Brad850 Posted October 11, 2016 Report Share Posted October 11, 2016 I've noticed over the past few months if the car sits for more than a few days, idle will be pretty rough for about 5 seconds. It then smooths out completely and I have 0 drivability issues. It threw a code once during one of the stumbling idle starts (cyl 4 misfire), so I installed new spark plugs and re arranged the coil packs. Fast forward to yesterday (car has been sitting for roughly 10 days). It started, stumbled for 2 seconds then died. Tried starting it again and it just cranked for 15 seconds. Tried again while opening the throttle, and it finally came to life, but when i let off the throttle it died. Last try, I kept it revving at 2k for about 10 seconds and finally it settled to a normal idle. No codes have been set and the car now starts (and drives) flawlessly. I've recently replaced spark plugs, coil pack wiring loom (wiring looks good), fuel filter (just today), and thermostat/temp probe. Does anyone know if this issue is indicative of something specific? I had a misfire during one of these funky idle episodes, so my guess would be coil pack or fuel injector issue. It hasn't thrown a code since that first time, so rearranging the coil packs hasn't proved anything yet. Link to comment Share on other sites More sharing options...
hootie6828 Posted October 12, 2016 Report Share Posted October 12, 2016 Low fuel pressure will cause a funky idle at startup, pressure bleeds down after sitting for a bit. Link to comment Share on other sites More sharing options...
Brad850 Posted October 12, 2016 Author Report Share Posted October 12, 2016 11 hours ago, hootie6828 said: Low fuel pressure will cause a funky idle at startup, pressure bleeds down after sitting for a bit. That could explain it. Could also explain why it was really tough to start it after 10 days, which is the longest I've let the car sit since I've owned it. Wondering if the pressure regulator could be the culprit. Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted October 12, 2016 Report Share Posted October 12, 2016 Not likely a FPR. Very common for the fuel pump/relay to fail. Do you have a mechanical gauge to check fuel pressure? Link to comment Share on other sites More sharing options...
Brad850 Posted October 12, 2016 Author Report Share Posted October 12, 2016 Hoping it's not the pump. I do have the gauge, so I can check it over the weekend. Wouldn't the relay just be a work or not work situation? Either the car won't start at all or it will? Not sure if this is related, but occasionally during fill up the gas pump will stop well before the tank is full, and I have to start pumping it again. Link to comment Share on other sites More sharing options...
gdog Posted October 13, 2016 Report Share Posted October 13, 2016 2 hours ago, B850 said: Hoping it's not the pump. I do have the gauge, so I can check it over the weekend. Wouldn't the relay just be a work or not work situation? Either the car won't start at all or it will? Not sure if this is related, but occasionally during fill up the gas pump will stop well before the tank is full, and I have to start pumping it again. Fuel pump relays can be real PITAs! Seen them fail from heat soak. Back when I was a tech at a dealer we had a customer bring in his car who said it died after he drove it like 20 miles or something. Thoroughly checked it out, found nothing wrong with it, but he kept bringing it back, like 3x IIRC. Finally I pack the car with VOM, tools, etc. (and my lunch) and just started driving... and driving.. and at right around 20 miles the car dies. I quickly find the fuel pump has no pwr and trace it back to the relay. While I'm looking in my toolbox for a spare relay, it starts working again. Why? Because the hood was up causing the relay to cool off.. Moral? Keep a spare in your glove box.. 2 hours ago, Ihatespeedbumps said: Not likely a FPR. Very common for the fuel pump/relay to fail. Do you have a mechanical gauge to check fuel pressure? @Ihatespeedbumps: you seem to know this '99+ vintage volvos pretty darn well... Do you know when they started using fuel pressure sensors in the rail? Was it '99 or later MYs? Link to comment Share on other sites More sharing options...
Brad850 Posted October 13, 2016 Author Report Share Posted October 13, 2016 Well I'm 99 percent sure it's not the relay, because I can always hear the pump when starting, and my car has never shut off. Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted October 13, 2016 Report Share Posted October 13, 2016 15 hours ago, gdog said: Fuel pump relays can be real PITAs! Seen them fail from heat soak. Back when I was a tech at a dealer we had a customer bring in his car who said it died after he drove it like 20 miles or something. Thoroughly checked it out, found nothing wrong with it, but he kept bringing it back, like 3x IIRC. Finally I pack the car with VOM, tools, etc. (and my lunch) and just started driving... and driving.. and at right around 20 miles the car dies. I quickly find the fuel pump has no pwr and trace it back to the relay. While I'm looking in my toolbox for a spare relay, it starts working again. Why? Because the hood was up causing the relay to cool off.. Moral? Keep a spare in your glove box.. @Ihatespeedbumps: you seem to know this '99+ vintage volvos pretty darn well... Do you know when they started using fuel pressure sensors in the rail? Was it '99 or later MYs? I worked on Volvos professionally for 10 years that's why ;) Fixed a lot of them. FPS didn't show up until 05 in most models and 04 2.5T IIRC. 13 hours ago, B850 said: Well I'm 99 percent sure it's not the relay, because I can always hear the pump when starting, and my car has never shut off. My strong inclination here is that the fuel pressure is bleeding off back to the tank which is causing a hard start condition.The longer it sits the worst it gets. A fuel pressure gauge will confirm this. If the relay has the original date code you're setting yourself up for failure if you don't change it. It will leave you stranded (voice of many experiences here) at some point. Link to comment Share on other sites More sharing options...
hootie6828 Posted October 13, 2016 Report Share Posted October 13, 2016 3 hours ago, Ihatespeedbumps said: My strong inclination here is that the fuel pressure is bleeding off back to the tank which is causing a hard start condition.The longer it sits the worst it gets. A fuel pressure gauge will confirm this. If the relay has the original date code you're setting yourself up for failure if you don't change it. It will leave you stranded (voice of many experiences here) at some point. Agreed. There is a check valve on the pump that is supposed to prevent this, but they fail and leave you with exactly the symptoms you described. Link to comment Share on other sites More sharing options...
Brad850 Posted October 13, 2016 Author Report Share Posted October 13, 2016 3 hours ago, Ihatespeedbumps said: My strong inclination here is that the fuel pressure is bleeding off back to the tank which is causing a hard start condition.The longer it sits the worst it gets. A fuel pressure gauge will confirm this. If the relay has the original date code you're setting yourself up for failure if you don't change it. It will leave you stranded (voice of many experiences here) at some point. I know I have at least 3 of them I was just saying I don't think it's the case here. But I could always be wrong of course. 20 minutes ago, hootie6828 said: Agreed. There is a check valve on the pump that is supposed to prevent this, but they fail and leave you with exactly the symptoms you described. Sounds about right to me too guys. I've been searching, and the fuel pressure check valve has come up a few times. Unfortunately it looks like it's integral to the pump, in which case I would have to replace the whole thing. I know andy and some other people have placed a check valve right before the fuel filter, although I really don't feel like splicing that line considering the amount of pressure in the system. If i find the time this weekend I will check to see how fast the pressure bleeds from the system and report back. Thanks again guys. Link to comment Share on other sites More sharing options...
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