1996 850 Base NT - Hard Start, No pressure at rail...

HawleyTronics · Post by **HawleyTronics** » 27 Feb 2013, 08:52

I bought a 1996 850 Base (Non-Turbo) about 8 months ago for $800, nice shape, runs great when it starts, great body, well maintained, etc.

It has always had a hard-start issue whereas it would have to be cranked over for about 5-10 seconds before it starts, runs rough for a few seconds, then levels-out and runs great. I think the exhaust smells a little like fuel (running rich?), but no black smoke when starting. It could also be running lean I guess. All I know is that it doesn't smell "normal".

I also had issues recently where it was throwing codes for TPS and MAF, so I replaced those and cleared the codes. (When the TPS failed, the car would start and run, but it was in "limp home" mode, so it was pretty much undrivable. Once I replaced the TPS, it cleared that issue.) Another thing to note is that when I removed the old TPS, it had liquid in it and I think it was fuel, of which I know it should not have any liquid in it. So could that be overflow from a bad fuel pressure damper?

Now it just shows codes for: P0304 & P0300, which is basically telling me that it isn't focused on one cylinder/injector in particular, but rather more generalized and maybe lack of fuel pressure, or too much fuel (unregulated) going to the rail/injectors?

I realize that the models of these 850's vary a little and that some have a FPR (fuel pressure regulator) AND a FPD (fuel pressure damper) and some just have a FPR, of which can be confusing to people who have not done any research. My particular model has both; the FPR is in the rear, passenger-side, near the fuel filter. And I have the FPD attached to the fuel rail. I have only one fuel line, no return.

Here are some things to note:
* I can hear the fuel pump make a sound when turning the key on, not loud, it can be barely heard.

* If I prime the system by turning the ignition on and off a few times before starting, it makes no difference with the starting.

* It is hardest to start in the morning (sitting overnight) and if it has been sitting for a long time.

* It is hard to start even if it hasn't sat for a long time, like if I drive it to the store and then try starting it after coming out of the store. Not as long of a crank time, but still doesn't start immediately.

* Yesterday when I got home from work, I pulled it into my garage, turned it off and I let it sit for an hour or so. Then I depressed the shradder valve on the fuel rail with the engine off, NOTHING came out, no pressure at all. So it isn't holding any pressure in the rail when sitting. I assume this could be caused by a bad check valve in the fuel pump?

* The car has PLENTY of power and is very responsive when driving. (I can pull away from your average Honda/Acura at the light without any problems.)

* The car is great on gas, especially when compared to my 1998 Sebring Convertible. I can put $20 in and drive 20 miles a day (to/from work) and it will last me all week.

So my question(s) is/are:

* Could this be a bad fuel pressure regulator? (I assume the FPR only comes into play when the vehicle is actually running and doesn't really come into play at the time of starting? Or does it?)

* Can a fuel pressure damper cause these symptoms? (I have yet to pull the vacuum line from the damper to see if there's fuel in it, but I will tonight.)

* Can the check valve in the fuel pump be the culprit? If so, I assume a replacement fuel pump would clear up the issue?

I really love this car and plan to run it until it passes on, so the longer it lasts the better. I just need to get her starting/running properly.

HawleyTronics · Post by **HawleyTronics** » 27 Feb 2013, 17:50

OK, so I checked the fuel pressure damper (attached to the fuel rail) and removed the vacuum hose from it. Dry as a bone, so no issues there. So I guess I can safely deduce that the issue is probably either the fuel pressure regulator (near the fuel filter) or the check valve in the pump. If it's the check valve, I know I will need to replace the pump. I am thinking I will replace the FPR first seeing as it is cheaper, and then take it from there...unless someone else has a better idea?

Post by **jblackburn** » 27 Feb 2013, 22:59

When I had a bad regulator, it was sucking raw fuel directly into the intake manifold and the car couldn't run at all well even after it got started.

I'd start my search with the vacuum line on the FPR, but if that looks ok, head to the check valve.

No fuel pressure after an hour or so is relatively normal. Check again after 2-5 min.

Question for you:
If you crank for ~5 seconds, let off, flip the key back to II again, and then crank, does it start right up or still struggle?

Post by **E Showell** » 28 Feb 2013, 07:41

Things that come to mind in no particular order that can cause hard starting are: bad engine coolant temperature sensor and old/bag plug wires, rotor, cap, plugs. When's the last time you did a full ignition system tune up, i.e., replaced plugs, plug wires, cap & rotor (excepting the coil -- which I am told don't have a slow failure mode, they either work, or don't)?

HawleyTronics · Post by **HawleyTronics** » 28 Feb 2013, 08:51

jblackburn wrote:I'd start my search with the vacuum line on the FPR, but if that looks ok, head to the check valve.

When you say vacuum line on the FPR, are you talking about the FPR under the car, near the fuel filter towards the rear of the car? Or do you mean the FPD (fuel pressure damper) on the fuel rail? Because I pulled the vacuum line from the FPD last night and that was dry as a bone.

jblackburn wrote:No fuel pressure after an hour or so is relatively normal. Check again after 2-5 min.

Did that last night too. Roughly 20 minutes after I shut the car off there was plenty of fuel pressure at the rail. I didn't measure it officially, I simply depressed the nipple on the fuel rail and it squirted out pretty fast.

jblackburn wrote:Question for you:
If you crank for ~5 seconds, let off, flip the key back to II again, and then crank, does it start right up or still struggle?

I can shut the key off and on as many times as I want. I can even push the gas pedal and it will still start after a few seconds. Makes no difference.

HawleyTronics · Post by **HawleyTronics** » 28 Feb 2013, 08:59

E Showell wrote:Things that come to mind in no particular order that can cause hard starting are: bad engine coolant temperature sensor and old/bag plug wires, rotor, cap, plugs. When's the last time you did a full ignition system tune up, i.e., replaced plugs, plug wires, cap & rotor (excepting the coil -- which I am told don't have a slow failure mode, they either work, or don't)?

I have had the car for about 8 months, and during the time I've had it, I've done the following:

* Replaced and gapped the plugs.
* Changed the oil and filter twice.
* Changed fuel filter.
* Replaced air filter.
* Replaced the TPS. (Recently)
* Replaced the MAF. (Recently)
* Cleaned the TB.

I have not replaced the cap and rotor or the wires yet, but wouldn't the car run crappy in general if the plugs, wires and/or cap and rotor were bad? The only issue I have at the moment is the hard starting. Once it starts it runs great.

Also, if it were the ECTS, wouldn't the temp gauge on my dash fluctuate erratically like I've read happens when the sensor fails? I have no issues whatsoever with the temperature gauge and no codes have ever been thrown for that. The only codes I get now are general misfires, and that probably happens when the car first starts because it is running rough for a few seconds. What other signs/symptoms of a failing ECTS are there?

Post by **rmmagow** » 28 Feb 2013, 10:41

Could still be cap/rotor/wires. My 98 V70 ran 100% better after replacing those parts, quick starts, no P0300's. Bougicord wires only, bosch cap and rotor. I also used volvo branded plugs.
Run the engine, hood open in the dark and see if you get a light show. That's not a 100% test, but if you see anything, that's bad.

Post by **jblackburn** » 28 Feb 2013, 11:29

Ok, your fuel pressure is just fine then, and the regulator isn't the problem either.

Have a look at the ECT's resistance values; it can cause hard starting.

Resistance values are here for water temps:
https://www.matthewsvolvosite.com/forums ... hp?t=52203

Post by **E Showell** » 28 Feb 2013, 11:50

Fluky dash gauge isn't a necessary symptom of a bad ECT since the dash gauge covers a pretty broad range of temps and will still read at 3 p.m. -- or so I am told.

HawleyTronics · Post by **HawleyTronics** » 04 Mar 2013, 08:29

OK, a funny coincidental thing happened over the weekend...

My GF had taken the car to work and she calls me saying that it isn't running right. The CEL was flashing and it was running very rough and had no power to drive normally. She was able to drive it home though. I read the codes and they were: P0300 P0304 P0305 and P0410. The 0300 codes were basically random misfires, of which I've seen before. The 0410 was Secondary Air Injection System malfunction, of which I understand will not affect the way the car runs/starts.

I bought all new plugs (OEM pre-gapped), and a Bosch rotor and cap. Runs good again, once it starts that is. Old plugs looked pretty black as I assume because the car is running rich.

The car still has the starting issue though, so I will check the ECT next since I have read everywhere that is one of the common troublemakers...