2000 4.0 OHC starting problem
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Joined: Oct 2006
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From: honolulu, hawaii
2000 4.0 OHC starting problem
Hopefully someone can help with a problem I am having with my 2000 SuperCab with a 4.0 OHC V-6.
When attempting to start the engine it will fire up with the normal cold engine fast idle, then immediately run very rough and stall. It will restart right away then die off. The problem is reminiscent of Chrysler products from the 60-70's with a bad ballast resistor.
Feathering the throttle does nothing at all to improve it, neither does attempting to start it with the throttle opened in various degrees.
The fuel pump and fuel filter (Motorcraft) were replaced a year ago because of a no start condition, the fuel system pressure (measured at the fuel rail schraeder valve) is 41 psi with the fuel pump hot wired at the relay. I've even attempted to start it with the relay removed and the circuit jumped so that the pump runs constantly, to no avail.
Fuel is fresh, there are zero MIL codes thrown, the coolant temperature sensor (CT) checks out OK, the PCV valve vacuum hose is intact, this problem came on suddenly, with no symptoms whatsoever.
The truck has 98K miles on it and I am the original owner.
Stumped here...
When attempting to start the engine it will fire up with the normal cold engine fast idle, then immediately run very rough and stall. It will restart right away then die off. The problem is reminiscent of Chrysler products from the 60-70's with a bad ballast resistor.
Feathering the throttle does nothing at all to improve it, neither does attempting to start it with the throttle opened in various degrees.
The fuel pump and fuel filter (Motorcraft) were replaced a year ago because of a no start condition, the fuel system pressure (measured at the fuel rail schraeder valve) is 41 psi with the fuel pump hot wired at the relay. I've even attempted to start it with the relay removed and the circuit jumped so that the pump runs constantly, to no avail.
Fuel is fresh, there are zero MIL codes thrown, the coolant temperature sensor (CT) checks out OK, the PCV valve vacuum hose is intact, this problem came on suddenly, with no symptoms whatsoever.
The truck has 98K miles on it and I am the original owner.
Stumped here...
2000 Ranger would have the 4.0l OHV
2001-2011 had the SOHC model
Check or replace ECT(engine coolant temp) sensor, this sensor tells computer when to set Choke Mode, i.e. when engine is cold it needs to run rich then slowly leaned out over the next 5 minutes of running
The high idle at startup usually means ECT is working, but.............it may be faulty and drops voltage down to under 1volt(engine warm) within a few seconds instead of a few minutes
ECT gets 5volts from computer, it sends back 2.5-3.5volts cold, under 1volt warmed up, inspect its connector as well, corrosion can cause this
41psi fuel pressure is a little low for 2000, expected is 55psi, 1997 and older ran 30-40psi(return), 1998 and up 50-60psi(returnless)
Don't think thats your problem, just mentioning it
2001-2011 had the SOHC model
Check or replace ECT(engine coolant temp) sensor, this sensor tells computer when to set Choke Mode, i.e. when engine is cold it needs to run rich then slowly leaned out over the next 5 minutes of running
The high idle at startup usually means ECT is working, but.............it may be faulty and drops voltage down to under 1volt(engine warm) within a few seconds instead of a few minutes
ECT gets 5volts from computer, it sends back 2.5-3.5volts cold, under 1volt warmed up, inspect its connector as well, corrosion can cause this
41psi fuel pressure is a little low for 2000, expected is 55psi, 1997 and older ran 30-40psi(return), 1998 and up 50-60psi(returnless)
Don't think thats your problem, just mentioning it
Last edited by RonD; Oct 11, 2019 at 03:54 PM.
Thread Starter
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Member
Joined: Oct 2006
Posts: 47
Likes: 1
From: honolulu, hawaii
Thanks
2000 Ranger would have the 4.0l OHV
2001-2011 had the SOHC model
Check or replace ECT(engine coolant temp) sensor, this sensor tells computer when to set Choke Mode, i.e. when engine is cold it needs to run rich then slowly leaned out over the next 5 minutes of running
The high idle at startup usually means ECT is working, but.............it may be faulty and drops voltage down to under 1volt(engine warm) within a few seconds instead of a few minutes
ECT gets 5volts from computer, it sends back 2.5-3.5volts cold, under 1volt warmed up
41psi fuel pressure is a little low for 2000, expected is 55psi, 1997 and older ran 30-40psi, 1998 and up 50-60psi
Don't think thats your problem, just mentioning it
2001-2011 had the SOHC model
Check or replace ECT(engine coolant temp) sensor, this sensor tells computer when to set Choke Mode, i.e. when engine is cold it needs to run rich then slowly leaned out over the next 5 minutes of running
The high idle at startup usually means ECT is working, but.............it may be faulty and drops voltage down to under 1volt(engine warm) within a few seconds instead of a few minutes
ECT gets 5volts from computer, it sends back 2.5-3.5volts cold, under 1volt warmed up
41psi fuel pressure is a little low for 2000, expected is 55psi, 1997 and older ran 30-40psi, 1998 and up 50-60psi
Don't think thats your problem, just mentioning it
BTW I am so glad that I bought this truck new in November 1999 and that it has the 4.0 OHV and not the OHC engine, which I've heard is a POS.
4.0l SOHC had faulty timing chain tensioners from 1997 to 2003/4, after that they were fine, and igf older ones are upgraded then they will be fine as well
40 ohms is not valid for ECT
Set OHM scale to 1,000(1k)
if outside temp is say 70deg, and engine is as well, cold, should see 37,000 ohm so 37 on 1k scale
At 200degF engine warm, should see 2,500, 2.5k
40 ohms is not valid for ECT
Set OHM scale to 1,000(1k)
if outside temp is say 70deg, and engine is as well, cold, should see 37,000 ohm so 37 on 1k scale
At 200degF engine warm, should see 2,500, 2.5k
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