97 850 T5 wouldn't start no spark solved, now fuel relay mystery

[dcarlson12]

Has about 236,000 km.

Parked it after it became hard to start and the PCV system needed replacement.

Has been parked for a couple years but used to be able to start it even if not instantaneous.

Last week when I tried to start it, it seemed to 'catch' but did not continue to run. It turned over find but wouldn't 'catch' at all.

Today I installed new plugs, rotor and distributor cap. Still now joy. One thing I noticed, which might be 'normal,' is the small 'valve' which is attached to the throttle body continues to 'hum' after I shut off the key. It eventually stops or will stop immediately if key is removed from ignition.

I tried to see if the coil was functioning by removing the high tension/output wire and inserted a screw driver into the coil and held a grounded wire close to the screw driver blade while my wife turned on the ignition and engaged the starter. I thought I saw some weak spark, however when I did it a second time saw no spark.
I then reconnected the coil output wire and put a screw driver blade into one the spark plug wire ends after pulling it from the spark plug. Still no spark when ignition on and starter engaged.

I checked the voltage on the input wire to the coil while ignition on and starter engaged. Voltage measured approx. 5.5 volts.
I was expecting 12 volts.

Recently installed new fuel pump and fuel pump relay and have pressure at the fuel rail.

Help!

[abscate]

You have weak voltage to the coil. check the main relays that connect voltage to the coils

[dcarlson12]

Thanks for quick reply.
Following the instructions at this link:
https://volvoforums.com/forum/volvo-850 ... oil-48079/

I did proper check of voltage from Red No. 15 wire to ground is approx. 11.6 volts with ignition key is 'on' position.
Then I checked voltage at blue wire ignition coil wire No.1 and it was 11.6 volts with ignition on and dropped to about 5.5 volts when starter was engaged.
In the link instructions, I don't see if this means the coil is bad or good. It only asks if the voltage is between 0.7 and 1.3 volts.
?????
Have not yet checked engine speed sensor ohms.
Does the 5.5 volts on blue wire Coil terminal No.1 during cranking, mean coil is bad?
Battery measure approx. 12.4 volts across terminal when ignition is off.

[abscate]

Losing 1volt from battery to coil is a lot

Ignition switch problem, what is the history on that?

Battery or power cable problem?

[dcarlson12]

Original ignition switch. The connector which plugs into the coil wire has some greenish corrosion inside it but I cleaned it with some degreaser but not Deoxit connector cleaner. But shouldn't 11.6 volts be enough to generate a good enough spark? Why does the coil wire No.1 blue read approx. 5.5 volts when cranking and not o.7 to 1.3 volts as described in the link?

[abscate]

That's resistance in the wires. The voltage drop is proportional to current flowing, so cranking causes the drop

[dcarlson12]

I have a Battery maintainer on the battery. I just went out and checked the battery with the ignition off and the battery maintainer disconnected and read approx. 12.9 volts across the battery post. When I turned the ignition to the on position to again measure the voltage at the coil red wire it measured 11.6 volts. However the battery at that point also measured 11.6 volts across the posts. The only loads at that point were the driving/head lights which I can't turn off and the valve or whatever it is that is humming below the throttle body. By the way, what is that valve?
Since the battery measures 11.6 volts, does that perhaps mean it is faulty? i.e. shouldn't it maintain at least 12.4 volts when the ignition is turned on?

[abscate]

Yeah, 11.6 volts is deeply, deeply discharged.

How old is the battery! Did it sit discharged for a month or more ?

If it does have enough juice to turn the starter though, it should start the car.

Hmmmmmmm

[dcarlson12]

Well it turned out to be the battery.
Took to Canadian Tire and they said it only had 100cca, supposed to be 600cca.
Installed new battery and after a bit of cranking and short bursts of starting it finally ran continuously and properly.

However, today I replaced the old/plugged PCV system. What a bear of a job. Thankfully FCP had posted a tutorial on Youtube which was very helpful.

Unfortunately when I tried to start it, the fuel pump did not run continuously. It would 'prime' the sytem for a few seconds and the car woulf start but immediately die from fuel starvation.

I removed the fuse/relay cover and removed the 103/fuel pump relay and plugged it back it. I then removed the #2/fuel pump fuse and turn the ignition to run position. I then plugged in the fuse and the relay clicked and the fuel pump ran for a second or two. I repeated contacting the fuse to it's terminals and the relay again would click/close. I could hear the fuel pump run for short periods of time.
But when I put the fuse back in and tried to start the car, it would again just run for couple of seconds.

I replaced the fuel pump about a year ago and I could hear it run ok as long as it received power. i.e. I knew it was not the problem

I had replaced the fuel pump relay before replacing the pump i.e. also about a year ago.

Fortunately I kept the old relay and when I installed it in place of the newer one, the car now starts and runs fine.

What the heck could have happened to the relay between yesterday and today that would cause it to fail?????

I am going to buy another/spare relay but can't figure out why the newer relay now does not work properly.

Can someone advise how the relay is supposed to work? i.e. is it supposed to latch or ???
Why would it only close for a couple of seconds.
And why would it fail overnight?

I disconnected the battery during all the maintenance work.

Thks,
Dwight