97 Grand Marquis

start
mercury

#1

97 Grand Marquis 4.7 V8 won’t start. The cas has sat in the driveway for a few weeks. It may not be getting gas or the gas has water in it. I tried starting fluid but the engine would not keep running.


#2

Turn the ignition switch to the run position so the dash lights come on for two seconds, and turn the ignition off. Repeat this a dozen times and then try starting the engine. This should cycle the fuel pump enough times to reprime the fuel system since the vehicle sat for a few weeks.

Tester


#3

When you turn the key to run, do you hear the fuel pump running for a few seconds?


#4

No, I do not hear the fuel pump come on. I measured the voltage and it was only 3 volts DC.


#5

Keeping in mind that I do not have a wiring schematic for this car and anything I say is a pretty much a wild guess, maybe this car uses a VLCM (variable load control module).
This module provides varying voltages to the fuel pump, cooling fans, etc. and throws yet another complexity monkey wrench into things.

Scanning for codes may reveal something but with a non-running car and without a scan tool you’re facing another snag.

I do have a wiring book for a Lincoln Mark VIII and these cars also use a VLCM. Will take a look at the schematic on that later and see if something there will mesh with the problem you’re having.


#6

Actually, the 97 is still a return type fuel system and the fuel pump should get full power all the time it is running. I think that they switched to returnless sometime in the 03 to 05 years. Those systems do drive the fuel pumps at variable power levels.


#7

How are you measuring the voltage? Where are you connecting your ground probe?
Measure the battery voltage. (I assume that it is good, but you shouldn’t make assumptions.)
Measure the voltage at the fuel pump fuse.
Measure the voltage at the fuel pump relay.
Measure at the inertial switch.
Measure at the pump.
Use the same ground reference point for each of these measurements.


#8

No wonder nobody can fix these new electronic marvels…VLCM ?? Sounds like a lot of fun…

I wonder how many new cars, at the end of the assembly line, won’t start or run…They must be pushed out the door and towed to a repair shop…


#9

My wrecked '94 Lincoln Mark and my current '96 Mark both have a VLCM so it’s been around a while.
Just another worthless feature IMO; along with the fuel line temperature sensors, variable intake runners, and numerous other electronic widgets.

Your comment about not running at the end of the assembly line is pretty funny Caddyman!
I got a good laugh out of that one but there may be an element of truth to it and wonder if car makers have an in-house repair facility to send the problem children that exit the line?


#10

They most certainly do! “No starts” at the end of the line are fairly common. But today, I can see it becoming overwhelming…Next to the repair shop is a body shop to take care of most of the little exterior imperfections…Many cars with “factory installed sun-roofs” would finish their assembly process here…


#11

Well, I had a 99 and a 2000 Grand Marquis, and neither had variable fuel pump power. I have two Lincolns now, and both of those do. My in-laws have a 2005 Grand Marquis, and it does have variable fuel pump power (returnless fuel system).


#12

I’ll take your word for it. What I suggested was just a wild guess seeing as how both of my Lincolns have the VLCM.

Question. Do the Mercurys of this vintage use a pump control module which varies the speed?
The schematic on my Lincolns show a VLCM which is tied in with the PCM and they also use a fuel pump control module. (which is not the pump relay)

The reason I was going this route is because of the low voltage. Stepped down voltage to the pump could be dropped a lot lower on an aged pump and clogged filter. The current draw will go up due to a worn pump and this means the voltage would drop even lower.

I can see the end of the assembly line now: “YO BOB! Grab the hook. We gotta 'nother one”.
:slight_smile:


#13

I understand the conjecture, and I can understand why. However, the 94, 99, and 2000 I had all had the old fashion return type fuel system. (I know that Lincoln was using the pump control returnless systems by 2000, and that Mercury was using them by 2005.)