Fuel issue - Stumped

[starliner]

Back on the topic of hose for just a skinny minute here, Do you happen to know the diameters of the hard lines that were fabricated or installed to handle fuel delivery and return? Coming from the factory, what may have been installed could have been a 5/16ths steel fuel delivery, plus two other associated lines, one for the return itself and the other for the vent line that gets attached to the charcoal canister for emissions.

What might be causing your starvation is that the steel delivery line is undersized for the amount of fuel that the motor is demanding. I am not a turbo guru by any means but with as much air being stuffed into the manifold as a turbo can be capable of, having sufficient fuel on hand to mix with it is probably extremely critical. Should the factory have, for whatever reason, gone with the same sizes of fuel lines for your turbo as they did for a naturally aspirated car, then they may not have anticipated an owner who would wish to explore the outer limits of turbo action.

Remember this is 1978 here and the mfgrs are looking for anything they can add that would both attract buyers and appease the EPA/CARB at the same time. They'd be touting the turbo as being fuel efficient and environmentally friendly and all that eco-jazz. If the turbo that is currently resident in your engine bay is not what may have come with the car from the factory, it may just require larger fuel lines in order to deliver sufficent fuel to the engine to keep it running.

Just a thought here.



Nick

Nick, a good thought.

3/8 for fuel, 5/16 return, 1/4 vent.

Plus, it even starved during a 1/2 mile ride on just the 2 barrels.

 

[starliner]

that's a clean ride.shot in the dark but try driving with the gas cap removed,vented gas cap/vapor lock issues aren't as popular as they used to be but it's worth a try.

Yyyup, tried that as well!

I feel better being stumped by this knowing that you guys are hitting all the checkmarks.

Right now, the plan is to froo the tank and replace all 3/8 hose with some very heavy fuel hose. I still am leaning towards collapsing hose.

I will also run air through the lines.
Maybe some 20 year old crud in the lines as 69hurstolds mentioned.

 

[starliner]

Yyyup, tried that as well!

I feel better being stumped by this knowing that you guys are hitting all the checkmarks.

Right now, the plan is to froo the tank and replace all 3/8 hose with some very heavy fuel hose. I still am leaning towards collapsing hose.

I will also run air through the lines.
Maybe some 20 year old crud in the lines as 69hurstolds mentioned.

 

[starliner]

Between 69hurstolds and Nick, I am optomistic. After 45 years, and sitting for 20 of them, the 3/8 steel line could effectively be 5/16 now. When I rebuilt the Quadrajet, it REAKED of really bad gas.
So dropping the tank, spraying some break clean down the line, blasting air through and see what i get. If it is really cruddy i might put some CLR down there or something else to break up any varnish. Rust first.

Hope it works. I am scratching my head so much im going bald.

Thanks guys, I really appreciate it.

 

[CopperNick]

So quit scratching all ready. If you are going to be attempting to purge the existing lines, now might be a good time to consider bumping your line size. For feed go to -8 or 1/2 inch with a 3/8s return. and bump the vent/tank breather line to 3/8ths as well, because if it is operational then those fumes have to travel the full length of the car frame to get to the canister for recycling. Stainless is a good option with the poor quality of what passes for gas these days and there is a variant called NiCopp which is a Nicker/Copper alloy that might work as well. NiCopp has one plus when compared to S/S in that it is easier to shape. I used to have S/S for my fuel lines in my own Monte and the stuff would kink as often as not when trying to replicate the existing shape of the factory lines. High pressure fuel line like what is recommended for fuel injection systems might also be a thought as it ought to be rated for use with high octane fuel as well as most of the race bred chemical soups that get run at the tracks. Would make it more impervious to corruption from the Carb mandated water that only smells like gas.


Nick

 

[starliner]

So quit scratching all ready. If you are going to be attempting to purge the existing lines, now might be a good time to consider bumping your line size. For feed go to -8 or 1/2 inch with a 3/8s return. and bump the vent/tank breather line to 3/8ths as well, because if it is operational then those fumes have to travel the full length of the car frame to get to the canister for recycling. Stainless is a good option with the poor quality of what passes for gas these days and there is a variant called NiCopp which is a Nicker/Copper alloy that might work as well. NiCopp has one plus when compared to S/S in that it is easier to shape. I used to have S/S for my fuel lines in my own Monte and the stuff would kink as often as not when trying to replicate the existing shape of the factory lines. High pressure fuel line like what is recommended for fuel injection systems might also be a thought as it ought to be rated for use with high octane fuel as well as most of the race bred chemical soups that get run at the tracks. Would make it more impervious to corruption from the Carb mandated water that only smells like gas.


Nick

Thanks Nick.
I thought that nickle copper was not appropriate for fuel. All we have locally is ni/copp brake line.
Coil kits are cheap enough, and I have a double flare tool.
Great idea to do a full upgrade, I want to see improvement in the problem first in order to isolate the issue at hand.
Today is the day. Here in New England, and working outdoirs, the weather dictates my schedule.

Joe

 

[spongbob]

What Motors in there ? Olds or buick you could be looking at a cracked intake in the bottom of the plenum hot exhaust gas leaking into intake . You might take the intake off and get new gaskets clean everything up and cut 2 sheet metal 18 guage tin plates and place them over the heat passages between intake and heads this helps if it's cracked in plenum intake ? Sometimes you can see the crack in the bottom of plenum with carb removed. Of course you could get a new one...you checked the tank sock ?. not the intake you say "? Then ..try wireing the choke halfway closed and driving say 40 mph for a couple blocks any difference in pull? If Better?back to the carb ?

 

[starliner]

What Motors in there ? Olds or buick you could be looking at a cracked intake in the bottom of the plenum hot exhaust gas leaking into intake . You might take the intake off and get new gaskets clean everything up and cut 2 sheet metal 18 guage tin plates and place them over the heat passages between intake and heads this helps if it's cracked in plenum intake ? Sometimes you can see the crack in the bottom of plenum with carb removed. Of course you could get a new one...you checked the tank sock ?. not the intake you say "? Then ..try wireing the choke halfway closed and driving say 40 mph for a couple blocks any difference in pull? If Better?back to the carb ?

3.8 Buick Turbo.
Yes, I did clean the sock.
I will try the rest that you said.
Thanks alot.

 

[spongbob]

Could ? Your cat converter/s be stopped up would seem starved by comparison on some cars some people un hook"... them and wire the pipe up and drive a couple blocks ( car may seem cold and loud" )or looking inside if you know what to look for if it's still the same disconnected ? then you eliminated that concern whitch brings me to the reason a converter would be clogged...leaky turbo seals ect

 

[69hurstolds]

Don't worry too much about going with garbage can diameter fuel line just yet. Work with what you have. Find and SOLVE the issue before throwing money and parts at it. I mean, even as well-intentioned as it is, we here still act like a government- spending other people's money. If you find out the fuel line is "hosed", then fix what's broke. Nickel/Copper line actually works pretty well as a fuel line. I wouldn't ever use plain copper alone as a fuel line. As with any fuel line, route it away from heat sources and keep it from vibration wear.

While a cat converter pluggage issue is not out of the question, if it revs well and is repsonsive to the throttle while unloaded, then it's likely not your cat clogging. That pancake style converter that's under there is pretty archaic though. Easiest way IMO, to determine if your cat is clogging is to run the engine with a vacuum gage attached to the intake somewhere. Start slowly increasing engine RPMs and if vacuum goes away or runs toward zero or engine dies, then you MIGHT have to investigate a cat clog. If you still have good vacuum, and the engine isn't choking, it's unlikely there's a clog.