Intermittent starting issue...
#1
Intermittent starting issue...
My 99 2.5 5 speed with about 155K has run flawlessly in the year I have had it (used as a daily driver), but it just had a little hiccup. After sitting overnight (and it's finally starting to cool down here in Atlanta), it took a long time too start. The motor turned over fine, and everything seemed normal, but it was like the ignition was not generating spark. After much cranking it lit off, and ran flawlessly (including a re-start), so I drove it to work. Then, after sitting for 9 hours in the parking lot (and the day got pretty warm), it did the exact same thing.
The next morning I did the 3 cycle key turn procedure (researched here) and it fired right up, and I could definitely hear the fuel pump running for those 2 second intervals during each key cycle. Since then it has been starting normally and running perfectly, and my code reader shows no codes. I know nothing of the history of the truck before I owned it, other than it seems to have been reasonable well-maintained.
Anybody have any thoughts on what this might be? My searches on this site seem to point to a fuel pump issue, but now the truck is running the same as always. Normally this is the kind of thing I would not much worry about until it happens more frequently, but I often have to drive the super-highways here in Atlanta, and it would REALLY suck for the truck to fail on those roads. Thoughts? Thanks!
The next morning I did the 3 cycle key turn procedure (researched here) and it fired right up, and I could definitely hear the fuel pump running for those 2 second intervals during each key cycle. Since then it has been starting normally and running perfectly, and my code reader shows no codes. I know nothing of the history of the truck before I owned it, other than it seems to have been reasonable well-maintained.
Anybody have any thoughts on what this might be? My searches on this site seem to point to a fuel pump issue, but now the truck is running the same as always. Normally this is the kind of thing I would not much worry about until it happens more frequently, but I often have to drive the super-highways here in Atlanta, and it would REALLY suck for the truck to fail on those roads. Thoughts? Thanks!
#2
The cycling of the ignition from OFF to ON, pause, back to OFF runs the pump. If the engine won't start w/o doing the cycles, then the likely problem is lack of fuel in the fuel rail that feeds the injectors. Cycling the key runs the pump and fills the fuel rail and pressurizes the fuel. If there is lack of fuel in the rail after sitting, it is one of several things.(none of which should make driving the perimeter a problem)
Things that allow fuel to drainback 1)check valve in fuel pump 2)leaky injector(s) 3)leaking fuel line. For 2, you'd likely have too much fuel in the intake and it might belch some black smoke on startup, for 3 you'd likely get the odor thing and for 1, it would just be harder to start. One last thing is on system that circulate the fuel not used back to the tank, there's a check valve in the regulator that could fail.
tom
Things that allow fuel to drainback 1)check valve in fuel pump 2)leaky injector(s) 3)leaking fuel line. For 2, you'd likely have too much fuel in the intake and it might belch some black smoke on startup, for 3 you'd likely get the odor thing and for 1, it would just be harder to start. One last thing is on system that circulate the fuel not used back to the tank, there's a check valve in the regulator that could fail.
tom
#3
Thanks Tom! That is very helpful. I never get any smoke on startup or other poor running symptoms. I have on occasion thought I caught a whiff of gas, but I am so frequently carrying dirt bikes or other gas leaking things I have never been sure. I will pay more attention to the things you suggest and trace the fuel line to check for leaks.
#4
#5
Starting in 1998 Rangers the fuel system was switch to Returnless(1 fuel line), and fuel pressure was put up to 60-70psi.
Earlier Rangers used 2 fuel lines and 30-40psi
In the Fuel pumps of both systems is a Check Valve, part of fuel pump.
It is basically just a "flap", it is pushed open when pump is running and then closes when pump is off.
This is needed to hold fuel pressure at the injectors while engine/pump is off.
On the older systems there was a fuel pressure regulator that could leak so fuel pressure could drop to 0psi while engine was off, if it was bad.
On the newer system there is just the fuel pump check valve or the fuel injectors that can cause fuel pressure to drop when engine is off.
(the newer system does have a pressure Damper at the end of the fuel rail, by firewall, it could leak pressure, but long shot and engine would run Rich)
A leaking injector will almost always cause Rich running code, so in the absence of any codes I would say the Check Valve in the fuel pump is leaking pressure when engine is off.
No fuel is being lost, so there should be no smell of gasoline, fuel is just leaking back into the tank.
If there was a leaking fuel line the smell would be constant, not once in awhile.
Leaking Check Valve can be over come by cycling key on and off after truck has been off for awhile, it will tend to get worse as time goes by, just FYI.
But failing Check Valve only effects fuel system when engine/pump is OFF, it has no effect on the system when engine is running.
So there should be no driving issues
Earlier Rangers used 2 fuel lines and 30-40psi
In the Fuel pumps of both systems is a Check Valve, part of fuel pump.
It is basically just a "flap", it is pushed open when pump is running and then closes when pump is off.
This is needed to hold fuel pressure at the injectors while engine/pump is off.
On the older systems there was a fuel pressure regulator that could leak so fuel pressure could drop to 0psi while engine was off, if it was bad.
On the newer system there is just the fuel pump check valve or the fuel injectors that can cause fuel pressure to drop when engine is off.
(the newer system does have a pressure Damper at the end of the fuel rail, by firewall, it could leak pressure, but long shot and engine would run Rich)
A leaking injector will almost always cause Rich running code, so in the absence of any codes I would say the Check Valve in the fuel pump is leaking pressure when engine is off.
No fuel is being lost, so there should be no smell of gasoline, fuel is just leaking back into the tank.
If there was a leaking fuel line the smell would be constant, not once in awhile.
Leaking Check Valve can be over come by cycling key on and off after truck has been off for awhile, it will tend to get worse as time goes by, just FYI.
But failing Check Valve only effects fuel system when engine/pump is OFF, it has no effect on the system when engine is running.
So there should be no driving issues
Last edited by RonD; 11-20-2016 at 01:01 PM.
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