1985 740 Turbo won't start

captwalker · Post by **captwalker** » 31 May 2009, 00:03

Hi Everyone, I sure hope someone can help me. Not sure what else to do.

Here's the problem: my 1985 740 Turbo won't start. The other week I put it in reverse as I was backing out of my parking spot, and it died--started up again right away though. Few days later I put it in drive coming out of my parking spot and it died again--started up right away. Few days later, put it in reverse coming out of my spot, and it died and would NOT start again. Haven't been able to get it to start since. The engine turns over but it just won't start, not even for a second. Thought it was the fuel pump at first, but then I realized the problem was the car had no spark.

Here's what I've tried:

*tried jump starting car--did absolutely nothing

*pulled the fuel line and there is fuel at injectors, so I ruled out the fuel pump

*change fuel pump relay--did nothing

*changed ignition coil--got spark back, but car still would not start (spark is there, but weak/intermittent)

*changed ignition control module--still have weak/intermittent spark, but car still won't start

*I found several vacuum hose leaks, including a hole in the vacuum resevoir tank--patched them up with duct tape but still the car won't start

*there were a lot of bare wires I found behind the ignition coil, possibly causing a short somewhere--I fixed them up with electrician tape and shrink tubing, but the car still won't start

*checked all the fuses, and they appear to be okay

Any thoughts at all would be much appreciated it. This is my first Volvo and I could really use some help. Thanks.

Post by **vegasjetskier** » 31 May 2009, 09:49

The fact that you have spark but it is weak indicates low voltage to the coils. Check the connections to the battery - make sure they are clean and tight. Same with any grounds that you can find, especially the coil ground. Resistance in the connections can reduce the voltage and weaken the spark. I'd replace the fuse for the ignition also. If you still can't get it to start, trace the wires that had the insulation burnt off of them back to their origins to make sure there is no missing insulation elsewhere - when it's melted off in one area, it's a good bet it's melted off elsewhere too. Do you have a distributor on that car? If so, check the cap and rotor for cracks and carbon tracking.

captwalker · Post by **captwalker** » 31 May 2009, 22:47

Thanks! There's a couple things you mentioned I haven't tried yet. I should clarify about those bare wires though--they weren't burned, the car's previous owner must've tried rewiring a bunch of stuff in this car. The wires are a big mess. The protective rubber around the wires was intentionally taken off by this guy, and he just left them all bare and in a jumbled mess.

I actually found some more wires today that were bare and in the same sort of jumbled mess. I went through and untangled them, and put some more electricians tape and protective tubing around them. Still no start with the car though. These wires that I found today seemed to connect to the hall effects sensor (I think), which I've been reading about here. You think this might be the problem? I'd never heard of a hall effects sensor until recently, so I don't really know much about it. I'm wondering if, with all these bare, tangled wires, the problem could just be a short somewhere? Any more thoughts from anyone are appreciated. Thanks.

captwalker · Post by **captwalker** » 03 Jun 2009, 21:38

Just in case anyone might find this helpful later, turned out the problem was the timing belt. Well, the ignition coil needed to be replaced too, but the reason the car wouldn't start ultimately was the timing belt.