Possible fuel pump issues in 05 gt?

David Calvo

Junior Member
Joined
Jan 27, 2020
Posts
8
Reaction score
0
Just bought an 05 GT and the fuel gauge wasn’t working so I swapped in a v6 fuel pump pump with fuel level sender and fixed a wire (wire to the fuel pump connector had been cut so I just reconnected it and the v8 fuel pump started reading the correct fuel level again too) and it worked for around an hour so I swapped the original v8 pump back in and I began facing the same issue from that point on. Issue is the car dies while driving and then won’t turn back on. It was able to turn on and run with the v6 fuel pump but I didn’t prime it (key on/off 5 or so times) yet it started up just fine, I drove around, parked it turned it off, and drove around some more until I got to a friends house where I was parked just idling and around 5 minutes in the engine just turned off. I was already driving it for around an hour so I’m not sure what could have happened. Once I swapped the v8 fuel pump back in the same thing started happening. It would take awhile to turn on and once it was on would only drive for a few minutes and then die and not be able to turn back on. Any ideas on possible fixes? Today I unplugged the fuel pump and reconnected it to make sure it was connected right and then I turned it on and it idle for around an hour until it shut off on its own. I just bought this car and plan on fixing things myself. I’m thinking camshafts sensor or fuel pressure regulator but I’m open to more ideas before I start spending money. Thanks
 

Midlife Crises

Senior Member
Joined
Jul 20, 2019
Posts
1,836
Reaction score
1,253
The first thing I would check is the pins and sockets in the connectors at the fuel pump hat and the fuel pump control module. These connectors are fragile and easy damage. A data log or analysis showing fuel pressure, pump voltage and duty cycle would be most helpful.
 

JeremyH

3V Fuel Guru
S197 Team Member
Joined
Jan 10, 2009
Posts
20,857
Reaction score
197
Location
Virginia Beach
The v6 and v8 pumps are the same. Not sure I followed your troubleshooting you listed 100% but if the v6 pump fixes theres no issue running it.

Just so your are aware, there is a hot start hesitation stumble shut off tsb associated with the 05/06 fuel hat. Fords solution is to replace with 07-09 fuel hat.

Since you found a cut wire suspect all that wiring to the hat plug as well.

There is no traditional fuel pressure regulator on the returnless ststem but a frps on the rail. If theres an issue it will usually throw a code same for cam position sensor.
 

David Calvo

Junior Member
Joined
Jan 27, 2020
Posts
8
Reaction score
0
I’ll check the wiring for the fuel pump again later today but I just think it’s very strange how on 3 different startups it was able to run for between an hour to an hour and a half and then after that it just died and wouldn’t turn on and would only crank no start. I may try putting the v6 pump back in after checking the wires and see how that goes.
 

Juice

forum member
Joined
Aug 24, 2017
Posts
4,622
Reaction score
1,904
Fuel pumps usually fail in that way. Run for a while and quit.
If you ever get stranded and think it maybe a bad pump, bang on the bottom of the gastank. That usually gets the pump running again, and you can be pretty sure its a bad pump.
 

David Calvo

Junior Member
Joined
Jan 27, 2020
Posts
8
Reaction score
0
The v6 and v8 pumps are the same. Not sure I followed your troubleshooting you listed 100% but if the v6 pump fixes theres no issue running it.

Just so your are aware, there is a hot start hesitation stumble shut off tsb associated with the 05/06 fuel hat. Fords solution is to replace with 07-09 fuel hat.

Since you found a cut wire suspect all that wiring to the hat plug as well.

There is no traditional fuel pressure regulator on the returnless ststem but a frps on the rail. If theres an issue it will usually throw a code same for cam position sensor.

Once I swapped in the v6 pump an hour later the car stalled out. I swapped in the original v8 pump back in and same thing. Car kept stalling while driving. All because I was trying to fix my fuel gauge which wasn’t working because of a cut wire smh. Anyways I rented a fuel pressure test kit and I’m about to see if the original v8 pump is supplying enough pressure and check if any more wires look cut. Last time I checked they looked crimped pretty good right before the connector but I didn’t follow it up much.
 

Midlife Crises

Senior Member
Joined
Jul 20, 2019
Posts
1,836
Reaction score
1,253
Are you saying it runs and dies with either pump? If so, that tells me the problem is not the pump. Wiring that has been pinched can be broken inside the insulation and make intermittent connection. Poor connections cause voltage drop under load and over heat components.
Find a friend or shop that can plug into your OBD port and you can see what the fuel system is doing. Pressure, pump voltage, pump command, duty cycle. There is a Lott of info available in real time. Jiggle wires while watching pressure and voltage !!!
 

JeremyH

3V Fuel Guru
S197 Team Member
Joined
Jan 10, 2009
Posts
20,857
Reaction score
197
Location
Virginia Beach
Theres not a spot on the rail to read pressure without a special adaptor but you can read it with a obd2 dongle like mentioned above. They are pretty cheap if you dont have one. Invaluable troubleshooting tool. I have been Using a blue driver with the app on my phone for about 5 years now.
 

David Calvo

Junior Member
Joined
Jan 27, 2020
Posts
8
Reaction score
0
Are you saying it runs and dies with either pump? If so, that tells me the problem is not the pump. Wiring that has been pinched can be broken inside the insulation and make intermittent connection. Poor connections cause voltage drop under load and over heat components.
Find a friend or shop that can plug into your OBD port and you can see what the fuel system is doing. Pressure, pump voltage, pump command, duty cycle. There is a Lott of info available in real time. Jiggle wires while watching pressure and voltage !!!
Yes, it runs and stalls with both fuel pumps but it first died when I installed the v6 pump so that made me think the v6 and v8 pumps were different (btw the v6 pump was yellowish plastic vs the v8 pump was white plastic) so that’s when I put the v8 pump back yet kept facing the same issue of stalling while driving.

Today I turned it on and it started right away and I drove it a few miles in various steep hills without it turning off. All I did was disconnect the electrical connectors and plug them back in but I didn’t leave it running as long as I have been when it stalls (usually an hour-1.5). Car is a wiring mess in the engine bay as well so I’m almost certain I will be facing more of this/other issues in the future. Car was just dirt cheap and I couldn’t pass up haha
 

Midlife Crises

Senior Member
Joined
Jul 20, 2019
Posts
1,836
Reaction score
1,253
I use the AutoEnginuity system loaded into a laptop for multiple vehicles. I also use the SCT data log system in the same laptop for Mustang only troubleshooting and programming. The SCT is easier to use. I don’t think it is possible to work on these vehicles without tools of this type. Or I should say, it is a great deal less frustrating.
 

Latest posts

Support us!

Support Us - Become A Supporting Member Today!

Click Here For Details

Sponsor Links

Banner image
Back
Top