98 v70 crank no start. replaced fuel pressure regulator

ghansenv70 · Post by **ghansenv70** » 13 Jul 2023, 21:38

i recently picked up a 98 volvo v70 2.4 na with a m56. it did about 700 miles from where i bought it from back home before breaking down. it was running rich when i bought it but i thought it to be the o2 sensor that was cut. it ran fine without considering it had no o2 sensors as the downstream doesn't exist (no bung). when it died it went up and down in revs and shuttered while driving. my friends pulled the plugs and they were completely black. cleaned them re gaped and reinstalled. they recommended that i replace the regulator so i did as well as the vac line connectors that had rotted through going in and out of the rollover valve. it is able to idle but doesn't want to run while driving and almost stalls out when starting in first. i dont know what else could be wrong with it since it previously drove fine with no o2 sensors. any ideas on what it could be or if anyone knows what the problem is. any help would be appreciated

Post by **abscate** » 14 Jul 2023, 03:17

First stop, cap rotor, these last a long time but eventually give up the ghost

A common mode of failure is the moisture from crankcase blow by gets into the distributor and fouls them up. You have to fix both the blow by and the ignition parts, Bosch only

Post by **Chuck W** » 14 Jul 2023, 04:09

I doubt it drove "fine" with no O2 sensors. Is it missing both or just the rear one?

Does the CEL work? If it was running as poorly as it sounds, it should've thrown codes. If no CEL, it's likely the bulb is burnt out or has been removed.

Pull engine codes before you throw any more parts at it. You'll need to fix the exhaust to reinstall the O2 sensor.

Post by **scot850** » 14 Jul 2023, 10:26

How does the coolant gauge work. It should sit at about the 3 o'clock position when warm. When the ECT (coolant temp sensor which is beside the thermostat) or it's connector get old or flaky, the car will run rich as well. But first point is to get the O2 sensors running correctly. Does the Lambda light come on when turning the ignition on? I also agree with Chuck on getting the codes checked. If you don't have a reader some of the larger parts stores may be able to do it for you.

Lastly, are you sure there is no bung? Unless the car has been straight piped, there should be a bung on the upper side of the Cat. or just behind it above the cross plate.

Neil.

ghansenv70 · Post by **ghansenv70** » 14 Jul 2023, 10:46

no it drove just fine until it got back to chicago. i can only see the upper bung for an o2 sensor because it looks like someone welded on a aftermarket cat or resonator as i dont have factory cats. i pulled codes and most of the were regarding to 02 sensors and 1 code for the maf

ghansenv70 · Post by **ghansenv70** » 14 Jul 2023, 10:47

coolant gauge also works just fine

ghansenv70 · Post by **ghansenv70** » 14 Jul 2023, 10:48

i know fuel is geting to the rail as i tapped the bleeder valve to test and fuel came out as well as idling fine