Check for any exhaust leaks. Towing something behind you with an exhaust leak keeps the hot air stuffed up under the truck, which boils the fuel in the tank. Top of the muffler is a common place for leaks, because it's so hard to see rust there.
Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?
- Thread starter 2001LC
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Did the same as you and no more fumes in the mountains.
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- #723
If noticeable different fumes w/Ethanol, than w/o Ethanol fuel: It may be a good idea to monitor engine coolant temp (ECT) and fuel trims (FT). Whereas it does seem our engine run leaner (hotter) on blended fuels. It should not cause overheating or running hot. Which may be why you're smelling fumes. I'd look for summer ECT of 194-197F in 03-07, 184 -187F in 98-02 with condenser fan.
I'm curious, if you've any engine compartment aftermarket components. i.e extra battery, air pump, etc,. Why? A smart young man @Calvinswartz just noticed: He had fuel issues, just after blocking heat sink of fuel pump resistor with aftermarket air pump.
Stalling not just in High, Hot, & Heavy
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If noticeable different fumes w/Ethanol, than w/o Ethanol fuel: It may be a good idea to monitor engine coolant temp (ECT) and fuel trims (FT). Whereas it does seem our engine run leaner (hotter) on blended fuels. It should not cause overheating or running hot. Which may be why you smelling fumes. I'd look for summer ECT of 194-197F in 03-07, 184 -187F in 98-02 with condenser fan.
I'm curious, if you've any engine compartment aftermarket components. i.e extra battery, air pump, etc,. Why? A smart young man @Calvinswartz just noticed: He had fuel issues, just after blocking heat sink of fuel pump resistor with aftermarket air pump.
Stalling not just in High, Hot, & Heavy
The engine compartment is completely stock and all components are OEM.
Non-Ethanol is a big key to this, for sure. I truly believe the EVAP system is broken by design, and the late model reroute exasperated the problem. The fuel pump resistor theory is super interesting. I've debated routing a 12VDC marine blower for when I turn the vehicle off.
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- #726
Collecting data, gives clues as to engine and coolant system health. From here we go through the basic, getting all as it should be.
So my next step would be to get some data. Data on ECT (engine coolant temp), fuel trims, CAT temp, RPM, MPH and IAT (intake air temp). I use bluedriver which allows me to log data as I drive, on my iphone. I can than go back over data for the entire drive/trip(s). I note if AC on or off, pulling a load ( full of gear on people, trailer, etc.), OAT (outside air temp), sunny & noon, AM, PM for hot or cool radiant heat from roads, cloudy, rian, etc. This allows me to look back at logs and see if cruising steady on HWY on flat ground, at a stop sign, pulling a hill, passing, etc. Which steady on flat HWY is what I like to see mostly. Stead cruising with foot very steady on gas pedal at ~65 MPH, the longer the time frame the better.
I also watch very closely, if ECT jump up above ~200F 03-07, over ~192F in 98-02, as I come to a stop at a light with and without AC on.
IMHO, ethanol is like adding water to gas. It will encapsulate water, which many older gas station have older storage tanks with ground water getting in them. We may than run lean. Lean = high cylinder head temp. So I'd run logs with tank of ethanol and without to compare data also. But many run ethanol without issue, and some get no relief running non ethanol gas.
The EVAP system since 2003- with the moving of the CC to rear, has been problematic. In that, just one event may damage the charcoal canister. Events like over heating, boil fuel, topping fuel tank past the first auto shut off, etc. We may than get excessive fuel tank pressure. Higher pressure = higher heat.
Some say all 100 & 200 series (4.7L and 5.7L) run hot (over 200F ECT) or all boil fuel. Or that all heavy (built rigs) boil fuel. I can assure you this is not the case. I know of many built rigs climbing high mountain pass on and off road. That have no issues whatsoever. Whereas, we don't know why some boil fuel regardless of engine and coolant system seemingly in perfect working order. I feel we are closing in on the reasons. I say reasons, as it's rarely just one point that needs correcting. Most come down to getting basic in-line, getting back to how it came from the factory mile one. But a few, noting has helped or totally cured (cooled down). These may be the fuel delivery related. Fuel pump resistor may be one needs looking at very close. This summer I hope to do some work along this line of thinking.
Data won't show you that the bare metal of the fuel tank lives within 6" of the exhaust.
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- #728
You're right data doesn't. But all USA market 100 series exhaust are configured the same from factory. Exhaust radiant heat is a consideration. But all do not boil fuel, have excessive fumes or overheat or depend on which fuel used!
I'll also note, some anecdotal info along this line: Belly pans for sure hold in more exhaust heat and transfer some of this heat too fuel system, i.e fuel lines and tank. But can only been viewed as contributing factor IMHO.
I based this on what I am seeing in:
I've see one mild built 07 with Slee belly pan. Where we see heat damage to wiring in the area between and near exhaust / gas tank. This one, we can not yet, get temps down and stop fuel boiling in all driving condition. Makes no difference in fuel blend used.
Yet I've others I see, 3 that come to mind at the moment:
2 others full built heavy's 07 with Slee belly pan, and 1 other heavy built 00LC (in the shop today) with some other belly pan. No trapped heat damage, fumes or boiling.
Yeah, they pretty much all do.
I'd sort of agree and sort of disagree. I've had 4 different 100 series over the last 15+ yrs and live in Phoenix where almost every summer we have at least a few days where the ambient temperatures exceed 115F. The highest temperature I specifically recall driving in was 122F. The elevation here isn't nearly the 12,000 ft or more in SW Colorado you'll see people posting fuel boiling problems, but the temperature is obviously WAY higher (I don't have a chart handy to suggest whether 85F at 13,000 ft is worse than 122F at 1,200 ft, but they are both pretty damn challenging conditions).
I'd agree with you to some degree because all 4 of my LCs would emit at least a small amount of fuel smell when I'd pull them into the garage on super hot days where none of my other cars did. I'd disagree with you in the sense that A) of the four cars, three rarely demonstrated a problem and only to a small degree on the very worst days (one when it was over 120F and none ever burped fuel or failed to start... just stunk up the garage), and B) very few people will ever experience those kinds of ambient conditions and it was happening only on the very worst days. My current 2002 did stink to high heaven when the temperatures would start getting above 116F or so, though I haven't experienced that since replacing the radiator about a year ago to see if it's still an issue.
So... I'd agree if you mean all 100 series fuel systems will demonstrate fuel boiling earlier than many other cars, but I'd disagree if you mean all 100s have fuel boiling problems. A properly functioning engine with a good cooling system, no leaks in the exhaust, the right heat shields, etc should avoid fuel boiling problem and fuel smells except under exceedingly harsh hot and/or high conditions. All cars will show problems under the worst conditions, and the 100 will start showing them earlier than some. None of my 100s have ever spewed gas out the filler, failed to start, etc even when the ambient temperatures were 122F (keep in mind real temperatures where the radiator, fuel lines, and tank are only 1-2 ft above black asphalt where the surface temperature are *considerably* hotter than the ambient temperature).
Right lots of variables but the fact remains that if you smell fuel vapors that means your fuel tank is not sealed. If the fuel tank is not sealed then boiling can happen. Boiling being the the worst possible symptom of the same problem. Fluids boil at lower temperatures at higher altitudes so at 1200ft in Phoenix it is tougher to boil than 5000ft or 12000ft etc. If it was water we could pull up a chart and see the exact temperature. So the conditions that you smell fuel in your garage in Phoenix it's a safe bet your same truck would boil the fuel in the same conditions up on a mountain.
Not sure we can conclude that without finding a chart for the boiling point for gasoline and how it changes with atmospheric pressure. I searched but didn't find one. I know it's a complicated issue as gasoline isn't a singular compound but a blend of many, each with their own boiling points... some as low as 95F at standard pressure.
But... much of that is beside the point. I was mainly challenging your contradiction of 2001LC's post where you indicated (paraphrasing) that pretty much all 100s boil fuel. That's misleading. They might be a little more prone to fuel boiling than some cars, but they are hardly a teapot waiting to boil your fuel for you. More importantly, and really the whole point of this thread, is that the one's that do have a fuel boiling problem can usually be improved through some combination of engine health, cooling system improvements, shielding return fuel from exhaust heat sources, and airflow under the car.
@2001LC's statement was not just about boiling "But all do not boil fuel, have excessive fumes or overheat or depend on which fuel used!"
You just stated you have excessive fumes.
I live in Colorado at around 6500ft.
I own two LCs.
One is a stock 2006 LC with 240k - zero boiling fume issues.
The other is a 2004 LC with 235k that is stock except for a lift and bigger tires. It has intermittent boiling issues from driving for 30-45 mins in 80+ degree weather with 1k elevation change. I’ve replaced the charcoal canister, cleaned the MAF & TB, and replaced the spark plugs. Tried running non-ethonal gas but it still boils. I’m considering replacing the fan, radiator, and fuel pump next. One thing I’ve noticed on this truck is that It does not start as ‘quickly’ as the 2006 and always ‘chugs’ for awhile in the cold weather. Could be unrelated, but who knows.
I own two LCs.
One is a stock 2006 LC with 240k - zero boiling fume issues.
The other is a 2004 LC with 235k that is stock except for a lift and bigger tires. It has intermittent boiling issues from driving for 30-45 mins in 80+ degree weather with 1k elevation change. I’ve replaced the charcoal canister, cleaned the MAF & TB, and replaced the spark plugs. Tried running non-ethonal gas but it still boils. I’m considering replacing the fan, radiator, and fuel pump next. One thing I’ve noticed on this truck is that It does not start as ‘quickly’ as the 2006 and always ‘chugs’ for awhile in the cold weather. Could be unrelated, but who knows.
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- #735
Very interesting and revealing! That replacing radiator solved fume smell.
Which speak to: "But all do not boil fuel, have excessive fumes or overheat or depend on which fuel used!"
As I was reading your post, my first thought was radiator. Than I came to the sentence, I felt very revealing:
"My current 2002 did stink to high heaven when the temperatures would start getting above 116F or so, though I haven't experienced that since replacing the radiator about a year ago to see if it's still an issue."
Fact is so many 100 & 200 series I see, are running hotter than they should. Hotter than they did mile 1 day 1 from the factory. Why, they're in need of a coolant service and tune.
Drivers very often, do not know they're running hot. Why? Our dash gauge doesn't reflect the true engine coolant temperature (ECT).
I've been logging ECT, fuel trims (FT), IAT (intake air temp), etc. on as many during test drives on hot days, as I can. Both before and after coolant service and tune up. Here is what I find:
- Stock 1998-02 should run at 184-187F up to and OAT of 100F (about as hot as i see in the mile high city of Denver) afternoon summer sun, both AC on max with light load (2 people). They may jump to 191F in very slow drive (rush hour stop & stop and go) or stop at light. But back right back down below 191F.
- The 03- without a condenser fan will run about the same ECT. Until OAT ~70F, above that I see 194F-197F in afternoon sun (hot roads).
- If the rig a heavy. i.e. iron bumper, winch, big extra lights, etc. Which is all more mass retaining more heat, adding weight and blocking air flow. It will add a few degrees to ECT. Speaking with Joey at Witsend, he seeing good results in heavy's, by add snorkels. In that IAT (intake air temp) is reduced. He deals more so with 80 series, is my understanding.
But fact is most are running hot, 10F to 20F above what they should:
Why? Because basic aren't keep in-line or they've a malfunctioning component.
In most cases when fume in garage after parking, is from the Charcoal Canister (CC). With the CC in new condition, we shouldn't smell the fumes unless perhaps excessive venting. The EVAP system vents to intake manifold while engine running, than atmosphere when not for about 5 hours IIRC. But some are vent from the gas tank, as they boil the fuel. This is most dangerous.
Once we do run hot or over heat, the EVAP system is being over worked. Very very often the charcoal canister is weakened if not damaged, from excessive fuel vapor or raw fuel. This can be from over time or even a signal event, like over filling gas tank in 03-up. It's in the 2003-up that we see most damage to CC. Just putting to much gas in the fuel tank of those, can damage the CC. The 98-02 CC fair much better an need replacing much less often.
Getting basic inline is only a first step. But in many, it cures the issue well enough. In 03-up, it then means R&R the CC very often. When to replace the CC is tricky. In that if all up stream issues not first corrected, we may just damage the CC again. A damaged CC (EVAP system) may also be at play, as a cause in fuel boiling. The chicken and the egg. I can't always say, which came first. But if basic not in line first, I can say we'll damage CC again.
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- Thread starter
- #736
Here again anecdotal evidence: NOT ALL BOIL FUEL
I did say I had excessive fumes... in one of my four 100 series and under pretty extreme conditions. And I have not experienced that since replacing the radiator, though in fairness I don't recall whether it's been over 115F since the radiator change. That doesn't mean I haven't driven when it's that f-ing hot... Phoenix gets like that more frequently than I'd like and I'm less likely to remember it being that hot if I don't have fuel smell to piss me off.
But the main point is this... we don't have to accept fuel smells or fuel boiling as a de facto condition of owning a 100. There are 37 pages in this thread with suggestions for maintenance issues or preventative maintenance that can reduce the likelihood of it being a problem. You'll never eliminate it as all cars will eventually demonstrate the problem if you push them hot and high enough.
I second this. I have access to a 04LC and two 05LCs besides my 04LC. Only one 05LC out of these 4 boiling fuel and hissing in Houston summer. Going to put torque pro and collect data out of it. I bet that is running hot.
My 04LC had the boiling/hissing sound twice. Both were on two different summer road trips, heavily loaded on steep highways. I haven't collected data at those times, but now I'm prepared for the next time. One sign of the fuel boil in both of my experiences is the truck feels sluggish and can't keep up with 65-75 speed limit on the steep hill. So I gave more gas but the truck struggled to keep up with the speed. I guess a lot of fuel returns back to the tank in this situation and causes boiling (just my thought).
There are millions of other vehicles in Phoenix driving around in the same conditions and they don't fill the garage with gas fumes. Phoenix is flat and low elevation, so you are just cruising around with very low load on the engine and yet you have this problem.
Yes there are 37 pages and since you are the expert you know that several of those pages include me modifying my 100 and solving this problem once and for all.
So no, not all 100s have this problem. Mine doesn't. All others do though.
Let me see if I understand you right.
You say that you have 4 cruisers to drive and only 1 exhibits fuel problems.
Then the next sentence you say it's happened to yours also
so we went from 25% to 50% in once sentence.