'85 240 woes...

- E
- Evi
  
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posted
15 years ago

Fri, May 2, 2008 4:37 PM

I'm having issues with my Volvo, and I can't quite figure them out. Maybe someone can help?

When I'm accellerating (or when I'm not), it feels as if something's pulling back on the car, or like it's not getting fuel for just a second. Almost like if you were running, but someone had a string tied around your waist and jerked on it every so often, causing you to slow down but not stop completely.

The impulse generator went bad, we replaced that. We changed out all of the spark plugs and wires (it was time for a tune up), and the battery connection is fine. I don't think it's electrical.

We went through the fuel system; we checked the line, the fuel filters, the pumps, the fuel pump relay, and all the wiring - it's all good. I can't really figure out what it might be.

Anyone got any ideas?

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- Bill Bradley
  
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posted
15 years ago

Fri, May 2, 2008 9:38 PM

As weird as it sounds, have you checked the gas cap? If the vent fails, the evaporative control system will pull a vacuum on the tank which the pump has to work against. Easy check: when the car is behaving this way, shut it off and open the gas cap. If you hear a sudden in-rush of air, that's your problem. I wouldn't rule out electrical though. Be sure to check ALL the ground wires to the block, especially the braided wire from the last bolt on the valve cover to the firewall, since a loose ground can cause a voltage error across sensors or even cause the injectors not to open. Also check the wiring harness at the firewall...sadly '85 is one of the years with the infamous GM-sourced wiring harnesses that have a nasty habit of crumbling when they get older.

Bill

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- James Sweet
  
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posted
15 years ago

Fri, May 2, 2008 9:48 PM

It's almost always the wiring harness that causes this, usually the coolant temp sensor or air mass meter wiring shorts to something else and the ECU thinks the engine is either colder or hotter than it is, making the mixture much richer or leaner than it should be but it's worth replacing the vacuum lines too.