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Volvo 740 electrical gremlin help



  • I have replaced my odometer twice in 350k miles.. or is it 400k?

    When it stops your car has less mileage. Hence car is worth more
    at trade in time. Not a factor in 25 year old cars. Big cities have shops that
    repair them in a few hours. It seems to be a specialized job and cheaper
    than buyin a new one.
  • I was able to fix a similar problem on my 740, please see post #21. If you do still have the problem, it's not much work to clean the oxygen sensor.
  • this 740 stalls out once in a while. we have tried to narrow down what makes this happen and came up with "whenever we go up a hill of some kind and then have a light to stop at at the bottom of the hill or top is when it seems to want to stall." Right after it stalls it's hard to get it to start up...takes a few tries. I thought it was an ignition problem but I tug on the keys and ignition area when it runs and it does not stall. I am thinking it's the fuel filter clogging up. I have had someone tell me it could be the head gasket???? Not sure if that makes sense or not. Any ideas out there or has anyone seen anything similar? thanks.
  • Electricguy, My son just bought a 1990 740GL wagon (4cyl, auto, non-turbo) and it is doing exactly the same thing you described. Unfortunately, after reading your posting we were unable to locate the "oxygen sensor" that you described so I would like to ask you for additional information. (1) What year is your 740? (2) Is it a 4cyl, non-turbo? (3) Is the "oxygen sensor" located in the exhaust or intake manifold? (4) Could you send a picture? I did some on-line searching for the "oxygen sensor" and it shows a tubular metal component that is attached in the exhaust system with a 19mm nut just before the catalytic convertor. This does not match your description, so I am thinking the component you are referring to must be something else. I appreciate your help.
  • richsrichs Posts: 3
    Try checking you master fuse box... #1 . It is in the consul. If I can recall.. Mine was , over the time starting to arc! Causing a poor connection. The main runs the main power AND the pump. Solved at first by using an electic grease... hope this helps.
  • Be sure they are replacing the correct coolant temperature sensor. There are two. One is connected to the dash temperature guage; the other one, up under the exhaust manifold is connected to the computer under the dash. My 240 gave me exactly the same problem and left me stuck numerous times until my mechanic and I figured it out. And yes, we swapped computer modules, idle control motors, you name it.
  • Also check the fuel pump and fuel system relays. They can arc also and cause all kinds of grief. Easy swap. Pick up a few spares on Ebay or CL and keep them in the console. Also download a relay diagram - just google it. I keep mine in the glovebox, which, by the way, has never seen a glove.
  • sallies2sallies2 Posts: 2
    Car won't start, acts like not getting gas. Fuel pump ok, lines ok, fuel injectors ok, fuel relay ok. No charge getting to the injectors. Still doing the exact same thing, "wants to" start but acting like no gas getting to it. Yes, it has gas in the tank. What else can we look for?
  • I have a 1991 volvo 740. I have owned it for 3 years and it has run great until now. Its not starting. I have had this problem for a while and would happen about once every six months but after 10 minutes or so it would start, but now its not starting at all. I have changed the spark plugs and wires, replaced the fuel pump. about a month ago its been doin it a lot lately but have got it to start using starting fluid but now it just wont start. Once it does start it stays running and doesnt die or have any problems. Any ideas? I have done a little research and could it possibly be the crankshaft position sensor? if so where is that located?
  • sallies2sallies2 Posts: 2
    I went thru all that too. Ended up that the problem was the little spot right where the injectors spark. Got that cleaned and it's been fine ever since.
  • so where the electrical connects are on the injectors?
  • mondobachmondobach Posts: 2
    Hello, I'm having the same sort of issues with my 1990 740GLE wagon. I have just had both fuel pumps replaced but still seem to be having the same issue. Did you ever get a response or find a resolution to this issue? I'd appreciate any help you can give me!
  • mondobachmondobach Posts: 2
    I'm hoping someone out there might be able to offer some help. I have a 1990 740 GLE wagon which I bought with about 91K miles on it a few years ago. It has intermittently had acceleration issues which have now worsened. I noticed that when I let the gas tank run down to about 1/4 I could hear the fuel pump under the drivers seat working erratically. As I result I always tried to keep the tank at least half full.

    While driving to get gas one night at about 30-40 MPH the car suddenly had no power...someone else in a post here stated the same problem by saying it was as if the accelerator had been suddenly disconnected. I rolled to the side of the road when it finally stalled. However, it immediately started up again and I was able to get to the gas station, fill up, and get home without further problem.

    This same thing has now happened a few times even with a 3/4 to full tank. My mechanic replaced both fuel pumps but I am still having the problem.

    The car will also sometimes not start. Usually when I turn the key to "on" I can hear the fuel pump activate. However, I have noticed that on the occasions that it doesn't start, I cannot hear the pump come on. I turn the key on and off a few times until I hear the pump activate and then it turns over just fine.

    So, my question is, what might it be that is not telling the fuel pump to come on when the car is started and could this same thing also be telling the pump to quit while the car is moving?

    I would greatly appreciate any guidance that anyone might be able to give to me!
  • bydebyde Posts: 1
    I have a 1990 Volvo wagon 740 base. I left work car started fine stooped at gas station and come out and go to start car and nothing power but nothing happening at starter power going to starter but nothing anyone have any ideas this is my only car and have a trip planed in couple weeks. Thanks
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