Hey, is there any way an 88 12 gallon tank will fit in my 86 GT? Or is that not a go? I dont have an 88 12 gallon tank yet but I was considereing swapping my smaller gallon tank out for the 12 gallon one... Any thoughts?
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11:10 AM
PFF
System Bot
IROCTAFIERO Member
Posts: 791 From: Montgomery, Al USA Registered: May 2005
Yep. It can be done. You need all of the parts that go with it. The main tank, the expansion tank, the lines that connect main to expansion tank, vapor canister if you don't have one, and the tank straps.
One strap will have to be modified to bolt the main tank in. Mounting holes for the expansion tank will need drilled. A hole or two will need to be drilled for the purge line and line connecting main to expansion tank.
Thats pretty much it. The extra couple gallons are nice to have.
Hey, is there any way an 88 12 gallon tank will fit in my 86 GT? Or is that not a go? I dont have an 88 12 gallon tank yet but I was considereing swapping my smaller gallon tank out for the 12 gallon one... Any thoughts?
It is pretty much a direct fit...I just did one in an 86 GT I swapped in a 3800SC that went to Cali. I had to mod the front tank strap but besides that it was a pretty direct fit. If you plan on dropping the tank then go ahead and get a new fuel pump and swap it out when the tank is out...
..and if you get a new fuel pump make sure its a Delphi or AC Delco, damn near all others are inferior and will leave you stranded sooner than later
I believe you can use just the tank if you don't feel like installing the expansion tank. The main tank itself is only an extra gallon or so, but on a Fiero every bit helps.
Yep. It can be done. You need all of the parts that go with it. The main tank, the expansion tank, the lines that connect main to expansion tank, vapor canister if you don't have one, and the tank straps.
One strap will have to be modified to bolt the main tank in. Mounting holes for the expansion tank will need drilled. A hole or two will need to be drilled for the purge line and line connecting main to expansion tank.
Thats pretty much it. The extra couple gallons are nice to have.
Yeah I could have used 2 more gallons last weekend instead of having to walk down I-65 in the heat and get harrassed by the fuzz. This sounds like a worthy modification indeed.
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11:25 AM
James Bond 007 Member
Posts: 8871 From: California.U.S.A. Registered: Dec 2002
..and if you get a new fuel pump make sure its a Delphi or AC Delco, damn near all others are inferior and will leave you stranded sooner than later
I believe you can use just the tank if you don't feel like installing the expansion tank. The main tank itself is only an extra gallon or so, but on a Fiero every bit helps.
X2 on the pumps. I've had great luck with both these brands but not so much with all others...
Technically you can probably get away without using the expansion tank if you're careful about how you fill it. This is not something I would do though. The 84-86 tanks have room for internal expansion of fuel. The 87-88 tanks do not. This is why they need the external expansion tank. Fill up your car too much on a warm day and you taking a risk. The expansion tank is very simple to install and a great insurance policy IMO.
Even with the expansion tank mine creaks when the tank is first filled. Drive for a few minutes and the fuel expands and fuel level rises further til there is no longer ANY air in the main tank. I'd be a bit worried without the expansion tank in my situation. The vapor canister also acts as sort of a pressure release for the system letting the fuel vapor and air escape to make room for the expanding fuel. Unlike the fiero canister though my 4.9 canister is solenoid controlled and fully closed with ignition off. No pressure release without the ignition on. The tank does not creak when I leave the ignition on and it will take a 1/2gal more.
If you were to run the fiero canister it would help. The problem would come when the tank is overfilled. Instead of the expanding fuel going to the expansion tank it would just travel to the canster and saturate it. This kills vapor canisters quite quickly. They cost more then the expansion tank and you do not want to replace them on a regular basis.
[This message has been edited by Fieroseverywhere (edited 07-27-2010).]
Ah, in that case ^^^ go ahead and put the extra work into installing the expansion tank. I'm not sure what it would take to install it though as I've only got an '86 with the stock tank.
Definately install the expansion tank, I never gave fuel expansion much thought until a news story last week indicated that we are being ripped off at the gas pump by stations that do not maintain an industry standard fuel temperature in the 60s (apparently an accomodation was made in Alaska to correct this but I believe it favored the vendor instead of the consumer since the opposite scenario is more prevalent). According to the investigation, fuel temps in the 80 degree range in the underground tanks result in a loss of 2 ounces of fuel per gallon to the car due to the expansion that results.
Perhaps that's also part of the reason automakers have moved to a returnless fuel system in addition to vapor polution. The old system adds a pretty good bit of heat to the fuel circulating through the rail.
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06:08 PM
PFF
System Bot
Fieroseverywhere Member
Posts: 4242 From: Gresham, Oregon USA Registered: Mar 2006
Ah, in that case ^^^ go ahead and put the extra work into installing the expansion tank. I'm not sure what it would take to install it though as I've only got an '86 with the stock tank.
Its actually very simple. First remove the passenger side inner fender well. Then 2 holes need to be drilled to install it. A close quarters drill would work best but I made due with a regular cordless and a short bit. There is a 3rd top mount bolt that can't be drilled with the rear clip on. Its not necissary for the install though. When removing from the old car this bolt can be a PITA. Easiest way I've found is to take off the quarter window. They you can reach that bolt easily.
Another hole will need to be drilled to run the lines from the main tank to expansion tank and from expansion tank to vapor canister. I jsut drilled a hole and put in a rubber grommet to protect the lines. 87-88 fieros have a hole cut under the battery tray for these lines to pass. 84-86 cars do not. That is why a 3rd hole needs to be drilled. I have pics from my install if anyone needs them. Total time to install expansion tank is about 30 minutes.
[This message has been edited by Fieroseverywhere (edited 07-27-2010).]
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06:41 PM
fieroguru Member
Posts: 12295 From: Champaign, IL Registered: Aug 2003
Here is some information when I was working on raising the vent tube to further increase the capacity of the 88 tank:
quote
Originally posted by fieroguru:
Fuel expands/contracts with changes in temperature and it is important to ensure there is enough room in the tank for it to expand or it could push fuel into the evap canister. Gasoline expands at a rate of 0.00069 per degree F. So a 100 degree change in temperature with a 12 gallon tank will require .828 gallons of additional space. Expecting a 100 degree change is probably extreme, but it provides a sence of scale.
Since my car is an 88, it has an external expansion tank on the upper passenger frame rail (I never measured it, but it might be .5 gallon). The top of the fuel fill vent tube is about 3" from the top of the tank. This creates an air pocket about 3" x 7" x 20" which is room for about 1.8 gallons of fuel (1 gallon more than needed for a 100 degree change - and assuming there was no secondary expansion tank).
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06:45 PM
Fieroseverywhere Member
Posts: 4242 From: Gresham, Oregon USA Registered: Mar 2006
Excellant! That may indicate there is enough space for fuel expansion in the main tank.... so long as you have an outlet for the fuel vapor/air to be pushed out. The fuel can use a portion of the fill tube to self level also. It may be possible, if filling slowly enough, to reach the top of the fill tube. So 1.8gal would be the max, probably a bit less.
Also brings up a point that maybe its possible to increase the capasity of the tank slightly if using an expansion tank. I had seen someone working on lowering the fuel pump height by modifying the sending unit slightly. Also might be possible to raise the height of the fill tube to get a bit more in there.
EDIT: Or maybe not... Also not quite a 3x7x20 free space there.
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07:29 PM
sspeedstreet Member
Posts: 2306 From: Santa Maria, CA Registered: Dec 2002
The vent tube angles down as it reaches the center, I measured mine from the top of the tank to the top of the vent from the fuel pump access hole. The other thing I suspect is the vent tube must have some type of perferation on the other side of the 88 baffle.
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09:19 PM
Fieroseverywhere Member
Posts: 4242 From: Gresham, Oregon USA Registered: Mar 2006
Nice. He did both. Lowered pump + raised vent = Increased capasity.
I forgot to bookmark that one all those years ago. This forum jsut has too many threads to remember them all.
I liked your idea of the snorkel. Simpler and looks like it would be effective. Did you ever do more with that? I thought a combo of that, this and a larger expansion tank could put the fiero up near the 15gal range.
[This message has been edited by Fieroseverywhere (edited 07-27-2010).]
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10:01 PM
Jul 28th, 2010
fieroguru Member
Posts: 12295 From: Champaign, IL Registered: Aug 2003
I liked your idea of the snorkel. Simpler and looks like it would be effective. Did you ever do more with that?
It didn't work, but the snorkel was still properly seated when I removed it. This is why I suspect there is an OEM hole in the vent tube between the rear of the tank and the back side of the baffle. On my next swap, I will probably just make a new vent tube and raise it all the wat to the top of the tank.
