Hard starting in extreme heat conditions (1 Viewer)

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Basalt, CO
I have been having an issue with my 2006 100 now that the heat of summer is here in Arizona. After driving at slow speeds off-road on hot days I am getting fuel coming out of the fuel fill area causing fumes. If I turn off the engine it will crank strong, but won't start until it has cooled off for about twenty minutes. It appears for be a vapor lock type situation or fuel is boiling within the fuel lines or filter in the engine compartment due to heat. I know this is not a new issue as I have read several posts regarding a similar issue. Most of these seem to be related to fuses or other sensors and/or immobilizer. I know the engine compartment gets extremely hot even though engine temp runs around 190 to 210 degrees. It's possible that my front ARB bumper and winch block the amount of air passing through radiator making the issue even worse. I have added a snorkel which has greatly improved the air intake temperatures. I have recently replaced fan clutch and the main relay thinking this might have something to do with it, but this has not helped. I have had no other issues with it starting except under extreme heat conditions.
 

RKRUGER

Formerly 'WFMRObb'
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Here in the Midwest, I've experienced this 3 times with our 2006 LC when temps are near or above 100 ambient. I believe it to be vapor lock related to ethanol in the fuel. If I switch over to Premium fuel, the issue disappears. It happened twice in the Black Hills /Badlands area and after switching over to Premium we went the rest of the trip without an issue.

Just a thought.
 
Joined
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Basalt, CO
Never thought of that, as manual states regular fuel. However, nowadays with all the ethanol in the fuel, I can see where this might be an issue. Would the ethanol cause fuel to boil at lower temps than fuel alone? Did your issue occur during slow off-road travel or normal street/Hwy speeds? Did it only occur when the ambient temperatures were close to triple digits? Thanks for your observation and insight on this issue.
 
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Ethanol has a lower evaporating point than gasoline, basically when this is happening you are running on 10% ethanol vapor and 90% gasoline liquid.
The fuel cannot "boil" inside the fuel lines, there needs to be space for it to boil, and there isn't any inside the fuel lines or fuel filter. HOWEVERm once it leaves the fuel injector, the ethanol vapor is useless and you're trying to run the engine on whats left as gasoline.
Around here all fuel has at least 10% ethanol, even premium. However, because premium fuel burns slower than regular it will run/start better.
My owners manual says premium is recommended but not required.
Ethanol free around me is to expensive to be used in a car, it runs at least $1.gal more than premium. However, buying 2gal at a time it is perfect for small engines.
Your ARB bumper and skid plates will not effect air flow enough to say so.
 

RKRUGER

Formerly 'WFMRObb'
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Trail/ forest roads as well as hwy speeds towing our M416 with RTT. Pushing it hard on the road was where it first occurred.
 
Joined
Sep 9, 2016
Messages
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Location
Basalt, CO
Ethanol has a lower evaporating point than gasoline, basically when this is happening you are running on 10% ethanol vapor and 90% gasoline liquid.
The fuel cannot "boil" inside the fuel lines, there needs to be space for it to boil, and there isn't any inside the fuel lines or fuel filter. HOWEVERm once it leaves the fuel injector, the ethanol vapor is useless and you're trying to run the engine on whats left as gasoline.
Around here all fuel has at least 10% ethanol, even premium. However, because premium fuel burns slower than regular it will run/start better.
My owners manual says premium is recommended but not required.
Ethanol free around me is to expensive to be used in a car, it runs at least $1.gal more than premium. However, buying 2gal at a time it is perfect for small engines.
Your ARB bumper and skid plates will not effect air flow enough to say so.
Would an octane booster help? Or, does it just need to be premium fuel in order to get the proper higher octane for it to burn slower
 
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Gump in the 406
Based on my readings, the troubles usually occur when the summer hits (hotter temperatures) and the gas stations are still selling winter blends (higher RVP aka Reid Vapor Pressure which equates to a lower boiling point). So you have fuel that has a lower boiling point combined with increasing outside temps, thus triggering vapor lock. Summer blends have a lower RVP (high bowling point), so the opportunity for it to happen is reduced.

Some suggest that 10% ethanol fuel only increases the potential for vapor lock by 10%...not sure how accurate that is.

(Ethanol absorbs water ~50 times more than ethanol free gas, so leaving ethanol in a vehicle/container that rarely gets used could create some issues if phase separation occurs).

By the way, more octane typically means more ethanol.
 
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Based on my readings, the troubles usually occur when the summer hits (hotter temperatures) and the gas stations are still selling winter blends (higher RVP aka Reid Vapor Pressure which equates to a lower boiling point). So you have fuel that has a lower boiling point combined with increasing outside temps, thus triggering vapor lock. Summer blends have a lower RVP (high bowling point), so the opportunity for it to happen is reduced.

Some suggest that 10% ethanol fuel only increases the potential for vapor lock by 10%...not sure how accurate that is.

(Ethanol absorbs water ~50 times more than ethanol free gas, so leaving ethanol in a vehicle/container that rarely gets used could create some issues if phase separation occurs).

By the way, more octane typically means more ethanol.
Can vapor lock occur with a fuel injected engine? I have heard some folks say it cannot. I am not sure.
 
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Gump in the 406
Also, changing altitudes can trigger this due to boiling point changing. Believe there were a few who experienced this in 100s in the hills last year.

Can vapor lock occur with a fuel injected engine? I have heard some folks say it cannot. I am not sure.
Can still occur, but less frequent.
 

aging fleet

Out adjusting my torsion bars
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This seems most prevalent in the '06-'07 vvti Cruisers, any reason why ethanol would affect those more than earlier 100s?
 
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Also, changing altitudes can trigger this due to boiling point changing. Believe there were a few who experienced this in 100s in the hills last year.



Can still occur, but less frequent.
You cannot vapor lock a fuel injected engine, vapor lock is when the fuel gets to hot and turns to vapor inside a mechanical fuel pump, a mechanical fuel pump cannot pump vapor. It can only pump liquids.
Fuel injection uses a electric fuel pump which is submerged in fuel inside the fuel tank, it stands vertically and literally sits on the bottom of the fuel tank and always draws from the bottom of the fuel tank, always.
Yes altitude can effect the "boiling" of the fuel inside the fuel tank, the less barometric pressure on the fuel the lower the boiling point.
 
Joined
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Messages
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Based on my readings, the troubles usually occur when the summer hits (hotter temperatures) and the gas stations are still selling winter blends (higher RVP aka Reid Vapor Pressure which equates to a lower boiling point). So you have fuel that has a lower boiling point combined with increasing outside temps, thus triggering vapor lock. Summer blends have a lower RVP (high bowling point), so the opportunity for it to happen is reduced.

Some suggest that 10% ethanol fuel only increases the potential for vapor lock by 10%...not sure how accurate that is.

(Ethanol absorbs water ~50 times more than ethanol free gas, so leaving ethanol in a vehicle/container that rarely gets used could create some issues if phase separation occurs).

By the way, more octane typically means more ethanol.
There is no such thing as winter fuel blends anymore, they were done away with decades ago. Winter blended fuel was nothing more than E-10 anyway since ethanol absorbs water and carries it to the engine to be burned off.
The idea behind winter blended fuel was to prevent gaslines from freezing.
Add to that, most gas stations get a fuel delivery once a week, so even if there was such a thing as winter blend fuel, it would be long gone no later than the end of March.
 
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It is not uncommon for fuels to be blended wrong and have to much ethanol, the minimum requirement for gasoline in the US is 10% ethanol in all gasoline rated for on road use.
It is federal law. The gas stations that sell ethanol free as supposed to mark those pumps as off road use only. Just like low and high sulfur diesel fuel, off road use for high sulfur and on road for low sulfur diesel.
There is no more #1 or #2 diesel, it is all just diesel now, they are even doing away with high sulfur diesel. High sulfur diesel ruins the emissions equipment on farm tractors and such.
Even tractors and combines have to use DEF and particulate filters now. Again, federal law.
Just like leaded gasoline, the "good gas" is being phased out.
 
Joined
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Messages
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I have been having an issue with my 2006 100 now that the heat of summer is here in Arizona. After driving at slow speeds off-road on hot days I am getting fuel coming out of the fuel fill area causing fumes. If I turn off the engine it will crank strong, but won't start until it has cooled off for about twenty minutes. It appears for be a vapor lock type situation or fuel is boiling within the fuel lines or filter in the engine compartment due to heat. I know this is not a new issue as I have read several posts regarding a similar issue. Most of these seem to be related to fuses or other sensors and/or immobilizer. I know the engine compartment gets extremely hot even though engine temp runs around 190 to 210 degrees. It's possible that my front ARB bumper and winch block the amount of air passing through radiator making the issue even worse. I have added a snorkel which has greatly improved the air intake temperatures. I have recently replaced fan clutch and the main relay thinking this might have something to do with it, but this has not helped. I have had no other issues with it starting except under extreme heat conditions.
I just had a thought, how much fuel was in your gas tank?
Here is why I ask, the fuel return line dumps fuel via a spray nozzle (like a garden hose nozzle) directly onto the fuel pump, this is to keep the fuel pump from overheating when the fuel level gets low, but, if you're at high altitude, less than half a tank of fuel and have been driving for a long time the lower barometric pressure, which lowers the boiling point of the fuel, the fuel pump will be hot, the fuel being returned to the tank will not be enough in liquid form to cool the fuel pump. The fuel pump overheats, and the truck is hard to start.
If you had a full tank of fuel then my theory is moot.
 

TheForger

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You cannot vapor lock a fuel injected engine, vapor lock is when the fuel gets to hot and turns to vapor inside a mechanical fuel pump, a mechanical fuel pump cannot pump vapor. It can only pump liquids.
Fuel injection uses a electric fuel pump which is submerged in fuel inside the fuel tank, it stands vertically and literally sits on the bottom of the fuel tank and always draws from the bottom of the fuel tank, always.
Yes altitude can effect the "boiling" of the fuel inside the fuel tank, the less barometric pressure on the fuel the lower the boiling point.
You most certainly can vapor lock a fuel injected engine. I would not say it happens often but it is definitely not uncommon. Also, vapor lock does not only occur in the fuel pump. It's not that complex of a concept it is simply the transformation of fuel from a liquid state to a gas state that causes a disruption in fuel being delivered to the engine. It can occur at any point in a fuel supply system (whether that be in the pump, the tank, the lines themselves, etc.). For example: if you park your truck on asphalt in extremely hot conditions and shut the engine off, the fuel in the lines near the engine is not moving and the mix of extremely hot air outside as well as the extremely hot air inside the engine compartment can cause the fuel to heat up enough thus forming vapor which can then cause vapor lock.
 

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