My 1985 Thunderbird gave up on me a few days ago. The engine turns over and I've got spark at the plugs. I'm guessing its a fuel pump problem. Is there an easy way to check the fuel pump? Also, as I understand, the pump is in the tank. Is there top access or do I have to drop the tank. Last question: I've seen fuel pumps anywhere from $75 to $250. What should I be looking for? Any illustrations or procedures would be greatly appreciated. DLL
In all likelihood it's the fuel pump at this age, but, you need to check the voltage at the inertia switch in the trunk when you turn the key on. When you cycle the key, there should be voltage at both terminals for about 3 seconds. If so, it's the pump or wiring to the tank. If not, look to the fuel pump relay. I know it's a crude test, but give it a shot of ether. If it fires and dies then the problem is likely from the relay to the pump. If it doesn't fire it's a concern with the EEC-IV system. There is no access hole, you must remove the tank to get to the pump. It is mounted on the fuel sender assembly inside the tank. I don't know where you are located, but be prepared to replace the fuel sender assembly also. The tubes to the sender are prone to rust. Even if they don't leak now, once you disturb them they will. If the rust is light (and you are in a temperate climate) this won't be a concern. If the rust is "flaky" anywhere on either tube then replace the whole sender. The design of the tank puts the outside of the sender in a depression in the top of the tank. That depression holds moisture, dirt, mud, and SALT that splashes up there during use and leads to rust.
After typing all of this I remembered that your 85 may have 2 fuel pumps. If the car has fuel injection that looks kinda like a carburetor (CFI) then it does have 2 pumps. The system is a bit more complicated. One pump in the tank (low pressure) and one pump on the right frame rail (high pressure). Cycle the key from off to on and listen to the pump on the frame and at the tank. If one runs but not the other, the dead one is likely bad. If they both don't run, the problem is likely the relay or upstream in the circuit. The same caveats about rust on the tank sender apply.
Tom, You made a good point. I didn't think of it but the fuel pump does normally make a noise as soon as the key is turned before the starter hits. I'm going to check that this morning. Whether there is a sound or not will at least tell me more.
Thanks much, Dale L
Tom Adk>
Check the impact shut-off in the trunk, too. II think it sits atop the left rear wheel well. Big button on the top.
PoD
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