bluemoose
Member
- Joined
- Sep 13, 2015
- Location
- Hurdle Mills, NC
So I have pretty much reached the end of the internet, and my wits, plus wasted a bunch of time and money trying to figure out the problem with my car. I'm finally giving up and creating yet another "stalling volvo" thread. The car is a 1990 740GL with Regina.
Symptom:
Issue gets worse when the car is warm. If the throttle is blipped quickly while sitting at idle, it will often stall, or hesitate and then rev up. If it is cracked open slowly the engine will rev up. In either case if the throttle is closed quickly and it falls back to idle it will try to stall or will successfully stall. Often the stalling behavior becomes dieseling behavior and the engine will run 'backwards' and blow vacuum hoses off. After it stalls it is a little hard to start again.
If the vacuum hose is pulled off the FPR idle speed will increase, but the same behavior persists when you blip the throttle. Reconnecting the vacuum hose results in idle decrease and sometimes stalling.
If I drive the car, after it gets warm, it will hesitate or seemingly start misfiring off-idle on acceleration. Once cruising it will usually run OK, but then at a stop when it falls back to idle it will try to stall. Sometimes just letting off the throttle is enough to make it stall.
What's been checked:
Everything I could think of.
-Compression was good.
-fuel pressure, inconclusive due to gimpy equipment. I have not yet tried again.
-ignition, everything is working fine as best I can tell
-timing was steady and advanced predictably at higher rpms.
-spark plugs look fine "brown toast" color.
-engine vacuum is good
-fuel relays work fine
-No OBD codes except the 3-2-1 code (supposedly caused by a dealer bulletin fix years ago?).
-IAC functions as best I can tell. It buzzes when I do the DTM test, and I cleaned it. Beyond that, hard to tell?
-All injectors fire during DTM test
-voltage steady 14.3
-TPS works fine
Parts/Money I've thrown at it:
-New battery (it died and wouldn't hold charge)
-Crank sensor (replaced as the culprit of an earlier stalling problem)
-MAP sensor
-Intake tube (had a big tear in it, but since Regina has no MAF sensor, it probably wasn't causing a problem. It was just unfiltered air, not unmetered)
-AC Delco Fuel pump, soldered into the original assembly
-Fuel filter
-short line between filter and tank hard line
- -4AN braided fuel line from filter to fuel rail (with a couple of hard to find fittings). I F'd up the original line trying to test the fuel pressure.
-spark plugs
-fairly fresh plug wires and rotor cap, but original ignition module
I've always felt like this was a fuel issue, and still do, but after replacing the entire fuel system it seems unlikely unless I did it wrong. At this point I'll take any ideas or suggestions, this has been going on several months and I haven't been able to daily drive the car for the last 3 months.
Symptom:
Issue gets worse when the car is warm. If the throttle is blipped quickly while sitting at idle, it will often stall, or hesitate and then rev up. If it is cracked open slowly the engine will rev up. In either case if the throttle is closed quickly and it falls back to idle it will try to stall or will successfully stall. Often the stalling behavior becomes dieseling behavior and the engine will run 'backwards' and blow vacuum hoses off. After it stalls it is a little hard to start again.
If the vacuum hose is pulled off the FPR idle speed will increase, but the same behavior persists when you blip the throttle. Reconnecting the vacuum hose results in idle decrease and sometimes stalling.
If I drive the car, after it gets warm, it will hesitate or seemingly start misfiring off-idle on acceleration. Once cruising it will usually run OK, but then at a stop when it falls back to idle it will try to stall. Sometimes just letting off the throttle is enough to make it stall.
What's been checked:
Everything I could think of.
-Compression was good.
-fuel pressure, inconclusive due to gimpy equipment. I have not yet tried again.
-ignition, everything is working fine as best I can tell
-timing was steady and advanced predictably at higher rpms.
-spark plugs look fine "brown toast" color.
-engine vacuum is good
-fuel relays work fine
-No OBD codes except the 3-2-1 code (supposedly caused by a dealer bulletin fix years ago?).
-IAC functions as best I can tell. It buzzes when I do the DTM test, and I cleaned it. Beyond that, hard to tell?
-All injectors fire during DTM test
-voltage steady 14.3
-TPS works fine
Parts/Money I've thrown at it:
-New battery (it died and wouldn't hold charge)
-Crank sensor (replaced as the culprit of an earlier stalling problem)
-MAP sensor
-Intake tube (had a big tear in it, but since Regina has no MAF sensor, it probably wasn't causing a problem. It was just unfiltered air, not unmetered)
-AC Delco Fuel pump, soldered into the original assembly
-Fuel filter
-short line between filter and tank hard line
- -4AN braided fuel line from filter to fuel rail (with a couple of hard to find fittings). I F'd up the original line trying to test the fuel pressure.
-spark plugs
-fairly fresh plug wires and rotor cap, but original ignition module
I've always felt like this was a fuel issue, and still do, but after replacing the entire fuel system it seems unlikely unless I did it wrong. At this point I'll take any ideas or suggestions, this has been going on several months and I haven't been able to daily drive the car for the last 3 months.
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