Let me start off that I'm not new to working on cars just to Volvo and this forum. I've been working mainly on BMWs.

My friend has an '89 740GL (non-turbo) that is having some issues starting and running. She has a new MAF sensor in the vehicle but it seems to get extremely warm. One time is was too hot to touch. That immediately told me it was either a faulty sensor or a bad ECU. I let it cool and charged up the battery some (do to the constant trying to start) and it fired right up. The car did run pretty rough at idle and maybe that's do to vacuum leak she has. Anyways, we shut it off and started to clean up and the car just didn't want to start anymore. We charged the battery again but that was no good. After letting it sit for an hour, I tried to start it and it would try to crank but immediately stall. Trying to crank it after the first initial start was no good. The car acted like it was either not getting fuel or it was not getting fire to the spark plugs. Letting the car sit for 10 minutes and trying to start it up again, it would do the same exact thing. Maybe the engine is flooding out??? Checking the MAF sensor, it was warm for a car that is not even running. I've searched the forums and ran across several threads that had similar issues but not exactly what is going on with her car. I will try another fuel pump relay and test the fuel pump tomorrow. I'm going to change out the vacuum hose that is dry-rotted.

Any suggestions?? Why would the MAF (mass air flow) sensor be getting warm to hot sometimes??? ECU??? Please help. She needs her car for classes on Monday. I don't want to buy an ECU or any other parts that I do not need. Thanks in advance.

BTW, this guy was having similar issues but never said what he did to fix it. What is AMM??? Oh, here is the thread, https://volvoforums.com/forum/showth...+sensor&page=2

I will also try some of these steps from http://www.stepbystepvolvo.com/ tomorrow.

 

Anyone?

 

The AMM has a burn off function upon shut down which might account for the warmth but they shouldn't get hot. I'd make sure it is an 916 amm. 88 back to 85 used the 007. They are not interchangeable and will produce lots of heat, then smoke, then...nothing! The car will start and run w/o the ammin limp home mode. They don't typically result in no starts. The fuel pump relay is a good suspect. So too the crank position sensor, the ignitor or ignition module located on the driver side forward of the strut tower, hidden behind air box on n/a cars. Also, be certain to check the plug connectors as they often get pushed back, bent and corroded..

 

Well, the car has ran flawlessly for a week. Now it's back to the same symptoms. She took the AMM back to O'Reilly but the new one is doing the same thing. It's getting extremely hot. I replaced a lot (rpm and ect sensors, fuel pump relay, spark plugs, sensor behind the airbox, ECU). Anything else I need to look at.

 

It seems that rebuilt AMM's are not reliable. There are many stories about that. I believe that car has an 007 but maybe an 016 which the later cars have. They do not interchange. (last 3 numbers in the Bosch number) I'd get one at a JY and try that. I've had great luck with used ones.
But that may not be the issue. The car has an injection relay/radio suppression relay I think, and those are classic for bad solder inside that exhibit exactly the symptoms you have. What is this part? "sensor behind the airbox" that you say you replaced, perhaps that's the relay I'm talking about?
You also changed the Hall sensor? I think that car is set up that way.
Again, go to the FAQ mentioned in one of these threads and go to the various fuel injection and engine areas.