Last week I posted a question about my 88 740GLE. Here's the problem: At idle after running anywhere from 30 seconds to 3 minutes, the Volvo suddenly dies. The tach needle immediately falls to zero. Wehn I immediately try to restart, the tach needle does not move and the car will not start. If after 30 seconds or so, it will occasionally start (quite hesitantly). After about 5 minutes of not trying to start it, it'll fire right up. It also dies if I hold the accelerator pedal steadily at about 2000rpms. Several posts from my previous post led me to believe that the Halls Effect Sensor was probably bad. So... I replaced the sensor, the distributor cap and the rotor. (Crappy job - what was Volvo thinking when they built THAT system?!) No joy. I then replaced the coil and the fuel injection relay from another Volvo I own. Still no joy. Same problem. Swapped out the ECU and mass air flow sensor. STILL no joy! Now I'm getting frustrated, as I don't really see what else there is to cause this problem.

If you've had this problem, perhaps you can shed some light? I'll gladly answer any questions about what I've done so far, but what I posted about is pretty much it.

You can email me at kdmiller2@juno.com or post here.

Thanks in advance!

Cheers~
Keith

Paul Spasske asked that I post the results, and since this may be a common problem in the future for 700 series owners, here it is:

As I had previously mentioned, I had changed the Halls Effect sensor, distributor cap, plugs & rotor as well as swapping out the Ignition ECU, Mass Airflow Sensor, coil and fuel injection relay. One of the reasons that I had mentioned that the tach needle died immediately is that fuel problems allow the tach needle to wind down. I'm not a Volvo guru by trade, but I've owned a ton of British cars and this is a common and easy way to determine the difference between an electrical fault and a fuel fault. (Wet plugs are a good indication of fuel too, I guess!) When I was in the Marines, we always used the KISS method (Keep It Simple Stupid). It still works well, and I always try to remember that MOST (not all, those British cars are different!) vehicles are pretty common when it comes to the wiring and basic function of their systems.

I posted my post again because I had basically changed or swapped everything I was aware of in the ignition system. Paul Spasske's suggestion to try the Power Stage was simple and quick, and yes, it solved the problem. (I forgot about it being an integral part of the ignition sequence.) There's a Volvo dealership about 3 miles down the road from me, but they're a lot more interested in selling the parts than helping solve a problem. That's one of the great things about internet forums. Chances are good that someone has had the problem in the past, and at $71 a hour labor rate, I'll take my chances at posting first.

Thanks to all that posted. My many humble thanks to Paul for pointing me in the right direction, but all of your suggestions were valuable!

Cheers~
Keith Miller
Hendersonville, NC
www.angelfire.com/nc/jandtautomart

basic diagnosis:-

are you getting spark (plug held against block test)
are you getting fuel (injector in the bottle test)

as the car is starting i would suspect a fuel problem, perhaps a FPR or filter/pump issue, sound like maybe a bloccked filter...cheap to change...

Dude, according to the volvo factory ignition manual (I also have an 88 740GLE), if you are getting spark, then the ignition system is fine.

DO you have spark? Get a spare spark plug, unhook the #1 wire and put the extra plug in it. Place the plug up on top of the intake manifold and crack the hood open... best done when dark. If you turn the key and peek your head over the steering wheel, you should see a repeating spark... if not, then you have an ignition problem.

I do not agree that the ignition power stage as posted below is the fault.

It seems more like a fuel-based problem... sticking throttle, etc.

Sorry I couldn't be of more help.

If the tach still isn't moving, It's probably the power stage (see ignition FAQ). The Hall effect sensor is an input to the ignition computor (ECU). The igniton ECU then shares this info with the fuel ECU to keep the gas going. The ignition ECU also has an output to the power stage. An output from the powerstage goes to both the Tach and the coil.
--
Paul NW Indiana '89 740 Turbo 103,000