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Why would a 1999 Mustang Cobra not be getting fuel even after installation of new fuel pump?
The car turns over but the pump doesn't pump fuel to the fuel rail. Fuel filter is new. We checked inertia shut off switch as well.
We let a relative drive it for two days while we went on vacation, it was parked for five days after that before we went back to pick it up. Everyone else swears it couldn't have been caused by bad gas (I personally think the relative put in some 86 octane instead of premium). They also say its not the gas cap, which can cause problems on Fords. Has about 10 gallons of 93 premium in the tank now.
This one has even stumped the neighbor who works at Ford testing engines. Please help!
The butterflies on the throttle body move the throttle cable, they are mechanical and do open and close. The fuel pump is installed correctly according to Ford installation instuctions from Headquarters. It is not getting electricity, the harnesses have all been plugged in correctly but something else is preventing it from getting power and turning on. Yes, we did check the fuses and used a volt meter to check for power. Fuel pump was ordered from a dealership new, it is not aftermarket. Thanks.
FYI - Today , we used an OBD tester and found that there were no stored codes.
The OBDII tester read no codes, except when the pressure sensor on the engine top was disconnected. We checked everything at the back of the car including the fuel pump driver module (fpdm) and all wires at the back of the car, the tester didn't notice when we disconected the fuel pump wires behind the bumper. In the end it turns out it was a wire going to the constant control relay module (ccrm) in the front passenger wheel well. The tire had rubbed a green wire with a red stripe in half. You could see a green spot on the other side of the splash guard. I had read about this about a week ago, another mustang owner wrote on a forum about it, but of course, I was "wrong" and my husband and his father had to be right. It wasn't until I stubbornly insisted that my husband check it, that he finally took a look. The lesson to be learned here is "check every wire first, even if you have to do it yourself and even a team of automotive engineers insist it is something else."
THANK YOU to everyone who answered, without your assistance we would not have been able to figure this one out. We truly appreciate your knowledge, experience and even your educated guesses. Thanks again.
10 Answers
- iamright2Lv 41 decade agoFavorite Answer
Do you have power at the pump? no power here problem is either Fuel pump Fuse,or Fuel pump relay. Power at pump, Bad pump.
- 1 decade ago
your fuel pump relay is bad.
or
the ECU is not commanding on, the said relay.
Stang, having a schematic for you car will be paid for 10 times over the day you get it.
get one. why not. $30k car and no $20 CD FSM. why?
the octane has nothing to do with this , forget it.
the pump gets power via the ECU.
by command.
for example you do not want the fuel pump running with out the engine running. it is dangerous to do so.
as is FP running in an accident or a ruptured gas line.
These are serious issues.
some cars even have a Fuel line pressure sensor.
if the ECU cant see pressure soon, it kills the pump.
again crash protection.
with out a schematic and the knowledge of these protective devices, you are just guessing.
thowing parts. spending money.
i could be just a bad connection in the dash.
schematic and a volt meter and do some easy trouble shooting.
BTW:
some cars pump gas for only 3 seconds at KEY ON.
others (like mazda) only pump when cranking and running and NEVER key on (no start)
see the vast differance there.
These are High rate pumps and need great respect.
just ask a firemen.
Another approach:
take the car to any shop and say.
sir, can i have a diagnosis ( after the tow)
and tell them not to fix it .
then based on the diagnosis , make you decisions.
You are out $100 for a tow and you saved wasting a ton of money on useless parts guessing.
Please accept that here are many ways to skin a cat.
if some one has a better way , Id like to hear it .
three choices.
I do
we do
they do.
its your car , do what is best for you.
I answered you and the other millions .
- ruskinflgatorLv 51 decade ago
First off-the difference in fuel doesn't matter-the pump doesn't care which grade of fuel, only th e engine computer does.
As to your pump problem, I'm assuming that the pump doesn't kick on, which would lead me to test the fuel pump driver module in the trunk, left side.
Its a little tricky to diagnose whether the main PCM or the fuel pump module is bad, but the basic test is to hook a fused Battery + wire to the red/black wire on the fuel driver module wiring connector(connector disconnected) and ground the brown/pink. If the pump runs, most likely its the pump module, but to be sure, the signal from the PCM needs to be verified. If the pump doesn't run with those two wires connected as I stated, then there's an "issue' in the wiring between the pump module and the pump itself. At the very least, disconnect the wiring harness from the pump module and check for continuity between those two wires-that would indicate an OK pump circuit, once again leaving the pump module or PCM as the culprit.
Source(s): ASE Mastertech - CoachLv 61 decade ago
Octane problem would not cause this either. Check the throttle body, the butterfly valve could be stuck shut not allowing air into the intake. You can also pull the fuel line off and make certain the pump is actually pumping. Just because its running does not mean its actually working. It could be clogged in the tank. GL
- 1 decade ago
have someone hear and see if the fuel pump runs for 2 or 3 seconds when you first turn the key on with out cranking it ...if it does not run check the fuses(might be a bad fuse) might be one for the fuel pump if OK make sure the pump is plugged in ..if OK it could be a bad fuel pump relay or a bad new pump..
- 1 decade ago
Not sure on the mustangs but i know some fords have a fuel pump shut off valve usually locate on passenger side kick panel usually a red button see if its depressed... some are in trunk area
- 1 decade ago
check if 12 volt is at the connector going to fuel pump if it is present than you have a poor ground for fuel pump. You need two thing for the pump to work 12volts and a good ground return to complete a current path for the pump to work
- Anonymous1 decade ago
there is a crimp in the gas line some where or a great big air pocket... Take the gas line off and blow through it and listen and see if you are bubbling in the gas tank if so hook it back up and try it again if it does not work then... there is some kind of a foul up in the carburator... Good luck... Grant from Pennsylvania
