hydrolic144

iTrader: (2)

Am I missing something here? My 89 GTA was converted to a carb setup. Guy installed an electric pump, not sure how many PSI but I think it may be too much. He did the typical hack job on the hatch area to access the tank pump, but upon getting under the car, I only see 1 line going into the fuel pump, and out to the carb. There are also 2 lines just sitting there and sometimes are wet on the ends like fuel has been coming out of them, not only that, I can smell fuel heavily when taking moderate turns. Do I need to cap off these lines? Did they do this wrong? If any pics are needed I can get some.

zraffz

Uh I wanna say I have three lines. One is delivery, one is return and I wanna say the other one is a breather.

hydrolic144

iTrader: (2)

Are you TPI or carb?

Guest

TPI cars originally have 3 lines you have to contend with. One is fuel pressure line, one is the return, and one is for the charcoal canister/vent line. On a carbed setup... who knows. With a mechanical pump on the block these cars only had 2 lines, one for fuel supply, and one for the charcoal canister. The return line, unless its being used to feed excess pressure back to the tank, is useless. It may be you have way too much pressure at the carb, but only you can verify that.

Sparkytfl

No, they have 3. They use the mechanical pumps with the return line. So gas, gas return, and charcoal canister.

hydrolic144

iTrader: (2)

I definitely see all the lines still there and what not. I think my best bet is to get a fuel pressure guage and see what it's reading. Also another thing, sometimes when i'm driving around and get home, I can hear my fuel tank bubbling for about a few seconds then it stops. Is this cause the fuel is hot? My rubber fuel line does run over my valve cover.

zraffz

I was running a TPI originally. I went to carb with an electric pump and a regulator. I ended up using 2 lines. Return off regulator, delivery to carb, and breather was cut.

hydrolic144

iTrader: (2)

I ended up capping off those two lines for now, I believe my cap is vented. Still gonna get a fuel pressure gauge to see what it's putting out.

Guest

I really doubt you have a vented cap. Of those 4 lines back there, one was the high pressure line, one was a return line, one was for the charcoal canister, and one is a tank vent (only allows incoming air, not outgoing).

I had an LG4 car, I dont remember any return line. The two G-body LG4's we have here dont have return lines either. I'm aware of some older truck/van applications with returns on mechanical pump systems but I cant say I recall any on cars.

//<86TA>\\

iTrader: (14)

my 86ta was an lg4 car and it had a return line with a mechanical pump

jharrison5

Only fuel injected cars use a return line. Since your car was originally TPI that is why you have three lines. If the other two have been open and you have been driving just cap off the other two see how it runs.

hydrolic144

iTrader: (2)

Well I got a fuel pressure gauge and looks like it's putting out just a 6psi. Which is good I assume? I capped off the two lines, but I still smell fuel heavily! Seems like only when I'm at a stop. Could it be coming from the opening of my carb maybe?

Guest

Interesting. I know the other applications had silly differences as to why the return was there like... equipped with AC or not.

gregsz-28

iTrader: (1)

My '85 lg4 car had a return line as well...

hydrolic144

iTrader: (2)

Anybody got any idea why I'm still smelling fuel? I've checked and triple checked my lines from front to back. No leaks.

Guest

Where does the second line in the photo above run to? Any idea?

sch151

Hello,

Hope you don't mind me chiming in but I have a few questions on this topic and I would appreciate any input anyone can lend.

I'm switching to a L98 350 TPI, out of a 1990 Corvette, in my 1985 GMC 4wd pickup that was originally carbed. I have three lines coming from my side tank(s). One (3/8"?) goes to the mechanical fuel pump, one (5/16"?) goes to the charcoal canister, and one (1/4"?) was the return line as this truck had the three hole fuel pump. I have been told to use the 3/8" as the feed, after installing an in-line HP fuel pump back by the tank, and the 5/16" as the return from the motor. I suppose the smallest (1/4") could be used as the tank vent? Or should I just make sure I used vented caps on the tanks and cap that line? I will not have to pass emmisions and will not be using the canister.

Appreciate any help with this.

Thanks...Scott
(520) 247-9581

//<86TA>\\

iTrader: (14)

that should work, the 1l4" line will do as a vet on sorts.

hydrolic144

iTrader: (2)

One is my fuel line, the other has like this breather looking thing on it? It's stock I know. Don't know what it's called though.

Guest

Thats the tank vent valve. White plastic thing?

There shouldnt be any fuel smell left, if its running at 6psi and those lines are capped off. Any signs of leaking at the carb? Also these tanks tend to leak at the filler neck, take a look there and see if it looks like its been leaking where the filler neck goes into the tank. Should be a bunch of residue from the neck to the back of the car, if it is leaking. The smell can get into the car.

hydrolic144

iTrader: (2)

Yeah that's it. No leaks at the neck but I do think I may have a possible leak inside my carb. I've checked all the lines. It's a edelbrock 600-650. Sat for about a year and I just threw it on top of my engine. No rebuild or anything. So it may be time for a new one. Also what's the deal with whiny fuel pumps?

sch151

Hey thanks for the response. I assume you meant "vent" instead of "vet"?

Also, if I can use the 1/4" line as the tank vent, should I install a filter/breather on it? Like one of those plastic breathers that go on rear axles to vent the differential.

sch151

Recently found out that I CANNOT use the 5/16" line for the return, I have to use it for the tank vent and will now have to use the 1/4" line for the return. Does anyone have an opinion on wether the 1/4" return will be adequately sized? Will fuel pressure increase at idle using the 1/4" due to it's smaller diameter?

Thanks....

five7kid

iTrader: (14)

Why can't you use the 5/16" line? It is the original return line.

Just so there's no confusion, there are 4 lines on every 3rd gen pick-up I've seen (admittedly, I haven't seen them all, but I'm sure they are representative). Fuel supply, fuel return, vent, and vapor recovery. Only the vent does not have a line to the engine compartment.

sch151

Just for clarification, referring to my post of 12-1-2010, I'm installing the TPI motor in a 1985 GMC pickup. That post identifies the original and available line configuration. Since I have dual tanks the fuel lines run through a valve (factory operated on the dashboard) that switches from tank to tank. The problem is the 5/16" line comes from both tanks, by-passes the valve, tees into one and continues forward to the charcoal canister. I'm sure this was done in order to vent both tanks at all times. The other two lines (3/8" and 1/4") fortunately do route through the tank valve so when the valve is switched the supply and return switch to the appropriate tank. AZTPI in Tempe, AZ has told me the 1/4" should work but I like second opinions in cases like this and this forum is excellent at that. If I were to use the 5/16" line in its present layout, I would return fuel to both tanks while pulling from just one so think I'm stuck with using the 1/4" as the return.

Sorry for the lengthy response...

five7kid

iTrader: (14)

Just for clarification, this is a 3rd gen f-body only board, so any discussion of an '85 GMC pickup has to relate to 3rd gen f-bodies. Putting a TPI engine into an '85 GMC pickup doesn't count.

sch151

Didn't mean to over step my bounds. Is it acceptable to continue discussing the TPI engine issues? Which is where I was leading to in reference to fuel pressure build up.

five7kid

iTrader: (14)

It's off-topic to this thread (another Board expectation - stay on topic).

If you want to try posting on the TPI forum, I'll let the moderators there decide whether or not it meets Board rules for 3rd gen f-body applicability.