blown99 Posted September 27, 2008 Share Posted September 27, 2008 02 f-350 diesel single fuel tank. Fuel gauge reads normal, then drops to below the empty mark (low fuel light comes on). Let the truck sit for about an hour come out and all is normal, drive it again and it acts up again. I am thinking about throwing a resistor across the sender connector terminals and going for a ride to try and rule out a harness issue. Anybody seen this before? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 27, 2008 Share Posted September 27, 2008 Bad sender? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 27, 2008 Share Posted September 27, 2008 This might be the ideal time to check out the new ICM test tool in IDS.... Quote Link to comment Share on other sites More sharing options...
blown99 Posted September 28, 2008 Author Share Posted September 28, 2008 Unfortunatly I don't have accesst oany of the high tech ford gadgets. I am leaning towards a sender even though I have not done any diag yet. Yesterday it read full for a while then dropped to empty. Key off for a while, go back to it and it read the correct reading for the rest of the time in use. Are there any computers that control this reading? I thought the dash was flashable?? Quote Link to comment Share on other sites More sharing options...
GregH Posted October 2, 2008 Share Posted October 2, 2008 Having the fuel level drop to empty is unusual for a sending unit failure. The resistance across the sender when the tank is full is about 150 ohms, and empty is about 15 ohms. Sending units will usually build up resistance on the wiper, causing high ohms spikes that will drive the fuel gauge upwards. Harness issues can go either way - short or open. Substituting in a resistor can definatly help out, but be aware that disturbing the harness can temporarily "fix" the problem, making you think the sending unit is bad. I'd start with a nice, thorough visual inspection. Take loose every connector in that circuit, looking for water or corrosion. Check the conduit for chafes/pinches/etc. How about jumpering in on the sending unit circuit at the instrument cluster, and monitoring the voltage during the concern? If your voltage is all over the place, then harness/sender issues are probably present. If not, then the cluster may be bad. The only computer in this circuit is the intstrument cluster. The later clusters were flashable as a sevice function. The earlier clusters were also flashable, but only during module replacement. There were no software updates on the earlier clusters... Quote Link to comment Share on other sites More sharing options...
blown99 Posted October 21, 2008 Author Share Posted October 21, 2008 Thank you for the specs. Since my last post the sender has not gone to empty, it has been staying around half or full, when the tank has about a 1/4-3/8 fuel. I drove the vehicle around until the problem occured, unplugged the sender and checked the resistance at the sender. Found the sender resistance to be very high, 5k ohms. Resistance would slowly and steadily climb with the meter on it. Dropped the tank and removed the sender. Found rust on all the sender components. Disassembled the sender and gained access to the wiper assembly. Found poor continuity on the ground side. Cleaned all parts, assembled and tested. Installed into the tank and rechecked the sender readings, still ok. Tommorrow I'll reinstall the tank and road test. Quote Link to comment Share on other sites More sharing options...
eastendpowerstroke Posted October 22, 2008 Share Posted October 22, 2008 You and I are both in the same area in the NE US, your only across the LI sound from me and I see the senders with the float arm just about rotted off from the poor quality fuel around here yours can't be much better. /forums/images/%%GRAEMLIN_URL%%/thumbup.gif you didn't get a p0460 code? Quote Link to comment Share on other sites More sharing options...
blown99 Posted October 23, 2008 Author Share Posted October 23, 2008 I didn't get any faults. Educate me on the p0460 code (don't have a book in front of me). This was my own truck. With fuel prices being high, the tank has been kept low and I used it only a few times this summer. I'm thinking condesation/humidity did it in. I use lots of additive every time I fuel up. We do have a lot of 466's blowing tips off lately, so I know what you mean about the poor fuel. Quote Link to comment Share on other sites More sharing options...
eastendpowerstroke Posted October 25, 2008 Share Posted October 25, 2008 P0460 Fuel Tank Level Indicator Circuit Malfunction I see this a lot set in memory I don't believe it turns the check engine light on, Mostly with a ticket "Customer states fuel gauge inop at times" and when I pull the sender out it's rusty as hell. As far as poor quality fuel I feel that a piece of steel that is always soaked and or splashed with fuel oil shouldn't rust. The failure pattern of fuel senders also seems to be regional, I see a lot of them but guys in other parts of the country don't. Quote Link to comment Share on other sites More sharing options...
slim Posted October 25, 2008 Share Posted October 25, 2008 The failure pattern of fuel senders also seems to be regional, I see a lot of them but guys in other parts of the country don't.I have never seen a rusty fuel sender on anything other than a vehicle that has been sitting for several years, so I'd say you are correct about that. Quote Link to comment Share on other sites More sharing options...
blown99 Posted October 25, 2008 Author Share Posted October 25, 2008 Pulled the fuel filter out. Figured I would inspect the heater element etc for rust. I have seen these rott out in the international applications. Everything looked perfect. Even my filter looked brand new, and it was a year old. That fault would be generated by the dash logic? Quote Link to comment Share on other sites More sharing options...
eastendpowerstroke Posted October 26, 2008 Share Posted October 26, 2008 next chance I get I'll shoot a couple pics Hey Slim you guys seeing many AFT axle steel tanks delaminating?? That seems also to be a regional failure /forums/images/%%GRAEMLIN_URL%%/shrug.gif Quote Link to comment Share on other sites More sharing options...
slim Posted October 27, 2008 Share Posted October 27, 2008 Hey Slim you guys seeing many AFT axle steel tanks delaminating?? That seems also to be a regional failure /forums/images/%%GRAEMLIN_URL%%/shrug.gif No, that's funny you asked, I have never found high restriction on the inlet side of a 6.0L, and I haven't seen a fuel tank replaced in the shop. I thought I must have been missing something the way everybody else talks about replacing tanks. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 27, 2008 Share Posted October 27, 2008 Shoot, we have done somewhere between 40 or 50 by now. Of that I recall only about three that were delaminated in a true sense. The remainder were all rusted internally in a recognizable pattern. Many of those trucs also required injectors. Quote Link to comment Share on other sites More sharing options...
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