1997 V90 starting issues

[AnthonyHardy2]

35psi at idle sounds normal to me for a 3 bar regulator since the vacuum at idle will lower the fuel pressure

 

[poulrais]

That's very close to 2.5 bar. Is it supposed to be a 2.5 bar regulator like the N/A 240s?

If it's supposed to be 3 bar it's a bit less than 10psi low.

Base fuel pressure is usually measured with the FPR's vacuum line disconnected. Mine was still connected so it is normal to see a fuel pressure reading that is like 4 PSI lower than the required base fuel pressure. Base fuel pressure for the V90 should be 3 BAR so 44 PSI minus 4-5 PSI because the vaccum line is on. So yes I think that I'm 5 PSI too low.

 

[poulrais]

I might just install an aftermarket checkvalve on the fuel line for now and I'll replace the pump over the winter.

 

[andyb5]

I might just install an aftermarket checkvalve on the fuel line for now and I'll replace the pump over the winter.

I’ve done this one a V70 R I owned, the check valves are a common issue and replacing the pump is isn’t easy so the quick fix is to install an external check valve.

My lessons learned to are to make sure the valve is between the pump and fuel filter (if possible) and to still give the pump a moment to prime before cranking.

 

[2manyturbos]

Base fuel pressure is usually measured with the FPR's vacuum line disconnected. Mine was still connected so it is normal to see a fuel pressure reading that is like 4 PSI lower than the required base fuel pressure. Base fuel pressure for the V90 should be 3 BAR so 44 PSI minus 4-5 PSI because the vaccum line is on. So yes I think that I'm 5 PSI too low.

You have to take into account no 2 gages will read the same. My gage on almost every Volvo running a 3 bar regulator will read 42 psi with the vacuum line disconnected and 37 with it connected. You are not far off. That may indicate a worn fuel pump or a slightly plugged fuel filter. With as many mile as the car has on it, worn pump is the most likely conclusion. It isn't that hard to change the pump. It makes more sense to change the pump vs. installing a 2nd check valve. Everything you put in between the pump and rail is a restriction. You would likely end up with even lower pressure at the rail.

 

[Khrrck]

You have to take into account no 2 gages will read the same. My gage on almost every Volvo running a 3 bar regulator will read 42 psi with the vacuum line disconnected and 37 with it connected. You are not far off. That may indicate a worn fuel pump or a slightly plugged fuel filter. With as many mile as the car has on it, worn pump is the most likely conclusion. It isn't that hard to change the pump. It makes more sense to change the pump vs. installing a 2nd check valve. Everything you put in between the pump and rail is a restriction. You would likely end up with even lower pressure at the rail.

Hey this is actually an area I know something about! (Fluid flow and pressures)

A good check valve of appropriate size should cause minimal pressure drop. Keyword is appropriate size. This guy at 3/8" drops about 1psi if you are forcing 1gpm through it which should be more than the car ever needs.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

However, the 1/4" version has 1/3 the CV and drops 8 PSI at the same flow rate. I don't know what size the main fuel line on the V90 is and the actual drop would likely be lower since you just aren't burning that much gas in one go.

You can calculate these numbers using this calculator. Specific gravity of gasoline is 0.77 or lower. Flow should be <1GPM. However good luck getting a CV for some of the commonly available parts store or Amazon valves, or finding a super high CV valve for a very small tubing size. Eventually the fuel pump replacement will be cheaper than the fancy high flow metal valve + barb fittings and adapters required to get a truly minimal flow resistance.

Pressure Drop & Cv Calculator - Milwaukee Valve

www.milwaukeevalve.com

If the check valve doesn't specifically say for gasoline, check the materials for gasoline compatibility. Nylon, steel and Viton are great, PVC not so much.

The good news is that if you are only dropping a psi or two at the check valve, as long as you are still *above* the FPR's pressure target as the fuel flows into the FPR, you will notice no difference downstream of the FPR. That's its whole job. it doesn't care if you're 15 psi over the target or 5, as long as it's not so high that it bursts it'll work fine.

Check with the vac disconnected from the FPR and see what your pressure is with pump running. Should give you an idea how much margin you have. Or even better if you have a test port on the pump side of the FPR, just check there.

Edit: 8/2026, these valves from Mcmaster are less expensive but they are plastic.

These valves are fuel rated, cheaper and have a higher CV. Even the 1/4" version should flow 1GPM with minimal pressure drop if the specs are to be believed.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

(If the link doesn't go directly there, click on "Plastic Threaded Check Valves for Oil and Fuel")

The downside is you will need a couple of NPT to barb fittings. If you go with plastic, nylon and PVDF both have much better gasoline resistance than bare polypropylene. Unless the part is specifically rated for gasoline, don't use polypropylene.

Keeping sunlight off the plastic is always a good idea too although PVDF has good UV resistance.

Whether they will serve as a fix for a failed pump check valve when installed close to the pump I leave as a question for the more experienced mechanics.

 

[Kjets On a Plane]

So, it appears my ‘98 V70R has developed this?
Most annoyingly, it didn’t do this all that often, previously?

Removing the pump looks like a total PIA on these?
The pump works, car starts right up immediately if I turn the key several times. .

Anyone cobble an external check valve onto the quick disconnect fittings by the filter / inline with it under the access panel?

There’s gotta be something decent quality off some random junkyard car / in my pile of earlier external fuel pumps and their respective check valves that can be installed ‘cleanly enough’ in the spirit of ‘remove this cobble-ry upon next fuel pump R&R.’

(Either fuel pump (or sender I suppose if that’s reason enough for you to dive in the tank (ODO works?) dies / you have reason to change it / possible upcoming long road trip and wish to change it as insurance?)

I might try draining the fuel lines, shooting some oil or paint thinner backwards with the air gun air while vibrating the bottom of the tank, maybe?
Try to give it the <1hr college try?

Might blow some junk off the tank sock (if done carefully with a fresh main fuel filter?) if nothing else?
I *think* have an NOS main fuel filter for one of these I found in the glovebox of one of these junkers?

Cliffs; much like the OP, Car sat 6-7 years running on 4/5 holes, but always started on the gas that was in it.

Don’t wish to hack and maim / ‘do no harm’ but I do wish to resolve the prolonged warm cranking (if I don’t prime the thing 3-5x…seems to start immediately in that case?), have no interest in fighting the AWD saddle tank fuel pump job when my pump and sender seem to work ‘fine’ (afaik?)?

It’s annoying, what can I say?

Car starts completely smoothly (when primed several times?) and injectors don’t drip w/rail removed & fuel relay closed manually , so I don’t suspect those?
(no other running issues noted / apparent, either?)?
(Well, usual annoying evap Shens but I’ll sort that out?)
I suppose it *could* be the FPR causing the leaking down?
Doubtful, but only (with basic tests?) eliminated injectors and external leaks as a possible cause at this point?

I see rubber tipped air gun and trying not to make a mess in my future…

 

[Khrrck]

Update to my previous post in this thread. These valves are fuel rated, cheaper and have a higher CV. Even the 1/4" version should flow 1GPM with minimal pressure drop if the specs are to be believed.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

(If the link doesn't go directly there, click on "Plastic Threaded Check Valves for Oil and Fuel")

The downside is you will need a couple of NPT to barb fittings. If you go with plastic, nylon and PVDF both have much better gasoline resistance than bare polypropylene. Unless the part is specifically rated for gasoline, don't use polypropylene.

Keeping sunlight off the plastic is always a good idea too although PVDF has good UV resistance.

Whether they will serve as a fix for a failed pump check valve when installed close to the pump I leave as a question for the more experienced mechanics.

 

[andyb5]

So, it appears my ‘98 V70R has developed this?

Removing the pump looks like a total PIA on these?

The pump works, car starts right up immediately if I turn the key several times. .

Anyone cobble an external check valve onto the quick disconnect fittings by the filter / inline with it under the access panel?
(…)
I might try draining the fuel lines, shooting some oil or paint thinner backwards with the air gun air while vibrating the bottom of the tank, maybe?

Yes, there’s an inexpensive, generic aftermarket external check valve that you can and the install takes 15 to 30 minutes. Check valve failure is super common and if it isn’t already bad, failure should be expected on all of the 98-00 AWD models at this point.

Let me go find pictures / info from when I did this on my 99 R and report back. I did mine in like 2012 and have forgotten the details so I have to reread my old build thread.

In the meantime, don’t shoot anything down the fuel lines into the pump. You’re risking damage to other parts and won’t really help anything by doing that.

 

[Kjets On a Plane]

^ok, I won’t shoot anything down the lines.

I’m amazed it worked for the 1st few test drives, but car was sort of well preserved / 95th percentile interior and UV time capsule in many ways?
The nivomats work well, suspension bushings are tight, engine runs strong…although I do live in fear of it to some degree?

I’ll see what I can cobble or link to your build thread?

Ought to be possible to come up with some barbs and plastic fuel line to add an off-the-shelf OE decent quality brass / metal (to some car or other?) external check valve back by the filter cleanly that’s easily accessed from above / not miserable to manipulate from below & easily reversible later if someone so chooses?

 

[andyb5]

The SUR&R-branded 5/16” check valve is what I used, and has been used by a bunch of other AWD P80 owners for at least a decade. Here’s the link for buying it on amazon - https://a.co/d/0du6cLMk

Having a hard time finding a photo of my check valve install right now. If I had a picture, it was saved on photobucket and they want a monthly subscription fee to see what I had uploaded. basically install that valve on the fuel filter inlet where the stock line from the pump attaches. I'll see if I have a photo saved on an external hard drive.

It can be done from the back of the car without touching the fuel tank (or pump inside it) and you should only need to unclip the line at the fuel filter. It may be helpful to take the rear passenger wheel off, but there are some minor differences in fuel filter location between the 98, 99 and 00 models that I’m not able to remember so you may not need to remove the wheel.

 

[Kjets On a Plane]

It’s a ‘98 and has the access hole for the filter under the carpet?
Looks pretty painless to add from the top and deal with the annoyance of the lack of check valve function.

I was envisioning dunking my pile of full car length used PET plastic fuel line ends in hot water and jamming it onto a barbed check valve / some sort of little adapter piece on the fuel filter inlet, yeah?

Evolutionary convergence? Looks like much less of a PIA than changing the pump?

 

[andyb5]

Yeah, putting the check valve on is much easier (and cheaper) than replacing the pump.

The factory procedure is to lower the entire rear subframe assembly (suspension and fuel tank) so you can access the fuel pump. Having done this with my car on a lift, it still isn't easy or quick.

The shortcut / faster options for replacing the fuel pump are:
1. Loosen the fuel tank hanger straps, then use a large prybar (think 2x4 or similar) to force the tank low enough to get the pump out.
2. Cut an access panel through the body near the lower pivot point for the passenger side rear seat, then remove the pump without touching the fuel tank, and rivet / bolt / weld the cut piece of sheetmetal back in place.

I've done the "fast" options 1 & 2 as well. The factory way is good if you want to repair some other things in that part of the car, but is a ton of work for just a fuel pump replacement. Removing so many parts also risks causing other problems while you're in there.

Shortcut 1 works decently, but you need to be careful about prying since the fuel lines on top of the tank are easily damaged. I have only done this method with the car on a lift, so no idea what the logistics of getting the rear of the car high enough off the ground look like or how feasible it is to carefully force the tank down while lying under the car.

I used the 2nd (cutout) easy method to remove the pump on a parts car, and it was super quick since I didn't care about being neat or resealing the opening when I was done. That said, @lookforjoe (Hussein) did that on his XR build, and it turned out nicely so it's more a case of being careful about how you make the cutout. Maybe Hussein has some photos he can share, I can't find any right now.

 

[lookforjoe]

@Kjets On a Plane This what you remove on either side to access the pump on right side & the crossover (if needed)

I made a finished removable cover, those pics are gone along with all my PB pics

 

[Kjets On a Plane]

^ive seen people do that and I’m sure it’s ‘fine’ but I can’t quite bring myself to do that?

Pump seems to work and run quiet so, add a check valve for now?
Idk if I’m keeping the car all that much longer so I don’t want to ‘hack and maim’ but idk that I’m going to put much more into it?

I rather just disclose and pass it on to the next guy in a ‘manageable’ state, if you will?
I’ll drive it and enjoy it a bit / work out the bugs, but I ain’t restoring this thing?

I’ll see if I can solve my evap mystery w/o messing with the tank…
…I think it’s the main purge valve / I’ll give it the college try before I just delete all that junk and revert to mechanical charcoal can (I kid… I have a pile of tested known good solenoid and junk to play some hybrid of ‘swaptronics’ actual correct diagnosis.

Has the recurring p0455…I think it’s the *mostly* valve on the radiator fan shroud, but will have to investigate further?

It’s against my religion to buy 4 new tires, cats or any emissions junk for a used car…just feels wrong somehow?

I’ll make sure the inputs to the engine are correct and precise, but anything new for the outputs or wear parts idk? Why?

 

[2manyturbos]

Yeah, putting the check valve on is much easier (and cheaper) than replacing the pump.

The factory procedure is to lower the entire rear subframe assembly (suspension and fuel tank) so you can access the fuel pump. Having done this with my car on a lift, it still isn't easy or quick.

The shortcut / faster options for replacing the fuel pump are:
1. Loosen the fuel tank hanger straps, then use a large prybar (think 2x4 or similar) to force the tank low enough to get the pump out.
2. Cut an access panel through the body near the lower pivot point for the passenger side rear seat, then remove the pump without touching the fuel tank, and rivet / bolt / weld the cut piece of sheetmetal back in place.

I've done the "fast" options 1 & 2 as well. The factory way is good if you want to repair some other things in that part of the car, but is a ton of work for just a fuel pump replacement. Removing so many parts also risks causing other problems while you're in there.

Shortcut 1 works decently, but you need to be careful about prying since the fuel lines on top of the tank are easily damaged. I have only done this method with the car on a lift, so no idea what the logistics of getting the rear of the car high enough off the ground look like or how feasible it is to carefully force the tank down while lying under the car.

I used the 2nd (cutout) easy method to remove the pump on a parts car, and it was super quick since I didn't care about being neat or resealing the opening when I was done. That said, @lookforjoe (Hussein) did that on his XR build, and it turned out nicely so it's more a case of being careful about how you make the cutout. Maybe Hussein has some photos he can share, I can't find any right now.

That is bizarre. I have removed several 960/S/V90 fuel pumps the exact same way I do it on a 940. Through the opening in the body. It takes all of 30 minutes.

 

[andyb5]

That is bizarre. I have removed several 960/S/V90 fuel pumps the exact same way I do it on a 940. Through the opening in the body. It takes all of 30 minutes.

Different chassis - my post is about the 97 850 AWD & 98-00 S/V70 AWD models, not a V90 or 900. Glad to hear Volvo's engineers were more sensible on the earlier chassis and saved the frustration for the FWD / AWD people...

KJets has a 98 V70 R that he is working with, so the topic detoured beginning in Post #27.

 

[2manyturbos]

Different chassis - my post is about the 97 850 AWD & 98-00 S/V70 AWD models, not a V90 or 900. Glad to hear Volvo's engineers were more sensible on the earlier chassis and saved the frustration for the FWD / AWD people...

KJets has a 98 V70 R that he is working with, so the topic detoured beginning in Post #27.

READ THE ENTIRE THREAD BEFORE POSTING. That finally has relevance...