine. Go figure. We determined that it must be the ignition coil and replaced it and the fuel filter just to be safe. The spark is blue now, so do ya'll think that was it? All these problems started in another town, 3 hours away. Hubby tried to drive it home yesterday, it stalled out after about 110 miles. This time, he thought it must be the exhaust was stopped up, as we knew that the converter needed changing, so he loosened the exhaust, diconected the C02 reg and was able to drive it the rest of the way home.
Another issue it's been having. when the gas tank gets low, around 1/8 of a tank, it drives like crap! it's a fuel delivery problem for sure, as all of a sudden it acts like it's running out of gas, and if you try to give it more, it stalls out. If you turn the car off, and restart, it will usually drive a little farther will no problem and then start acting up again. Obviously I try to keep her tank full, but I was wondering if you thought that the coil could be related to this issue.

I know I need to adress several issues, and I would just like to know if you think i'm on the right track or if it could be something else alltogether. To clarify, i belive i need a new converter.

abbeyforbes · Post by **abbeyforbes** » 08 Apr 2012, 12:42

ok, converter seems to have been gutted, so that debunks our clogged exhaust theory. Muffler, likewise, seems clear. ideas?

lummert · Post by **lummert** » 08 Apr 2012, 20:46

If the outside temp was hot when this happened, combined with the fact that the tank was low on fuel sounds like a problem I was having. When it would get hot in the summer my 88 760 Turbo wagon would stall. After letting the car cool it would start and I would drive to the nearest gas station. This happened several times and each time it took 5 gallons to fill the tank. On March first the main inline fuel pump quit. 2 weeks later when it was 85 degrees with about 36% humidity the engine stalled again and there was no fuel pressure. Since I was close to home I called a friend with a tow strap. By the time the friend got there the engine would start and run, so I had him to follow me home.

Since then I have replaced the gauge sending unit and intank fuel pump. I tested the old pump in a container of fuel with a hose connected from the pump and pump connected to the battery and it was dead. I now have to just wait and drive to make sure everything is fixed.

Post by **billofdurham** » 10 Apr 2012, 12:27

+1.

With the two pump system the in-tank pump is a priming pump for the main. If the priming pump stops working the main can cope if the fuel level is above half but it really struggles once the level gets lower. If the in-tank pump has failed it must be replaced as soon as possible as it will cause the main pump to fail.

Bill.

abbeyforbes · Post by **abbeyforbes** » 12 Apr 2012, 03:55

i see. that would definately make sense, thank you.

Car has always run very smooth on idle,however, it now hiccups about every 5-6 second, and when accelerating from a stop, it tried to gutter out and stall. If it does actually stall, I can shut off and restart no problem. What I do to keep this from happening is to let off the brake and let the car start moving, then very gently accelerate, once up to 35-40 it's fine. pisses of the drivers behind me, but it works. Do you think that problem could be fuel pump related as well? and just to let you know, we changed the fuel filter this weekend, prior to this new symptom.