39 PSI at idle, and it raised up when I revved. This would be normal, I'm assuming? Or should I replace the fuel filter. I know this sounds bad, yes, but I have no clue how old that fuel filter is. For I know it could be the original! I just figured I wouldn't touch it unless I needed to because it was restricting fuel delivery thus lowering fuel pressure below stock for the N/A 2.4L.

1995Volvo850

 

Your numbers are spot on.

 

I read somewhere on here its supposed to be 43 psi? Is that for the turbo 850?

 

Spec is 43.5 psi; both turbo and N/A are the same. And like you noted, should go up a few psi when you blip the throttle. Your gauge could be off a bit..

If your fuel filter hasn't been replaced in 60K mls or so, it's due.

 

I see nothing wrong here

 

I have no clue how old that fuel filter is.

Good idea to replace it as you have no idea how much water and crud might be in there and just waiting to become a problem. If you have any touch-up paint put the date and mileage on it. That way you always know when it was done last.

Your numbers look fine.
The fuel pump should always be pumping more volume and pressure than you need. The regulator which has a vacuum line to it monitors vacuum to adjust for load. More load as in giving it more gas pedal will allow the regulator to open up and give the injectors a little more pressure so the injectors can physically squirt in more fuel. Less throttle is high vacuum and that makes the regulator cut back on the PSI and in so doing the injectors squirt less fuel.

The computer controls the amount of "ON" time for the injectors but in increasing the pressure the same injector will flow more fuel for the same amount of "ON" time.
That's why your pressure rises a bit when you rev the engine and drops back as it comes back to idle.

And being off a few PSI could be a worn regulator or a gauge that isn't totally accurate but you're close enough for a daily driver

 

My 850 turbo balks for a second or so when I hit the gas. Getting lousy mileage - about 14 mpg, used to be 18-19 mpg. 210,000 miles. Could it be the regulator or the vacuum line to the regulator? Also, once in a while it refuses to start, but will after about 5 - 10 minutes. Seems fuel related - almost catches but doesn't. Also, what effect would a bad fuel injector exhibit?

 

From the mileage drop it sounds like it's gone rich. If the fuel regulator has gone bad one way would be for it to leak fuel into the vacuum line. Easy way to check would be to start it up and let it run a couple minutes and then take the vacuum line off the regulator and see if it's wet with or smells of raw gas.

Injectors will usually go bad one at a time. They will start to clog and you'll have a cylinder that is uneven or feels like a miss.

You could also have a bad coolant temperature sensor. It's screwed into the thermostat housing just below the thermostat. If it's out of range and sending a signal to the computer that the engine is colder than it really is. You'd be injecting too much fuel all the time and it would make it difficult to restart hot.

 

This is a very good thought. I have seen one on an S40 so bad that it would act normal then all of a sudden sputter and die. Couldnt start it after that. It would cool off then start again. Drive awhile then die. Totally the sensor.

 

If it was the sensor wouldn't it show up on the interior gauge? That's what happened on our S70; gauge went wacky and showed red-hot when the engine was still warming up; threw a code too. New sensor in therm housing fixed it.

 

This is where not being a Volvo expert can bite me. I know a lot of cars run a separate ECM temp sensor and coolant temp gauge sensor. Not sure on the 850's 2.3 which it is. Might be there are two.

 

I was wondering about that, too. I haven't noticed any fluctuations in the temp gauge. Has looked normal. I just see two wires coming out of the sensor - so I doubt it has a separate sensor.

 

I'm at my wits end. Replaced both fuel pumps, temperature sensor, MAF, injector relay (radio supression?), fuel pump relays, had the injectors machine shop cleaned, and still won't run.
If I spray stater fluid, or even simply raw gas into throttle body, the car starts for a second. Then dies.
This has been the trouble all along.
This just in: Fuel pressure regulator is leaking into vacuum line raw fuel. So I disconnected it, and plugged up the fuel line to at least get pressure. How much pressure that is may amaze me if I knew, since I couldn't get the clamps tight enough on my plug...but in any case the car did not start at that time I tried, even with the leaking plug.
Question: How critical is the pressure? Is crazy high pressure going to prevent starting, so my test is useless anyway? I have ordered a new one from Ebay, as here in South Dakota I maybe have the only Volvo within a few hundred miles.
Question: Pleae tell me, is there ANY OTHER PART left to replace? Could the pressure regulator be that critical to starting, so my troubles may be over?
Does anybody know of a way to test the computer itself? It seems to me that is about the last thing, unless the distributor may have some mystery...though since it fires up when starter fluid is used seems to be not the problem.
One last idea I had, is there a possibility the starter/ignition switch is bad and when released into run position dies? How to test that one? Thank you to anybody with a new idea.

 

Fuel pressure regulator is bad, replace it.