Powerman5K Posted March 27, 2023 Author Share Posted March 27, 2023 Hi John, I am sure you know this; have a dual tank harness off vehicle. Found splice location S154 on the main harness about 1 to 2 inches towards the front of the vehicle from the junction of the front tank/main harness connection. "It had a repair" It can be accessed through the opening of the front tank and frame by the fuel filler hose from below. I have a cheesecake frame, so everything is accessible!!! So I ran Gary's test over the weekend and have confirmed my Sending unit is bad. Given that I installed a new sending unit 9 months ago, I will NOT use the same brand. As I don't want to do this again for a VERY long time, does anyone have brand recommendations? Thanks in advance for your thoughts! Link to comment Share on other sites More sharing options...
Powerman5K Posted March 27, 2023 Author Share Posted March 27, 2023 So I ran Gary's test over the weekend and have confirmed my Sending unit is bad. Given that I installed a new sending unit 9 months ago, I will NOT use the same brand. As I don't want to do this again for a VERY long time, does anyone have brand recommendations? Thanks in advance for your thoughts! Anyone ever use Spectrum? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 27, 2023 Share Posted March 27, 2023 Anyone ever use Spectrum? I’m running Spectrum fuel deliver modules in Big Blue and they work well. Link to comment Share on other sites More sharing options...
Powerman5K Posted March 27, 2023 Author Share Posted March 27, 2023 I’m running Spectrum fuel deliver modules in Big Blue and they work well. OK. I stayed away from them originally because they came with a plastic float and looked cheap. I opted for one that had a brass float thinking it was better. That's what I'll buy then. Thanks for the info. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted March 29, 2023 Share Posted March 29, 2023 If this is any help to anyone, I have found another possible ground problem. The top of the sender assembly has contacts going through it, and one of them is for the ground wire. It is possible, and I have seen it happen, for the "joint" between the sender assembly and this contact to corrode. If this happens, it will increase the resistance until your gauge no longer reads at all. This is what happened on my truck. When I found what the problem was, I took the sender out and cleaned it as best I could. The gauge worked fine for a short time, and then gradually read less and fuel in the tank, as it corroded again. I'm going to have to take it back out and try something else I've been planning for a while. More on that if it works. By the way, has anyone else installed the 38gal rear tank? If so, what did you do for the sender? Link to comment Share on other sites More sharing options...
Littlebeefy Posted March 29, 2023 Share Posted March 29, 2023 If this is any help to anyone, I have found another possible ground problem. The top of the sender assembly has contacts going through it, and one of them is for the ground wire. It is possible, and I have seen it happen, for the "joint" between the sender assembly and this contact to corrode. If this happens, it will increase the resistance until your gauge no longer reads at all. This is what happened on my truck. When I found what the problem was, I took the sender out and cleaned it as best I could. The gauge worked fine for a short time, and then gradually read less and fuel in the tank, as it corroded again. I'm going to have to take it back out and try something else I've been planning for a while. More on that if it works. By the way, has anyone else installed the 38gal rear tank? If so, what did you do for the sender? I am very annoyed by this. I, too, installed a brand new sending unit when I built my pump-on-a-stick and it immediately failed. I have a new unit sitting on the shelf that I was going to put in (which involves more than just dropping the tank and R&R of sender since I'm using a hydramat and custom pump for my ProFlo EFI). It does not make sense to me to go to the trouble of replacing it if there is a high likelihood that it will fail again. My wiring and gauge tested fine and I've got a ground strap on the tank; the sender is a piece of sh!t. What is the problem here? Is there a flaw in the design of this part that causes them to be so prone to failure? Can some preventative action be taken besides simply testing before installation? If there is no good as-stock replacement, what is the best workaround? Has anybody adapted another sending unit? Has anyone installed a separate aftermarket sender that worked well? Does anyone know if the sending units on the later trucks suffered the same problems as ours do? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 29, 2023 Share Posted March 29, 2023 I am very annoyed by this. I, too, installed a brand new sending unit when I built my pump-on-a-stick and it immediately failed. I have a new unit sitting on the shelf that I was going to put in (which involves more than just dropping the tank and R&R of sender since I'm using a hydramat and custom pump for my ProFlo EFI). It does not make sense to me to go to the trouble of replacing it if there is a high likelihood that it will fail again. My wiring and gauge tested fine and I've got a ground strap on the tank; the sender is a piece of sh!t. What is the problem here? Is there a flaw in the design of this part that causes them to be so prone to failure? Can some preventative action be taken besides simply testing before installation? If there is no good as-stock replacement, what is the best workaround? Has anybody adapted another sending unit? Has anyone installed a separate aftermarket sender that worked well? Does anyone know if the sending units on the later trucks suffered the same problems as ours do? Interesting. And good question, Chad, if there is a way to prevent this. Like soldering it. Or adding anti-seize compound. Or maybe dielectric grease. As for later sending unit, I hate to jinx it but my fuel delivery modules are working well. Some time after the Bullnose era Ford went to an integrated pump, sending unit, and control valve and called that an FDM. I'm running them on Big Blue and have had no problems. But, be aware that the resistance range for the senders is upside down and backwards to what the Bullnose gauges need. So I'm running a MeterMatch unit to adapt them to the gauge. And the external plumbing is different in that there's only a wye for the supply and a wye for the return. Plus, you should have the later tanks as well since the FDM's have a tab that is in a different position than the tab for the Bullnose tanks. Link to comment Share on other sites More sharing options...
Littlebeefy Posted March 30, 2023 Share Posted March 30, 2023 Interesting. And good question, Chad, if there is a way to prevent this. Like soldering it. Or adding anti-seize compound. Or maybe dielectric grease. As for later sending unit, I hate to jinx it but my fuel delivery modules are working well. Some time after the Bullnose era Ford went to an integrated pump, sending unit, and control valve and called that an FDM. I'm running them on Big Blue and have had no problems. But, be aware that the resistance range for the senders is upside down and backwards to what the Bullnose gauges need. So I'm running a MeterMatch unit to adapt them to the gauge. And the external plumbing is different in that there's only a wye for the supply and a wye for the return. Plus, you should have the later tanks as well since the FDM's have a tab that is in a different position than the tab for the Bullnose tanks. So to make your fuel level sender dependable you have to replace your gas tank, fuel pump harness and sending unit and install an electronic device for your fuel gauge? Â Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 30, 2023 Share Posted March 30, 2023 So to make your fuel level sender dependable you have to replace your gas tank, fuel pump harness and sending unit and install an electronic device for your fuel gauge? I'm not saying that you have to. Just saying that's what I did and it seems to have worked. Having said that, if you look at Ford's history of fuel systems they clearly didn't have a solid solution for many years. They changed and changed and changed - surely because there were problems. Link to comment Share on other sites More sharing options...
81-F150-Explorer Posted March 31, 2023 Share Posted March 31, 2023 I'm not saying that you have to. Just saying that's what I did and it seems to have worked. Having said that, if you look at Ford's history of fuel systems they clearly didn't have a solid solution for many years. They changed and changed and changed - surely because there were problems. Even Factory Ford Fuel Senders for 1980-1984 were prone to fail in a similar fashion after awhile and/or read wonky in my experience. If the aftermarket sector just copied them, then there you go... Link to comment Share on other sites More sharing options...
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