1990 Volvo 740 GL intermittingly won't start

[[email protected]]

I have a problem with this car not starting after running it constantly for 45 minutes to an hour. Stop it and go back and it will not turn over. THIS DOESN'T HAPPEN ALL THE TIME.The horn blows. the lights come on, the battery is charged. You can't jump start it. After 15 to 20 minutes the car starts as if nothing was wrong with it. I've taken it in to the Volvo Service department and everytime they check it, the problem doesn't happen. They've checked out the electrical system, ie battery, battery cables and starter plus relays in the fuel system.To me it seem like the problem is in the ignition switch, like something is overheating and when it cool off, the car starts. I've read other problems like this but their car will turn over but won't start. Need some feedback.

[Kmaniac in California USA]

I just need a little clarification here. After reading through your post, I seem to understand that your starter does not engage during the no-start condition. If this is not the case, please clarify.

Assuming that your starter is not engaging, or cranking I offer the following:

If your car has an automatic transmission, you should have a Neutral Safety Switch. This prevents your starter from engaging when your transmission selector is in any gear except Park (P) or Neutral (N). When your starter has failed to work, have you tried to start the car in BOTH Park and Neutral? The next time this happens, hold your key in the start position and move the trans selector between R - N - D to see if you catch the switch.

If your car has manual transmission, the switch should be connected to the clutch pedal. For a manual transmission car, hold the key in the start position and pump the clutch pedal to see if you can get the starter to engage.

Another possibility is the starter solenoid. The electrical contacts in the solenoid supply the power that makes the starter turn over. Over time, these can corrode, causing interrmittent no start conditions. However, if this is the case, you will hear the starter click each time you attempt to start. It is also possible that the solenoid is failing to pull at times, possibly due to dirty connections to the solenoid itself. This would cause no noise when the key is turned to Start.

Here are some things to look at. If I have assumed too much, then please give us a detailed description of what happens when you turn the key, including what noises your hear and how the dashboard lights display. It would also help to know whether you have automatic or manual transmission. Good luck with your car.

[[email protected]]

You are correct, the starter is not engaging. I have an automatic transmission. I've tried starting it in Park and in Neutral and it won't start in either of these, however I've never tried putting the transmission shift selector between the R-N-D. Next time I'll try this. This has happen to my daughter's Jeeta and doing that worked. I never thought about it for the Volvo. You're on the right track. There is no noise coming from the starter. The service department checked the starter but it wasn't under the described condition. Whenever they checked the car the problem seems to disappear. MAYBE THE STARTER ARMATURE HAS A BAD SPOT. One tech. suggested that next time this happen tap on the starter with a piece of wood. Any comments. Thanks for your reply.

[Kmaniac in California USA]

Your problem has peeked my curiosity. ...and we all know what curiosity did! Besides, I am always up for a good challenge.

The wiring schematic in my Haynes manual shows a lead from the ignition switch to the "starter inhibitor switch" and a continuing lead from the inhibitor switch to the starter. I suspect you are dropping a contact somewhere between the ignition switch and the starter.

As a do-it-yourselfer, this is what I would probably do in your situation. The starter inhibitor switch is attached to the shifter mechanism inside the center console. I would disassemble the console to the point that I would reveal the starter inhibitor switch and the wiring connections. I would identify which wires control the starter (purple coming from the ignition switch and blue/green going to the starter), carry a volt-meter and a jumper wire in the car. When it fails to start again, I would check the power coming from the ignition switch into the inhibitor switch. If no power is present, the problem is the ignition switch. If power is present, I would then jumper across the switch to see if the starter engages. If the starter does not engage with the jumper in place, the problem is in the starter. If the starter engages with the jumper, the problem is the inhibitor switch.

Again, this is what I would do as a do-it-yourselfer. What you decide to do is entirely up to you. Someone else might suggest replacing the ignition switch, starter inhibitor switch and starter all at the same time, the shotgun approach. However, this would be very expensive just for the parts alone, not to mention the labor charges if you cannot do this yourself. Then again, you could give the car to a mechanic with instructions not to return it until the problem presents itself and is corrected. However, the labor charges for this approach could exceed the price you paid for the car.

Hitting the starter with a block of wood or any blunt object is a viable approach if something is hung up in the starter. I have done this with a Ford starter with success. In fact, I diagnosed the interrmittant start problem with my 1986 740 by whacking the main fuel pump with a rock. But this may not cover all possible problems. I believe that this is a problem that you will have to solve on your own. Trying to pay someone to figure it out for you may be cost prohibitive. I hope you are up to the task. I am sure the solution is simple. Trying to find the problem to determine the proper solution is what takes time and patience. Please keep us posted as this situation unfolds.

[[email protected]]

The car finally did the act of not starting after driving it almost morning on last Friday 9/30/05. I tried the things we discussed. Putting the gearshift between R-N-D, This didn't work, hitting on the starter didn't work. To make a long story short, the problem was in the connection coming from the key switch going to the starter near the gearshift. I unplugged the connection, cleaned it and put it back together. The car started right up and has been every since. Will keep you informed of any new changes that occurs. Thanks for the help.

[brandon376]

Thanks, guys, for this back and forth. I have/had a similar problem on my 1989 740 GL: sometimes (esp. when hot), when I turned the ignition key to "start", I would hear a "click" -- but not a solenoid "click" -- that sounded like it was coming from the relay box behind the ashtray. I took off the console, which is held in with two/three screws, found the inhibitor switch and checked for current with a 12volt test light. At this check, I had current and the engine started. I kept a jumper cable with me -- as you suggested -- and the next time the starter would not engage, I jumped the two wires at the inhibitor switch and IMMEDIATELY the starter engaged and the engine started. Thanks for your solid efforts. Another example, in my opinion, of the good folks who own Volvos.

[nisan17]

Brandon376,

Wouldn't you be better off just changing the inhibitor switch?! I have the same problem with my 91 740. Basically on really hot days, and now it's happening on just warm days. I'll have to check my inhibitor and connections. Thanks much...Hopefully I can save myself from spending $125 for an ignition switch.

[brandon376]

intermttent start problem CONTINUED: After weeks without incident on my 1989 740 GL, yesterday with the car parked in a hot Brooklyn, New York, sun for five hours, I turned the ignition key and nothing. I jumped from the battery to the starter solenoid -- as I have in the past with the ignition key turned to "on" -- and the car started immediately. My guess is the problem is in the ignition switch so I'll need to expose the transmission switch again, keep a jumper ready, and then expose the ignition switch. Seems to me this circuit is a straightforward one so the current path should be traceable once the ignition switch is exposed, but what I still can't figure out is why this non-start condition occurs only when the car is warm, or if I recall correctly, when the car has been sitting idle for a day or two.

[Norman Sufficool]

This is a common problem on starting systems that have no inhibitor relay to carry the load. There will develop voltage drops from poor connections, arcing ignition switch contacts or inhibitor switch arcing and result in too low of a voltage to the solenoid to make it pull in and energize the starter. That starter solenoid draws many amps to energize and if there are weak connections anywhere in the circuit, usually based on specific conditions like heat, then there will be less than 9 volts to the solenoid when the ignition switch is turned to the start position. By using a jump wire to bypass the system you are giving it a full 12 volts right off the battery that causes it to spring to life. The best cure is to find where the voltage drop is by putting a volt meter across suspected connections or components such as the inhibitor switch or the ignition switch and look for unusually high voltage drops while trying to start. 1 or 2 volts is too much in any single component. In times in the past, if the circuit was difficult to trace or test, I would just use a universal relay to energize the solenoid, supplying the power right off the positive post of the battery and drive the relay with the solenoid wire that would normally go to the starter solenoid. That way, the ignition switch/ inhibitor switch circuit would only be required to supply sufficient current to energize the relay. Of course, you aught to understand the circuit that I am describing before using it. And be sure to use safe and secure wiring practices, taking consideration for routing wires and mounting the relay in a place that is safe from damage and shorts and providing a fuse in the supply side of the circuit at the battery. Use at least 14 gauge wire for the power circuit to the starter solenoid and the battery supply to the relay contacts.