740 Do these symptoms sound like a bad air mass meter?

The car is a 1987 740 gle non turbo automatic, has new spark plugs, wires, cap and rotor, timing belt, and ignition timing is rock solid. Also has a new alternator and battery.

Alright so the issue I have been having is my volvo had been idling erratically and would misfire under constant rpm, but seemed to drive just fine for awhile. I had a similar issue at one time which turned out to be a small amount of corrosion on the #3 injector, and I have cleaned all electrical connections for the engine. (air mass meter connection, idle air controller, all injectors, distributor, coil, etc.) As well I cleaned the idle air motor out.

After I did all of this it seemed to idle perfectly at ~750 rpms, and then once in awhile it would again do the missing, and erratic idle and if I held it with no load at around 2k rpms and released the throttle it would die, and be difficult to start, and it would switch between running well and running like crap without hesitation, and vice versa.

So the other night I was driving and it had one of its fits, and the engine lost power and would barely chug along, so I parked the car and pulled my bicycle off the rack and rode home.

What I am wondering is if this sounds like a problem a failing air mass meter would cause, or potentially a bad connection for the fuel pump?

Thanks for any input,
-Sean

Disconnect the AMM and see if that helps the problem. AMM supplies a voltage signal under air flow to the computer to determine how much air is being taken into the engine. It should idle fine without the AMM connected and feel bogged when driving because there is no communication to the computers. Also, the Bentley and Haynes I believe supply voltage testing parameters for the AMM so you can determine whether it is in spec or not.

Is your harness biodegrading? Check the connector and wiring for the AMM too..

So today I went to the u pull yard and every volvo there had both the air mass meter and fuel regulators removed..... So unplugging the AMM does nothing really, car won't run on its own right now, but will pop over with ether.

Any ideas or links to online manuals?

The only valid test for a bad AMM is to replace it with a known good AMM. If you have a fuel pressure tester, check the fuel pressure the next time the car gives you trouble. It could be a dying pump. The most likely cause of the problems is a bad AMM. The symptoms you describe are classic AMM failure issues.

A relay perhaps if not pump itself.

I am going to charge up the battery and start some more testing, I will keep this updated.

So What I have found, may be a dying fuel pump. Is there any issues anyone can for see with me replaceing the intank pump with a walbro and by passing the high pressure pump?

This sounds almost exactly like the problem I'm having and just posted about...

funky_monkey58 said:

So What I have found, may be a dying fuel pump. Is there any issues anyone can for see with me replaceing the intank pump with a walbro and by passing the high pressure pump?

Click to expand...

It should be fine. Remove the pump from the line though.

Well I replaced the little pump today with a new one and it seems to have fixed the issues, tomorrow I am installing the new inline pump and a fuel filter I have sitting here.