Gonna try and keep this short and sweet. My grandma had a local idiot change her plugs and wires(i would have but had no idea she needed it done) on her 91 740 Non Turbo.

She drove it around the block and it shut off. will turn over but not fire.

i sprayed some starter fluid in the TB to see if i could get it to fire and rule the fuel pump when out, but did not happen. what did happen was that it backfired through the intake.

assuming timing belt is fine, when you pull the oil fill cap you can see the cam turning as it should.

I checked for fuel at filter. (loosened and primed pump). then checked at the injectors by pulling up the fuel rail with injectors attached and turned car over. has fuel going to all cylinders.

pulled plugs and checked gap(almost 2.5 times OE recommendation so i closed the gap on them). also ensured that it had the correct firing order per the distributor cap markings

cant remember if i checked for spark or not, being that i dont remember im pretty sure i missed that.


is there a crank position sensor on these cars or what else should i look for? i dont feel it jumped time as she doesnt drive the car hard.

im very mechanically inclined but not so much on non obd2 volvos lol so any help from the volvo community is welcomed before we just take it to a Euro shop.

 

What brand plugs and wires were used?
I'd check the Crankshaft Position Sensor first. No way to check it though--has to be replaced...

 

As lev stated there is really no test for the CPS. Usually when they fail it is due to cracked and flaking insulation so the best check is inspection. It is located on the top of the bell housing where the engine and transmission are mated. It has a single black/gray wire that looks like coax cable and runs to a connector on the firewall. Check for cracked or flaking insulation. If it is flaking, then replacement is in order.

 

Sorry, but no. Just because a CPS is not looking shabby doesn't mean it's OK--I have seen plenty that had no outward signs of deterioration but were in fact bad. It has to do with resistance, and you can't tell by just looking at it.

 

Any resistance values I should look for? Went ahead and bought a CPS through our parts supplier and will hopefully have it checked out/changed on Sunday. As far as plugs I believe the guy put in copper auto lites..I'm gonna change them bc they looked like crap. Is there a recommended brand? Like my Mazdaspeed 6 loves NGKs etc. And wires I think we're OTS duralast

 

I use copper NGK, and Bougicord wires. Still, it may run crappy but should run even with those plugs/wires.

 

I use Volvo branded or Bosch copper ('super') or NGK. and ++ on the bougicord spark plug wires, they are the only ones that are factory design and spec.

 

Alright we got it runnin. Had to hold the gas like it was flooded(probably was lol). It's now backfiring out the exhaust. Running rough. Any ideas on this? Worth trying different plugs and wires or anything else standing out to yall?

 

on our Mercedes E320 (1994, with the M104 3.2L twin cam straight 6 and HFM-SFI injection), the test for the CPS is to unplug it, and measure its DC resistance, it should be between 740 and 820 ohms, then have someone crank the car over and you should see around 0.5-0.7 VAC give or take. no idea if these values are in range for LH2.4 Volvos.