Did the LS swap into my 86 K5 blazer and I'm using the obs dash and gages. Since the truck was originally carburated, the fuel gage sending unit did not have mount for electric fuel pump. Installed a sending unit and fuel pump assembly from a 97 truck. Fuel pump and everything works fine except gage shows full all the time. Is there a certain value resistor I could splice in to compensate for the difference in the senders?
Use a multi-meter and measure the sending unit values (out of the tank, so you can move the float) and then check it again in-tank to make sure it's moving. Then you'll need to read the original one and see where your difference is. I personally would have gutted the stock pump and just ran a siphon tube with an external pump. (this would also mean no more dropping the tank if your pump dies!)
And is it possible the float is just stuck at the top of the tank? The idiots at o'reilleys gave me a yukon XL pump for my yukon and the only difference was the float arm would catch at the top of the tank and hang there, reading full. Pulled the damn tank 3 times to figure that one out. Thought it could be a possibility if you're using miss-matched pump and tank.
yep, I've thought about the advantage of the external pump now, live and learn, this is my first ls swap. But yes, I read the resistance range on the original and my friend has another sending unit like the one I put in, gonna measure that one, then calculate what resistor I'd need to splice in. Just thought someone might have already figured it out. Thanks for the reply.