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Thread: Loss of power

  1. #11
    Join Date
    Jan 2009
    Location
    Melbourne
    Posts
    82

    Re: Loss of power

    Thanks Johnnojack, I think you may be right!

    I have gone further with my diagnosis since and I can find no electronic problem at all. I have since measured the resistance of the valve circuit and it checks out fine. I have also applied 12V to the valve itself and it clicks over just fine so it cannot be seized up as suggested by the the diesel guy.

    So, I kept looking further and found that when I reached down to the fuel hose where it is fitted onto the banjo fuel line going into the pump, I seem to be able to rotate the hose on the barb fitting quite easily even though there is a spring clamp on it. In fact it seemed like it was slipped off half way. Now, why did I miss this before? The fuel hose joins onto the fuel line quite low on the side of the engine in a hard to reach spot and I kind of assumed that it must be ok.

    So, now I pushed the hose on all the way without changing the clamp just to try if things are better. And I was just about to test this when my battery gave up! This is despite I have put a brand new battery in just about 4 months ago, probably because I have been starting and stopping the engine a few times and also I have put a Jaycar SMS kit in my car to tell me if someone is breaking in, which I think sucks up too much power to keep the mobile phone charged.

    So, I will try to charge up my battery tomorrow morning to see if I can finally start as my car is booked in at the diesel place for Friday, so I haven't got much time to figure this out now.

    If it was the hose, then this would agree with the computer diagnosis that their may be air in the fuel line.

    Hopefully I can avoid the pump reconditioning now...

  2. #12
    Join Date
    Jan 2009
    Location
    Melbourne
    Posts
    82

    Re: Loss of power

    Bad Luck!

    I have got my battery working and can start all fine.

    However, things did not improve even when I have forcefully pushed the hose on the pump banjo.

    Since, then according to earlier advice from tbird, I have now completely removed all fuel hoses an put in a new one that I have immersed in a jar filled with clean diesel. This now cuts out fuel hoses and filters and tanks, etc. Still the same problem.

    Then I disconnected the return hose where it was running into the pollack and put the return line into the jar as well, in case the return line was blocking or something. Still the same issue. I was thinking that if the problem was the fuel pressure regulating valve then I should probably be seeing a lot of fuel being returned when I was trying to rev the engine up. That is why maybe the IP is starved of fuel as Johnnojack was saying. However to my surprise no fuel is returned whatsoever on the return line.

    The last thing I am thinking is to pull off the whole return line hose from the IP in case that is blocked, but after that I am at the end of my line... :-(

    Sounds like IP needs to be looked at after all?! By the way, my engine has done 180 000kms since new.

    Surfie

  3. #13
    Join Date
    Dec 2007
    Location
    Lake Macquarie (just south of Newcastle) NSW
    Posts
    1,363

    Re: Loss of power

    Quote Originally Posted by surfie View Post
    However to my surprise no fuel is returned whatsoever on the return line.
    Short of time right now but perhaps this is the key to the problem.

  4. #14
    Join Date
    Jan 2009
    Location
    Melbourne
    Posts
    82

    Re: Loss of power

    Now that you mentioned it, in hindsight, the pump did not appear to suck up much diesel from the jar either. Trouble is I don't know what is normal, because I have never tried it while is was good.

    But it make sense that it is not sucking up much fuel and hence nothing is returned.

    As far as I know there is no lift pump in my diesel tank. I do use a lift pump for my oil though. It does not appear to run on either of them, although I am not about to try it on oil now.

    I think there is not much left apart from blaming the IP now. Problem is that it is rapidly getting worse, at this stage I am looking at a tow to get it in. Now even fast idle is failing.

    Surfie

  5. #15
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,128

    Re: Loss of power

    Quote Originally Posted by surfie View Post
    Now that you mentioned it, in hindsight, the pump did not appear to suck up much diesel from the jar either. Trouble is I don't know what is normal, because I have never tried it while is was good.

    But it make sense that it is not sucking up much fuel and hence nothing is returned.

    As far as I know there is no lift pump in my diesel tank. I do use a lift pump for my oil though. It does not appear to run on either of them, although I am not about to try it on oil now.

    I think there is not much left apart from blaming the IP now. Problem is that it is rapidly getting worse, at this stage I am looking at a tow to get it in. Now even fast idle is failing.

    Surfie
    You need to get the regulating valve out. If the O rings are stuffed then fuel just bypasses back to the inlet side of the pump instead of building up pressure. Look thru the VW thread to see how to get it out (modify a cheap 6 sided socket).

    Another thing to check is if the front seal of the IP is leaking, see if there is any fuel leaking from the timing cover.
    Johnnojack
    4WD Isuzu Jackaroo 3.1 170,000km on WVO,(2017) 2 tank home built system 6 solenoids. Mk. 9 version. Improvements under investigation

  6. #16
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,128

    Re: Loss of power

    Quote Originally Posted by surfie View Post
    Bad Luck!

    ..... I was thinking that if the problem was the fuel pressure regulating valve then I should probably be seeing a lot of fuel being returned when I was trying to rev the engine up. That is why maybe the IP is starved of fuel as Johnnojack was saying. However to my surprise no fuel is returned whatsoever on the return line.

    Surfie
    Surfie if the fuel pressure regulating valve is faulty/leaking back, then you won't get much fuel returned if any, just to make that clear.
    Johnnojack
    4WD Isuzu Jackaroo 3.1 170,000km on WVO,(2017) 2 tank home built system 6 solenoids. Mk. 9 version. Improvements under investigation

  7. #17
    Join Date
    Jan 2009
    Location
    Melbourne
    Posts
    82

    Re: Loss of power

    Thanks Johnnojack. I thought earlier you mean that if the regulating valve is not working then "too" much is returned and that is why there is not enough fuel left. If nothing is returned shouldn't I have more than enough fuel then in the pump?

    Also, I went for a test drive to see if I can make it to the diesel place at 10kms/hour :-) and it is blowing white smoke, which I think means no fuel. I will get a tow now.

    I could not see fuel leaks or at least not enough to explain how much is missing. Or is it possible that it is getting air through the leak?

    Surfie

  8. #18
    Join Date
    Dec 2007
    Location
    Lake Macquarie (just south of Newcastle) NSW
    Posts
    1,363

    Re: Loss of power

    You should be getting a LOT of fuel through the return.
    I think it was tbird that has measured it and I think it was about 5 litres/minute from memory. Anyway it is a lot. About 90% of what goes in goes back through the return on these IPs.
    I think Johnnojack is on the right track. If that regulating valve is bypassing back to the inlet you will get very little drawn from the jar, nothing back through the return and very little to the injectors.
    Sure your IP man will fix the regulating valve as part of the IP overhaul but the IP should not need a complete overhaul at only 180,000 km.
    You might be able to get at the regulating val;ve without removing the IP which might save a lot of work/labour.

  9. #19
    Join Date
    Dec 2006
    Location
    Townsville, North Queensland
    Posts
    611

    Re: Loss of power

    Reading back through this thread I do see anywhere that you have mentioned that you have removed the inlet banjo bolt and checked for an inlet screen into the I.P.

    If there is one and it is clogged with crap, it would be giving you these problems.

  10. #20
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,128

    Re: Loss of power

    Quote Originally Posted by surfie View Post
    Thanks Johnnojack. I thought earlier you mean that if the regulating valve is not working then "too" much is returned and that is why there is not enough fuel left. If nothing is returned shouldn't I have more than enough fuel then in the pump?

    Also, I went for a test drive to see if I can make it to the diesel place at 10kms/hour :-) and it is blowing white smoke, which I think means no fuel. I will get a tow now.

    I could not see fuel leaks or at least not enough to explain how much is missing. Or is it possible that it is getting air through the leak?

    Surfie
    I'll try to explain how your IP works in as few words as I can. There is a vane pump inside your IP at the front. This draws fuel from the tank through the filter. Output from the pump goes thru the regulating valve in the body of the pump to the main chamber in the IP (the body of the IP). This fuel which is at a pressure of between 20 and 150psi feeds the rotating high pressure piston in the distributor head at the back of the pump. This piston produces the very high pressures in the distributor head and hence to the injectors
    If the regulating valve is no good then pressure cannot be built up in the IP as fuel simply bleeds back to the inlet side of the vane pump. Without pressure in the IP the high pressure piston cannot deliver sufficient pressure to the injectors. Result power down to 10kmh top speed.

    Directly in front of the vane pump is the main shaft seal. If this is shot then air will be sucked in - same result as above. You can identify this by having clear hoses into and out of the IP
    Johnnojack
    4WD Isuzu Jackaroo 3.1 170,000km on WVO,(2017) 2 tank home built system 6 solenoids. Mk. 9 version. Improvements under investigation

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