1998 V70XC - EVAP P0455/DCT EFI-611, Instant 0 psi After Engine Off. Related?

VolvoOwl98 · Post by **VolvoOwl98** » 13 Apr 2026, 00:25

177k miles. I've been hunting down the source of the notorious P0455 (AKA DCT EFI-611) code that's throwing my CEL, and at this point I've replaced nearly every component of the EVAP system (which was/is very much needed).

Recently I checked my fuel pressure at the fuel rail using the gauge sold on IPD's website, and it went up to and held a steady 40 psi when cranking up and idling. No pressure drops while I let it run for about 2 minutes, but as soon as I shut off the engine the needle very quickly (over the span of 5 seconds) dropped back down to zero.

I was wondering if there's some connection between the two. I changed the fuel pump relay fairly recently and know that isn't the issue. It drives okay, but my fuel economy isn't doing too great, with average MPG's being in the 17s on a better day with a good balance of city and highway driving.

I know that it can achieve better fuel economy, as there was a short time when I first began replacing components in the EVAP system that my MPG's were holding at a good 22-23 average with the same route of driving. During that short time, Saskia also fired up right away without any difficulty, even on a cold start in a non-heated garage in the winter.

The RPM's will also sometimes dip down a bit when at idle or very close to approaching idle on deceleration, which prompted me to clean the Idle Air Control valve, but that didn't clear up the issue. Also, when the CEL was reset after having the battery disconnected to replace some vacuum lines in the engine bay, when the light came back on after about 100 miles of driving the RPM's took a drop at the exact same time the check engine light came on.

Current symptoms to help diagnose:
- CEL and codes
- Fuel pressure drop
- Some difficulty starting when engine cold
- Poor fuel economy
- Intermittent RPM dip when at idle (and when CEL re-illuminated with system check (assumption))

Of curious note, fuel economy does seem to improve once the engine has warmed up, particularly if it's gone for a more spirited drive). Current;y there's no issue when the car is being refueled, in fact it seems to be happier when it's got a full tank even though there's more weight in the back.

Any help or direction would be greatly appreciated!

Post by **abscate** » 13 Apr 2026, 04:26

First I don’t think your fuel pump pressure is related to the evap code. If the pressure is ok running, it should be good. Bleeding down fast usually means a worn check valve or possibly a slight fuel leak .

The evap system is buried on top of the fuel tank and any leak in any hose or sensor will code the system ( usually after 100 miles of drive cycle) so it’s quite a treasure hunt on that chassis. I have a code on my s70 awd ( same system on evap)

Make sure the evap purge hoses under the intake manifold are all good , the turbo models purge the canister ftom both the manifold and the air snorkel snout in front of the turbo - all those hoses need to be new and tightly connected.

Vova585 · Post by **Vova585** » 13 Apr 2026, 08:54

Disregard the evap at this time. Starting is your priority. As abscate said- check valve or the fuel leak. If your car is not smelling like gas upon engine running, and you dont see any gas leaking...I would then- remove injector rail with injectors attached and fuel lines attached. Remove the fuel pump relay and put the wire "bridge" between 30 and 87 posts. Your pump will start running. Now look if any of your injectors are leaking fuel. If they are- replace injector(s) at fault. Replace o-rings(top and bottom) of the remaining injectors(the rubber will be so worn, those o-rings are cheap) so you will not have to chace air leak after. Of there is no fuel leak(still replace all injector o-rings), your problem is check valve. You can buy one of them and install it in line as a cheap alternative. Or replace with proper part/assembly.
Reconnect everything, install the fuel pressure gauge. Start and run the car so all air is bleeded out. Turn off the car. Pressure should drop, but not to 0. Around 1-0.5 bar should be resting pressure. Your starting issues will be greatly improved after fixing this(if it is injector, your catalytic and emgine will say TY as well).
Evap is best diagnosed with smoke machine.

VolvoOwl98 · Post by **VolvoOwl98** » 17 Apr 2026, 07:23

Thanks for the input on this, I’ll see about pulling my fuel rail and checking on the injectors/seals this weekend.

VolvoOwl98 · Post by **VolvoOwl98** » 19 Apr 2026, 18:05

Well, pulled the fuel rail last night and took a look at the injectors.

They took a bit of work to pop out, good news is that hooking a screwdriver under the electrical connector part and applying backpressure to the opposite side while using leverage of the screwdriver worked like a charm to pop them out.

But the bad news…

There’s cracks on the plastic for some, and an entire chunk missing. No damage was caused when I took them out, I was incredibly careful and neither heard nor saw any breakage.

I put new rings on and buttoned everything back up, did the usual priming and run to check for leaks (none). Re-ran a fuel pressure test, and there was a noticeable improvement upon engine shut-off. Instead of taking 8 seconds to reach zero (which I know isn’t instant, apologies if the title miscommunicated that), it took 17 seconds with the new seals.

On a test drive it was a bit peppier, and got about 2 MPG’s more on my usual driving circuit, which was driven in the exact same manner and very similar conditions (avg. 18).

With that in mind I’m going to order a new set of injectors and get those installed. Will update once they’re installed.

Vova585 · Post by **Vova585** » 19 Apr 2026, 19:46

First fix what needs to be done. Either put a proper fuel pump which will have a good check valve, vs viewtopic.php?t=66588 method. Then fix evap issue and later we can talk about the rest of upgrades.
Injectors are 300 for bosch or something similar to that. You can send your injectors to redline injectors and they charge $25 per one for cleaning with testing before and after. Or you can buy repair kit for cheap, change top filter and put the bottom ends into ultrasonic cleaner from harbor freight for 30 min and you will likely be greatly improved. Dont get me wrong, I am crazy about putting new parts myself, but I think that your money are better spent addressing issues which are 100% broken now.

Adding this video for reference. Hope you went with a cutting access method for pump replacement and not dropping tank(unless it is a show room car)

VolvoOwl98 · Post by **VolvoOwl98** » 19 Apr 2026, 20:45

Injectors are 300 for bosch or something similar to that.

FCP Euro has Bosch 9454556 injectors at $32.49 apiece ($162.45 total for 5) that matches the ones currently installed, so they’re not too bad in terms of cost. My line of thinking was that one of the components that helps hold on the o-ring being damaged should be addressed to prevent fuel leakage (and thus a potential bit of fire…), and it completely eliminates the injectors as a cause. To me injectors seem more of a 100% broken item than the fuel pump assembly, which is still functioning (not perfectly as shown by the pressure, but it’s still pumping).

Don’t get me wrong, I will absolutely be ordering the replacement fuel pump assembly (IPD 140277) as well to cover the bases. The last time I have anything documented for the fuel pump is a CarFax statement documenting its replacement at 77,309 miles on 6/10/2008, and I hope it’s been addressed since then, but it might not have been.

VolvoOwl98 · Post by **VolvoOwl98** » 19 Apr 2026, 20:50

Adding this video for reference. Hope you went with a cutting access method for pump replacement and not dropping tank(unless it is a show room car)

Thanks, that helps with locating the various EVAP hoses to check on in the future. I’ll be using the cutting method to remove the fuel pump. I care about looks, but not as much as things being functional

If I wanted this to be a showroom car I wouldn’t be using it as an adventure wagon

VolvoOwl98 · Post by **VolvoOwl98** » 27 Apr 2026, 02:00

Update on the current status of things:

A few days ago the injectors were replaced which resulted in some improved throttle response and an improvement in the distinctness of fuel pressure gauge movements.

Upon cranking from a cold start at each turnover interval of the engine the fuel pressure moves up a marginal amount until it hits 30 psi and starts running under combustion. Psi hovers around 35 for a few seconds before building to 40.

Up next as stated by abscate and Vova is the check valve for the fuel system. Once some financials are worked out a nee fuel pump will be ordered and I’ll install it. Hopefully that’ll fix up the issue.

If there’s any tips/tricks/recommendations people have for changing the fuel pump via the hole-cut-in-the-metal method they’d be much appreciated. I’ve read through several discussions about it, though it never hurts to be as prepped as possible (especially if there’s something that hasn’t seen a lot of attention on the topic).

Post by **abscate** » 27 Apr 2026, 03:24

If your hardware isn’t terribly rusty you can do the tank drop method. You have to remove the driveshaft and viscous coupler to get the clearance and then carefully lower the fuel tank, leaving the rear axle carrier in place.

The Ekaterina resurrection thread has my pics and links to some other threads on this but no info on the cutting method.

Make sure you get the right pump. The Volvo pump is no longer available. The insert type pump is but is bit tricky to get into the cartridge, very different than the FWD pump