What did you do to your Volvo today? Topic is solved

[454cid]

I've been driving my "new" Mercedes for the last few days, so the 850 has been parked next to the driveway. I was walking past it, as I was going in and out of the garage, while working on an HVAC filter change on the Mercedes. I noticed a blade of grass or two sticking out of the rear door on the 850. It pulled out easily enough, and later I grabbed the keys and opened the door, to see what there was to see, but there was nothing. I don't know if something was attempting to start a nest of some sort, or the wind carried grass just right to wedge it in there. Seemed very strange. I'll watch to see if anything more shows up. I get wasps trying to nest in door jambs, but that doesn't involve grass.

Also, the HVAC filter in the Mercedes was ORIGINAL, from 1996!!!

[RedBrickCollector]

Fuel pressure gauge finally arrive and it was a bit of a surprise.

I'm getting steady 55 PSI at idle or revved.

Key to Pos II it primes at 55 PSI then slowly drops to around 25.

So does this mean I need to look at my regulator and return lines? Could this mean my hard starting with hot is flooding because there's too much fuel?

Edit: added units

[454cid]

So does this mean I need to look at my regulator and return lines? Could this mean my hard starting with hot is flooding because there's too much fuel?

Too much fuel? I'm guessing it's sort of the opposite.... too little pressure. Try this next time you start the car hot. Turn the key, so that the fuel system primes, but instead of continuing to turn the key to engage the starter, turn it off. Then try to start the car as normal. This will give you two priming cycles, and hopefully build sufficient fuel pressure to start the car, more normally.

[RedBrickCollector]

I'm guessing it's sort of the opposite.... too little pressure.

It reads high at start/idle, 55psi.

I think I've discovered why though, the vacuum line is not connected.

The puzzling thing is my vacuum tree is already fully occupied by lines and caps. Does anyone have a reference diagram? Searching gives me results for the rest of the vacuum like turbo

[bmdubya1198]

I'm guessing it's sort of the opposite.... too little pressure.

It reads high at start/idle, 55psi.

I think I've discovered why though, the vacuum line is not connected.

The puzzling thing is my vacuum tree is already fully occupied by lines and caps. Does anyone have a reference diagram? Searching gives me results for the rest of the vacuum like turbo

The fuel pressure regulator vacuum line should connect to a metal pipe that runs along the rear coolant pipe. It then has a second rubber vacuum hose that connects to the intake elbow from that metal pipe, if I remember correctly.
55 PSI is definitely a little high based on the numbers I'm seeing for a 1997 850. You should see about 44 PSI with the vacuum line disconnected, and a little lower with it connected. You may just have a bad regulator.

[RedBrickCollector]

Thanks for the responses, I think I've been confused by two different "FPRs"

The one that has a disconnected vacuum line is the fuel return, the one connected to the fuel rail

it seems to already have the line to connect to the intake manifold tree, I just need to figure out why on my car it's already fully occupied.

For sure there are even more vacuum line issues as based on this thread
viewtopic.php?t=54895 the line on the intake manifold after the MAF is supposed to connect to the regulator but mine goes to the boost control valve

Edit: removed a plug on the tree to connect it with new 4mm silicon tubing and now it reads as such
55PSI for priming
48PSI at idle
Bumps up to 50 if I blip the throttle.
I blew through the return line and could hear bubbles in the tank

I think this means either I have a bad regulator or a gauge that reads high.

[bmdubya1198]

Thanks for the responses, I think I've been confused by two different "FPRs"

The one that has a disconnected vacuum line is the fuel return, the one connected to the fuel rail

it seems to already have the line to connect to the intake manifold tree, I just need to figure out why on my car it's already fully occupied.

For sure there are even more vacuum line issues as based on this thread
viewtopic.php?t=54895 the line on the intake manifold after the MAF is supposed to connect to the regulator but mine goes to the boost control valve

Edit: removed a plug on the tree to connect it with new 4mm silicon tubing and now it reads as such
55PSI for priming
48PSI at idle
Bumps up to 50 if I blip the throttle.
I blew through the return line and could hear bubbles in the tank

I think this means either I have a bad regulator or a gauge that reads high.

48 sounds reasonable allowing a margin of error for the gauge. Your car may have a different setup for the FPR, as Volvo changed it SEVERAL times over production of these cars. Most of them I've dealt with have been either down low on the back left corner of the engine, or in the rear near the fuel filter on '99+ cars.

[volvolugnut]

Fuel pressure gauge finally arrive and it was a bit of a surprise.

I'm getting steady 55 PSI at idle or revved.

Key to Pos II it primes at 55 PSI then slowly drops to around 25.

So does this mean I need to look at my regulator and return lines? Could this mean my hard starting with hot is flooding because there's too much fuel?

Edit: added units

So the drop to 25 PSI is over minutes? Hours? A check valve usually will prevent drop back to the tank for many hours.
Perhaps you have a leaky injector that allows a fast drop in pressure and may cause your other problems.
You can remove and test injectors with a bit of home built tools. Rebuilt injectors a rather inexpensive.
volvolugnut

[RedBrickCollector]

48 sounds reasonable allowing a margin of error for the gauge. Your car may have a different setup for the FPR, as Volvo changed it SEVERAL times over production of these cars. Most of them I've dealt with have been either down low on the back left corner of the engine, or in the rear near the fuel filter on '99+ cars.

My setup is the rail mounted regulator. Seems hard to find.

As a sanity check I let the fuel dry out and hooked up the gauge to a tire. Maybe a couple PSI over excepted but that still puts me at nearly 10 PSI over. 48 PSI was measured at idle with the vacuum line attached.

I'll call it good for now and look into higher priority things, but a fuel injector rebuild and a new regulator are now added to the long list of things I want to do, especially since one injector has a missing pintle cap. Engine does feel better especially before boost.

Now I need to figure out if the turbo flutter I hear is normal and why a new serpentine belt tensioner is still rattling...

Edit: @volvolugnut the drop to 25psi was within minutes. After blowing through the lines and hooking up the vacuum though, next read held in the high 30s for over half an hour while I took a break.

[bmdubya1198]

My setup is the rail mounted regulator. Seems hard to find.

As a sanity check I let the fuel dry out and hooked up the gauge to a tire. Maybe a couple PSI over excepted but that still puts me at nearly 10 PSI over. 48 PSI was measured at idle with the vacuum line attached.

I'll call it good for now and look into higher priority things, but a fuel injector rebuild and a new regulator are now added to the long list of things I want to do, especially since one injector has a missing pintle cap. Engine does feel better especially before boost.

Now I need to figure out if the turbo flutter I hear is normal and why a new serpentine belt tensioner is still rattling...

Edit: @volvolugnut the drop to 25psi was within minutes. After blowing through the lines and hooking up the vacuum though, next read held in the high 30s for over half an hour while I took a break.

Weird... maybe you just have a bad regulator.