This is topic What could be causing my car to do this?? in forum Tech Talk at Northern California Ford Owners  .


To visit this topic, use this URL:
https://californiafords.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=011548

---

Posted by RioredGT (Member # 2300) on :
 
My 98 GT has been giving me problems lately. After driving it around (it's always happened when running errands) for a couple hours I'll park it and come back to turn it on five minutes later and it won't start. It tries to turn on(with a very, very rough idle) but it dies right away. It sounds like a car with no gas eventhough it has a 3/4 tank. Then if I let the car sit for 15 minutes it starts up just fine. Each time it's happened to me(last night was the third time) I've had to let it sit for longer periods of time. It's gotten to the point where I had to have someone pick me up and then go back and pick my car up later when it starts up just fine.

I'm almost certain it's fuel related. Could it be a bad fuel pump? Since it's happening intermittently how can I check it? I replaced my fuel filter about 10K miles ago so I'm thinking that's ok. Any ideas?
Any help would be appreciated.
 

---

Posted by blind (Member # 3052) on :
 
get a fuel pressure guage and hook it up to it when its running fine, then drive it for awhile and keep it with you in the car, when it acts up put the guage on while you are trying to start it.
 

---

Posted by TRIXSNK (Member # 2844) on :
 


[ July 05, 2005, 15:20: Message edited by: TRIXSNK ]
 

---

Posted by RioredGT (Member # 2300) on :
 

quote:

---

Originally posted by blind:
get a fuel pressure guage and hook it up to it when its running fine, then drive it for awhile and keep it with you in the car, when it acts up put the guage on while you are trying to start it.

---

Cool, thanks for the idea.I'm assuming a basic mechanical gauge, something I can pick up at the local parts store, is all I need?? Will this tell me that it's the fuel pump that is bad? Also, off hand do you know what PSi's my cars pressure is supposed to be at?
 

---

Posted by SmokinLX (Member # 1684) on :
 
How many miles are on the car? stock fuel pump still in there?
 

---

Posted by RioredGT (Member # 2300) on :
 
The car is a 98 GT but only has ~45K miles and yes the stock fuel pump is still on there. The car itself is pretty much stock as far as engine mods go. Only has full exhaust and K&N FIPK.

[ July 05, 2005, 20:48: Message edited by: RioredGT ]
 

---

Posted by blind (Member # 3052) on :
 
if while you are trying to restart and the fuel pressure is lower than when its running normal then I'd say its the fuel pump.

I have no idea what a 2v 4.6L should be at for fuel PSI stock, a 5.0 is 36psi with the vacume on is all I know

the mechanical guage is what I bought from kragen when my fuel pump died, it confirmed I had 0 fuel PSI when it would die, it was also reading around 20psi instead of 36 when it was running. Stupid guage was $50 but I was able to return it
 

---

Posted by RioredGT (Member # 2300) on :
 
I just went out a bought a Fuel Pressure tester(a gauge and bunch of attachments) and hooked it up. Turned the ignition and the gauge jumped to 30 psi and the same when I turned the car on and let it idle. Any one know if the 30 psi is what it's supposed to read?? I'm assuming it is since it's running fine.

Hopefully now that I have the gauge it will tell me something when the car decides to act up.
 

---

Posted by RioredGT (Member # 2300) on :
 

quote:

---

Originally posted by blind:
if while you are trying to restart and the fuel pressure is lower than when its running normal then I'd say its the fuel pump.

I have no idea what a 2v 4.6L should be at for fuel PSI stock, a 5.0 is 36psi with the vacume on is all I know

the mechanical guage is what I bought from kragen when my fuel pump died, it confirmed I had 0 fuel PSI when it would die, it was also reading around 20psi instead of 36 when it was running. Stupid guage was $50 but I was able to return it

---

Thanks for your help...
 

---

Posted by Brian Keegan (Member # 648) on :
 
I know very little about Mustangs as I sell Ferrari parts. This symptom, a "hot re-start problem" on the Ferrari's is the result of a failed check valve. The check valve is supposed to keep the fuel system pressurized to factory specs (whatever PSI that is). If the check valve fails, the pressure bleeds off, so when you hit the key the fuel pump has to run long enough to build the pressure up to specs before the car will start AND run properly. You can hook up the gauge as someone suggested, that's a good idea. Next time the car won't start, see if you can hear the fuel pump run with the key in the "ON" position. If not, gently turn the key toward the "START" position WITHOUT engaging the starter until you hear the pump run for say 10-15 seconds.
Then try and start the car.
Good Luck.
 

---