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740 & 760 760 GLE hard start and excessive fuel consumption

So, as the title states, I have a V6 760, that is becoming increasingly hard to start, ie: it cranks for 3 to 5 seconds before it fires, and the fuel consumption is pretty horrendous, more so than normal.

I thought I’d ask the collective brain trust here if anybody has any ideas where to start.

I’ve searched and searched, and being as they weren’t the most popular choice when sold new, not many of them are around. So info on issues is a bit thin on the ground.

Anybody have any ideas?

Thanks in advance

Paul
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Comments

  • DCW242Duncan (@DCW242) - point cook. victoria
    What year of 760?
  • What year of 760?

    It’s an 89.. good point, always forget to mention something 🤷‍♂️
  • 89 should be efi v6 i would check the vacuum line to the fuel pressure regulator, its common for them to leak fuel back into the intake.
  • 89 should be efi v6 i would check the vacuum line to the fuel pressure regulator, its common for them to leak fuel back into the intake.

    Hi Timbo
    I have replaced all the vacuum lines a couple of months ago... everything seems fine
    Could it possibly be a faulty fuel regulator??
    Has a strong smell of fuel when starting up .
    Cheers
  • Yeah thats what i meant the fuel reg leaks into the vacuum reference line which sucks raw fuel back into the engine. The vacuum line should be dry it will be obvious if theres fuel leaking.
  • Awesome Timbo, I will check and will let u know ..
    Cheers
  • I think i have a brand new bosch reg at the workshop if you end up needing one
  • Ok, so, curiously, there seems to be no fuel leaking from the vac line on the FPR, when i pull the line off the back of it, the revs drop, only a very small amount, then they pick back up again when plugged in. So I’m guessing it may not be the FPR at fault.

    There seems to be a hose possibly missing from the throttle body as per attached photo of this means anything ?ewh8vbcw8hgw.jpeg
  • That wont be helping the fuel mixture if you cant work out where its supposed to go then block it off for now
  • There’s no hoses dangling anywhere, can’t find anything online that gives me any sort of vac line diagram, so I’ll take your advice and block it until I can figure out where it goes.
    I’ve found a fitting in the charcoal canister that’s also missing a hose, but it’s of a smaller size.
    The mystery continues..
    the old girl has done half a million km’s, it’s allowed to have a fault or two 😂

    Is there a good service manual that you could recommend to purchase?

    I’m guessing I’m going to need one lol
  • It looks like that hose is missing from both the throttle body and the charcoal canister. The hose is nylon, with rubber end fittings which explains the different sizes. I'm 100% sure that if you check the engine bay of another 760 with B280F engine, you'll find that fitting will have a hose on it
  • That would explain the different sizes.. being the nylon/rubber ended hose..
    I haven’t seen another 760 in god knows how many years, but I’ll see if there’s anybody has one on the forums.

    Cheers all for your help, not confident it’s going to fix my issue, but hopefully it might go towards finding the fix
  • Another thing which comes to mind is the coolant temperature sensor.
    RallybrickmartinALVO360
  • +1 for the coolant temp sensor. Had the same issues on my 89' redblock and fixed it. They look like a similar bosch part.
    Rallybrick
  • I’ll have a look... seems like a weird fix, but I’ll give almost anything a go
  • gavinhGav (@gavinh) Parmelia, Perth
    @Rallybrick had an out come on the 760?
  • G’day Gav

    Not yet mate, had to fly back to work, not home until next Tuesday, so I’m going to tear into it and try and figure out what it is.
    The fuel pressure reg is fine, no leaks, the coolant temp sensor was within range, so I’m wondering if it’s down to a fuel pump on its way out 🤷‍♂️
  • gavinhGav (@gavinh) Parmelia, Perth
    Aye, what about the iac valve? Being stuck, can't remember if it had some sort of erg valve?
  • Something worth having a look at for sure.. it’s perplexing to say the least

    I’ll be servicing it the break when I’m home, so I’ll
    Get stuck in and see what I can figure out.
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