- Volvo_Fuel Pressure Regulator 001.JPG (201.54 KiB) Viewed 1637 times
- Volvo_Fuel Pressure Regulator 002.JPG (186.45 KiB) Viewed 1637 times
I've just spent a few hours reading over many posts re: P0455 GROSS EVAP leak. As noted in another post, mine's back. I re-read my old posts, mostly on BITOG, and then saw a diagram that really got me to thinking: (Diagnosing an EVAP Leak on Motronic 4.4)
This diagram, for a NA, shows something I never considered before: That the fuel pressure regulator is fed with a vacuum line! Here it's shown supplied by a T-fitting via the TANK line. This got me thinking that the ghost I have been chasing could be due to a split in a rubber elbow or hose having to do with the FPR.
If I correctly remember, the three lines connected to the CharCan are VENT, PURGE and TANK. I've using this diagram for a few years now and while it explains many things well, it completely leaves out any connection to the FPR. I looked up the emissions system on Lisle Volvo's site and there is about 5 of them, depending on a code. I'd been reading about a rotted hose connected to the roll-over valve located close to the fuel filter. Except mine isn't there. It's actually located on the tank! The TANK line connects (1) FT press. sensor (2) ROV and (3) ORVR valve to the CharCan. This is a hard plastic line, unlike the softer, rubber hoses on earlier 850s, and connects to the CharCan using an odd connector that you have to slide out a bracket before the line can be released.
The sled's CharCan & SOV & "air filter (4)" is located in the rear, just forward of the RR tire.
So I took a picture of this area. Note how yellowed the rigid plastic fittings are. Also the FPR just appears to hang there, 100% relying on the rigid fuel lines for support. It's nearly laying on top of the pass steering bellows! Surely this can't be correct? Why wasn't it attached to the firewall? There is a very short piece of rubber that's now 19yrs old and also another piece of two or rubber tubing as shown. I followed this as best I could up, fwd and across and it appears to connect to the IM, to the side, below the vac tower Christmas tree. I won't be able to inspect it further until it's light out, I jack up the front end and remove the pass. tire.
Perhaps in my version, Volvo decided to supply vac from the IM, instead of from the PURGE line as diagramed above?
So there are four fuel lines connected to the FPR here? Two go back towards the tank, while two (send/return?) go to the fuel rail? Sorry, but just haven't thought about this before. Never pulled the injector rail either. And as you can see, it's still original save for the blue silicone hose.
"Xtrattitude4U" post really got me thinking. His 98 V70 NA is obviously different than my T5 and once again, Volvo AB rearranged EVAP parts from one model to another, causing confusion for us all trying to sort the dreaded P0455 and slay the troublesome troll.
I found this diagram on Lisle and fortunately, it shows ALL of it w/o the part prices. Look at the mess of vacuum hoses, connectors, rubber elbows, rigid lines, fittings, etc. all connecting & branching off of the FPR (29)! Holy Cow Meow! What a place for a critical vacuum leak!
Note on the CharCan that only two lines are shown: VENT and PURGE. TANK is left off. The VENT line can't cause a P0-455, but the other two can. I've removed the J-hose more than a few times and it's held vacuum fine. So has the CharCan. But I may replace the former just to do it. Also, the special connector on the TANK line is suspect to me. I cut off the special connector on the PURGE line where it connects to the CharCan and used silicone tubing as it badly SQUEAKED when moved and seemed suspect.
This diagram shows the TANK line (34). (11) is the air filter for the SOV and connects to it through hose (10), the "L-hose". Completely different than the many descriptions, photos and diagrams that appear for some '98 cars. Plenty of confusion for us DIY-types and others troubleshooting EVAP issues.
For good measure, I started with KISS. I bought a new OEM gas-cap in Oct 2015 and the seal was badly torn by Aug 2016. My indy gave me a replacement seal, I reset the CEL and thought I was good. So this evening, I polished some scratches/rough areas on the bottom of the aluminum filler opening where the gas nozzle had been hitting it for 19yrs. until it was smooth. Then I applied a thin layer of silicone grease to the seal and tightened the cap firmly. I'm leaving the neg. lead off overnight to reset the codes, then will see how long it takes for Troll455 to reappear. Past experience has taught me to remain skeptical at "easy" solutions.
In the beginning of this post, I thought I may have found an area I'd previously overlooked re: Troll455. At this point, I reckon I've been fooled again. However, I have found another area to clean up and install new vac hoses in.
One last thing, I'm going to pull both the PURGE & SO valves, carefully inspect (they're less than 5yrs old), clean with alcohol rather than carb-spray and relube the seals with AT-205 since I still have some. The former lives a hard life, cycling thousands upon thousands of time and in a HOT location. The later much less so as it's only energized when an EVAP test needs to be done.
Onward through the fog of EVAP and Troll455....
