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    #1

    Volvo 740 turbo issues

    I am having a little trouble with my newly acquired Volvo 740 turbo estate.
    There is a cut out that is annoying the shit out of me. As soon as the car is under load (intermittently) it is as though there is a fuel cut. Every now and then the car stalls too and you have to wait a while before restarting. I think it is maybe the fuel pump relay.
    I am not sure if it is a coincidence or not but twice I have unplugged the air mass meter (or hotwire meter) and reconnected it and the car has started again, the cut outs under load resume though. The reason why I am not sure it is the AMM is because I have had it unplugged and was driving for some time before it went into limp home mode.
    Could it be a fuel pump relay? Fuel pump was replaced ~30000km ago and fuel pressure regulator was replaced around 60000km ago.

    It also only seems to be running 5PSI, are they not meant to run ~7?
    I really need to fix tis before I wind the boost up, please help!
    Rust is lighter than carbon fibre.

    My Italian 510
    Tags: None
    #2
    if the fuel pump and regulator have been replaced, then someone else has been chasing problems.

    I dont know much about these things, Forg is da man on wallow-vo's.

    could be a million things, from fuel starvation, from a grubby air mass plate, to a dry solder joint on the air mass meter to a crank angle sensor to an ignition module.

    start at the start, check the fuel pressure, and the next time it dies, check for spark at the leads.
    Turns out, far too much has been written about great men and not nearly enough about morons


    Originally posted by seedyrom
    my neighbours called the cops...... not because of the sound of me working in the garage was too loud, but because i taped a cardboard box to my back, covered my self in vaseline and pretended i was a snail on their lawn

    Comment

      #3
      Me will ask Volvo list for suggestions; I agree with Jim though, it does sound like someone's been half-arsedly looking for the source of the trouble & not found it. What age is it? I'll see if I can find out what the fault-tracing procedure is for getting error messages out of the ECU.

      The 240's & I think some of the 740's have these wierd "relays" that're actually solid-state modules (for more than on/off logic), and the solder cracks after 20yrs ... you just need to pull 'em & resolder 'em, they sometimes don't even look dodgy AFAIK. The yanks have had problems with underbonnet wire insulation becoming all biodegradable, so if underbonnet shorting-out is possibly an issue that might be worth sussing ... although I've not heard of those issues from Oz 700-series owners.

      I've mostly skimmed over 740 posts on the Volvo list, but I seem to have seen a lot of people replacing AMM's & finding that's not the problem; dunno if that indicates that the AMM is a common problem or whether it indicates that it's not.

      Which fuel pump was replaced? They have one in the tank as well.

      I think they run 9psi? I say that 'cos I think the 740HP was 12psi (using a very simple boost-control & ignition-retard module; yet I think Volvo asked an extra 5% list-price or something ).


      *edit* Just a thought, check for crap on the inside of the air-supply piping, maybe just after the turbo. After I got my intercooler cleaned-out I was told it had been ~80% blocked!
      Soft roaders represent an excellent compromise between the needs of the hardcore 4x4 user and the convenience of a city hatchback. Its clear to see why they have become so popular in todays society.

      Comment

        #4
        I'll bet its the in-tank pump.

        Does the problem go away or is minimised when the fuel tank is full?

        Sounds exactly like my (mechanically injected) 240, and VERRY similar to the old EFI 760T. Both were dead in-tank pumps.

        the source:
        "that fool that send that message i dont want no old car to buy .the question was not the dizzy it is the toyota pin out that i wanted to no.that goes to the dizzy."

        Comment

          #5
          The in-tank pump is the cheapest too, I bought a new one about a year ago for ~$135.
          Soft roaders represent an excellent compromise between the needs of the hardcore 4x4 user and the convenience of a city hatchback. Its clear to see why they have become so popular in todays society.

          Comment

            #6
            Thank you for the replies. I am not sure which pump was replaced, the receipts just say that "a" pump has been replaced. The mesh on the AMM was quite grubby but has been cleaned.

            Last night it did not seem to be giving any problems so we wound some advance into it with absolutely no detonation. So we put max advance on it and there was still no detonation. We then added a little boost, no detonation, then a little more there only 1 little ping so we wound the timing back a little. With the vaccum line from the wastegate completely open it was still getting only ~8.5PSI!!?? The reason why I do not think it is fuel pump related is that the problem would have reared its head as soon as advance was wound in and certainly when the boost was upped.
            Despite being an 87 model it has a TD05-12B with a weird BOV on the turbo.
            Current line of thought is crank angle sensor or ignition module. I will invest in a multimetre this weekend methinks.
            Forg-the piping all seems to be quite clean too.
            Rust is lighter than carbon fibre.

            My Italian 510

            Comment

              #7
              The wastegate on them is adjustable, innit? Not that that would affect you, if you've disconnected it ... hmm.

              What's the receipt for the pump say? If it's ~<$140 or so it'll be the in-tank one, I'm pretty sure the under-car one will be at least double that. Pump dodginess isn't always consistent ... you're right, it probably isn't, but it's worth keeping in the back of your mind.

              The resolder-the-relay thing, particularly with fuel pump & overdrive ones, is common (as is dirty power-window switches, if a window stops working the switch contacts will need a quick clean).

              Volvo weren't entirely consistent with their parts & when things went on, but it does sound like someone's fitted a later-model manifold & turbo dunnit? Possibly cheaper'n reco'ing the T03; the Mitsubishi does apparently give better throttle response though.
              Soft roaders represent an excellent compromise between the needs of the hardcore 4x4 user and the convenience of a city hatchback. Its clear to see why they have become so popular in todays society.

              Comment

                #8
                Oh, BTW:

                http://www.swedishbricks.net/700900FAQ/FAQSummary1.html
                Soft roaders represent an excellent compromise between the needs of the hardcore 4x4 user and the convenience of a city hatchback. Its clear to see why they have become so popular in todays society.

                Comment

                  #9
                  Thank you, starting to think that maybe it is the in tank pump. Another member on Turbo bricks had the same symptoms and they were cured with the pump. The boost leak has been fixed, there was a big vacuum leak, the car is now running ~6PSI and goes heaps harder! I was quite amazed at how well it went actually!
                  Rust is lighter than carbon fibre.

                  My Italian 510

                  Comment

                    #10
                    Went for a run in it, strange problem. Any luck since Friday?
                    Originally posted by 350stato
                    100% agree with Shifty

                    Comment

                      #11
                      It appears to have been the in-tank pump. Has been changed and the car runs beutifully now!
                      Time for a little bit of boost methinks...
                      Rust is lighter than carbon fibre.

                      My Italian 510

                      Comment

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