Cranks ok but no start 98 V70 turbo

Post by **erikv11** » 26 Oct 2023, 11:04

Intermittent crank but no start in my 98, turbo car.

Happened twice so far on this drive from CA to IA. Stop at rest stop or gas station, upon restart it stumbles and dies. 10-30 minutes later starts fine, runs for hours.

No codes.

Like a heat soak issue but who knows. Swapped fuel pump relays I carry a spare it’s not that. Fuel pump replaced 18 months ago Delphi brand (roadside replacement). There is no fuel injector relay on a 98, it is handled by J relays I think (?) I can try swapping those at home. No pressure gauge with me but fuel pressure at the rail is positive.

Sensor problem? ECT but then why is fuel economy great, why no symptom when running? Troubleshooting advice or guesses (C/C/TPS?) welcome.

Just got it restarted near Lincoln NE, not going to shut it off again. Will be Idling while I get gas in Des Moines …

Post by **scot850** » 26 Oct 2023, 12:35

It could be the ECT. If it had failed though, I would have expected you would notice the temp gauge being off. Having said that, what does the gauge show when you start? You are experienced with these cars, so you know to check the connector on the ECT. If it is registering correct at normal operating temp it may run fine during running. If it is bad starting then I would expect it to be difficult to start when cold not just hot.

Other options include the electrical portion of the ignition switch.

What about the MAF? If it fails to start when hot, try disconnecting the plug to the MAF an see if the car then starts. It could be the start of it failing. When the car is running it is getting cooler air fed to it. When stopped heat soak may be causing it to fail until enough cold air is drawn by it.

Lastly, you say fuel pressure is not an issue, so for now we will put that to one side.

Neil.

Post by **erikv11** » 26 Oct 2023, 12:45

Despite unplugging the MAF so many times in the past just to irritate abscate, I didn’t even think of that. Good idea!

ECT connections look good. Was afraid to really mess with the connector for fear of making it crumble sec they do sometimes. Temp gauge behaving for now I’ll keep a close eye on it.

Electrical portion of the ignition switch replaced with Volvo part about two years ago. This car has been with my daughter so it got a lot of (but not all) new parts.

Post by **MoVolvos** » 26 Oct 2023, 15:26

scot850 wrote: ↑26 Oct 2023, 12:35 It could be the ECT. If it had failed though, I would have expected you would notice the temp gauge being off. Having said that, what does the gauge show when you start? You are experienced with these cars, so you know to check the connector on the ECT. If it is registering correct at normal operating temp it may run fine during running. If it is bad starting then I would expect it to be difficult to start when cold not just hot.

Other options include the electrical portion of the ignition switch.

What about the MAF? If it fails to start when hot, try disconnecting the plug to the MAF an see if the car then starts. It could be the start of it failing. When the car is running it is getting cooler air fed to it. When stopped heat soak may be causing it to fail until enough cold air is drawn by it.

Lastly, you say fuel pressure is not an issue, so for now we will put that to one side.

Neil.

+1 on the ignition switch. The plug portion was oxidized on mine and did similar. Starts, stumbles and dies or crank no start. Has only happened once since the cleaning.
.

Post by **abscate** » 26 Oct 2023, 16:06

Despite unplugging the MAF so many times in the past just to irritate abscate, I didn’t even think of that. Good idea!

Post by **scot850** » 26 Oct 2023, 16:19

jmartin919 · Post by **jmartin919** » 31 Oct 2023, 14:33

So does the temp gauge on the dash use the same signal as the ECT? I just tried starting my 2000 S70 and it started and then immediately died. Same thing second time. Third time it started. Hooked up my scanner and it gave an ECT reading of about 150 degrees but my dash gauge read very low/off scale. After running for a few minutes the dash gauge moved up to normal temp and the ECT reading stayed about the same.

Post by **abscate** » 31 Oct 2023, 15:43

jmartin919 wrote: ↑31 Oct 2023, 14:33 So does the temp gauge on the dash use the same signal as the ECT? I just tried starting my 2000 S70 and it started and then immediately died. Same thing second time. Third time it started. Hooked up my scanner and it gave an ECT reading of about 150 degrees but my dash gauge read very low/off scale. After running for a few minutes the dash gauge moved up to normal temp and the ECT reading stayed about the same.

I mapped the 99 00 ECT and temp gauge reading so for reference in a thread referenced......

viewtopic.php?t=88486

jmartin919 · Post by **jmartin919** » 31 Oct 2023, 16:42

So would you say the dash temp gauge gets it's measurement from the ECT?

Post by **Sveedy** » 31 Oct 2023, 17:26

I would say "yes", as I'm not aware of an individual sensor for the temp gauge. You could always just unplug the ECT, and see if your dash gauge works.