building a new fuel system..

[Txchevy18]

Ok well I've had it with my dual tank setup! With the body lift the previous owner installed they make all kids of noise due to clearance issues with the body when i flex. I was goin to just raise them up again with new backets but, I would really like to get rid of them all together. I guess it has something to do with the fact that the tanks are outside the frame rails that makes me uneasy and that building sliders to protect them is PITA!.. O and the passenger tank is the only one that works thanks to the previous owner bypassing everything when he installed an electric pump.

Im thinking of re-doing the entire fuel system with a fuel cell and new lines. Im leaning towards all ss braided and AN fittings since Ive always wanted to use the stuff and I plan to swap in a 5.3 or 6.0 at some point in the future and regular 3/8 rubber line wont handle the pressures of EFI.

Ive read all the legal stuff concerning runing a fuel cell but, since my truck is so old most emission places wouldn't know the diffrence as long as there is a fuel cap under the gas door. Ive also talked to several local and state officers who run fuel cells in their street driven cars and say its just a technicallity..

So this what Im working with a 85 gmc k20 , 9" lift , on 40's , mild sbc 350 350hp, 700r4( still havent destroyed it..), np208 , 10bolt w/ 4.10's high steer x over locked w/ hydro assit, 14sf with posi and 4.10's.

This truck is my dd (I only drive 5miles round trip to work and I have a 03 crew cab for towing duties) so I dont want to take any short cuts. My thoughts are a summit 20 gallon fuel cell with sending unit...http://http://store.summitracing.co...4294920243+400304+4294894951+115&autoview=sku
Im thinking ill mount it under the bed just behind the rear axle where the spare went and build a skidplate / crossmember for it.

Then run their fuel system kit as well.. http://http://store.summitracing.com/partdetail.asp?part=SUM-PUMPKIT7A
Which includes 20ft of 6 an line, a sumit brand fuel pump ( looks like a rebadged holley blue) summit regulator ( non return) and a summit 40micron fuel filter along with the nessecary fittings to connect it all. I just need to supply a 90* from the cell and a 8an to 6an reducer union and a fitting for the new carb.. more than likely a edelbrock preformer 600cfm.. (5/8-20 thread to -6an).

I pretty sure that -6an will flow plenty for this and or the future motor, tho if if im wrong plz tell me! My biggest concern are the fact that the regualor in that kit is return less and the fuel cell has a return..

Do I need a return to keep the fuel pump cool or can i cap it off and forget about it for now?
Also what about a second filter after the pump? Ive heard of guys running a 100micron before it and a 10micron after. Any thoughts?

What about the two fittings on top? Im guessing vents maybe install a set of rollover valves on some ss line and run them up the bedsides?

Thanx Guys,
Cory

 

[dyeager535]

What about just using a K5 tank (small or large) mounted in the bed? Sending unit and pump would be taken care of, and it would be out of the way, but only if you didn't use the truck bed.

I suspect you could fit one or both K5 tanks under the bed if you wanted to.

I've been hearing a fair amount about the fuel cell foam coming apart in the cells, with EFI you really want something to keep the pump submerged. Foam seems like one more thing to go wrong to me. Stock GM fuel filter ahead of the pump and be done with it IMO. Still get to play with the AN stuff, since there are AN adapters for the Saginaw fittings.

 

[Txchevy18]

Thats not a bad idea, but I still need to use the bed. I haul scrap from the jobsite for my grandpa ocasionaly, and to haul the 4wheeler to the trails along with camping gear. I could mount it under the bed tho like on a k5 if its not too tall and build a trap door on a hinge like I had planned for the fuel cell. Any idea on the height of a k5 tank? Im guessin its about 14".

I had considered using 1 in the first place but finding one has been a pain so far at least in useable shape.. I need 1 for my k5 as well since the repair kit I did isnt holding. I was also concerned with the foam becoming an issue.. Is it a better idea to just remove it? Is the ethanol in the fuel partially to blame for the deteriation of the foam by chance?

Are the -an fittings and ss braided line really neccesary in my application or is there a better way to do this? I had considered aluminum tubing but it ended up close to the same price by the time u add in the fittings. From what I have read the gen III motors require about 60psi and rubber line just wont support it. I want to do this once and be done with it.

Thanx,
Cory

 

[dyeager535]

Pulled this off a previous post: 31 gallon tank depth 12-3/4". The smaller tank I believe is roughly 10" deep, 27 gallons?

I suspect for what a fuel cell runs, you can get a new steel K5 tank in either size. Mine was right around $120 a few years back. (gastanks.com I think) I think the foam just breaks down with time, probably no different than a kitchen sponge. Ethanol and what not probably doesn't help, but by now I'd expect that to be planned for in the design.

Is GM even using steel or braided anymore? I've seen a couple of newer GM vehicles that had the plastic fuel lines, and they were higher pressure setups.

Personally, if not in the rust belt, I think steel lines are the best. Not even sure what the TBI truck fuel lines are made of, but mine don't have a spec of rust on them, even after me re-bending them. They aren't aluminum, but I can't believe steel wouldn't have rusted at least a bit by now. Steel line, and if you can get it, real braided/armored hoses for the frame to engine and frame to tank connections. One good thing about using GM fittings, those braided fuel lines are everywhere in the wrecking yards.

Only problem with the factory setup is the proprietary fittings if using GM hard parts, (assuming the gen III setups still use the same style as TBI/TPI) the throttle body end, the fuel filter, and the sending unit. I suppose you could just as easily cut those off the sender and fuel rail, put your AN fittings on there, and only use two adapters for a stock fuel filter.

Other option is if someone like Ford used a more standard fitting that you can install cheaply yourself, and used a standard fuel filter, is to go that route. No adapters needed (cheaper) and no monkeying around with adapters when you had to change the fuel filter. (cheaper and easier than finding aftermarket fuel filters)

 

[Chevy305]

using an electrical fuel pump a return line should be used. Also if you really do plan on going to an LS type motor they will need a return. I've never heard anything bad about the foam, it just prevents the gas from sloshing so much.

Also 4.10s and 40s? you might need some more gearing...

 

[Txchevy18]

Ya i had planed on the return in the future just wasnt sure if I needed it right away. I think this project is going to teh back burner.. the city just told me I have 3 weeks to get my blazer inspected and driveable or it will be classified as an abandoned vehicle and be towed away under a bs city ordinance... Just ****ing great.

And ya it does need gears but, belive it or not it doesnt do too bad with the 4.10's. You only notice it when you get on it while playing. It will still smoke 40's leavin the light tho. Im tryin to decide if I wanna sell the 10bolt and 14sf and move up to a 60/14 combo or just throw 5.13's in it and call it done.. this truck is not a crawler.. mostly beach and mud, and dd sometimes.