I have cut a hole to my fuel pump in an 88 iroc before it was not possibe to pull the pump strait up due to the angle of the fuel lines unless you was to cut them,if you cut you should clip them somehow if you saw them you would get shavings in your gas lines as well as maybe make a spark.

Nice job, 330hp. It's a good idea, no matter what anyone thinks about it. They're all just jealous cause you're making 330hp, and they're not.

I got the idea awhile back when reading my Hyundai's repair manual. Small cars, and probably all cars today, have access to their fuel pumps right through the bottom of the car. GM's designers should've thought about that before they ever installed the pumps in the tanks. But all they probably saw was $$$ for the future replacement. Back then, the dealers had it made for stuff like that. The aftermarket was very slow to catch-up to the thirdgen.

Funny, these guys call it a "hack job," and they'd "never" do anything like that to their cars. But they'll gladly ruin the interior to install a stereo system, or "decorate" their cars with so much aftermarket crapola that the car, parked on a street corner, would be mistaken for a prostitute, lol!

If people are really so worried about structural integrity, then simply framing the cutout will make the bottom even stronger than it ever was as an intact piece of sheetmetal.

Nice job.

Heh, LOL....if they were pissed with 330hp out of the LO3 305.....they will want to kill me for the new motor and drivetrain!!!

From 330 hp to a little over 450!!!

I agree that the access hatch is the way to go. I'm getting ready to put one in my car. It doesn't hurt the frikin structural integrity of the car one iota. Work smart, not hard guys.
I've changed a pump before and it's a pain in the ****. That hatch will make it a much easier job, period.
Some people don't want to cut their cars, which is fine. Most of those people probably think that 82-92 f-bodies are actually going to be valuable in another 10 years. Maybe their optimists, that's cool.
It's the people that knock it and have never changed a fuel pump in one that I burn me up.

Just be sure to put a good sealing material around the hole to prevent water, and most importantly carbon monoxide from getting into the passenger compartment.

When i think cut out a hole for access I immediatly think of something like this...




http://www.carcraft.com/featuredvehi...gto/index.html

You do not want to cut past the corner (downslope). The bend is where the sheetmetal gets its strength from back there. Keep your cuts to the flat surfaces for best structural integrity. I also think on this one you cut a little to far behind the pump. I cannot think of a good reason to remove that extra material. Other than that it looks like you got it centered real well and the color coordination was a smart touch.

I cut as far back as i did because i could not tell very well where the pickup was or how far back it was. i could have made a smaller hole and worked from there but i was concentrating on making it neat. one unseen benefit of the rear portion of the cutout is that it made wiring for the pump easier. Its difficult to remove that plug and get new wire up there.

I have noticed absolutely no difference in structural rigidity. I also doubt that cutting an inch or two of the downslope would cause any loss of strength.

also on the issue of strength. there is a plate of heavier material than what was removed that is used as a cover and if fastens with quite a few screws.

i doubt that cutting any sheetmetal in that area would harm any structural integrity whatsoever......even less so if you have any sort of chassis stiffening, such as subframes, or a cage, or in my case, both

You would be incorrect. The area in the back is formed similiar to a box. It ties in the left and right side of the frame acting as a third member. Just like the front is tied in by the crossmember and the firewall. As long as your cuts are on the flat part, do not get to large, and are properly sealed you will be fine. You will have suffered structural loss if you take material out of the bends that form the "box" in the rear hatch area. Most subframe connectors run the lengthwise to add stiffness they do not tie in left to right so you would have put nothing back as far as strength in that direction. Now a full cage (but how many people are actually running one) would give that strength back no problem.

I don't want to get in a flame war so this is my last comment on the subject. I work with sheetmetal fabrication and my info is based on my experiences with sheetmetal stress and load testing as well as some knowledge of how our unibody's are formed. You cannot just take out whatever material you want out of the hatch area and be OK. You better put some thought in it.

I understand your concerns, and i believe you are right, If you take a lot of material from the area. In my case i took a small percentage of material. Had i taken a 2 foot section or extended a lot further forward then i do believe strength would suffer. But there is a lot of material there. If it wasn't for the corregations or the fact i never saw the top of the tank before i would have cut a round hole, since this would eliminate any stress raisers and i believe it would effect strength the least.

Here's a question for both this subject and for anyone else, as well. There is the stamped SEMI-boxed rail running right under the gas tank which attaches to the frame rail on the drivers side and to the panrod bracket on the passengers side. Is there any good from a stability standpoint, to FULLY box that rail?

I don't know exactly what the effects of boxing that support would be on the overall ridgidity of the frame structure, but in general whenever you see supports that are a 3 sided box they can benefit from being boxed completly. Typically those types of formed supports are made from stamped sheetmetal which is a much cheaper process (from a manufacturing standpoint) than buying tubing and having welded construction. Our lower control arms in the rear are a perfect example of this. The only downside I could see to welding in a fourth side and creating a true box out of a support column would be the added material weight.

What spawned my question is the fact I have a host of Spohn products back there and it definetly looks out of place with the upgraded suspension. I have the rear end lowered now. Putting in Global West springs and Earl brake hoses. I will box it now rather than later...maybe paint it red to match the Spohn components.

That sounds pretty slick! It will look great when your done. Funny when I started my suspension stuff, painted my sway bars, and differential cover deep chrome oil pan, I completly cleaned the underside of my car and took pictures, my girlfriend thought I was crazy spending that much time on something nobody sees. Maybe she was right

That's not crazy! Crazy would be having her join you under the car for a little fun...now that's crazy.

To each their own I guess but if it really takes all that time you guys said it does to drop a tank there is something really wrong. It's your cars, do what you want but don't get so pissy if someone calls it a hack, because well...in MOST cases it is....

well i work with real steel, and i say differently.

thousands of people have done this and has anyone ever heard of someones car completely bending in half or disintegrating because of it? i think not

and like i said before, add some chassis stiffening as well, and you'll never even know the difference.

i love how theres always a "sheetmetal engineer" or a "gas tank filler neck engineer" or whatever the case may be when a certain question comes up.

well i do this and study this and what not......who cares, it works in practice, and thats all that matters, you can think whatever you want, but if it works anyways, then your just being igorant.

dont take your ground effects off, cause your engine will fall out

thats like calling a chopped and channeled hot rod a hack job, come on

it would be a hack job if you cut it out with a hacksaw, did a **** poor job, and covered the hole with galvanized sheet metal, secured it with self tapping sheet metal screws and covered the seam with caulking

that would be a hack job

I did mine in about an hour and a half.

Of course i was working at the Pontiac dealer at the time and had access to any tool i needed to make the job easy
we had a jacking table to lower my FULL gas tank, air tools and lift.
It's really not that bad even if i had to do it in my drive way i can't see it taking more than 3 hours

WOW......

After reading each post above this one, I have learned something very valuable.

Hack job = feul pump access door, shaved door handles, shaved gas cap, shaved antenna, aftermarket spoiler, aftermarket shifter, custom sub woofer installation, aftermarket stereo system, custom lighting, neons, hydrolics, rollcage, custom doorpanels, custom headliner, aftermarket hood (espescially if hood pins are used), suspension lowering, posi rear end, 4 wheel disk brake conversion kit, aftermarket sunroof in a hartop (can you believe my friend actually did that to his third gen?), aftermarket ground efx, aftermarket exhaust, alarm system, sparkplug access doors (that one's actually pretty funny), custom stearing wheel, aftermarket power windows, aftermarket power locks, custom window wipers, custom cup holders (why don't we have those, btw?), and of coarse we can't leave out any engine or transmission modifications and/or substitutions

My point is, If all of our cars were stock, there would be no use for a website allowing us to share ideas and pics of all of our cool crap. It wouldn't BE cool crap! I would be one of however many colors, that looked exactly like the one next door.

Thumbs up, my man.

P.S I had aftemarket exhaust that i had to cut in half to drop my tank to change my pump. Wish I had known you then.

LOL@comparing what you're doing to hotrod like work, now THAT'S funny...

Yeah and I've seen hack jobs like that where people have used hacksaws...notice I said it'd be a hackjob in MOST cases...you can place yourself in whatever category you wish...

in some of the guy's defense here, it took me an awful long time to drop the tank the first time, although i definitely went about it all wrong.

first off, the tank was full, which made it a huge pain, second the exhaust is welded up so it was in the way the whole time, and third, it was obvious that there were a bunch of bolts in my rear suspension that were never off before.

so maybe the first time is a bitch, i can guarantee if i ever had to do it again it would only take a couple hours.

And i actually took another approach to not having to go back in there again. i swapped to an external inline pump while i had it all apart.

http://www.poorformance.net/tech/fuelpump/fp.html

i dont put myself in any category, i do things the right way period.

doing something "hack" as you call it would get us DQ'd at inspection before an MTRA event, and send us home short about 5000 bucks. we dont hack anything, period.

if you wanna be a moron, and drop your entire gas tank to pull the sending unit, as opposed to making a neat and clean door that changes it into a 5 minute job, then i guess your time is worth alot less than mine, and everone elses, so whatever

To each their own I guess...I guess you can make it look nice but I wouldn't trust the integrity of that structure if I was in a rear-end accident. I'm not expert but I AM in the body repair industry...I just wouldn't trust cutting part of that panel for the sake of putting in a door.

Be careful you don't want to point out any reason you may have experience or valid useful knowledge on the topic at hand 383backinblack might get upset.

It was my father's idea.

We own a 15,000 square foot Collision Repair shop. We are known as the top quality repair shop on the big island of Hawaii.

If this project is done correctly, it will NOT affect structural integrity to the point of weakness.

So I am also in the body repair business, I say it's a good idea. The gas tank itself would have to be crushed nearly halfway just to make the sheetmetal bend back there, being that the pump is in the middle and the door is relatively small.

You'd have to be rear ended really hard by something really big for this to even be an issue.

I really don't think that flat panel of thin steel adds much strength, i would dare say in a rear end collision (compression) it will add roughly no strength what so ever. It may be usefull in terms of chassis stiffness, by tieing the left and right side together. Making a small hole in it won't affect that either. If you don't believe me, think of a lightening hole in a sheet metal structure like a wing rib. So long as you don't add a stress riser to HIGHLY stressed part your ok. making a round hole or rounding the corners or making a strong cover plate will negate any loss of strength here.

Now besides the debate on strength/safety, it's really up to the car owner to decide what works for him. if your not comfortable, thats fine but if you are have fun. Personally i find it a comfort to know i can get at the pump in minutes and change or trouble shoot it. i have not lost a second of sleep over any loss of strength or safety. Just my 2 cents

the integrity of the structure??? the car has an 8 point roll bar and subframe connectors....


and even if it didnt, i wouldnt be the least bit concerned about it

im in the common sense and intelligence industry, and thats the dumbest thing i've ever heard.

ya, cause i have experience to the contrary.

thousands of people have done this.....it hasnt killed anyone.

so your theory and application of tons of useful knowledge and experience from the "body repair industry" is useless.

bring your A game next time

here's mine with ALL tools required to do it, really quite simple.

clearance between the tank and body panel:

damn, that must have taken forever with that tiny cut off wheel

I do believe you have lost track of the conversation. I am neither against the idea nor am I in the body repair industry. Perhaps it is you who forgot to bring any game.

[QOUTE] 383BACKINBLACK
"the integrity of the structure??? the car has an 8 point roll bar and subframe connectors.... and even if it didnt, i wouldnt be the least bit concerned about it im in the common sense and intelligence industry, and thats the dumbest thing i've ever heard". [END QOUTE]

I also find it interesting that suddenly you think this whole conversation is about you and your particular car (which is obviously not typical). If you are running a full cage nobody is concerned about your car having structural loss. This was a general topic forum and I believe thats what the previous comments are refering to.

Heres a technical question maybe somebody can answer (get this topic back into containing useful info) The hard lines that are being cut and replaced with rubber hose. Is a basic hose clamp and rubber fuel hose adequete for holding that connection? I would think under 42-50PSI a more aggressive clamp maybe should be used?

it doesn't seem like rubber hoses and hose clamps are the way to reattach cut metal fuel lines carrying 45# fuel pressure...what would be the safest way to do this? compression fittings don't seem to be the way to go either...

yes, but note clearance pic... wanted to make sure i didn't hit the gas tank. it's not the 4th of july yet.

i was thinking the same thing. maybe inserting a threaded end and then flaring the metal line. at that point you could attach a threaded hose end, like those fancy red and blue aeroequip fittings.
for now, my car runs - and i will leave it at that for a couple days untill i can think of a better way of attaching it, and fabricating a trap door.

I used AN unions for my pressure and return lines. There aren't any compression fittings rated for use at 50 psi on fuel systems. The rubber you saw in my pictures was also fuel injection hose with fuel injection clamps. You should definately not use regular carburator fuel line on a FI system. You can use a 45 degree double flare and union though.

If just put in an inline pump instead of replacing my in tank pump, would it just draw through the old pump or would it cause a problem?

That "hole" idea has one fatal flaw...You are cutting a hole in a high stress area of the already (relatively) weak unibody construction of the car. Namely right between the two rear shock towers. The location of this hole would counteract any suspension upgrades you have made by transfering cornering force into the, now weakend, area of the unibody; thereby causeing deflection of the "frame". This causes more squeaks and more importantly reduces cornering ability by allowing deflection of an unanticipated piece of the car. As we all know, a well built chassis/suspension minimizes unanticipated deflection.

Someone did this to my car, but in a much more violent way...

please re-read the posts!! nobody is suggesting you butcher the car like yours has been! That is an extream case of a hack job. When done properly it is not an issue.

If you think a hole in the floor is not an issue then more power to ya...I am just saying that no matter how neat of a job you do, it will still reduce your chassis rigidity and thus your cornering ability; unless you put in a roll cage and triangulate the area. Thats the truth take it or leave it!:lala:

Your absolutely wrong. The flat deck adds little strength it is basically a flimsy piece of steel. The biggest job for this area is to close the floor from the outside elements. No body is suggesting cutting a flap out of the floor. In my case i used a plate and numerous fasteners to restore the floor and close the hole. In your case the opening caused stress raisers that propagated cracks. You can if well equipped cut a round hole with virtually no loss of strength or stiffness even if you leave it open ( i'm not suggesting driving like that ). You can use a hole saw to make smoothly rounded corners in t he case of a square whole. If you don't believe that you can remove metal from a flat sheet without reducing strength take a look at a wing rib from an airplane. It is common practice to use "lightning holes" to reduce weight. In fact pound for pound removing weight in this manner results in a greater strength to weight ratio. Another example is the "I" beam. in terms of strength to weight it is stronger than a solid beam. The reason that there is so much debate about this mod (i believe) is because the people who are against it aren't considering the METHOD of the metal removal. In the case of your car (extream) it was poorly, and recklessly done. If done properly it is not an issue.

I see we are back to the debate.

Found this over at fbody.com. Thought you guys might like the pics.

http://www.fbody.com/cgi-bin/lt1/read.cgi?msgid=177776

I would consider this a job well done, very far from a hack job. Even fourth-gen guys are doing it!!! I highly doubt that this small hole will decrease chassis rigidity, especially when it is sealed back up.

its like with anything in life, Its all how you do it.

When the pump went out in my iroc, it took me about an hour to get the tank out (having no exhaust makes it really easy). Only an hour, but an hour of cussing, throwing tools, and weird contortionist positions to get that damn thing out. When i finally did wrestle it out of there, i looked up and saw the neatly cut HINGED AND LATCHED door that the previous owner had taken extensive time to make I felt like a dumbass..... Oh well, i still feel better doing it the way it was ment to be done.


So let me get this straight, you were working with a welder right above your gas tank and now youre wondering why people are calling you ignorant?

Oh well i suppose ive seen worse. In high school auto tech i saw a kid attempt to weld his exhaust hangers onto his gas tank luckally coach caught him just as he was lighting the torch

Laiky,
You are talking about crush strengh when you reference wing ribs and I beams. I am talking about torsional rigidity. an I beam is not torsionally rigid, that's why skyscrapers sway. Air Plane wings are not all that torsionally rigid; this is why you can see the wings bounce when the plane goes over a bump when it is still on the ground. It's all a matter of how, and to which axis you apply the force to. Not trying to argue, just trying to illustrate that we are talking about apples and oranges; in a way we are both right.
No hard feelings I hope?

None at all! i enjoy a discussion.

You make a good point about I beams, i was tring to give an example of how removing material can actually make something stronger. That is not the case with the fuel pump mod, i agree. I beams are very strong though in bending. i disagree on the wing issue. a wing is designed to bend without breaking it is not usually designed to twist. depending on the design, it may need to twist though (i believe it has to do with the chord length tapering off) but anyhow, i am not an aeronautical engineer and there are way too many different wing designs made to even attempt to argue that point. I think if the mod is done well its a non issue, so long as you make the hole in an appropriate manner and close the hole the same way!

if you cut the material in between the ribs, and dont cut across them, the strength og the piece will be virtually un changed.

i'll get pics up of my stainless steel door soon