[66Barrier]

I just bought a 66 with tri-power and I have trouble starting it after it sits 1 week or more. I drive the car on weekends and it sits during the week. If I start it during the week, it fires up after pumping the pedal twice. If I let it stand 1+ weeks, it won't start without squirting starter fluid into the center carb. Any ideas?

Nate

[66Barrier]

I just bought a 66 with tri-power and I have trouble starting it after it sits 1 week or more. I drive the car on weekends and it sits during the week. If I start it during the week, it fires up after pumping the pedal twice. If I let it stand 1+ weeks, it won't start without squirting starter fluid into the center carb. Any ideas?

Nate

[doug vander plaats]

Welcome to the board 66!!
Don't know carbs as well as most of these guys (I hope an expert steps in here), but it sounds like my 67 4 barrel. After it sits, I have to pump the gas pedal like a 16 year old in love to get it to fire, after that it's fine. I was told the fuel is draining back out of the carb, and the pumping is needed to refill it. I hope someone more knowledgable than myself has some tips for you.....I just replied because our problems are similar and I wanted to welcome you! These are a pretty good bunch here, and someone knows exactly what is needed.

Again, welcome!!
Doug [img]smile.gif[/img]

[goatseeker]

Welcome aboard!
If it's a carb related problem Carbking (Jon Hardgrove) has seen it and fixed it before. He has been a very valuable source for me on my '66 tripower. Try him at www.thecarburetorshop.com or maybe he'll jump in here.
It does sound like fuel draining back while the car sits though. Shouldn't do that from sitting only a few days.
Good Luck!
Tim

[66Barrier]

Thanks for the welcome guys. This is my 1st GTO and I'm trying to fix it right so I don't hose up a piece of history.

I thought it might be fuel draining back in the lines. Is there some sort of check valve to keep fuel going in 1 direction? Several people have advised an electric fuel pump. I think that would probably fix the problem, but is there a 'stock' solution? There must be guys with tri-power that run mechanical fuel pumps and don't have my problem.

Thanks again
Nate

[78 GHOST]

IMHO your problem is twofold: fuel is draining back out of the carb. feed line over time. More importantly, the float bowl fuel is evaporating which is what is usually used to start the engine. There is enough fuel in the float bowl to run the engine for a short period of time. Therefore, you can use the accellerator pump to prime the engine and then start it, and this will cause the mechanical pump to refill the supply line and float bowl.

How to prevent evaporation??? Perhaps Jon will chime in here as I still have that problem. My "fix" to avoid using starting fluid is to crank the engine for a few (say 5-10 seconds) to start refilling the float bowl, then stop to let the starter cool, then crank it again, stop, pump the crap out of it, then start it up. Works every time for me. If I could prevent evaporation, this would not be an issue.

-Matt

[ July 15, 2002, 05:53 AM: Message edited by: 78 GHOST ]

[78 GHOST]

double post

[ July 15, 2002, 05:53 AM: Message edited by: 78 GHOST ]

[Virginian]

I don't know why the gas is draining out of the line, but the fuel in the bowl is evaporaing because the bowl vent is open, probably too much, at closed throttle. I adjusted mine so the vent is closed, or so close to it you can't see it, at closed throttle. The later carbs and replacements don't have a vent, so I don't see why you really need it anyway, but the factory three dueces definitely does have a bowl vent on the center 2GC.

[Zimtok]

The evaporation on my tripower was helped by resetting the carb vent as they have stated above.If you don't know where the vent is at...it is on the top of the float bowl toward the drivers side just above the linkage. The linkage pushes up on a strip of spring metal that opens the vent.

As for the fuel draining back down the lines... try a new fuel pump, the valves in the pump should prevent the fuel from draining back.

An electric fuel pump will give you the ability to turn on hte ignition and wait for the pump to fill the carbs BEFORE you crank the starter.

[66Barrier]

I found the carb vent last night. It was open 1/8-1/4" at the closed throttle position. I will try adjusting it to see if evaporation is effected. I also discovered my choke is not functioning at all. I'm learning a lot about these 3 2's - thanks for the help.

Nate

[carbking]

66Barrier - the external vent of which you are speaking should be slightly open when the throttle is closed, don't readjust this, or you won't like your idle.

Remove the aircleaner from the center carburetor (with the engine not running). Observe the 1/4 inch tube inserted at about a 45 degree angle back into the airhorn. This is the bowl vent; where the gasoline is evaporating. Don't plug it. The carburetor will not function without the vent. Every carburetor must be vented. With no vent, gasoline could not move into and out of the bowl.

Guys, there are two "tongue in cheek" answers on prevention of evaporation. The first is buy new old stock gasoline (from the 1960's) with a reasonable Reid Vapor Pressure. The second is don't put gasoline in the tank. If there is no gasoline in the tank, it cannot evaporate.

My own solutions:

Driver - replace mechanical pump with electric.

Showcar - Remove air cleaner from center carb, open choke, pour 3 tablespoons on gasoline into carburetor, CLOSE CHOKE, start engine. My 1964 normally requires 2 applications. Replace air cleaner. Gasoline is much safer, and easier on the engine than starting fluid. While cranking the engine for 10 - 15 seconds will refill the carburetors and allow the car to start, the starter is a bear to change.

Todays gasoline is so volatile it is going to evaporate. Just learn to live with it.

Jon.

[Zimtok]

Carbking knows his stuff...

Sometimes we just pass on info without thinking it may be wrong.

Thanks for the save on this one Carbking.

[carbking]

Zimtok - thanks for your comments.

This evaporation problem is much worse in the summer due to the heat.

My 1964 GTO show car still has the original pump, and I prime it to start. My 1968 Datsun currently in the restoration shop also has the original pump, as I plan to sell it as a show car (no negative comments please, it will blow the doors off the '64 tripower GTO mentioned above) once the restoration is finished. We have replaced the mechanical pump on every other vehicle I own (drivers) with an electric pump. One vehicle ('68 Ford shop truck with 390) will percolate the carburetor dry in less than 1 hour!

The electric pump is the only way to fly on a driver.

Jon.

[66Barrier]

An electric fuel pump sounds like it will help my problem. My pop uses one on his 53 Nash which often sits for months. It starts right up every time. He mounted the pump back near the gas tank.

So if I go ahead with an electric fuel pump... the next questions are - fuel pump flow capacity, pressure, brand name, mounting location, pressure regulator?, etc.

Thanks again

[carbking]

66Barrier - unless this is a race car, go with a 5 to 7 pound self-regulated pump and no inline regulater. Pressure loss in the line should have the pressure at maybe 4 - 6 at the carbs. Too much pressure will cause drippage problems, and flooding. The self-regulated pumps do a better job than the inline regulator (in my opinion). I personally use Carter pumps because of business ties, but other brands will work as well.

What have others on this forum used?

Jon.

[Virginian]

Carbking, I hate to disagree with you, but closing the EXTERNAL vent makes no difference, especially at idle, at least with my car. You can press it closed with the air cleaner off and the engine running and see, and the other and later carbs, otherwise just like it, have no external vent. I just don't see what purpose it serves. I'm not questioning the vent that goes to the throat, just that little external one. Since the pressure is lower in the throat area with the engine running, all I can see is that air flows into the bowl thru the external vent and out into the throat thru that vent. To add to my disenchantment, it's unfiltered air.
I agree totally on the electric pump being better, although not original. I used a Holley with excellent results on a '73 Trans Am I had.

[carbking]

Virginian - friendly disagreement is the root of learning.

The external idle vent helps to relieve pressure build-up in the bowl in extremely hot weather and stop-and-go driving due to percolation. Closing the idle vent valve can cause an extremely rich condition in the above circumstances. Perhaps in my earlier post I should have used the words "may not" instead of "won't".

The external idle vent should be adjusted to close just off idle. Virginian is correct about the pressure differential being lower in the airstream, but as the air velocity at idle is small, there will be no air "siphoning" effect of unfiltered air entering the bowl through the external idle vent. Rather vapors in the bowl escape through this vent. When properly adjusted, it is a one-way vent.

In more moderate climates, this vent may be of little consequence.

Not all 2-GC carburetors have the vent. Later carburetors were mandated a design change, as the vent contributes to smog emission.

In the for what its worth category, my 1964 GTO with tripower will idle at 550 RPM in Drive (doggy-matic transmission) here in Missouri the hottest day of the summer without heating. However, I never use the AC until on the highway.

Jon.