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1986 Volvo 240 Automatic -- Idles Weakly when Engine is Cool

I have a 1986 Volvo 240 DL automatic with about 250000 miles. I am having a problem where the car seems to have a weak idle when it first started cold (not meaning necessarily cold weather outside, but the engine is cool and not warmed up). By weak idle, I mean it seems to be struggling to maintain an idle, like there is not enough fuel being supplied. And this weak idle also translates into weaker acceleration, I don't feel the power when the idle is like this. The car only exhibits these symptoms when the engine is cool, it hasn't been driven for many hours/in the morning when I leave for my commute first thing. The car will exhibit this weak idle for the fist mile or two, but then afterwards, the car runs fine once the car is warmed up; the weak idle clears up, and the power is normal. Any ideas what can be causing these symptoms.

Things I'd also like to note on what has been replaced on the car:

  • The car recently completely died on me on the first stretch of my morning commute. I made it within the first mile of my home, came to the stop light. When I hit the gas, the car died. I tried to crank it back up, but to no avail. Had to call a tow truck. The mechanic replaced 2 fuel pumps, and a fuel filter, and I was up and running again.

  • Fuel pump relayed replaced within the last year

  • CIS motor replaced within the last year

  • Throttle body cleaned within the last year

  • Distributor cap and rotor were replaced within the last year

*Spark plug wires replaced within the last year, mechanic said spark plugs seem fine

I thought I re-called reading on here before that a bad fuel pump check valve could cause these symptoms. Is that true? My car starts right up just fine, no hassles at all. And most of the time it will hold the idle after a first started it, but the idle is weak. Though I sometimes have to coax it to not die when backing out in the morning when the engine is cold by first hitting the accelerator and then throw it into reverse, otherwise the car will die on me (this happens sometimes, not all the time)... because of the weak idle when engine is cold problem. Any ideas? If you say, yes, about the possibility of the fuel pump check valve, then I'm considering bringing it up with my Volvo mechanic. Thank you.

Reply to
Gary Busey
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Reply to
Gary Busey

Unless the "CIS motor" is the "idle air control valve", aka "idle motor", the IAC is what you need, I think. I think we also need one on our '88, but my housemate hasn't gotten around to making an appt. for it to be looked at, yet.

Reply to
Michael Cerkowski

One other note I'd like to make is there seems to be some clicking underneath the car in the morning when I drive (when I'm accelerating, pushing the gas pedal), or when the engine is totally cooled. I'm pretty certain it has something with the fuel delivery system down there, underneath the car (just my hunch). Maybe something in the fuel pump system or something? But I've just replaced both fuel pumps and fuel filter.

The clicking symptoms were there prior to replacement of the fuel pumps and filter, and still exists. The clicking noise (seemingly from the fuel pump system underneath the car) only presents itself as the car is under acceleration, and while the car is still exhibiting the "weak idle" as descibed below. Once the "weak idle" symptom has stopped after the first mile or two, there is no more clicking noise from underneath the car and no more problems with acceleration and power.

I'm still at a loss as to what's caus>I'd also like to note that this "weak idle when engine is cool" has always

Reply to
Gary Busey

Yes, I think that's what it is referring to. It's been done already. According to my Volvo repair manual, CIS can stand for "Constant Idle Speed system" or "Continuous Injection System". I think the part I'm referring to is the former.

Reply to
Gary Busey

I don't know if I can help with your problem, but fuel pump check valves cause problems with hot starting. And each new fuel pump comes with a new valve.

Your problem seems to be caused by a problem with the "choke" circuits. There is a temperature sensor on the side of the head that indicates the coolant, they often fail, and so does the wiring going to them, then the computer might be assuming your engine is warmed up all the time.

Reply to
Mike F

Have the throttle body cleaned and set up by a Volvo mechanic. This is a common problem with the B230 enging and is simple to correct.

Reply to
Rod Gray

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