If any of you have not been following, here is the situation. I have a 1988
Mercury Grand Marquis, with 93,000mi that I just drove close to 3000 miles
across country with absolutely no problems. A few days after arriving here,
the car wouldn't start. I replaced the battery (twice) and the EEC and fuel
pump relays. Still no start. I am trying to decipher the posts here to
check things out further. I am systematically going through each suggestion
here starting with the obvious ones first:
1) I have checked the inertia switch ('crash switch), it is okay and
2) I sprayed starter fluid in the air filter passageway to the fuel injector
housing. Car starts up great, then stops.
3) I 'hotwired' the fuel pump (added extra ground from the tank to frame to
be safe), pump kicked on okay.
4) I have now checked for spark by using a screw driver in the spark plug
wire. It sparks well (not weakly).
5) Checked all wires going to the relay for insulation breaks, found one
small one, replaced with electrical tape.
6) Checked the wires going from the fuel pump relay, through the inertia
switch, to the fuel pump by hotwiring that circuit only (small pulses of
juice). Fuel pump turns on.
The wiring diagrams that I am using (matches my relay wires) are here:
If I have done the ECM test properly (following Thomas's suggestion), then
the ECM may be the problem. I hooked a jumper wire into the socket of the
tan/lt grn wire of the relay. I DID NOT jumper the yellow to orange wire
(see link above) sockets. I attached the jumper wire to the hot side of my
multimeter and grounded the other side. I cranked the engine over. I did
not get any reading with the multimeter setting at 10. Could someone tell
me if I am doing this right?
Thank you and take care, Sharon
addendum per Stan's suggestion:
I put the fuel pump relay back in it's socket, used my multimeter to test
the tan/lt grn wire for any movement when I turned the key in the 'run'
position (not cranking). Flatline, it never moved.
With the ignition turned on, do you have 12 volts at the red wire
going to the fuel pump relay?
(There should be)
If you ground the tan/lt green wire at the the EEC self test
connector, does the engine run?
(this will mimmic what the ECM does to ground the fuel pump
relay, which is; pulls that side of the relay winding to ground)
pump relay, which is; pulls that side of the relay winding to ground)
I actually stripped the insulation off of the tan/lt grn wire to get a good
connection for the alligator clip. I clipped the other side to the ground
at the self tester. Car will not start. Cranks, but no gas. I even tried
inserting a bare wire into that ground connection to make sure I was getting
a good metal to metal connection. Still, no start. There are already two
wires that are tan lt/grn coming into that tester. I would think they make
the ground ok. I am going to try one other thing. Nope, that didn't work
either. I tried grounding the ground off the self test plug. Just to make
sure IT was grounded. Then I tried doing a straight ground off the tan/lt
grn wire on the relay. Still nothing.
Any other suggestions? Thanks for helping. Take Care, Sharon
Sounds like either the red wire or tan/lt grn wire is not conected to the
It could also be a bad relay but I don't think so.
I would test the relay just to be sure it is good.
Take the relay out of the socket and put +12 volt on the conector that would
go to the red wire and then ground the conector that would go to the tan/lt
grn wire and it should click.
wrote in message news:nonelson->
Okay, in a round about way, you did connect the tan/lt green wire
to ground as i directed. This -should- have forced the relay
closed and turned on the fuel pump.
How does the new fuel pump relay compare to the old one
physically? Is it the same shape, same color, same terminal
configuration? Is there a Ford part number on it, is it the same
as the old relay? If you look at the terminal end of the new
relay, do you see any numbers that identify the terminals,
numbers such as; 85, 86, 87 30, 87a, ?
I'm thinking that AutoZone sold you the wrong relay, you have
power to the primary (red wire) you by-passed the ECM when you
grounded the tan/lt green, you can make the pump run by jumpering
the secondary, so the only thing left is that the terminals in
the relay connector aren't properly matching the terminals on the
relay itself. Two seconds (or so) after you turn the key on you
should be able to measure 12 volts at the tan lt/green wire, you
can take the measurement anywhere in the circuit, at the relay
itself, at the EEC self test connector, from your posts so far,
you haven't seen 12 volts at the tan/ lt green under any
circumstances when the key is switched on, this means that the 12
volts on the red wire are not making their way thru the relay
coil windings, either because of an open in the windings or
because the terminals don't match up.
No, it is not. There are more terminals on it (5 vs. 4) and it is black and
grey, but it is the part number that both PartsAmerica and AutoZone show for
my car and cross reference to the old part number.
I couldn't agree with you more, that is why I took the original 'new relay'
back to AutoZone and went through all their info. They swear that the extra
terminal is not used.
Take Care, Sharon
I'd have a lot more confidence in that relay if it came from a
NAPA, CarQuest or from a Ford dealership. Autozone, Parts
America and other such bubble pack palaces tend to sell offshore
third world built junk which often times does not work correctly
out of the box. The only way to know for sure if that fuel punp
relay is correct would be to pry off the cover and physically
trace down the terminals to their respective contacts and coil
Sounds like a version of the Bosch ISO relay which is somewhat
popular for certain automotive applications, it has five
terminals, two for the coil winding, one hot, one normally
closed, one normally open. If the terminals were numbered, it
would be pretty easy to direct you as to which colored wire
should go to which terminal.
Some testing which you can do in the morning, weather
voltmeter negative (black) lead connected to battery negative,
relay unplugged from socket;
Yellow relay wire reads 12 volts always (it should)
Red relay wire reads 12 volts with key switched on (it should)
Jumpering the yellow wire to the orange wire, the car starts and
runs (it should)
Switch your meter to ohms or continuity test;
red lead on (touching)the tan/lt green wire at the relay socket,
black meter lead on (touching) ECM connector harness terminal 22,
meter shows low ohms or continuity (it should).
I just went out and tried to start the car, several times. Then I went to
the self test connector and hooked it up with a paper clip. No flashes of
the engine light. So, even though this car cannot start, IT thinks it is
just fine. LOL "A better Ford idea!" Thanks and take care, Sharon
OK, I looked at the diagram, at the relay. Using a12 volt test light.
Yellow wire- should have 12 volts all the time, check it while cranking the
If it does have 12 volts all the time, remove the relay. With a jumper wire,
jump from the yellow to the orange wire. The pump should run and the car
should start. Please dont say cranks over if you mean running. Cranks is the
starter cranking the engine, starts is the engine actually running. If it
starts, then say it runs or it starts. Sorry but it can get confusing. Post
back with your results. Maybe if we do this one step at a time we can
firgure it out.
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