'92 940 Cranks but no start

odddit

Been having some trouble with the ol' blue meanie, Was driving to work and the engine just clicked off. After a minute or so it managed to start again, got it to a safe place to park, left it. Would run run for max ₁ minute at a time.
Suspected the fuel pump was bad, and I had one on hand so I've swapped that, good fuel pressure now, but it just cranks and won't fire at all anymore. Checked the coil and it's reading good, crank position sensor seems to be working, only thing I can think is it might be the timing belt has jumped a tooth or two, as the belt seems a little slack and the belt marks aren't lining up with the marks on the camwheel.
Wondering if any of you have any alternate ideas of what it might be because pulling all the front of the engine off and retiming it will be a bit of a hassle. The heater core is leaking a little as well, plan to bypass it for the time being. Any help much appreciated.

ramrod

Sounds like a typical fuel pump relay failure

They open when hot, turning off the fuel pumps then they cool down the dry solder joint closes up running the pumps again

Take it apart and have a look at it

odddit

ramrod If it's a fuel pump relay failure would the fuel pump still prime? Because when I go to crank, I can distinctly hear the fuel pump triggering, and the pressure is good. Does it also control the injectors?

jamesinc

If the timing belt has too much slack in it and the marks on the crank and cam gear are out of alignment, honestly you should address that first.

How old is the belt?

If it's slipped one tooth it'll run like garbage, if it's slipped two teeth it won't run at all.

But, if you're not wanting to pull the belt, just do a compression test, if the numbers are healthy then you know the timing is basically OK.

Either way, adjust the belt tension, turn the crank (clockwise) a tad to make sure the belt has all its slack on the tensioner side, then release and re-tighten the tensioner bolt to set the tension. You don't need to remove the timing cover to do this, you just remove the rubber bung on the front of it, this gives you access, just make sure not to push the bung right through the cover when you're reinstalling it 😅

odddit

jamesinc I replaced the timing belt maybe a year, year and a half ago. The timing cover is pretty munted so I've been running without the top half of it until the replacement gets here. I'll give it a crack re-aligning it because the slack is a bit excessive next time I go out to work on it. Fingers crossed it runs this weekend, not a fan of the tram to work.

Major Ledfoot

Have you checked for codes?
https://www.volvoclub.org.uk/faq/EngineOBDCodes.html

odddit

Major Ledfoot Hadn't thought of that because I don't have a scanner, forgot that it can do it with timed flashes on the dash thank you.

Major Ledfoot

odddit
The timed flashes are on the diagnostic box itself.
The fuel ECU and the ignition EZ-K can be tested from the diagnostic box.
Both should flash code 1-1-1 - if not, there's a problem. See the link supplied earlier for process and codes.
What results have you gotten?

ramrod

Check for spark if you can hear the pumps running

Ramrodfunk

My 2 cents.
My '93 240 would run .get warm and then die. Wait till it cooled down,start and go,get warm and die.
The period between getting warm and dieing became increasingly shorter until it wouldn't start.It would crank but not start.
On the inner passenger side guard near my battery is the "ignition amplifier module" (known by other names also). This is what failed in my car. It drove me mad because it barely gets a mention in any of the manuals. Bently's mentions it in passing.
I'm assuming the lay out of your car is similar.
There is a method of checking with Ohmeter but beyond me.
Good Luck

Brad

Check the radio suppression relay. Mine 940 stopped dead on me a few weeks ago and this relay was the problem. I had a spare in the glove box and was back on the road in a few minutes. I finally got around to having a good look at it today. Below is a photo through a microscope of one of the pins inside the relay. A few others had small cracks around them.

Philia_Bear

Lead free solder doing its thing

itsabitsa

@odddit I'm sure you'll have already thought of this, but my diagnostic tuppence worth:

will it run if you squirt a bit of starter fluid into the intake?
are you getting a spark on each plug? Are the plugs clean?
have you checked the in tank pump?
Recently had a pump fail and was recovered - apparently bad fuel is quite common in NSW....

odddit

Tried a new radio suppression relay and some start ya bastard and it fired up fairly nicely, drove it around until it got up to temp to recharge the battery a bit and it conked out, at least on my home street this time.
How's this though, as I'm pushing it to a parking spot, someone in a skoda overtakes me, and steals the parking spot I was aiming for! What a move.
When it was up to temp, and conked out, on trying to re-start it the fuel pump was making a strange noise, or not making a noise at all, so I'm suspecting the fuel pump relay again. Will pull it and see if any repair is possible.
Anyone know what to look for with the fuel pump relay?

ramrod

Cracked solder joints

The relay can be bypassed to get it going with pumps permanently running

odddit

ramrod Are they super hard to repair? I've done some soldering before but no great amount.

ramrod

The only way to know is to look at it under a magnifying glass though it should be obvious if there is a dry joint

Brad

The fuel pump relay on one of my 940s let me down a while ago. Below is a photo through the microscope at 20x magnification of one of the solder joints. A few others were in similar condition. I've had a go a repairing it but it still doesn't work. My soldering skills are crap though so that's probably why. I'll need to have another crack at it.

Philia_Bear

Reflow using silver bearing solder (60/38/2) for best success and long term reliability