scottmoyer

Ok. I posted some stuff on the TPI board looking for advice, but haven't received anything yet, so I'm coming back to this forum asking for opinions and advice on my gas tank.

https://www.thirdgen.org/forums/tpi/...ml#post6090625

I removed my tank to replace the fuel pump and sending unit since I've been having the boiling gas problems on hot days. I've read that it could be the pump, the sending unit, the Fuel Tank Vent Valve, charcoal canister, canister valve or vacuum lines. Since this all started after the Florida mandate to use ethanol, I believe the issue is in the pump, sending unit, vent valve or return lines. I can address all of these with the tank dropped!

I found some grime or sludge where the filler neck meets the tank. I cleaned it up and found what appears to be two pinholes. I haven't pressurized the tank to see if leaks, but I'm thinking it does due to the grime that was present. I couldn't get any gas to come out of the holes when I turned the tank on it's side, but there must be vapor or something, or it may just be a coincidence. What do you guys think? Just solder pin holes in the surface? Should I seal it somehow? Looking for advice.



Also, I see a lot of aftermarket sending units out there. I also heard that Walbro had issues with their pumps at one point. What is recommended as a quality sending unit and pump that won't break the bank? Thanks

chevypower91

Wow. Your boiling gas issues would drive me nuts if i was experiencing it. You mention that this all started when using ethanol, could that actually be the culprit? Here in Canada, most of the gas uses ethanol, except some of the higher brand gas like shell v power. I used to use ethanol and never had any boiling gas issues. What i do have however, is the smell of gas. I know they had a recall about that with pin holes around the fuel neck, but my fuel pump was replaced 20 years ago and I'm guessing that they would have addressed that also?

Regarding the two pin holes, instead of welding, wpuld the use of an epoxy be a safer option?

Btw, your '87 is beautiful.

Benny

burnout88

A little JB weld will seal that no problem. I used it on a pin hole I found in my tank 10 years ago and it's still holding strong.

scottmoyer

I fixed it today with a fuel tank repair kit that my neighbor had. It's like an epoxy that requires being blended and applied within 30 minutes. They say it can be sanded after a few hours if needed, but I don't need it. It should be rock hard by morning.

Drew

iTrader: (58)

I'd solder it. The OE joint between the tank and filler neck appears to be lead solder, but even if it isn't, it'd be extremely easy to seal up the pin holes with a soldering iron and decent solder, assuming you can get it clean enough.

The question I have is what did the inside of that tank look like? I've got a couple tanks laying around and none have rust that heavy on the outside. I just finished cleaning out a tank that'd been sitting a few years, and the inside was bad enough that it required care to get flakes of corrosion out of the tank, multiple flushes. I think if the tank I was working with was that bad on the outside, I wouldn't have bothered cleaning it. Even then if it weren't a baffled tank, I'd probably have just replaced it.

I went with a Delco pump. At the moment I can't remember if I went with a standard L98 replacement pump or the pump for a TTA, there wasn't much difference. I did opt for the Delco pickup strainer that's basically the same as the later "dual 1LE" blah blah blah strainer. After all that's what came out of the 3.1L V6 tank I'm reusing.

okfoz

Just an FYI, I am still not sure exactly what is causing the boiling (bubbling) of the fuel. My 86 work van has a 4bbl, and I could hear it boiling in the tank a few days back, which kind of threw me. I think you are right, it has to do with something they are adding to the fuel to have a lower flashpoint I am not sure if it has to do with ethanol (which is the most logical choice) or if it has to do with something else they are adding to fuel to help it burn better.

Honestly I would not think it would be as big of a deal like it would be on a carb car, because on FI when the fuel is forced through the fuel lines it is pressurized in which the fuel would then be less likely to have bubbles. However in a 4BBL you would have to worry about vapor lock.

John

scottmoyer

First hot day since I've replaced the fuel pump and sending unit. Took the car out for about 30 miles in 90* plus temps. Brought the car home and the issue is still there. I had my hopes up, but... I also spoke with South Bay Fuel Injectors this week and will try new injectors. It can't hurt after 30 years. I may also replace all vacuum lines since the originals might have hair line cracks that I won't find without a smoke generator.

thtanner

iTrader: (1)

Assuming you also have your heat shields in place, and your exhaust/muffler are in good shape? I could see exhaust gasses heating the tank.

I have had my car in 100F+ temps idling in traffic with no fuel boiling. Spectra sending unit, Delco EP381 pump.

scottmoyer

I'm not sure I understand why so many bring up the heat shields and possible exhaust routing. Just a reminder that my car is bone stock with only 20k miles on it. All heat shields are in place and the exhaust is as it came from the factory. These cars didn't have this issue back in the day and shouldn't be having it today with everything still being original.

I recently replaced the fuel pump, sending unit, fuel filter and canister check valve. I will next try the vacuum lines and injectors. I also rebuilt the fuel tank vent valve. If all of the older cars had this issue, I would think the issue is gas related, but when some say they never have this happen, and they use the same gas that I do, tells me there is something in the fuel system that is causing this. I hope I can find it.

Tibo

iTrader: (15)

May factory sender had spontaneously gone bad so I replaced it with a Spectra brand. The part number was FG20A. AutoZone sells them for $186 but I found a Spectra on eBay for a bit less. I replaced it at least four years ago and it's still working fine. Appeared to be an exact duplicate of the factory unit.

burnout88

Scott, did you ever try a new OEM gas cap?

scottmoyer

Yes I did. New gas cap has been on for a few years now. Below are the things I've replaced and what I may still need to do.

Replaced:
Gas Cap
Fuel pump
Sending Unit
Fuel Filter
Vapor Canister Purge Valve
rebuilt the Fuel Tank Vent Valve

To be replaced:
All Vacuum lines
Fuel Injectors
and if needed, new fuel lines from the tank to the engine. (last ditch effort here)

bjpotter

If that doesn't work, you might try an optical heat sensor along the fuel line and tank. Look for any unusual temps. If its expansion of gas, it might turn up.

burnout88

Ok, I that's what I thought. Are the injectors multec's or Bosch?

Tibo

iTrader: (15)

I'm curious about the fuel pump having something to do with it. I've always understood that the fuel pump is cooled by the fuel, when the boiling is noticed is the tank level less than half? Did you install the fuel pump with the foam insulator on it? Is the pressure at the rail stock pressure?

scottmoyer

My fuel pump was installed with a fresh "full" tank of gas. The pump itself does have the foam insulator. My reason for replacing the fuel pump and sending unit was because the issue started sometime after I had the fuel pump replaced in 2007. I had a shop do the work and I wasn't sure they did it correctly and with quality parts. My thought was that the new pump might be running hotter than it should, heating up the gas. I replaced the pump/sending unit with quality parts and I can now rule that out as part of the issue. The original sending unit was still in the car, so the first shop only replaced the pump itself.

I may try to blow out the vent line from the tank to the charcoal canister. I can't remember if I did that or not. I can also now rule out a clogged in tank filter, and also the external fuel filter. My neighbor has an '89 IROC-Z, so I might also borrow his fuel tank vent valve to see if it's not drawing in air like it should.

redneckjoe

you think the fuel pressure regulator could have anything to do with it?
very odd problem.
what grade gas are you running? the reason i ask is i read that different grades have different boiling points. summer and winter blends too.


maybe try a vented cap or leave yours loose? i found this comment while looking around, as i found your issue perplexing;

"You are having a venting problem. Thinking back to chemistry class, a cylinder of water under enough vacuum will boil at room temp. That is what is happening in your gas tank, under enough vacuum the boiling point of the gasoline is dropping enough to boil at air temperature. Somehow a vacuum is being formed, which is starving your engine of fuel, and boiling your gas. That big whoosh is air rushing in. Gas does not boil at 90F, it will evaporate, but not boil, think gas can in the sun when it is 105F, even winter blends don't boil."

scottmoyer

Well, I'm not the only one experiencing this issue, but I'm really gonna try to resolve it!

The fuel pressure regulator could be the issue also. After 30 years, I may need to gradually replace some of these parts, and when I find the one that fixes my problem, I'll let everyone else know.

My gas, since replacing the fuel pump/sending unit/filters, is non ethanol 89. I will not try a vented gas cap. I've already replaced my cap with a new one and I want things to work as designed.

You're in FL. Do you have this problem in your car when the temps hit 90* plus? If not, then the issue is not the gas, so we can rule that out.

redneckjoe

yes, i'm in FL. no fuel boiling issue with any vehicles i own. however, my camaro is converted to carb with a vented cap.

i was only suggesting a test with your cap loose to see if it made a difference. i understand you want it working properly as it should with a non-vented cap.

really hope you get it figured out, as i'm curious what the ailment is.

F-body-fan

First time reading the post. The pinholes (which you already resolved) look like something that was probably always there when the neck was solder in. I'll bet they didn't go down into the joint. But sealing them like you did is a good peace of mind.

My car 87 is still original, but with almost three times the miles on it. I never experienced boiling gas. Like you said, they never did it years ago, so why would it today. I would agree with that. I have had several 87 back in the early 90s & never experienced boiling fuel.

I am curious why your pump was replaced back in 2006? My car has what I believe is a fuel pump issue & its had it for decades. When my car sits overnight, (or sometimes days) it will start up normal for a moment, but then will stumble for a couple seconds & recover. Then the next time it won't do it at all. somewhat random. I feel my fuel pump is somehow letting air in the lines. I have been over everything else over the years & the car runs great otherwise. Do you recall why the pump was changed on your car? I noticed with my 89 GTA, the ECU cycles the fuel pump after the engine is shut off. Not sure what year they started doing that, or why.

I read through both threads but didn't get a good sense of the symptoms your car is having. starving for fuel when its hot I assume?

Did you notice a change in fuel pressure when its hot?

scottmoyer

I needed to replace my pump in 2006 because the car died as I went through an intersection. I could not restart the car. After letting the car sit a day, I turned the key to the on position and never heard the fuel pump activate. I checked the fuel pump relay and determined it was good, so I had the fuel pump replaced.

I don't have a fuel pressure gauge, so I haven't verified what my pressure is at what time.

DynoDave43

iTrader: (11)

Scott, just so I (and maybe others) can catch up...this thread looks like it started out about the filler neck. I also read the first post in the "other" thread linked in your first post.

I see you are trying to fix "gas boiling". But what exactly is the issue? Stalling? Hesitation? Is there a driveability problem? Excess pressure when you open the cap? A noise you hear from the tank after you shut the car off?

scottmoyer

Dave, yes this thread started as something different, but has morphed into what you see here. I've been chasing the boiling gas issue for a few years now and it was first noticed when I did the Hot Rod Power Tour in 2011. After driving at highway speeds into Nashville, driving the stop and go traffic in town, at 95* plus temps, the car just shut down. At the time I didn't know why. I now know that it was because the fuel pump shut off due to heat. I usually drive locally now, so I haven't had driveability issues since 2011, but after a drive in the heat, I get the boiling gas scenario. Also, if I stop to get gas, the tank is so hot, the filler neck swells and the gas cap doesn't fit when putting it back on. It starts the clicking before being seated and gas will spew all over the car on right turns due to an open cap.

When releasing the cap, there is huge pressure that I haven't verified if it's blowing air or sucking air. Probably not the best option, but maybe this weekend I'll take the car out with the charcoal canister vent line disconnected at the fuel tank. Maybe it's not venting properly and I haven't verified that yet. I'll also used air and blow out that vent line to if it's clogged. Who knows. It might be something simple.

F-body-fan

As I was reading your post I was starting to think maybe the fuel pump doesn't have enough volume to keep circulating the fuel & maybe the fuel rails were overheating because of it. Typically the continuous flow of fuel returning to the tank helps keep that system cool. But then you mentioned the tank actually gets hot. Hmmmm.
No doubt your heat shield is still in place? so if that's there it almost has to be the fuel pump its self is getting the fuel hot, or the lines. Did you say it's an oem pump, or don't you recall? I am not a big fan of aftermarket fuel pumps.

F-body-fan

One other thought too about the pressure in the tank. It must have a purge valve. Newer cars are electronic, but I think our 80's cars where vacuum controlled. I don't have my cars near my home, so I can't look, but it should have a vacuum controlled purge valve near the charcoal canister somewhere? Think thats how they were controlled.

okfoz

A While back I was driving our 1986 Work Van, it is a 4BBL V8 350. After the drive in the "heat" I could hear the gas boiling in the tank. I think it has to do with the Fuel more than the car.

Scott, Locally I was able to buy pure unleaded gasoline, can you get that in FL? I paid almost double, but it might solve a problem.'

John

DynoDave43

iTrader: (11)

Or at least try it once, to see if it helps with the issue. I thought gas at marinas was alcohol free?

https://www.buyrealgas.com/

scottmoyer

Post #18 says that I'm using non-ethanol 89 in the car. I've been using it for a couple years now.

okfoz

I am not sure about Marinas, however AV Gas I think is Alcohol Free. However I think it might be Leaded, at least it used to be. I am not sure if Boat Gas has Lead in it or not.

You definitely do not want to use Leaded Gas in a 3rd gen it will fowl your O2 sensor and probably a lot of other things.

John

thtanner

iTrader: (1)

Have you ever considered the fact your car is cursed?

I'd love to hear a resolve to this one day, lol.

87gtaredonred

Scott, Ive been reading your posts, I also have the exact same issues. Driving me bananas!!! On a cooler days there isn't an issue, but as soon as it gets over 80 if your drive more than a few hours, I'm boiling gas!!! I cured mine a lot by rerouting my return line it helped a lot but still have to watch it. My car is bone stock all the heat shields are in place, like you said in your previous posts my tank is actually hot to the touch, even after I let it set for a while, I can walk out put my hand on the muffler and heat shields and and they fell cool put my hand on the tank its still warm, it almost like the gas gets warm and just will not cool off until it sits for like hrs. With the exhaust and everything that runs under the tank I can see why it should get warmer after awhile but I cant figure out why some people claim not to have this problem. I'm like you Ive been on this for 10 years now and still scratching my head. My best advice is to reroute your return line and install a regulator after the filter so atleast your not getting heated fuel returned to the tank. That has really helped me. But like I was saying on a hot day you still have to watch it.

F-body-fan

Kinda funny, because I googled it & "They" say gas will boil at 300+ degree's, but then there are reports that it happens at 100-400 degrees. The latter answer is, don't boil gas on purpose to find out. lol But, It's probably safe to assume its not 100 degree's & not 400 degrees. I would guess on somewhere between 150-200 though. depending on the fuel, pressure, etc.


Maybe pick up an IR temperature reader & start comparing tanks temperatures on cars driven for more than a couple hours & see where your is at. I just drove 3.5 hours with my truck pulling a trailer. I could have easily checked the tank temps. I will try to remember next time.

87gtaredonred

it boils at 110 to 120, trust me I know, tested it several times lol

F-body-fan

No kidding? well that's not very high is it.
If the Ambient temperature is 75-80 degrees, I could see some fuel pumps warming up the fuel another 30 degrees easily over longer periods of time. Pretty small tanks on these cars. plus the returned fuel from the rail is going to be slightly warmer than when it left the tank. I wonder if any of these pumps have any specs regarding efficiencies & operating temps.
Probably not.....

87gtaredonred

My thoughts exactly!!!! And to think when its already a sunny warm day, if our car is parked on hot asphalt that's going to be even hotter, with the heat of the asphalt coming up, just a thought!

chazman

iTrader: (4)

I've got a similar issue with my '85. Following along.

87gtaredonred

Just to post somewhat of an update, just for fun I swapped the fuel pump over the weekend, I ditched the ac delco for a bosch, I did some testing over the weekend, my problem points to the pump heating my fuel, which I will explain later. Upon the new fuel pump install I will say its 100% quieter, I honestly cannot even hear it prime. Seems to fire up instantly. I really cant test if for a few days, our weather sucks its in the 50s here in NC. All last week it was in the 80s. Think its gonna be warm by the end of the week, so I will report back hopefully by the end of the weekend with what I found.

F-body-fan

87GTA, Your post reminds me of what my 87 Iroc has done for over 20 years. When it sits for 24 hours or longer, it will fire right up & then stumble for a few seconds, then smoothen out. The only thing I have not done is pull the fuel pump, but it acts like its getting air in the rails / fuel lines. Maybe this summer I will leave it sit & then run the fuel pump for a minute or two & then start it. I noticed in later year TPI's the ecm runs the pump longer initially & after the engine is turned off. I made a post about that when I first joined the forum.

87gtaredonred

Well i finally have somewhat of an update!!!!! Finally had a good hot day here in nc today close to 100. I drove this car for 3 hrs, not 1 noise from the pump no smell of gas not bubbling or carrying on when i cut it off, best of all no pressure when i released the cap. Now after i let it sit a few minutes off yeaaa i got a poof but thats normal from what i can tell when the car is off and hot it has no way to vent. So if that bosch pump didnt fix me ive atleast gotten alot closer. The 12 years ive had this car and the 2 acdelco pumps ive put in ive never had that good of results. I honestly thing those new delco pumps are just junk amd cant handle the heat ans they way they run i honestly think they agervate the problem even more on a hot day. I post more as i drive this summer, hope this helps someone

87gtaredonred

Sorry guys for all the typos in my last post, trying to do it fast and on my stupid phone

scottmoyer

My pump is a Delphi pump. Still experiencing the issue, but haven't driven the car much lately. Involved in many other projects, but will hopefully start tearing into this again on my end, soon!

burnout88

I don't know the obsession with putting in stock fuel pumps. Most of the Ac Delco pumps have turned into imported junk. I compared a stock delco pump to this Holley 255 and the build quality was noticeablely superior on the Holley. I live in AZ were summer temps hit 115 to 120 degrees on a regular basis. Every since I put that Holley pump in I never had a fuel boiling problem again and it runs quiter then the stock pump and bolted right in like a stock pump. I can also run a 150 shot of nitrous on it and it never skips a beat.

https://www.holley.com/products/fuel...s/parts/12-914

87gtaredonred

I agree 1000%

chazman

iTrader: (4)

Good to know, Brian!

scottmoyer

With my car, the original pump worked fine for 20 years without issue. To me, using parts that the manufacturer used, if they lasted that long the first time, I should be good using it again. The problem is that they might not be the "same" part that was manufactured for the assembly line. Many people have issues with after market not being of the best quality, so it comes down to what you know. If I knew the Holley pump was a better pump, I would of used it.

I did create a thread in the TPI board I think, when I was getting ready to replace mine, asking for suggestions on who made good pumps and sending units. I don't think I got many responses.

87gtaredonred

My thoughts excatly, thats why i put in 2 acdelco pumps chasing this problem. 20 30 years ago i think it was the way to go. Now i think acdelco is like the goverment who ever bids the cheapest gets the job

Bob88GTA

iTrader: (2)

I'll throw my 2 cents in here.
First thing.....Good job Scott for fixing the holes in the tank neck. I guess your tank is not Holy anymore! Little Friday humor guys. Anybody offended by that remark, I'm sorry.

Second thing is I been involved in many threads with the boiling gas deal. I spent 23 years in the Mojave Desert with my 88 5.7 GTA and NEVER had an issue. I replaced the pump with a AC Delco unit over ten years ago.....no boiling gas issue. I move to Huntsville Alabama 8 years ago and use this 93 Octane 10%Ethanol crap gas......and I then have issues. I switched to 100% Pure Gasoline at $2.69 a gallon, drive for 4 hours with the AC blowing in my face on a 95 degree summer day......and no boiling gas on shutdown,at idle, in traffic, or in my garage. Mine has been fine on Pure 100% gas. And my little vent thingie by the rear end is operational along with my emissions canister vent purge solenoid.
I dont know. Just my 2 cents....really 4 now.

87gtaredonred

Well it was pretty much 95 100 degrees here today, i drove the car from like 10:30 till like 4, not 1 issue of boiling gas or hard start problem after sitting for like 20 minutes or so. No noise what so ever outta the pump, its freaking amazing. So im pretty sure this 10 year old problem is solved

burnout88

Scott, have you tried changing fuel brands and running premium fuel. I recommend Shell premium. 93 octane if it's available in your area. Fuel quality can affect boiling.

chazman

iTrader: (4)

Pure gas hasn't been available in my area for at least a couple decades or so. I wish I had a convenient source.