Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?

[Eyedaho]

Physics. I deal with pumps at work all the time. The largest is 4,000HP. If you recycle discharge back to suction and the delta P across the pump is high, due to the inefficiency of the pump and adiabatic heating, the fluid heats up. Our fuel pumps are small scale but they can eventually increase fuel temperature.

Better explanation HERE

Yes. There are other factors in our fuel system that likely contribute more heat to the fuel though, right? Like the fuel pump being immersed in the fuel, and the fuel picking up heat from the engine and exhaust system. Those last two are things that people in this thread have been working to reduce, which are things that we can actually control.

 

[jerryb]

quiet with all the physics stuff. these people are trying to argue. Delta P&T will F them up.

 

[Jack90210]

Physics. I deal with pumps at work all the time. The largest is 4,000HP. If you recycle discharge back to suction and the delta P across the pump is high, due to the inefficiency of the pump and adiabatic heating, the fluid heats up. Our fuel pumps are small scale but they can eventually increase fuel temperature.

Better explanation HERE

Cool link. I suspect that this is a problem only when the fuel level is low and the ambient temperature is high, but still.

 

[jerryb]

3 more pages and we'll be there.

 

[Chrisek]

So I’m still trying to figure mine out (04 LC). Started having evap codes with OEM tank, went to LRA 40gal main tank and new hoses. Codes went away for 2000 miles and are back with a vengeance (every drive cycle)! I have never had “the smell” but I finally took it to my Toyota dealer for this specific issue (before it was too hit or miss) and it is pumping up to 18psi. All the “normal” codes PO451/455/etc seem to be related to a pressure valve so far out of its range that the ecu thinks it is faulty. Got a new code today: P2418 (6 codes total on this reset). Thoughts on what to chase next? Like everyone else, have already replaced charcoal canister and vent line. And all lines touching the tank were new (also new OEM fuel pump) when tank was replaced.

 

[Patassa]

Physics. I deal with pumps at work all the time. The largest is 4,000HP. If you recycle discharge back to suction and the delta P across the pump is high, due to the inefficiency of the pump and adiabatic heating, the fluid heats up. Our fuel pumps are small scale but they can eventually increase fuel temperature.

Better explanation HERE

Also deal with pumps quite a bit, you're not wrong, recirculation can be a problem but at least here it's generally only a concern on the higher energy pumps and it's cavitation we worry about only in the case we're going right back to the suction, we're pumping gasoline too. Even on the higher energy pumps and the operators block in a pump and let the min recirc line rip, it takes a while to start cavitating. I'd be shocked if this little pump could appreciably heat up the gas in the tank through recirculation especially if it's mixing with the entire volume of the tank, not going directly to the suction. I've been wrong before though. What kind of pump is the fuel pump in our tank?

 

[hoser]

Relevant test:

Fuel heating caused by 1 vs 2 pumps *test results inside* - LS1TECH - Camaro and Firebird Forum Discussion

Fueling & Injection - Fuel heating caused by 1 vs 2 pumps *test results inside* - My first fill of E85 resulted in fuel belching out my tank vent and loss of fuel pressure at WOT. In addition to switching to E85, I had also just put the hood back on the car, and upgraded the radiator fans to...

ls1tech.com

 

[nikoli]

Relevant test:

Fuel heating caused by 1 vs 2 pumps *test results inside* - LS1TECH - Camaro and Firebird Forum Discussion

Fueling & Injection - Fuel heating caused by 1 vs 2 pumps *test results inside* - My first fill of E85 resulted in fuel belching out my tank vent and loss of fuel pressure at WOT. In addition to switching to E85, I had also just put the hood back on the car, and upgraded the radiator fans to...

ls1tech.com

Hate to be that guy, esp since I didn't read thru the whole thread, but at first glance this seems like a flawed test. Not saying it doesn't have any value to this thread but this seems like something that should be taken with a huge grain of salt.

 

[hoser]

Where's the flaw?

 

[nikoli]

Where's the flaw?

My first thought was that it's a test of 1 pump vs 2 pumps... with E85 fuel... so its relevance to stock 100 series fuel system seemed diminished, as far as this thread is concerned.

My second thought was that they chose not to run the test individually... ie run the test on one pump, then run the same test with two pumps... while keeping all the variables the same.

My third thought was that they didn't really spell out the conditions.

Last, the thread starter person seemed to jump to conclusions and make claims that weren't necessarily proven... and coupled all that with a healthy dose of hyperbole in the process.

Now that I'm reading through the thread it seems that some others pointed some of this out too.

I'm not saying it's worthless info. But I wouldn't say it's much more than just some info that can be taken or left.

 

[hoser]

This is not about 1 vs 2 pumps. The 1st pump ran until the 90 minute mark where he added the 2nd pump. You can just ignore everything after the 90 minute mark if you choose.

The question brought up over the last few pages of this thread is, "Will forcing the fuel pump to run at full speed help or hurt fuel temps?"

The linked "test" is relevant because he is measuring fuel temperature over 100 minutes. The engine is not even on. There's nothing else generating heat. The voltage isn't constant... the battery is dying over the course of the test. A constant 12V would probably increase the temperature more.

It's certainly not a super scientific test. It's just some dude on a forum like any one of us. But the results are relevant. YES, running fuel through the system in itself raises the temperature of fuel. In his case, with E85, it raised the temp over 10 degrees in 90 minutes.

Maybe somebody would be willing to redo this test, in a 100 and on 87-91 octane fuel.

 

[Chrisek]

So, here is another way to look at this, these are coming on 25 years old, and at that point emissions no longer a big deal in USA. Would the fuel pump still operate if the tank was not pressurized at all?

 

[hoser]

Hate to be that guy, esp since I didn't read thru the whole thread, but at first glance this seems like a flawed test. Not saying it doesn't have any value to this thread but this seems like something that should be taken with a huge grain of salt.

My first thought was that it's a test of 1 pump vs 2 pumps... with E85 fuel... so its relevance to stock 100 series fuel system seemed diminished, as far as this thread is concerned.

Idk, the guy who solved his issue is here saying he did so without modifying the fuel rails at all. I'd be inclined to follow his advice from this thread.

Bold claims without much evidence leads to reaching for evidence to support the claim, rather than solve the problem.

Earlier in the thread it seemed that ethanol was cited as the virus, but I didn't see much good evidence of that. So far in this thread I've seen a poster cure his symptoms and form a pretty solid hypothesis that the symptoms are largely related to the proximity of the gas tank and heat sources. This is much more productive and scientific imo.

I can't help but LOL.

First you say that test was irrelevant because he's on E85 fuel.

I don't think you realize the poster you follow so much for this problem is also running E85 fuel.

 

[jerryb]

the evidence is the boiling point temp at equal pressure of ethanol.

1. ethanol boiling point is less. Producers were given exemptions to mandates, not sure if still true on exemptions.
2. when a pump uses excess current it gives off heat.

you should supply spec running voltage to the fuel pump.
you should want your product to spend as little time possible at the heat source. And or control the transport container.

there are no mysteries here.

 

[Chrisek]

the evidence is the boiling point temp at equal pressure of ethanol.

1. ethanol boiling point is less. Producers were given exemptions to mandates, not sure if still true on exemptions.
2. when a pump uses excess current it gives off heat.

you should supply spec running voltage to the fuel pump.
you should want your product to spend as little time possible at the heat source. And or control the transport container.

there are no mysteries here.

Maybe my issue is different, I have no fuel smell. When the key was in the acc position (motor not running) the fuel tank pressurized to 18psi. Any overlap with these issues?

 

[2001LC]

Fuel pump creating heat, E85, hot days, high altitude, belly pans trapping heat, engine running hot, A/T running hot, EVAP system not functioning as it should, etc. all contribute to fuel boiling.

But I cann't say this enough. Fresh off the factory floor, 100 series do not boil fuel. Even built, with all system to spec, don't. Until system(s) get out of spec.

Bypass fuel pump if you like, rather than installing a new fuel pump. But don't be surprised, if you find yourself down a rabbit hole.

 

[nikoli]

I can't help but LOL.

First you say that test was irrelevant because he's on E85 fuel.

I don't think you realize the poster you follow so much for this problem is also running E85 fuel.

...well I trust anyone reading this thread can see that I didn't say it was irrelevant.

I also trust that anyone reading this thread is able to understand that my choice to heed @J1000 advice in mitigating fuel related problems has zero to do with the relevance of the link you posted.

That said, I'm glad I helped you laugh.

 

[nikoli]

This is not about 1 vs 2 pumps.

Well... the link you posted is... which is what I was referring to when I said what I said.

The 1st pump ran until the 90 minute mark where he added the 2nd pump. You can just ignore everything after the 90 minute mark if you choose.

Okay.

The question brought up over the last few pages of this thread is, "Will forcing the fuel pump to run at full speed help or hurt fuel temps?"

Seems the question has been over the degree <pun intended> to which it raises temps, since it's common knowledge that pumping can cause heat. Just ask your wife how I know this.

The linked "test" is relevant because he is measuring fuel temperature over 100 minutes. The engine is not even on. There's nothing else generating heat. The voltage isn't constant... the battery is dying over the course of the test. A constant 12V would probably increase the temperature more.

It's certainly not a super scientific test. It's just some dude on a forum like any one of us. But the results are relevant. YES, running fuel through the system in itself raises the temperature of fuel. In his case, with E85, it raised the temp over 10 degrees in 90 minutes.

Maybe somebody would be willing to redo this test, in a 100 and on 87-91 octane fuel.

Okay.

 

[Joe422]

Fuel pump creating heat, E85, hot days, high altitude, belly pans trapping heat, engine running hot, A/T running hot, EVAP system not functioning as it should, etc. all contribute to fuel boiling.

But I can say this enough. Fresh off the factory floor, 100 series do not boil fuel. Even built, with all system to spec, don't. Until system(s) get out of spec.

Bypass fuel pump if you like, rather than installing a new fuel pump. But don't be surprised, if you find yourself down a rabbit hole.

This

I got as far as covering my fuel lines (feed +return) in the DEI reflective sleeves... which helped a little. Also attached a larger insulated shield to the Catalytic shield, to block more heat away from the fuel lines. The all seemed to help somewhat... but not completely. Reduced it enough where I just need remember to vent a little by little on looooong uphill 4Lo trails, on warm days. No more fuel boil.

I do plan to try adding a fan near the hoses to blow across the fuel lines, (at the section near the cat)... I personally believe its the radient heat of the cats that are overcooking the fuel. I want to evacuate some hot air from that area.

If i go beyond that... it will be an external fuel cooler w/ fan. Cooler fuel is always a good thing. Just gotta make sure its robust enough and good quality so you dont introduce too many points of failure/leak, etc.

 

[J1000]

I can't help but LOL.

First you say that test was irrelevant because he's on E85 fuel.

I don't think you realize the poster you follow so much for this problem is also running E85 fuel.

I do run E85 because it's $2 a gallon. Currently there is regular E10 Premium in my tank. Boiling has been more of a problem for me with normal gas than E85.... Well actually I haven't had this problem in years. I fixed it

If YOU had been paying attention you would know all this too.