1999 4.0 hard starting at times
#1
01-15-2018
1999 4.0 hard starting at times
I have a 1999 4x4 4.0 4dr and it has a hard starting problem at times. I got a factory rebuilt 18k ago and was running fine until the end of December when the temp out side dropped to freezing and below at night. I live in Northern California. Sometimes it will start at the first hit and others (usually after it has been started in the morning) it will crank for awhile before it fires off, and it always starts. Replaced the crank positioning sensor (had the problem many times B 4) and it did not change. Once started it seems to run ok.
Question: could it be a fuel related problem (injectors? put cleaner in, no change) or do I have a vacuum leak some where. Or am I having this problem because the state changed to the winter formula gas 90/10 and the ethanol batch sucks or will not ignite because of the cold temps outside?
Question: could it be a fuel related problem (injectors? put cleaner in, no change) or do I have a vacuum leak some where. Or am I having this problem because the state changed to the winter formula gas 90/10 and the ethanol batch sucks or will not ignite because of the cold temps outside?
#2
01-16-2018
Cycle key on and off 3 times before trying to start engine.
This will build up any lost fuel pressure
1998 and up Ranger needs 55-65psi fuel pressure, fuel pump has a check valve/back flow preventer built in to hold pressure when it is off, but these can leak.
Fuel Filter may also be a 3 hose model which also has a valve that can leak pressure, gas flows back to the tank.
So if truck sits for a few hours fuel pressure can drop to 0psi
Each time you turn on the key the computer runs fuel pump for 2 seconds to Prime the system, this adds 10-15psi of pressure.
So cycling the key on and off 3 times should get you above 35-40psi which should be enough to start, if lost pressure is the problem.
Yes, the cold is a big factor.
Gasoline can't be ignited by a spark, yes movie guys get that wrong, lol.
Only gasoline vapor can be ignited by a spark.
The colder the gasoline is the less vapor it will have, this is why all gasoline engines need to be Choked when cold starting, even fuel injected engines.
A cylinder needs about 30% gasoline vapor for a spark to ignite it
On a Carb the Choke Plate worked by closing off air intake which increased the vacuum suction on the Jets, this pulled in more cold gasoline, and hopefully enough to get that 30% vapor point after gasoline was heated by compression.
Fuel injection has the computer and computer has TWO temp sensors, it has ECT(engine coolant temp), and AIT(air intake temp) sensors, it uses these to determine how much extra fuel to add to start cold engine, to get to that 30% vapor point.
Computer doesn't have a fuel pressure sensor, it "assumes" 55psi, so if pressure was lower then it wouldn't be adding enough fuel to get to the 30%
Repeated cranking of the engine warms up the cylinders from compression strokes, so more vapor is created and you can get to that 30% point.
Quick Start(ether) is used because ether has a low vapor point much lower than gasoline, so helps to start gasoline or diesel engines in very cold temps, once an engine starts the cylinders heat up almost instantly, 900+degF in there when cylinder fires, so in coming COLD gasoline mix vaporizes fast
Methanol/ethanol actually helps in the cold temps.
ALL gasoline has water in it, "bad gas" is when there is too much water in it, but it all has water.
Water and gasoline don't mix, they can't bond so water settles to the bottom of the gas tank when vehicle sits long enough, a few weeks, driving keeps it mixed but it is still separate.
When temps drop below 32degF the water in the gas tank, fuel lines and injectors will freeze, and that would be bad, lol.
Methanol/ethanol can bond with water, and when it does it changes the waters freezing point to -100degF, so no chance of freezing, and methanol/ethanol can also be burned with the water so water is gone and you get a little power, not much but not 0 either, lol
So Winter Fuel means "anti-freeze" has been added to the gasoline, and thats Methanol/ethanol.
Methanol/ethanol also raises Octane levels so prevents pinging/knocking in winter or summer
This will build up any lost fuel pressure
1998 and up Ranger needs 55-65psi fuel pressure, fuel pump has a check valve/back flow preventer built in to hold pressure when it is off, but these can leak.
Fuel Filter may also be a 3 hose model which also has a valve that can leak pressure, gas flows back to the tank.
So if truck sits for a few hours fuel pressure can drop to 0psi
Each time you turn on the key the computer runs fuel pump for 2 seconds to Prime the system, this adds 10-15psi of pressure.
So cycling the key on and off 3 times should get you above 35-40psi which should be enough to start, if lost pressure is the problem.
Yes, the cold is a big factor.
Gasoline can't be ignited by a spark, yes movie guys get that wrong, lol.
Only gasoline vapor can be ignited by a spark.
The colder the gasoline is the less vapor it will have, this is why all gasoline engines need to be Choked when cold starting, even fuel injected engines.
A cylinder needs about 30% gasoline vapor for a spark to ignite it
On a Carb the Choke Plate worked by closing off air intake which increased the vacuum suction on the Jets, this pulled in more cold gasoline, and hopefully enough to get that 30% vapor point after gasoline was heated by compression.
Fuel injection has the computer and computer has TWO temp sensors, it has ECT(engine coolant temp), and AIT(air intake temp) sensors, it uses these to determine how much extra fuel to add to start cold engine, to get to that 30% vapor point.
Computer doesn't have a fuel pressure sensor, it "assumes" 55psi, so if pressure was lower then it wouldn't be adding enough fuel to get to the 30%
Repeated cranking of the engine warms up the cylinders from compression strokes, so more vapor is created and you can get to that 30% point.
Quick Start(ether) is used because ether has a low vapor point much lower than gasoline, so helps to start gasoline or diesel engines in very cold temps, once an engine starts the cylinders heat up almost instantly, 900+degF in there when cylinder fires, so in coming COLD gasoline mix vaporizes fast
Methanol/ethanol actually helps in the cold temps.
ALL gasoline has water in it, "bad gas" is when there is too much water in it, but it all has water.
Water and gasoline don't mix, they can't bond so water settles to the bottom of the gas tank when vehicle sits long enough, a few weeks, driving keeps it mixed but it is still separate.
When temps drop below 32degF the water in the gas tank, fuel lines and injectors will freeze, and that would be bad, lol.
Methanol/ethanol can bond with water, and when it does it changes the waters freezing point to -100degF, so no chance of freezing, and methanol/ethanol can also be burned with the water so water is gone and you get a little power, not much but not 0 either, lol
So Winter Fuel means "anti-freeze" has been added to the gasoline, and thats Methanol/ethanol.
Methanol/ethanol also raises Octane levels so prevents pinging/knocking in winter or summer
#3
01-17-2018
Thank you for the information. I will check the fuel filter and give the 3X's start a try today and see what happens. I should also tell you that the last owner "hogged" out the inside if the fuel filler tube so that its almost a straight tube and has no little flapper in it. Now that I think of it I should have the gas cap checked. I will post what happens. Cheers.
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