Gas/Fuel vapors/fumes visible from gas door

[FerrisBueller]

Waterproofing some cheap temp sensors with epoxy and adhesive-backed heat shrink tubing. Epoxy keeps water from coming in the tip, the heat shrink keeps water from working it's way up from further down. I will add the heat shrink the entire length of the wire after the epoxy hardens.

The module auto records the timestamped temperatures onto an SD card. Planning to put one sensor at the end of the fuel supply line near the engine, one at the beginning of the return line by the engine, and one at the end of the return line by the gas tank. The 4th sensor will go wherever I feel like needs it.

Then will just let it run and record during trips.

 

[FerrisBueller]

Leaving for silverton today, will get some data on the road and trail

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Did you get any interesting data from your trip?

 

[bloc]

Did you get any interesting data from your trip?

Fuel gets quite hot all around when driving across north Texas in 100f heat, and even hotter when sitting on a freeway barely moving.

I barely spent any time on trails though that trip so the data we need will have to wait for this summer.

 

[grinchy]

Ambient or engine room temp would be interesting.

 

[2001LC]

I see some very interesting data point being collected. Logging ECT, FT & AT (engine coolant temp, fuel trims & auto transmission fluid) along side these, may prove interesting/useful.

 

[bloc]

I see some very interesting data point being collected. Logging ECT, FT & AT (engine coolant temp, fuel trims & auto transmission fluid) along side these, may prove interesting/useful.

Good points. I seem to remember @linuxgod saying ECT doesn’t move around much even under heavy loads like towing as long as the cooling system is healthy.. but ATF temps may.

Thinking through how the fuel moves in the system I do believe under hood temp can really impact fuel temp.. after all I think it is the time spent in the rail before being returned to the tank that adds the most thermal energy.

 

[2001LC]

Good points. I seem to remember @linuxgod saying ECT doesn’t move around much even under heavy loads like towing as long as the cooling system is healthy.. but ATF temps may.

Thinking through how the fuel moves in the system I do believe under hood temp can really impact fuel temp.. after all I think it is the time spent in the rail before being returned to the tank that adds the most thermal energy.

I was a bit shocked first time I logged ATF temp in a 200 series. Even with properly maintained coolant system, they do run hot. Its fins (oil cooler rad) also get clogged with bugs, cotton, grasses, etc. and than AT really runs to hot. Radiant heat from engine, CAT, AT, road & OAT all play a in fuel boil. As does pressure.

If someone has fuel/line temp data without all the others. It can result in a lot of question.

 

[isthatalexus]

Coming from a place of zero knowledge or research: my hood is totally trashed with peeling paint, and the plan is/was to remove, sand, primer, and then wrap with matte black 3M. Would it make sense to build in a hood scoop of some sort to cycle more air through the engine bay? Maybe a horizontally mounted fan pushing air out...or in?

Intercooler-style, but facing the other way(?). (again, have not begun to think about water/debris in/egress, engine bay aerodynamics/back-pressure, or other smart stuff)

Maybe Mad Max styling with integrated pop-up bi-pod for freedom seed distribution system? Start new trend of HTS (hood-top swag) to counter the RTT trend...and tame the recent increase in MPG?

Either way, hood looks like arse, so something will happen.

With ambient wheeling temps frequently above the 100 deg F mark in my area, heat mitigation feels like a good thing to think about.

 

[linuxgod]

Coming from a place of zero knowledge or research: my hood is totally trashed with peeling paint, and the plan is/was to remove, sand, primer, and then wrap with matte black 3M. Would it make sense to build in a hood scoop of some sort to cycle more air through the engine bay? Maybe a horizontally mounted fan pushing air out...or in?

Intercooler-style, but facing the other way(?). (again, have not begun to think about water/debris in/egress, engine bay aerodynamics/back-pressure, or other smart stuff)

View attachment 3277737

Maybe Mad Max styling with integrated pop-up bi-pod for freedom seed distribution system? Start new trend of HTS (hood-top swag) to counter the RTT trend...and tame the recent increase in MPG?

View attachment 3277761


Either way, hood looks like arse, so something will happen.

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With ambient wheeling temps frequently above the 100 deg F mark in my area, heat mitigation feels like a good thing to think about.

I doubt a hood scoop will do much for you, but if you want to look cool, have at it. In practice unless you're actually channeling air into a very specific location I think you're more likely to end up creating a "high pressure" area which ends up impeding the flow of air through the radiators and across the engine. If you wanted to "scoop" air I think you'd need to also build a baffle underneath to direct it over the fuel rails (or wherever the heat is causing problems). I'm by no means an expert in fluid dynamics though.

 

[isthatalexus]

I doubt a hood scoop will do much for you, but if you want to look cool, have at it. In practice unless you're actually channeling air into a very specific location I think you're more likely to end up creating a "high pressure" area which ends up impeding the flow of air through the radiators and across the engine. If you wanted to "scoop" air I think you'd need to also build a baffle underneath to direct it over the fuel rails (or wherever the heat is causing problems). I'm by no means an expert in fluid dynamics though.

Yeah, anything beyond surface work on the hood is probably bad. (self-described Toyota engineer, if real, is probably right)

After reading that Supra post, I'm going to look at which of my (PO's) mods could be 'breaking' the OEM engine bay air management goodness. Not that any of this changes the root issue of this thread.

(Is anyone porting a sacrificial A/C port to the fuel returns somewhere yet?)

 

[FerrisBueller]

Anyone know what the fuel hose size is? I was collecting an online shopping cart of parts for adding a small fuel cooler in front of the condenser fan (the idea being that if it's hot enough to have the A/C on, then the fan will also pull air through the fuel cooler), and was assuming 3/8 fuel line. But when I measured an OD of 1/2" (ish) and the connected hard line of about halfway between 5/16 and 3/8, now I'm not sure what the ID really is (3/8 or 5/16) without actually disconnecting a hose somewhere.

 

[bloc]

Anyone know what the fuel hose size is? I was collecting an online shopping cart of parts for adding a small fuel cooler in front of the condenser fan (the idea being that if it's hot enough to have the A/C on, then the fan will also pull air through the fuel cooler), and was assuming 3/8 fuel line. But when I measured an OD of 1/2" (ish) and the connected hard line of about halfway between 5/16 and 3/8, now I'm not sure what the ID really is (3/8 or 5/16) without actually disconnecting a hose somewhere.

Assume anything you measure on these is metric.. 1/2 (ish) would probably be 12mm (which sounds huge for a 400hp engine), 3/8 10mm, 5/16 8mm. I'll try to get under there and take some measurements before long.

Also I wouldn't like the idea of fuel running to the front of the vehicle in case of an accident. Yes the fuel pump should shut off but that's not an assumption I'd want to make given the risks. I do feel a heat exchanger under the rear of the vehicle could get the job done, even if the air is hot under there, it'll most certainly be a lot cooler than the air under the hood at low speeds, and the fuel returning to the tank through the rails given the additional radiant heat. This is actually making me wonder whether some kind of wrap around the rails would help.. potentially an experiment for me when temps go up and I start the logging again.

 

[JohnJB]

Assume anything you measure on these is metric.. 1/2 (ish) would probably be 12mm (which sounds huge for a 400hp engine), 3/8 10mm, 5/16 8mm. I'll try to get under there and take some measurements before long.

Also I wouldn't like the idea of fuel running to the front of the vehicle in case of an accident. Yes the fuel pump should shut off but that's not an assumption I'd want to make given the risks. I do feel a heat exchanger under the rear of the vehicle could get the job done, even if the air is hot under there, it'll most certainly be a lot cooler than the air under the hood at low speeds, and the fuel returning to the tank through the rails given the additional radiant heat. This is actually making me wonder whether some kind of wrap around the rails would help.. potentially an experiment for me when temps go up and I start the logging again.

All great points. I’d also add that I’m unsure if and when you’ve experienced fuel boiling issues @FerrisBueller but I’ve had issues at altitude when ambient temps are well under 70 degrees. The idea that it’s more likely it be an issue when A/C is running might be a misnomer, but all I’ve learned in my 200 time is that this issue varies widely between vehicles.

 

[FerrisBueller]

All great points. I’d also add that I’m unsure if and when you’ve experienced fuel boiling issues @FerrisBueller but I’ve had issues at altitude when ambient temps are well under 70 degrees. The idea that it’s more likely it be an issue when A/C is running might be a misnomer, but all I’ve learned in my 200 time is that this issue varies widely between vehicles.

Agreed, it can affect different vehicles in different ways. My thought was that getting the cooler in front by the grille would cover multiple potential scenarios. First, when it's cool outside and A/C is off (no fan), it would still cool well because it's away from all the hot components and is located where there's plenty of fresh air. Second, when it's hot outside, the A/C would likely be on and condenser fan would then provide airflow through the cooler.

Sufficient passive cooling might still be possible from the undercarriage, as long as it's on the passenger side (so it's not soaking next to the exhaust pipe). Ideally it would be outside the frame rail to avoid heat buildup between the frame rails, although that would make it more vulnerable than if it was kept somewhere in between.

 

[CharlieS]

Sounds dangerous to me.

I've mentioned this before, but some early Porsche 996 had a recirculating fuel system with a fuel cooler on top of the engine, plumbed into the AC, if I recall correctly. I wonder if that could be repurposed?

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[bloc]

Sufficient passive cooling might still be possible from the undercarriage, as long as it's on the passenger side (so it's not soaking next to the exhaust pipe). Ideally it would be outside the frame rail to avoid heat buildup between the frame rails, although that would make it more vulnerable than if it was kept somewhere in between.

My thought wasn't actually toward passive, but potentially with a small fan that could be triggered by ignition on or maybe a temp switch.

Agree completely on heat soak and exposure concerns though.

 

[FerrisBueller]

Sounds dangerous to me.

Agreed. Even though it would cool more efficiently in the front, there is too much risk of a bad situation becoming much worse.

 

[TeCKis300]

If you're serious about solving the fuel boiling issue - use the below as a template for the solution. What's common is that cruisers mount everything high and tight in the chassis increasing the degree of heat soak. Chassis skids further exacerbate the issue.

I was under my truck doing some more mods. And since I have a fuel temperature sensor, I can tell what works and what doesn't. If you want to argue with me then just put me on ignore, please. If you want to prove me wrong, get your own fuel temperature sensor. Here's two good ones: Amazon.com: Innovate Motorsports 3904 MTX-D Dual Gauge Kit -Ethanol/Fuel Temp, 1 Pack: Automotive and Amazon.com: Zeitronix ECA-2 Ethanol E% Content Analyzer Kit with Blue Display Gauge: Automotive If you have constructive criticism, please post it.

Reminder, this thread is about boiling fuel. Your #1 point of reference should be the fuel's temperature. Everything else is secondary. No, I do not expect everyone to have fuel temperature because it's not available stock or without some elbow grease but I've got one.

The following are my mods to combat fuel temperature in order of their effectiveness. I have also done lots of work on my evap system which I've detailed in this thread: 100 Series Charcoal Canister Replacement Truck is well maintained and has many new parts over the last 1-2 years, too many to list but if you are thinking "but did you replace your _____" the answer is probably YES!


#1: Extensive heat shielding. Earlier in this thread there was talk about extra shielding on the catalytic converters, but I found recently over the past few weeks that there are far more important areas to add heat shielding. I've been doing this by driving a lot and then scooting under the truck on my creeper and feeling around with my hands and figuring out where things are hot and where they aren't and then doing it again.

There is an area here on the fuel tank where the stock metal guard doesn't cover and there is no heatshield between it and the exhaust pipe.

Bare fuel tank exposed within 12" of exhaust pipe (darker tank shield seen below exposed tank side with rough texture):

Here and on the tank shield itself I used adhesive backed heatshield material: Amazon.com: Second Skin Thermal Block - Automotive Heat Shield - Reflective Aluminum, Insulation & Adhesive (8 sq ft, 4 Sheets) - Made in USA: Automotive - https://amzn.to/3juiU2t This stuff blocks the radiant heat with the silver metal barrier but also insulates with a cloth layer underneath and sticks with adhesive which makes it easy to put anywhere. I use this small roller to help get a good bond: Amazon.com: LUMITECO Automotive Car Audio Sound Deadening Application Wheel Roller, Heat Abatement Mat Wallpaper Application PU Smoothing Tool Seam Roller: Automotive

I did the whole side of the fuel tank. I also extended the factory heatshield in a few more places:

Lastly, I used some embossed heatshield material to shield the front crossover y-pipe from the front of the fuel tank: Amazon.com: Design Engineering 050503-16 Floor and Tunnel Shield: Automotive This stuff is really lightweight and easy to bend and and cut and work with but also extremely effective at blocking radiant heat.

#2: Moving return fuel line off the engine to the firewall. This just eliminated the steel return fuel line that is bolted directly to the engine cylinder heads on the rear of the engine reducing the amount of heat returned to the tank from the fuel rails. I also covered the fuel line as well as the rest of the lines with heatshield: Amazon.com: Design Engineering 010448 Cool-Tube Extreme Heat Reflective Sleeve, 0.75" x 9' - Black: Automotive - https://amzn.to/2ZZs0ds

#3: Catalytic converter and fuel line shielding: These were the first mods I did to try and combat fuel temperature, but I would only rate them #3 on my list. Every other mod was more effective at lowering the fuel temperature. I have no doubt this mod is effective in some way, but not as much as the others. If doing heatshielding under the vehicle, then this should be done no matter what anyway IMO. It's also the easiest of all the mods. I used this heatshield for the fuel lines: Amazon.com: DEI 010441 Cool-Tube Extreme Heat Reflective Sleeve, 0.5" x 9' - Silver: Automotive - https://amzn.to/2WYqZjS

#4: Passive dual-pass finned fuel cooler. More of an experiment than anything I bought this inexpensive multipurpose cooler and plumbed it to the return line right before the fuel tank. I used quick connect fuel connectors so that if there is ever a problem with the cooler I can simply disconnect it and return the lines to stock without any tools. I placed it in the rear area above the frame rail. This area is always cool to the touch compared to the rest of the vehicle when I have been poking and probing for the last few weeks, it gets a surprising amount of air flow.

First I set it up to pressure test:

It passed.

I

Looking inside:

Mounted above the frame rail by the evap canister away from danger.

I used this 12" fuel cooler: Amazon.com: HotRod99 12" Satin Aluminum Finned Dual Pass Heat Sink Cooler Transmission Cooler Black Includes Two 1/4 NPT Fittings: Home & Kitchen - https://amzn.to/2WYwxe4
Some 5/16 Gates fuel hose: https://amzn.to/302b4D9
and 1/4 NPT to 5/16 fittings: https://amzn.to/3044yMe


Before doing these mods my fuel temperature would routinely get to be 30-40F higher than ambient and sometimes even 50F or more if the tank was low and/or it had been hours on the trail etc. After doing these mods the fuel now stays between 10-20F above ambient even when low, though I have not done a long offroad trip with the newest mods.

This is about the hottest fuel temp I've recorded to date (127F), though I would bet it gets even hotter. This was before mods. This was at 1/4 tank of fuel driving home in 95F ambient temperature probably 3-4 hours running non-stop. I'm waiting for similar conditions to record a snapshot of the temperature now after all of the mods.

 

[grinchy]

If you're serious about solving the fuel boiling issue - use the below as a template for the solution. What's common is that cruisers mount everything high and tight in the chassis increasing the degree of heat soak. Chassis skids further exacerbate the issue.

Read a few pages on in the quoted thread. Interesting.