Alex Bruene Posted January 4, 2008 Share Posted January 4, 2008 One of my co-workers seems to have become involved in an on-going problem with an LCF that every now and then becomes a no-start due to air in the fuel system. Today it was towed in, and upon removal of the secondary filter cap, air came hissing out. No fuel was present. It is a dual tank vehicle, on one prior visit, the right tank was completely empty, and the left tank was full. For that reason it got a new transfer module. Today both tanks are at the same level (as it should be). The HFCM has also been replaced, and the pick-up lines in the tanks have been inspected. Is there anything you guys think could be going on? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted January 4, 2008 Share Posted January 4, 2008 One of my co-workers seems to have become involved in an on-going problem with an LCF that every now and then becomes a no-start due to air in the fuel system. Today it was towed in, and upon removal of the secondary filter cap, air came hissing out. No fuel was present. It is a dual tank vehicle, on one prior visit, the right tank was completely empty, and the left tank was full. For that reason it got a new transfer module. Today both tanks are at the same level (as it should be). The HFCM has also been replaced, and the pick-up lines in the tanks have been inspected. Is there anything you guys think could be going on? I did see this once on a 6.0 and it turned out to be a bad HFCM. In the VT service manual, it shows the air bleeder port drilled in the side of the secondary FF housing, very similar how a 6.0 is set up. Here is a 6.0, the bleed port is in the white plastic insert: I'd make sure there was no blockage at this small bleed hole. If it were to be blocked with crap, it would cause your problem. I'd also take the return line off and check for return obstruction. Remember you'll be blowing through the DTRM in the HFCM so there will be some resistance. I would also check return flow with the engine running behind the HFCM. This is a commonly overlooked fuel pump and system test that works well. If the system is good, return flow will generally be strong, like a pint in 15 seconds. If the pump is weak, filter(s) are clogged, excessive voltage drop, etc. return flow will be weak. If return flow is weak, you could have excessive air buildup in the secondary FF. Has anybody checked fuel pressure under load? I checked the IH info for TSI's and saw none. Good Luck! /forums/images/%%GRAEMLIN_URL%%/grin.gif Quote Link to comment Share on other sites More sharing options...
International Tech Posted January 5, 2008 Share Posted January 5, 2008 Have u checked to see if youre not getting combustion in the fuel? Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted January 5, 2008 Share Posted January 5, 2008 LCF? Has anything been done to the fuel system? Moved tanks,lines,etc? Seen one that had a leak and sucked air causing a air lock/blockage. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted January 5, 2008 Author Share Posted January 5, 2008 The fuel has not been modified. The lines have been removed from the vehicle and inspected. He checked the air bleed today, and it was clear. After gettng the air out of the system, it runs perfectly well... and normally will for about a month or so between break-downs. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted January 6, 2008 Share Posted January 6, 2008 Quote: it runs perfectly well... and normally will for about a month or so between break-downs. This wouldn't possibly be happening after doing a P/M, would it??? Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted January 6, 2008 Author Share Posted January 6, 2008 No, Larry. We do all the maintenance on this fleet. And, unfortunately, there is a bit of a language gap between us and the driver, so getting all the information necessary is not always that easy. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted January 12, 2008 Share Posted January 12, 2008 Alex any update on this one? It almost sounds like return check valve stuck. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted January 12, 2008 Author Share Posted January 12, 2008 No Larry. I have nothing. After getting the truck started, and doing a bunch of inspections, the customer decided that he was going to take it. This fleet pays the drivers by delivery, so they are VERY impatient... but they are the first ones to complain that they are having problems getting their trucks fixed... /forums/images/%%GRAEMLIN_URL%%/banghead.gif Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted March 20, 2008 Share Posted March 20, 2008 IH just released a recall on VT275s for a new fuel pressure regulator and installing a low fuel pressure switch that's wired to the PCM with an overlay harness. It will set codes and turn on a light on the dash when FP drops out. AFC Number: 07916R AFC Date: March 17, 2008 I wonder if this has any relevance to this problem? Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted March 21, 2008 Author Share Posted March 21, 2008 Sorry for not updating... I think that I may have "accidentally" stumbled upon the issue. The guy that was originally working on this issue was off one day when the truck came back in... I found that the fuel guage didn't appear to be reading right, so after calling the customer, we discovered that the fuel guage was having intermittent issues (which would have been really good info. from the start)... after putting a new sender in the left tank, it's all been fine. I imagine that the left tank was running out of fuel when the sender was not working, then when the sender started to work, it would transfer fuel back into the left tank, thus making it difficult to figure out it was actually run out of fuel. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 22, 2008 Share Posted March 22, 2008 This topic got me thinking. With three different tank configurations available on the LCF I asked myself where the fuel was drawn from and how is the fuel is transferred on dual tank configurations. The system is basically identical to the F650/750 system except the fuel is drawn from the left tank on the LCF and transferred from the other tank by way of a transfer pump. I have yet to see a dual tank set up because we sell trucks with an aft-axle tank but this is good to know. /forums/images/%%GRAEMLIN_URL%%/wink.gif Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted March 22, 2008 Author Share Posted March 22, 2008 Yeah... they have senders in each tank, and a transfer module in between. The fuel guage reads off the left tank, and the transfer module will transfer fuel from the right tank to the left tank as the level in the left tank goes down. In a properly working system, the fuel levels in both tanks should be within a couple of inches of one another. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 22, 2008 Share Posted March 22, 2008 Do you know how many people are baffled by this? /forums/images/%%GRAEMLIN_URL%%/crazy.gif Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted March 23, 2008 Share Posted March 23, 2008 I give up, how many? /forums/images/%%GRAEMLIN_URL%%/grin.gif Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted March 24, 2008 Share Posted March 24, 2008 Give me the "Good old days" when we had tank transfer switches on the dash, when one gets low switch over and on our way we go. Better yet why not put a crossover tube and draw fuel from both at the same time, like they used to do. No make it more difficult when there are electrical contact problems. Quote Link to comment Share on other sites More sharing options...
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