No fuel condition, 1984 Marquis/CV
 

Mercury badge, but should be the same as the Crown Victoria - 1984 Mercury Colony Park wagon with 302 and throttle body FI.

It’s been sitting for a while. Currently it starts and runs with starting fluid. I have confirmed no power to the fuel pump and no fuel flow at the engine. What I’ve checked so far:

drained tank and added fresh gas
could not get it running except with fluid
confirmed pump was not turning on by listening at the back of the car
checked for voltage at the pump, confirmed no power
checked inertia switch, found it had been tripped, reset it with no change
tested and replaced bad fuel pump relay, no change

i figure at this point it’s either an open circuit in the pump harness or there is no voltage at the upstream side of the relay. I don’t know much about this particular era of Fords, are there any common issues that would make either of those more likely, or perhaps a third option I haven’t thought of?

thanks for any help

Welcome to the site..

If the relay was bad, and no other issues, replacing it should have provided current to the inertia. If the inertia switched was closed, current then should be present at the pump connector. If the inertia isn't hot/active, look back towards the relay. You can do some testing on the relays connector base for switched, and load supply voltages, as well as a ground supplied to close the relay. Does the relay 'click when the key is cycled. Computer supplies fuel pump ground for timed ops no start/cranking, and continuous grounding for run times..

I tested the inertia switch and it functions like it should. I’ve got 12 volts at the pump power wire into the relay with the ignition switch on, but only 6v going out of the relay to the pump. That’s weird. If the power is there, it doesn’t make sense that there would not be the same amount coming out when the ground is made. I’m going to try jumping the two and bypassing the relay to see if the pump comes on. I don’t think it will because I still have 0v at the pump connector.

I think maybe the meter doesn’t have time to settle out before the power to the relay is cut off. I put a jumper across the two pump power wires to bypass the relay. The pump doesn’t come on but with the extra time I was able to get a much better ground for the tester and I’ve got 12v at the pump connector, so it looks like the next step is replacing the pump. The only question is which one - this car only has one fuel pump in the tank rather than a low pressure in the tank and a high pressure on the frame rail.

There is a terminal in the diagnostic plug that when that terminal is grounded with the key on the fuel pump should run. That check when done should answer if the fuel pump is operating. Don't forget to make sure it has a good ground connection back there. Also , if you got hold of a fuel pressure gauge and connected it to the fitting on the fuel rail, with the pump operating you could confirm if it is producing the correct pressure.

Thanks for the help guys. Pulled the tank out of the car. I can see why the pump failed. The strainer wasn’t even attached to the intake.


https://cimg2.ibsrv.net/gimg/www.for...3d0d7b924.jpeg

Just ordered a new sending unit, fuel pump, and gas tank. The old tank has about 2 inches of rust flakes in the bottom, and the float on the sending unit was full of rust holes. The guy I bought the car from said he last drove it two years ago but I think it was probably closer to 8 years. Everything else looks good, so hopefully it will run fine once I get this taken care of.

Glad you are replacing the tank too.

If you forgot, it might be a VERY good move to blow out the lines from the tank to the fuel filter. As you know garbage that gets into the pump can destroy it. Some of that garbage can be floating around in the lines and everything you can clean out now will pay off up the road.