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Vapor return line


jframe

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Ok, I posted in October about disconnecting my vapor return line from the fuel filter, and plugging everything, and my off idle and first gear stumbles went away. Since it is warming up in Alabama, and I was concerned somewhat about vapor lock, even with a more efficient Vintage Air system, I hooked everything back up. The stumble under hard acceleration from a stop and most of the way thru 1st is back. Telriv, I believe, mentioned the fuel pump may be going bad. I am sure it has been replaced; it's a sealed unit, but reckon it would be a good idea to change it, since they are relatively cheap? The tank and fuel cap are both vented, and it's just weird to me how this is happening. I would like to have the vapor line hooked up, but it runs so much better without it. I plugged it off again last night, and the issue was virtually non existant. Any ideas of what can be done? Got my gauge issue fixed, and another little problem rears it's head, lol.

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                     I ran into this one time in my shop about 35 years ago and we were scratching our heads big time. The problem

turned out to be that someone had installed a non vented gas cap on the car when it called for a vented cap. the 65 requires a vented gas cap,

so check and see if the problem goes away when you remove the gas cap......if so it is not a vented cap or the vent is stopped up. If that isn't

the problem then consider me stumped.

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Cap is new, and it's vented. I currently have the a/c fuel filter on with the third port capped, and it seems like a lot of pressure on that vacuum cap. If you slide it off with the engine hot, it will spray gas, not vapor. I am going to reinstall the non-a/c fuel filter; then I won't have to worry about it. Just seems like an odd problem, and It's been like that since I bought the car. Switching to the non--a/c setup seems to be the only fix.

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Fuel line can delaminate internally and plug or restrict flow.  Have you replaced the sections of flexible line (preferably with something ethanol resistant like Gates Barricade)?  You might also check to see if the metal lines are damaged and crimped.  Finally, did you check to make sure a PO didn't do something like plug the line?

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Is this just a 3 port fuel filter? There should be gas squirting out. The third port just lets any vapor out that occurs if the gas boils. In normal operation it sends gas back to the tank. There should be an orifice in the third port to restrict how much gas can come out.

 

It should make no difference, period. Since it does, the implication is that the fuel pump cannot deliver enough volume to both fill the carb and pump gas through that little orifice. I would put a fuel pressure gauge on (temporarily, one of the "fuel-vacuum" ones for carbureted cars) teed in at the outlet of the filter, and then try it with and without the third port plugged. The fuel pressure should be whatever the spring in the fuel pump determines (probably 5 or 6 pounds) while the float valve is closed. When the float valve opens you will see a kick or drop, but the pressure shouldn't go away. I would see if it looks radically different with the port plugged.

 

It sure sounds to me like the fuel pump is not keeping up, not enough volume. This could be a problem with the pump, or it could be a problem with the cam lobe inside the engine that runs the pump. Let us know what you figure out.

 

P.S. a restriction at the tank could do it too. You already verified the vented cap. The fuel pickup may have a sock on it, and those can plug. Usually when they do you have much bigger driveability problems than what you describe. I am just throwing it out there (I really suspect your fuel pump and/or whatever drives it).

 

Edited by Bloo (see edit history)
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30 minutes ago, jframe said:

I am going to reinstall the non-a/c fuel filter; then I won't have to worry about it. Just seems like an odd problem, and It's been like that since I bought the car. Switching to the non--a/c setup seems to be the only fix.

 

Wait a minute... You added the three port filter where there wasn't one originally? Does an a/c car have a different fuel pump?

 

I still wouldn't expect a problem, as I have added these "return lines" to various cars over the years that couldn't deal with hot weather, and never had to upsize the fuel pump. Still, if the non-ac car uses a different fuel pump, that would be an interesting bit of information to add.

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                       I'm not sure on that.......all of the 60's GM cars with vented caps also had vents on the tank itself.....

my 69 GTO came with a vented cap and a huge vent hose on the right front corner of the tank.

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1 hour ago, RivNut said:

I have a question. Why do you need a vented cap if the tank is vented?

 

You don't, but maybe the factory took a belt and suspenders approach? The tank has to be vented somehow, through a vent hose, or through a vented cap, or through a charcoal canister (newer models).

 

It needs some kind of a vent. If there is no vent, as it uses fuel a vacuum can form in the tank, eventually preventing the fuel pump from delivering more fuel.

 

The hose the OP refers to isn't really a tank vent at all, it is a fuel return hose. It is a completely separate issue from how the tank is vented.

 

I thought I completely understood vapor lock, but things I have read in these forums recently have led me to question all that. Nevertheless, here is how I think the return hose works: If the fuel boils in the fuel pump, or the line leading to the carb, and the float valve is closed, the vapor has a place to go, back to the tank. Hopefully it will be replaced with non-boiling gas. When nothing is boiling, it just leaks a little gas back to the tank. The amount of gas leaked back is controlled by the orifice. It isn't a lot.

Edited by Bloo (see edit history)
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The vent hose on a first generation Riviera is in the shape of an upside down horseshoe and it looks over the filler neck.  It's visible when you pull down the license plate to expose the gas cap and filler neck. It seems like to me that a vented cap on a first generation Riviera is a waste.  If you leave the cap off, you lose a gallon of gas every time you accelerate.  Gasoline could be clogging the vent in the cap.  I'm betting that a miniscule amount of fuel could be lost through the vent in the cap as well.

Edited by RivNut (see edit history)
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1 minute ago, RivNut said:

The vent hose on a first generation Riviera is in the shape of an upside down horseshoe and it looks over the filler neck.  It's visible when you pull down the license plate to expose the gas cap and filler neck.

 

Yeah, I don't get it. That should be plenty.

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9 minutes ago, Bloo said:

 

Yeah, I don't get it. That should be plenty.

That's why in post # 5 I suggested that the vent tube in the tank could be clogged.  A new three port filter could be bad out of the box too. 

 

Hopefully he's hooked up the single port faci g down to the fuel pump and the larger of the two ports facing up to the carb.  It does look strange when mounted properly.  The vent hose off the small port on the filter goes up then makes a U-turn before it goes down and connects to the steele return  line.

Edited by RivNut (see edit history)
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The car is an original a/c car, and the 3 port filter was new and hooked up correctly. I replaced it when I first got it cause I thought that was why it had a stumble. It just runs a ton better with the 2 port filter and the vapor line plugged off for some reason. As a side note, I noticed tonight after I filled it up that the gauge seems to be in great working order, but it seems to be leaking gas around the sending unit, which it did AFTER we fixed the gauge. This will be the THIRD time in 2 weeks the tank has had to come out. We made a new gasket last week, and used a silicone type product by Permatex that swore it was for fuel pumps and the like and was resistant to gas. Guess not. Will this issue ever completely go away, lol????

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5 hours ago, RivNut said:

I have a question. Why do you need a vented cap if the tank is vented?

Good question, I don't understand it either.

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19 minutes ago, jframe said:

We made a new gasket last week, and used a silicone type product by Permatex that swore it was for fuel pumps and the like and was resistant to gas.

 

No silicone sealer is very resistant to gasoline. Whatever the gasket or o-ring is, get a new one. I hear hylomar is ok with gas but I don't really believe it. The only thing I ever found that held back gas at all was "seal all". Now that there is so much alcohol in the gas, stuff that worked back in the day may not now. I don't know.

 

The gasket has to work without sealer on a gas tank or you are going to have a really bad time. Over and over. Don't you have an o-ring and a lock ring on a Riviera? If not, and there are screws, with threads that could seep, and they aren't individually gasketed consider some weak loctite on those, like purple or maybe blue. Copper washers might be another option.

Edited by Bloo (see edit history)
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9 hours ago, Bloo said:

 

No silicone sealer is very resistant to gasoline. Whatever the gasket or o-ring is, get a new one. I hear hylomar is ok with gas but I don't really believe it. The only thing I ever found that held back gas at all was "seal all". Now that there is so much alcohol in the gas, stuff that worked back in the day may not now. I don't know.

 

The gasket has to work without sealer on a gas tank or you are going to have a really bad time. Over and over. Don't you have an o-ring and a lock ring on a Riviera? If not, and there are screws, with threads that could seep, and they aren't individually gasketed consider some weak loctite on those, like purple or maybe blue. Copper washers might be another option.

No locking ring, just a little round gasket with 5 holes for short screws. Only seems to do this when full, which would make sense. I just don't think there is a split anywhere because it just started when I took the tank down on a lift, and we bent the sender arm and fixed the gas gauge. Only other thing we did was add an extra ground wire to the sender. When I first installed the sender six months ago, I didn't use anything other than the gasket it came with, and it never leaked. Now, it is, so I ordered a new gasket from CARS this morning, along with tank strap cushions which were also missing.

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1 hour ago, jframe said:

No locking ring, just a little round gasket with 5 holes for short screws. Only seems to do this when full, which would make sense. I just don't think there is a split anywhere because it just started when I took the tank down on a lift, and we bent the sender arm and fixed the gas gauge. Only other thing we did was add an extra ground wire to the sender. When I first installed the sender six months ago, I didn't use anything other than the gasket it came with, and it never leaked. Now, it is, so I ordered a new gasket from CARS this morning, along with tank strap cushions which were also missing.

Dont think the straps ever had insulators, just an FYI

Tom

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38 minutes ago, 1965rivgs said:

Dont think the straps ever had insulators, just an FYI

Tom

Will it be ok to use them? Already ordered the silly things.

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1 hour ago, RivNut said:

If you isolate the tank from the frame, where are you going to get a ground for the sending unit?   ?

VERY TRUE! Good thinking, I just cancelled them. On an even BRIGHTER note, I went home at lunch to drive it and burn some of the fuel down so we can pull the tank again and try to reseal the sender, and now IT WON'T START. Lights all work, dash lights up with ignition switch on, but no turning over and no click. I am guessing the starter, but I am about ready to light this damn thing on fire.

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3 hours ago, RivNut said:

If you isolate the tank from the frame, where are you going to get a ground for the sending unit?   ?

 

I would hope he would add a ground wire. On a system that relies on a perfect ground to get to "E", I wouldn't want to trust tank straps for a ground. That sounds like a good way to run out of gas.

 

I am not arguing in favor of insulators, honestly I don't know if they are a good idea or not. I am arguing in favor of a good ground.

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11 minutes ago, Bloo said:

 

I would hope he would add a ground wire. On a system that relies on a perfect ground to get to "E", I wouldn't want to trust tank straps for a ground. That sounds like a good way to run out of gas.

 

I am not arguing in favor of insulators, honestly I don't know if they are a good idea or not. I am arguing in favor of a good ground.

When I pulled the tank on the 64, I crimped an eyelet to a piece of wire and put it on one of the screws that hold the sending unit to the tank.  I did the same thing to the other end and used a sheet metal screw to attach it to the under side of the body.  

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15 minutes ago, Bloo said:

 

I would hope he would add a ground wire. On a system that relies on a perfect ground to get to "E", I wouldn't want to trust tank straps for a ground. That sounds like a good way to run out of gas.

 

I am not arguing in favor of insulators, honestly I don't know if they are a good idea or not. I am arguing in favor of a good ground.

Yep, we added a ground wire when we bent the float arm on the sender, just for insurance. Now, if I can figure out why it won't START. I think I need a priest and some holy water.

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1 hour ago, jframe said:

IT WON'T START. Lights all work, dash lights up with ignition switch on, but no turning over and no click. I am guessing the starter, but I am about ready to light this damn thing on fire.

 

Battery terminals clean? I don't mean just on the outside, but the surface where the terminal actually squeezes the post, both on the terminal and the post. Never assume a battery terminal is ok. Cables good?

 

Is the battery charged? Sure it didn't get run down by accident? Some cars can fool you and be pretty dead, make no click, and still have lights. I think the Riviera is capable of this but I am not sure.

 

If all that is ok, does your starter solenoid look like this one?

 

Starter_Sol.jpg

 

If it does, clip the lead of a test light to a good ground, and poke the poker at the terminal marked "S" in the picture. Have someone turn the key to start. If the light lights, but no click, there is likely a problem with the starter. If it doesn't light, look at the ignition switch (or the wiring).

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Brand new battery and cables. Both clean. I really need to go home and look at the shifter and make SURE the thing is in park or neutral, lol. I didn't really look at lunch; not much time. The battery showed 87% on my trickle charger. I am leaning towards a possible neutral safety issue, starter, or ignition switch. Got a jack and jackstands, but the older I get, the more I don't like em. I am spoiled here at work by having a shop with lifts and racks.

 

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2 hours ago, jframe said:

VERY TRUE! Good thinking, I just cancelled them. On an even BRIGHTER note, I went home at lunch to drive it and burn some of the fuel down so we can pull the tank again and try to reseal the sender, and now IT WON'T START. Lights all work, dash lights up with ignition switch on, but no turning over and no click. I am guessing the starter, but I am about ready to light this damn thing on fire.

You stated you added a ground wire to the sender? If so, no need for another ground.

Before you put a match to it let me know, I`ll take it off your hands, LOL  ?

Tom

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Well, the no crank issue appears to possibly be a neutral safety switch thing. Came home from work, tried to start in Park, and nothing. Pulled it back to neutral, and it spun right over. Cranked it again in Park 2 or 3 more times.

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29 minutes ago, jframe said:

Well, the no crank issue appears to possibly be a neutral safety switch thing. Came home from work, tried to start in Park, and nothing. Pulled it back to neutral, and it spun right over. Cranked it again in Park 2 or 3 more times.

My guess is that it is a little out of adjustment on the safety switch, possibly a result of the collision your car had.  

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12 hours ago, Seafoam65 said:

My guess is that it is a little out of adjustment on the safety switch, possibly a result of the collision your car had.  

Good possiblilty, I didn't actually take anything apart; I'm just going to drive for a bit and see how it does. Got to get this stupid gas leak fixed first. Hopefully the proper sending unit gasket from CARS will do the trick.

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If you promise not to start the car while in Drive or Reverse, you can by-pass the neutral safety switch with a short piece of jumper wire.  ?

 

Standard transmission cars from the era didn't have a neutral safety switch, they had a clutch.

 

 

Edited by RivNut (see edit history)
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28 minutes ago, RivNut said:

If you promise not to start the car while in Drive or Reverse, you can by-pass the neutral safety switch with a short piece of jumper wire.  ?

 

Standard transmission cars from the era didn't have a neutral safety switch, they had a clutch.

 

 

Wow, THAT would be a revolting development, lol. Right now, it's starting fine in Park AND Neutral. May have just not been in the detent good, or like Seafoam said, may need an adjustment as well.

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