Gas tank won't fill to full. Reply #30 – October 05, 2013, 10:57:34 AM haystack,you want 5v coming out of the ivr,,, thats the goal.there is also a resistance wire off the ignition switch which is a thin solid conductor approx 18awg that leads up to your instrument cluster.you will find this thin wire on the plug in on your igntion swtich parallel with a larger gray/yellow wire.my sons full ananlog cluster had unreliable guages and i found this little gray wire connection at the spade connector to be broken. the insulation was holding the wire in place.people who take the column covers off and on bend up thier wires and this one particular wire is a single solid conductor.it will have 12v going into it but on the other end up at the cluster, it will be lower , not like the evtm says but low enough around 5 to 7v.next would be the ivr. Quote Selected
Gas tank won't fill to full. Reply #31 – October 05, 2013, 11:51:56 AM thanks Scott, I will check this when I get around to it.about the dash reading 84 mph, that is just a touch under 25 mph. swapping a 99-04 t-5, the oss, which plus right into the vss, reads speed, traction control, and abs. the mustang computer splits these signals up, where our cars don't.so dash reads about 4 times as high, until I can get around to finding a 94-98 transmission which used the same setup our cars did, and swap the tail shaft. Quote Selected
Gas tank won't fill to full. Reply #32 – October 09, 2013, 03:36:35 PM Well I went to the gas station today and filled the Thunderbird up (one of the 3 stations I usually stop at). The gauge said 10 gallons were in the tank. The pump said it took 12 to fill up (10+12=22 the tank capacity). I turned on the car and the gauge said F. So now the stupid thing wants to work right again. Instead of saying 18 when the tank is full the gauge has randomly decided to go back to displaying F :wtf:. Quote Selected
Gas tank won't fill to full. Reply #33 – October 10, 2013, 10:22:54 AM sounds like the same thing climate control does sometimes... the symptoms come and they go.these are probably examples of the problems that came in the door at the dealership then went back out the door unresolved all the time.there's no real way to troubleshoot these fickle or intermittant issues when there is no real clear way of simulating or introducing a fault when we dont clearly understand where the source of the fault might be.oh wel... atleast now you can pull the codes off your cluster. Quote Selected
Gas tank won't fill to full. Reply #34 – October 10, 2013, 05:02:48 PM I'm going to pull codes from the cluster as perhaps it is still at fault. It a random problem like this that comes and goes that drives a person nuts. The only thing I can think of is that it *could* be a grounding issue. I know Mark VIIs built before 1990 are pr0ne to having faulty gas gauge readings. The fix is to install a ground strap between the tank and frame of the car. I might try that with my Thunderbird and see if it makes a difference. It's cheap and worth a shot. Quote Selected
Gas tank won't fill to full. Reply #35 – October 12, 2013, 10:47:58 AM i wonder what safety bullet items there are to list since the oem tank did not have a chassis ground.for instance,,,,welding on the frame...........you are injecting a voltage throughout the frame of the car,,, the welder has a ground clamp.at some point the gas tank ground strap becomes resistive due to corrosion or just age...could that not introduce a voltage drop and current flow to ignite fumes?this is an interesting comment you have made,, and not haveing a ground strap oem is probably engineered for a reason.dono... chime in all you ASE guys!!!! Quote Selected
Gas tank won't fill to full. Reply #36 – October 12, 2013, 10:48:13 AM i wonder what safety bullet items there are to list since the oem tank did not have a chassis ground.for instance,,,,welding on the frame...........you are injecting a voltage throughout the frame of the car,,, the welder has a ground clamp.at some point the gas tank ground strap becomes resistive due to corrosion or just age...could that not introduce a voltage drop and current flow to ignite fumes?this is an interesting comment you have made,, and not haveing a ground strap oem is probably engineered for a reason.dono... chime in all you ASE guys!!!! Quote Selected
Gas tank won't fill to full. Reply #37 – October 12, 2013, 10:50:27 AM on the flip side,, in my work world,,,we have to bond diesel fuel tanks of generators to the exterior ground ring by way of cad welds... so,, it must be ok to "chassis" earth ground a fuel tank wihtout any worries of what i said in my earlier post.... Quote Selected
Gas tank won't fill to full. Reply #38 – October 12, 2013, 10:50:41 AM on the flip side,, in my work world,,,we have to bond diesel fuel tanks of generators to the exterior ground ring by way of cad welds... so,, it must be ok to "chassis" earth ground a fuel tank wihtout any worries of what i said in my earlier post.... Quote Selected
Gas tank won't fill to full. Reply #39 – October 12, 2013, 02:10:47 PM I know the tank on my car has a plastic shield under it. The tank straps never touch the actual metal tank but instead the plastic shield. I have to assume that the sender is grounded not through the tank (since it is insulated) but instead through the wiring harness. The 84-89 Mark VIIs that have issues with the fuel gauge don’t have a little ground strap running from the tank to the chassis. Ford fixed the problem on the 90-92 Mark VIIs by adding that little ground strap from the factory. I’m wondering if doing the same thing on a Fox Thunderbird/Cougar would fix the problem? Quote Selected
Gas tank won't fill to full. Reply #40 – June 18, 2014, 05:35:44 PM Holy thread revival!I fixed the problem early this spring and forgot to post the solution. It turns out that somehow the fuel filler neck and slipped lower into the tank than it should be. The plastic shield it sits in cracked and the neck in turn sank. since it sat lower fuel was getting pushed up the neck before the tank was full. I pulled the neck up to the correct height and repaired the plastic shield the neck mounts to behind the fuel door. Vola the tank now take up to 22 gallons and the dash says it's full. It ended up being a mechanical rather than electrical fault after all. Quote Selected
Gas tank won't fill to full. Reply #41 – June 18, 2014, 06:07:16 PM Mine went on a tantrum a few weeks back and kept saying more gas and miles till empty after I had driven it 15 miles and not added any gas. Did it 3 days straight, then stopped.... I'm not even gonna start to mess with any of it until the issue stays. It's reading correctly as of right now.... Quote Selected
Gas tank won't fill to full. Reply #42 – June 18, 2014, 07:07:40 PM Quote from: V8Demon;434968Mine went on a tantrum a few weeks back and kept saying more gas and miles till empty after I had driven it 15 miles and not added any gas. Did it 3 days straight, then stopped.... I'm not even gonna start to mess with any of it until the issue stays. It's reading correctly as of right now....How full was the tank? It takes quite awhile for the gauge in my Thunderbird to come off F. F is 22 gallons. The next number below F is 20 so it will take a good 30+ miles of "normal" driving to get it to come down. Quote Selected
Gas tank won't fill to full. Reply #43 – June 18, 2014, 07:45:18 PM That's awesome! Does anybody know how to make the fuel pump not suck air on a hard left? Quote Selected
Gas tank won't fill to full. Reply #44 – June 18, 2014, 08:54:09 PM Quote from: TheFoeYouKnow;434975That's awesome! Does anybody know how to make the fuel pump not suck air on a hard left?Or in my Thunderbird's case not suck air with less then 1/2 tank and a full throttle launch and/or passing maneuver? The car rears up so hard that gas sloshes away from the pickup :hick:. Quote Selected
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