Tough one - intermittent stalling

Volvord · Post by **Volvord** » 14 Jul 2004, 20:20

I usually have most of the answers but right now I am looking for your input. 1987, 765TI (B230FT) engine runs well with smooth power but has just recently started stalling. More precisely the engine will cut out momentarily, if this happens at idle the engine will stall, at higher rpm's just a quick "blip". Whenever it does stall there is not troubles restarting.

The problem is so internittent that diagnosis is difficult but luckily I have a parts cars so it is easier to try replacing the most common faulty commponents, so far I have replaced: Hall Effects, IAC, Radio Suppression Relay, Fuel Pump relay, Ignition Amplifier, check and cleaned grounds, checked fuel pumps (both working but unable to check pressures), checked adjustment on TPS, coil has excellent spark.

Looking of ideas, experiences, solutions?? Thanks gentlemen

Guest · Post by **Guest** » 15 Jul 2004, 06:08

Having the same prob with a 90 740.This car will do it driving down the road to.Once you stop it will start back up but it is starting to do it more often lately.

Post by **matthew1** » 15 Jul 2004, 10:38

Sounds like a wire getting warm, expanding, touching something else and shorting.

Volvord · Post by **Volvord** » 15 Jul 2004, 18:25

With further investigation these years of 700 series were prone to deteriorating engine wiring harness. So this weekend I will be replacing the harness (just happen to have a spare on the parts shelf)

Volvord · Post by **Volvord** » 17 Jul 2004, 14:14

Here is an update.
I replaced the engine wiring harness but the problem continued, although I am happy I replaced the harness as it would have given problems in the very near future considering the condition it was in.

Well that left on item that never seems to give troubles on a Volvo, the ECU, so I replaced it and the engine has not died or stalled since.

Post by **matthew1** » 17 Jul 2004, 17:27

Whoa... well if that does it I'm happy for you. Post back after a week or two and let us know if the fix holds.

TAFinley · Post by **TAFinley** » 21 Jul 2004, 07:08

Sounds as if you've already corrected the problem, but I had the same thing happen on my '85 245 GL and the fix was different.

Symptoms were as you described, intermittent stalling at idle and just a "blip" of a stall at highway speed.

Unfortunately, this was about 6 years ago, so I don't remember how I diagnosed it, but the problem was that the throttle position sensor was fried. I do remember that I washed down the engine shortly before this problem surfaced and was very careful to protect the distributor, MAF unit, and ignition control module, but not the throttle position sensor. I suspect it got shorted out during the engine wash.