S70 B 5254 S Cranks, Won't Start

berley · Post by **berley** » 28 Apr 2013, 17:20

HISTORY: 148k miles, has good strong spark, plugs look wet but not soaked after 5 secs of cranking, 1 yr old plugs, 4-5 yr old Volvo wires, 20psi at the fuel rail, fuel damper is located under the fuel rail, new crank position sensor (ohm reading was 2.83K ohm), S0172 and S0505 codes, I think I discovered the cause of the codes...one vacuum plug was missing on the plastic 6 port manifold under the throttle cable pulley...it has now been replaced, grounds look good and the warning lights turn on with the ignition. The car has been running well, albeit a little rich, 23 mpg city, no starting problems, no idle problems, no stumbles, no recent repair work. About a week ago it just Would Not Fire!

QUESTIONS: I have read about the different types of regulators on the '98, and pinching off the fuel return line to determine if it is the pump or the regulator. If I understand this correctly, I don't have a return line from the fuel rail, and my regulator is in between the pump and the fuel rail and is located in front of the left rear wheel. Is there a test to determine if I need to buy/replace the pump or the regulator?

I measured the fuel pressure with an "industrial" air pressure gauge, so I am not "positive" the reading is correct, should the car start with 20psi? Can the regulator "fail" at 20psi?

I already purchased a cam position and coolant temperature sensor, but do not want to install them until I learn more about the fuel pressure. I looked on FCP, but could not determine which regulator to purchase, how do I tell if I have EGR, or can anyone tell me the correct P/N?

Thanks in advance!

Post by **jblackburn** » 29 Apr 2013, 08:26

A 1998 should have an air pump (SAS) and no EGR. You'll have a small, bendy rubber hose that connects to the front of the air intake box for the air pump.

20 PSI seems very low. Yours is a different FPR setup than my T5 though, so I don't know how much help I would be.

berley · Post by **berley** » 29 Apr 2013, 18:22

Thanks for the info. Anyone out there know if it is ok to bypass the regulator, as a test to see if the pump is OK?

See if I have this correct, this is the setup that I need to pull the vac hose off the regulator and smell for gas, indicating a cracked diaphragm.

berley · Post by **berley** » 01 May 2013, 21:13

UPDATE: I devised a better way to measure the fuel pressure and I am now confident that I have 43.5 psi at the fuel rail. STILL WON'T FIRE! My next step is to replace the Cam Sensor and then the Coolant Temp Sensor. I'm trying to stay one step ahead of Winston "Gentlemen, we have run out of money, now we must think" Churchill. Any suggestions before I just start swapping out parts?

sleekitwan · Post by **sleekitwan** » 01 May 2013, 22:18

Hi, do not know specifics of the car, but that helps me focus on basics:

1 - Fuel + Air

2 - Spark and compression (or compression only on diesels)

You got wet plugs so you have fuel. I am going to assume you have air where you live (!) and in any event we need not worry about turbo as it does not cut in until a few rpm over start-cranking speeds.

So it's the spark. Straight off the bat, have you pulled a plug (or got any old spare) and laid it on the cylinder head and turned the engine via the ignition key/starter motor? Do you see a spark?

Basically, that would test if you had ANY spark at all. Then, if you DO, it's about the TIMING of the spark eg you can look into magnetic pulse generator (your crank position sensor) etc. Note however, the one caveat below (the ignition module point).

My own guess, from here (!), is you feel it is totally dead/unresponsive? No 'pop' or 'fart' not even the lamest attempt to burst into life?

So, maybe it is the thing that generates the spark - the ignition module (basically coils or whatever they generate the spark with in your car). Usually these days, it's a block of something potted in black plastic.

Just had a look online - seems you might have a single 'pencil coil', one per cylinder? So, if NONE are sparking, you are looking for whatever is COMMON to all of them eg some kind of ignition module thingy that sends the signal/power down to the individual pencil coil and spark plug.

HOpe this helps advance things, there is just one more piece of advice: it is very common to SEE a spark (like I asked you to check for earlier) yet the blasted engine will not start/run properly. This arises when the spark gets sent to 'somewhere' but then finds an easier route to ground or 'earth' on the vehicle rather than go to all the trouble of crossing that laborious 0.7mm (or whatever) air gap you have carefully set between the electrodes of the spark plug.

THIS IS BEST SEEN IN THE DARK! Crank the car when it's dusk or dark with the bonnet up, see if you see any 'tracks' of electricity pulsing across the coils. DIRTY cables and so on are enough to cause this by the time the car is getting on a bit.

I once just CLEANED a lady's Honda cables with WD40 while it was running (yeah, you know what happened) and it went from misfiring wreck to smooth as silk while jolting my arm for fun.

Thet's me, that's what I got for you. Be methodical.

berley · Post by **berley** » 01 May 2013, 22:57

Thanks for all the great information! I do have a nice strong blue spark, so I have eliminated the coil packs, arcing to ground etc. I replaced the dist cap when I had it off during the crank position sensor replacement, but not the rotor...it looked "good", some gorilla must have tightened the rotor bolts, and once again I knew I had good spark. The only things left are compression and timing. I can't imagine I could loose compression in all 5 cylinders instantly, so that leaves timing. I guess I'll start with the cam position sensor. That will be the task for tomorrow evening, unless I "get a better offer".

One more piece of evidence...before replacing the crank PS, there wasn't even a sniff of a start. After replacing the crank PS there was just the barest hint of a start, still no real coughs, burps, farts etc. Also, starting fluid has had no effect.

Thanks again!

oldschoolvolvo · Post by **oldschoolvolvo** » 02 May 2013, 07:30

i had a crank-no-start condition that was fixed by replacing the cam position sensor. the problem with my car only happened when the car was hot after driving...it would not want to restart. when the car cooled down, it would start. regardless, a new cam sensor fixed my problem.

Post by **rspi** » 02 May 2013, 08:18

Hey guys, a car needs 5 things to start... A '98 model should NOT have coil packs.

It's best to check them in this order:

1. Spark - Checked
2. Fuel - Checked
3. Timing - Does the cam turn while cranking the motor? Look in the oil filler hole while cranking or check the belt physically.
4. Air - Assumed good - The temp sensor or MAF could be bad.
5. Compression - These white blocks are know to experience burnt valves. If compression is low, try wetting the chambers with some oil and cranking the heck of it them. If compression is zero in any cylinder, pull the head.
Timing -

Post by **rspi** » 02 May 2013, 08:19

If the cam sensor is bad it will not spark or give fuel.

berley · Post by **berley** » 02 May 2013, 08:40

All excellent information! Now I have lots of things to test tonight. I will definately let everyone know what I discover. Have a GREAT day!

I have read that a bad coolant temp sensor will prevent starting, is it like the cam sensor in that there will be no spark or fuel if it is bad??

Thanks Bob