Problems after fuel filter replacement

Post by **jimmy57** » 21 Sep 2019, 11:37

I was picturing the regulator on the rail but the mid 90's brought a lot of changes to where they put the FPR. Does your car use the two speed pump system with a ballast resistor near the HVAC blower inlet? I really figured the Euro versions didn't get the same RULO vapor mitigation hardware.

Issues after fuel filter replacements are rare. Like the rarity that a vehicle with NO prior issues gets an oil change and the oil light will not go out because the oil pump lost prime. There are a few fixes but the shop fix is to raise the back of vehicle 3 feet if the pump is in front, front of vehicle for rear pump and on white motor Volvos you raise the LH side. Wait a 3-4 minutes and crank it up and it's fixed. Never see the car again.

Fuel filter change and then almost immediately rest fuel pressure issues happened years ago when CI fuel injection was the flavor of the day.

Post by **misha** » 21 Sep 2019, 12:13

kallekula wrote: 21 Sep 2019, 11:23 EDIT2:
Who the hell wants a car that always starts on the second time after ditting overnight? It would drive me personally absolutely nuts. This is no problem you can accrpt and continue living with. It has yo be fixed.

It drives me nuts too...especially that the problem started after installing oem filter.
I could use Wix or some other crap...but with Bosch...this shouldn't happen.
And it costs double than Mahle(Knecht) KL85.

And...relax...the most important thing is that it starts and have no driveability issues....it's just one extra turn of the key than ussual one and only if it sits more than 12 hours.

Post by **misha** » 21 Sep 2019, 12:22

jimmy57 wrote: 21 Sep 2019, 11:37 I was picturing the regulator on the rail but the mid 90's brought a lot of changes to where they put the FPR. Does your car use the two speed pump system with a ballast resistor near the HVAC blower inlet? I really figured the Euro versions didn't get the same RULO vapor mitigation hardware.

No...the pump speed is constant and also is a fuel pressure.The difference for M4.4 than other "regular" 850 is that FPR is in the back,near the fuel filter and older 850s including T5(M4.3)have it on fuel rail.On fuel rail i just have a fuel pressure damper.
The same management is used in U.S market '98 s,v,c70.

I doubt that problem is in filter itself....i guess that it's some kind of problem with "quick connections" on fuel filter.
i'll check those as soon as i have a bit time for it.

You mentioned that fibres could flush from new filter and got catched in fpr causing it not to seal well....i guess that 3Bar pressure would flush it too.Especially after a month.
We'll see.

This is the old picture of my FPR at the rear of the car:

Post by **erikv11** » 22 Sep 2019, 21:13

Ah too bad, you can't just open that up like you can with this one that is very common in US spec m4.4 cars viewtopic.php?t=83922.

And I realized my m4.4 850 (1996 NA) has the FPR at the rail - fuel system comes in several flavors, even within a single engine management!

Post by **wizechatmgr** » 22 Sep 2019, 22:31

What's the fuel pressure at before and during cranking on the first attempt?

Post by **misha** » 23 Sep 2019, 05:52

Didn't measured it yet,but if problem occured right after fuel filter replacement it has to be something with the filter or "quick connections" ...which are not that quick at all(like somebody mentioned before on MVS).

I'll investigate further and keep you informed.

Post by **misha** » 24 Sep 2019, 02:15

Hmmm...this morning it started instantly.

Post by **abscate** » 25 Sep 2019, 02:56

Was it a Siberian market filter for cold weather?

Post by **wizechatmgr** » 25 Sep 2019, 13:16

abscate wrote: 25 Sep 2019, 02:56 Was it a Siberian market filter for cold weather?

ROFL@ Siberia filter model. I wonder if there was just a little air that was still in the line. That or something worked it's way out - either way, if after the 2nd day it still is working right - I'd chock it up to bad luck.

Post by **misha** » 25 Sep 2019, 14:45

Hmmm....2nd morning in a row....starts instantly.
The problem is ....whatever i try...i.must wait for it to sit overnight to see results.

We'll see how it will behave next few days.
I still don't believe that it had some kind of air pocket in 3bar pressurised fuel system for a month.

Never had this kind of a problem after fuel filter replacement.