head scratcher

shegarty · Post by **shegarty** » 04 Feb 2018, 09:53

howdy folks - for those of you that have contributed to this discussion already, thanks so much - however, I am still chasing a hard start issue (most recent details here). I believed that I have narrowed it down to a fuel pressure issue but after replacing the fuel pump, the fuel pressure regulator and associated vacuum lines along with a badly corroded main engine ground (lucky find) I am still having the same issue. I also did a pressure test on the injectors and found that they were not leaking down. The long and the short of it is that after sitting for longer than 18-24 hours or so it cranks and does not want to start under normal starting procedures. After repeated cranking it will start and runs rough for 10-15 secs. If an attempt to start it is made in under the 18-24 hour period it starts up just fine. I am totally at a loss with this and am not sure what to do next ... any ideas???

As an aside I won't be able to get my hands on a fuel pressure gauge until tomorrow and it appears that the fuel blew the diaphragm in the one I cobbled together from some old air fittings.

Post by **abscate** » 04 Feb 2018, 10:25

Lets wait and see how the fuel pressure at the rail is behaving - hook up a good gauge and monitor the Fuel pressure during the cold start.

Post by **rspi** » 04 Feb 2018, 11:25

So, does it start or not? If you crank it for 5 seconds like directed in the owners manual does it start and run? Is the CEL on? What parts have been replaced other than the fuel pump?

(It is not the responsibility of the reader/helper to search out what you have done).

shegarty · Post by **shegarty** » 04 Feb 2018, 14:47

It does start but when it has sat for over 18hrs or so it requires as much as 10 seconds of cranking for it to start. Today it required multiple tries (3) of 10-12 seconds of cranking before it would actually run and idle properly. Over the last 2 1/2 years I have replaced all of the following; fuel filter, cap and wires, ECT, cam sensor, crank sensor, fuel pump, fuel pressure regulator and associated vacuum lines. No CEL but it does have a recurring P0455 evap code.

I plan to get the pressure gauge on the rail again tomorrow and see what happens. I won't be able do a long sitting start though as I will likely need to drive it to pick up the gauge. I will however be able to monitor fuel pressure and see if there is a drop over time as before.

Post by **wizechatmgr** » 04 Feb 2018, 16:04

Were all or only some of those parts Volvo? Reason I ask is things like the ECT and Cam/Crank sensor can be very picky.

When was the last time the fuel pump relay was replaced? Have you tried jumpering the fuel pump relay by chance?

Post by **RickHaleParker** » 04 Feb 2018, 16:49

Ah shoot! I thought this was history.

What kind of scantool do you have?

In the last cold snap when the temperature dropped to 0°F (-18°C), my '98 C70 would crank but not start and was throwing a DTC for the altitude sensor. Took the altitude sensor in the house and let it warm up, reinstalled and it fired up.

Thing must have a bad altitude when it is cold

shegarty · Post by **shegarty** » 04 Feb 2018, 16:58

I use an OBDLink LX that I connect to a tablet via Bluetooth. I did have a code for the altitude sensor a while ago but I cleaned the sensor, cleared the code and reinstalled the sensor and the code has not come back again. This one is really puzzling me as it starts fine if it has been sitting for under 15-18 hours, even if it's -20 C.

shegarty · Post by **shegarty** » 04 Feb 2018, 17:01

wizechatmgr wrote: ↑04 Feb 2018, 16:04 Were all or only some of those parts Volvo? Reason I ask is things like the ECT and Cam/Crank sensor can be very picky.

All parts were OEM

When was the last time the fuel pump relay was replaced? Have you tried jumpering the fuel pump relay by chance?

I replaced the fuel pump relay a while ago with my spare and I just installed a brand new one when I replaced the fuel pump.

Post by **RickHaleParker** » 04 Feb 2018, 17:22

I use an OBDLink LX that I connect to a tablet via Bluetooth.

I been using 850 OBD-II. It does not have a slick interface but it is written for Volvo cars 1996-98 and it does have a little bit of programing capability, Service light, Tire Size, Country Code.

Thanks for the tip. I'll try cleaning the altitude sensor, with luck the bad altitude won't return.

This one is really puzzling me as it starts fine if it has been sitting for under 15-18 hours, even if it's -20 C.

How far back in time does this problem go?

shegarty · Post by **shegarty** » 04 Feb 2018, 17:33

RickHaleParker wrote: ↑04 Feb 2018, 17:22 I use an OBDLink LX that I connect to a tablet via Bluetooth.

I been using 850 OBD-II. It does not have a slick interface but it is written for Volvo cars 1996-98 and it does have a little bit of programing capability, Service light, Tire Size, Country Code.

Thanks for the tip. I'll try cleaning the altitude sensor, with luck the bad altitude won't return.

This one is really puzzling me as it starts fine if it has been sitting for under 15-18 hours, even if it's -20 C.

How far back in time does this problem go?

I had a look at the scan tool software and I am going to see if I can get it to work with my dongle, I think it might be a proprietary link with the software I already have.

From what I read you need to use a MAF cleaner on the altitude sensor, anything else will damage it. I have been chasing the hard start problem for about 2 years now. The problem is that it is so intermittent. It began as only being temperature dependent and now appears to have graduated to a time related issue at all temps. Having said that it never happened during warmer weather in the fall.