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  • SN95 V6 Mustang Tech

Slow Turnover

  • Thread starter Thread starter matrdefndr
  • Start date Start date Jul 20, 2007
M

matrdefndr

New Member
Jul 19, 2007
4
0
0
Jul 20, 2007
#1
  • Jul 20, 2007
  • #1
Hello All,

This is my first post as a new member today. I found your message boards seeking information concerning my '98 V6 Mustang and I was wondering if any of the knowledgable folks here could give me out.

After an extremely hot day (98 degrees for the Northwest) my car began behaving odd when I tried to start it. Instead of cranking one or two times, it now requires approximately 20 times to turn over from a cold start. I have a brand new air filter, my plugs are clean and the battery is reading a stable 12.5 volts. (new as of spring last year) My alternator seems to be healthy as the overall voltage while operating is a steady 14.5 volts.

On a warm start, the engine will generally turn over like it used to with one or two cranks before this behavior started, although it does seem to slightly depend on how much time has passed since it was turned off. By slight, I mean the behavior usually recurs an hour after shutoff. Additionally while I'm driving, the engine seems to have the same power and responsiveness it always has had, so this seems to only be a case of when I start the vehicle, not while I'm driving.

I'm coming up with a blank, the only other things I can think of are the injectors may be dirty, the starter motor may be going out or those whiz bang electronics that all modern vehicles have may be on the fritz. Any ideas?

Thanks for the help!
 

cjones

Founding Member
Jul 20, 2002
1,561
0
37
Avondale, AZ
Jul 20, 2007
#2
  • Jul 20, 2007
  • #2
is the cranking speed normal(like it was)?? if not, what is the battery voltage when you are cranking the engine??

if so, what is the fuel pressure when cranking the engine?? the fuel pump should come on for 2 seconds when the key is ON to prime the system.
 
M

matrdefndr

New Member
Jul 19, 2007
4
0
0
Jul 20, 2007
#3
  • Jul 20, 2007
  • #3
cranking speed is normal; no slower cranking like I would expect with a dying battery.

The voltage on the battery during cranking dips to 11 volts plus or minus a few tenths.

I don't know how to determine fuel pressure on this vehicle. Directions?

I do hear an electronic noise for the duration between 1-2 second when the key is put in the ON position. I assume this is the fuel pump priming the system, since it isn't necessary for me to pump the gas like I would with a carb.

Thanks!
 

cjones

Founding Member
Jul 20, 2002
1,561
0
37
Avondale, AZ
Jul 21, 2007
#4
  • Jul 21, 2007
  • #4
there should be a test port on the fuel rail. you would hook up a pressure tester there.
with KOEO there should be should be 30-45psi. turn key OFF and pressure should not fall more than 5psi in one minute.

also, when it would normally have this symptom, turn the key ON for 2 seconds, OFF for 10 seconds, ON for 2, OFF for 10, ON for 2, OFF for 10 and then try to start. did it start right up??
 
M

matrdefndr

New Member
Jul 19, 2007
4
0
0
Jul 21, 2007
#5
  • Jul 21, 2007
  • #5
Unfortunately, I don't have a gauge right now that will fit with the test port on the fuel rail. I'll look into finding one if required further.

If I do the on/off sequence you describe, the engine turns over normally with no trouble. I would assume this indicates a possible fuel system leak. Do you know of any parts in this system with a tendency to fail over time?

Again, thank you for your assistance. I appreciate it.
 

cjones

Founding Member
Jul 20, 2002
1,561
0
37
Avondale, AZ
Jul 22, 2007
#6
  • Jul 22, 2007
  • #6
3 things will normally cause that.

faulty fuel pressure regulator - you'll need a pressure gauge and hose clamp(locking pliers designed to pinch a rubber hose without damage) to check it

faulty fuel pump check valve - you'll need a pressure gauge and 2 hose clamps(locking pliers designed to pinch a rubber hose without damage) to check it

leaking injector/injectors - you'll need a pressure gauge and 2 hose clamps(locking pliers designed to pinch a rubber hose without damage) to check it

also, check the fuel pressure regulator vacuum hose for fuel and along the fuel hoses/lines for leaks
 
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