Stumbling at start up

Post by **Sveedy** » 13 Sep 2020, 16:55

So Sveedy sat for a little over two weeks without being used. When I went to start her she fired right up, but then started stumbling and stalled out. Started right up again and as long as I feathered the gas I could keep her running, but it was rough. After about 45 - 60 sec of that she started idling normally. I chalked it up to not having been started in a couple of weeks - maybe gas leaked out of injectors or something. But today she did it again after only a couple of days of sitting. Starts and runs great the rest of the day.

I am going to start her up tomorrow and see if it happens again in that time frame. If so any thoughts ? Seems/feels like a fuel issue of some sort.

Post by **abscate** » 13 Sep 2020, 19:02

This is the 1996 Turbo?

Good to check the fuel pump relay, the Engine coolant temperature sensor, and read up on lawn mower syndrome.

Post by **Sveedy** » 14 Sep 2020, 09:31

Thanks for the ideas.
I just went out and started her up - no issues today. Maybe she was a bit peeved that I didn't drive her for a couple of weeks.
Still weird that there was a problem after only sitting for a couple of days. But if all's good now then I'll just see if the problem reoccurs.
I do have a few other fuel relays with which to switch out, if needed. ECT is only a few months old. Proper Volvo part from FCP.

Post by **misha** » 14 Sep 2020, 12:07

Could be fuel pump check valve.

Post by **Sveedy** » 14 Sep 2020, 13:34

That's something I haven't yet touched. Where is it located ? I also have yet to replace the fuel pump. Filter, injectors, relay all have been replaced. I don't know if this is related but I sometimes get the flashing CEL under wot. I'm running a VAST ecu and was told that the flashing indicated a lean condition. So might the pump be going out ? No vacuum leaks etc to be found.

Post by **misha** » 14 Sep 2020, 15:05

Fuel pump check valve is integrated in fuel pump output line(in the sleeve where fuel comes out).

Flashing CEL always indicates misfiring.

Post by **Sveedy** » 14 Sep 2020, 17:01

Damn. That means I've been going down the wrong path on that one. I sent data logs to Arron, the tuner, and he said that the flashing CEL was do to a lean condition causing engine knock. Doesn't happen all the time - I can control it based on how fast I push the throttle. Keep in mind that his tuning is more sensitive to engine knock by a lot, so that makes sense to me. I think he was looking at my fuel trims etc when he said that.

Post by **Sveedy** » 14 Sep 2020, 17:01

Damn. That means I've been going down the wrong path on that one. I sent data logs to Arron, the tuner, and he said that the flashing CEL was do to a lean condition causing engine knock. Doesn't happen all the time - I can control it based on how fast I push the throttle. Keep in mind that his tuning is more sensitive to engine knock by a lot, so that makes sense to me. I think he was looking at my fuel trims etc when he said that.

Post by **FLXC90** » 15 Sep 2020, 15:02

That lean induced knock IS a misfire of sorts. It's an ignition event outside the normal parameters. Knock sensors detect it, ECU retards timing, and things get back to "normal", or you let up on the fun pedal and it goes away. Maybe it's time for the upgrade! Unless Aaron sends you a new flash. Did you tell him about the stumble? Although I would suspect fuel drainback as well. If it sits again, try the key to 2, off, 2 off, then start to prime the rail.

Post by **Sveedy** » 15 Sep 2020, 18:22

I will let her sit and see if priming the fuel rail helps. Didn't start her today. I haven't sent Aaron a datalog in some time. I keep putting it off thinking I'll change something else. But I will make a current one and see what he says.

If it is the check valve does that mean I'm replacing the whole fuel line ?