The hugest TBI conversion write up, EVER

[Mastiff]

[ QUOTE ]
Problem for me is that both lines are the same diameter, both lines come into the tank very near each other, both smell like gas, etc. It's basically impossible to tell them apart by eye. There must be some test that will give me a definitive answer. Guess I'll probably end up dropping the tank to be on the safe side. /forums/images/graemlins/crazy.gif

[/ QUOTE ]

Are you saying that you don't even have the lines connected to the steel lines anymore? If so, it'd be kind of tough. Working from the steel lines, I could trace the main line to the mechanical fuel pump, plus when the rubber line was removed, it would pour gas forever. The return line would spill a little gas but stop shortly. The vent line was dry. To double check between vent and return line, I went to where I know the vent ended up near the charcoal cannister and blew into it with it open and closed and could tell the difference in resistance.

If you just have the tank, I'm not sure how to tell. It's possible that only the main "from" line is submerged, in which case you could blow bubbles or else see which one you could siphon gas from. The vent and return could be tough to differentiate, but the vent was skinnier in my case. If they're the same diameter, I wonder if there'd be any problem using the vent as return anyway?

 

[pizpump]

If I use the vent line as return, I'll still need to vent the tank...right?

Can that be done without dropping the tank out and welding in a fitting?

 

[pizpump]

[ QUOTE ]
and vapor doesn't extend into the tank at all.

[/ QUOTE ]

It doesn't?

Are you certain about this?

How are you relieving the pressure in the tank?

 

[pizpump]

[ QUOTE ]
Are you saying that you don't even have the lines connected to the steel lines anymore?

[/ QUOTE ]

Precisely!

 

[Mastiff]

[ QUOTE ]
If I use the vent line as return, I'll still need to vent the tank...right?

Can that be done without dropping the tank out and welding in a fitting?

[/ QUOTE ]

Do you currently have 3 lines coming out or only two? I'm not certain that the vent can be used as a return, but if it can, you could just get a vented gas cap to vent the tank. I mean, assuming you don't have emissions nazis that will ping you for bypassing the charcoal cannister.

 

[pizpump]

I'm going to give it a shot and see what happens. If I can blow into the vent line without restriction, I'm hoping the fuel will flow through it as well. Guess I'll just have to wait and see...

The vented gas cap should do the trick. It's a 77 so emissions isn't a factor.

 

[pizpump]

By the way, your write up on the conversion is top notch. I'm going to print it out and have it with me during the changeover. /forums/images/graemlins/waytogo.gif

 

[Mastiff]

[ QUOTE ]
By the way, your write up on the conversion is top notch. I'm going to print it out and have it with me during the changeover. /forums/images/graemlins/waytogo.gif

[/ QUOTE ]

Thanks. Go ahead and post up or mail me if you think I can help with something.

 

[K5 NUTT]

I like the right up...i've done the swap twice now...the last time i just built the harness myself and saved the coin. I have a book collecting dust due to lack of time to show others how to do it also...

It started many moons ago...and on the first go around i too delt with customefis...allthough back then he was ebay only with no web site...basically i sent him the money...after three months and no product recieved i railed him and got my money back....so i would recommend to steer clear from mr. i'm waiting on parts.

If you have any questions pm me as i am well versed in tbi...just ask the az gang. Some helpful hints....87 to 91 K5 baffleed tanks (aftermarket $95 thru rockauto.com) is the way to go...andvance timing to 12 to 14 degree's advanced...and turn up the fuel psi regulator while you have it apart changing the injectors...i'll walk you thru the simple process....and yes a small cap hei is a drop in...with a modified bone yard harness and or a Howell harness...and there 2 pulse vss is $85.Also if your motor is close to stock a stock chip is just fine...

My chalet now runs strong and true and pulls down 12 mpg even when climbing vail pass on the way to stormtroopers house....and someday dave is going to let me convert his K5....lol.

DW /forums/images/graemlins/usaflag.gif

 

[dyeager535]

[ QUOTE ]
Are you certain about this?

[/ QUOTE ]

Absolutely. The vapor line is just soldered to the tank, and there is a valve or filter of some type on the gas side of the sender.

I plugged the hose coming off of that, and used a newer gas cap, built a lot of pressure up in the tank.

page 2, "gas cap" is what I HAD to use to relieve tank pressure. That cap bleeds pressure easily, the newer ones do not. That cap is what a non-evap rig should have, but every auto parts store I checked at, listed the same gas caps for too wide of a range of vehicles.

Without EVAP, they need some way to breathe, and that gas cap is it.

 

[pizpump]

[ QUOTE ]
87 to 91 K5 baffleed tanks (aftermarket $95 thru rockauto.com) is the way to go...

[/ QUOTE ]

Thanks for the tip. If the carbed tank/external pump route doesn't work out, I'll look into that option. Don't want to spend more money then necessary and another tank is definitely not in the budget (especially since this K10 already has 2)!

 

[pizpump]

[ QUOTE ]
The vapor line is just soldered to the tank, and there is a valve or filter of some type on the gas side of the sender.

[/ QUOTE ]

Is it a check-valve?

Is there any reason why gas wouldn't flow back through it?

Also, can you give me a make & part number for that gas cap?

Thanks in advance!! /forums/images/graemlins/ears.gif

 

[dyeager535]

I can probably test it to see if its a check valve, I have a sender out of the tank now. Would make sense to be a check valve, the EVAP gas caps allow ambient air in, but the tank won't vent through them. (at least not until very high pressure)

I can't give you a make and number. This is an old one (metal cap) and I have yet to find one. As I mentioned, when I talked to the parts stores, the part numbers for the gas caps was the same for vintages/models of trucks that shouldn't have been, at least in my thinking.

For instance, my friend has an '83 350 C30. It has no evidence of EVAP on it whatsoever, and no indication there was ever EVAP present. However, when checking the numbers for a cap from that application, and comparing them to say a 1983 K5, the stores say they are the same. So unless the vehicles without evap later on vented from the tank somehow (which seems unlikely to me, but I guess it's possible) the parts stores are wrong.

Just not that many one tons with the bed off to check how they were setup. /forums/images/graemlins/frown.gif

 

[pizpump]

[ QUOTE ]
I can probably test it to see if its a check valve

[/ QUOTE ]
No need. There is definitely some restriction there (much easier to blow into the feed line), but ended up trying it anyway. Ran the pump straight into the vapor line and could hear the gas peeing back into the tank. Almost brought a tear to the eye...
/forums/images/graemlins/peace.gif

 

[dyeager535]

Yeah I forgot about this thread, but I did test mine. It seems to be some kind of filter. Flows both ways, but its restricted by the piece on the fuel side of the sender.