Carb Problem - So frustrating!

[William G.]

Hello,

I guess my age must be getting to me, or else Murphy, as in Murphy's Law just won't leave me alone!

Two weeks ago I completed replacing the gas tank in my 67 roadster. Florida condensation and rust did it in! So, today I put in fresh non Ethanol fuel and cranked the engine until I had fuel in the bowls. Good news, no leaks up to to the carb. However, even after replacing the needle and seat in the 67 fuel bowl twice since I almost set the car on fire two months ago, I still can not get the needle and seat to shut off the fuel flow. It still fills the bowl and flows out of the vent on the top of the bowl.
I used to work on an IMSA car, so I am versed in taking things apart and restoring them, but this has me frustrated to the point of wanting to trash can this aftermarket holley! I have the original 67 Holley safely stored away after spending a lot to have it restored after the alcohol in the fuel left in it darn near destroyed!
The last time I installed the new needle and seat, I checked the float height and set it a couple of degrees shy of parallel to the top of the bowl. Everything seemed to be working fine until today when again, I had fuel flowing out onto the top of the engine.
Does anyone out there have a suggestion?

Thanks,

Bill

[Bill M.]

Re: so frustrating!

Maybe there was grit in the fuel line that clogged the seat again.

[Richard M.]

Re: so frustrating!

Yes maybe grit in there, or....

A sunken/bad float. Only way to verify is remove it give it the "shake test".

Or a out of spec fuel pump. I.E. too much pressure. Spec is around 5-6 psi iirc.

[Patrick H.]

Re: so frustrating!

What's the condition of the fuel pump?

When it died on my 72 a couple of years ago - 3 days before PV - it was pushing extra fuel into the carb.

[William G.]

Re: so frustrating!

I am not going to rule out a bad fuel pump, but until the time when I had to let the car sit a while, everything was working fine.

A little back gorund. About a year ago, I decided to replace the original rubber brake hoses and found rust in the "silicone fluid!" That had been in there for probably 30 years, as the calipers were stainless sleeved By "Vette Brakes" and that is what they suggested to avoid Florida condensation and rust! I traced everything back to the Master Cylinder, which was the original 67 unit and found a layer of rust inside of it! Having rebuilt the MC a couple of times over the years, it was honed to the point where I was not comfortable reusing it, so I ordered a new reproduction. After getting the new MC in, It leaked. Found a bad machining of the rear outlet of the MC bowl. The unit was replaced a second time and finally all was sealed.
Due to some medical issues, I was unable to test drive the car until about a month ago. I expected the engine to be running poorly, having set for a while. Well, it blew out a lot of blue smoke and I found the carb flooding gas into the intake manifold. I taped on the float bowl above the needle and seat and it seemed to stop the flow. Restarted the engine and decided to drive around the block. At the first stop sign, the engine quit! I was able to restart it and turned the corner. When I went to shift to second gear, the throttle was stuck at 3000 RPM, so I continued around the block and back into my garage. When I got out and opened the hood, the whole top of the engine was bathed in gas! Why it never ignited, I don't know, but it was a blessing, or was it?
I took the aftermarket Holly off and rebuilt the bowls with new needles and seats. Figured all would be good. I also bought a transfer pump and started pumping the old gas out of the tank. That's when I discovered the whole inside of the original tank was coated in rust. A new tank has been installed, with a new, reproduction sending unit, which by the way is not working! Yes, I cleaned all of the old wiring connections!
I also changed the engine oil and filter, not knowing how much gas may have gotten past the rings and into the oil.
Yesterday I took the coil wire out and most of the spark plugs and cranked the engine over until I had good solid oil pressure. Today I put in four gallons, on top of the gallon and a half I put in to check the sending unit O ring, that should be about five and a half gallons of fresh non ethanol gas. Cranked the engine over again until the system was primed. The inserted the coil wire and fired the engine off. It ran for maybe thirty seconds before I shut it off to check for leaks. All was dry except for the gas coming out of the vent hole on the top of the primary fuel bowl.
I am using a 66-67 style front fuel bowl, so I can use the threaded fuel line, rather than a hose to the banjo fitting the carb would normally have. The float inside is a hard foam plastic one, not the brass tank style of the old Holley's . Yes, the brass were prone to leak and sink!
I guess the next thing, when we get back from a three week trip, is to order another rebuild kit and go through the whole carb again. For the sake of maybe lessening the frustration, I may change the fuel pump also, as I really don't know how old the one I put on about 8 years ago, when I rebuilt the engine, really is. It could be as old as the car!
Just more time and money to maybe get another ride in my car before I go in for neck fusion surgery June 27.

Bill

[Richard M.]

Re: so frustrating!

Bill,

With a little time and plumbing modification, you could put a pressure gauge on the pump outlet and verify if that's root cause, or not.

I'd do that before changing it as it's a pain in the "neck" to replace it.

Rich
P.S. Pinched nerves are not enjoyable. This may help.
Gary C told me about this one.... TENS unit from Amazon....
https://www.amazon.com/TENS-7000-Dig...kSL&ref=plSrch (https://www.amazon.com/TENS-7000-Dig...kSL&ref=plSrch)

[William G.]

Re: so frustrating!

Hey Rich,

After having my right arm, from my shoulder to my hand in pain and going numb, I went to the doctor. I was first given injection in my shoulder, which had no effect. Then she sent me for an MRI. It showed I have four ruptured discs between C3 and C7. Two of them are putting significant pressure on my spinal cord. The surgeon wanted to do the surgery last January, but insurance denied it. What do they know medically, they just see numbers! It took two months to get an approval. The wife and I have a trip scheduled this next week and I refused to cancel it after a year and a half of planning. In June I will have five vertebrae fused!. Three months of very limited use and then three more for total fusion. I just pray I still have god neck movement. Doc says I will, so I have to believe him.

Bill

[Richard M.]

Re: so frustrating!

Hope all goes well Bill.

Sorry I got a bit off of the "fuel issue" topic with ailments of the body. I should've refrained.

So when you get time please let us know what you find with the leaky carbs. Last time I had a tripower in front of me was when I restored a L71 back in 2015/2016.

In that one, they were brand new Holly carbs out of the box. Unfortunately the one who packed them in a box with pieces of foam popcorns finding their way into the vents and clogged them up on first run/breakin. Had to rebuild all 3 to get the debris out of everywhere.

Rich

[Richard M.]

Re: Carb Problem - So frustrating!

What's the condition of the fuel pump?

When it died on my 72 a couple of years ago - 3 days before PV - it was pushing extra fuel into the carb.

Patrick did you do a pressure test or did you just swap it out? Is that the sealed type pump?

Rich

[William G.]

Re: Carb Problem - So frustrating!

Yes, I also got carried away using the forum as a "private message", sorry

From 67 on, GM used non rebuildable fuel pumps. I wish they would have waited a year so I could rebuild mine. Last night I checked Zip Products and a replacement pump is $36. I may check some of the local parts stores to see if the price is better, as well as availability.

I also know that the position of the pump is not the easiest to get to. GM, to offset the drivers weight for racing, moved the engine 2" to the right, which squeezes the available room other vehicles have. Just part of the fun working on these thigs! Still in all, they are easier to work on than the new ones!

At some point the previous owner must have had fuel delivery problems from the tank, as the filter sock was missing off the pickup when I took it out. That filter sock si/ was not one of GM's better ideas! There is a bronze filter in the carb fuel inlet, which I removed and checked for debris. There was none! After the potential fire a month ago, I did remove the bowl and installed two new needles and seats. It is still leaking out of the front bowl, which is the 67 style as indicated previously. No adjustment screw and no sight screw. You have to remove the bowl to set the float!
I don't have time now to remove the carb and disassemble it again, but will after we get back from a three week trip. We'll see if there is any debris to be found, but I doubt it! Sometimes I wish GM would have used the Carter carbs on the higher horsepower engines,as they are not prone to so many problems as the Holley"s have.

Bill

[Patrick H.]

Re: Carb Problem - So frustrating!

Patrick did you do a pressure test or did you just swap it out? Is that the sealed type pump?

Rich

Sealed.

It started having excessive pressure (gas coming out the top of the carb), so I started to assemble the tools to check the pressure.
Shortly thereafter the puddle of gas on the floor assisted in my diagnosis, so I never checked the pressure.

My diagnostic guru (Gary Bosselman) told me it was the pump to start with, and the pump proved him right.
It takes a lot less time and hassle to swap a fuel pump than to set up a pressure test assembly, so I'm glad the pump leaked and gave the big clue.

[Duke W.]

Re: so frustrating!

I am not going to rule out a bad fuel pump, but until the time when I had to let the car sit a while, everything was working fine.

A little back gorund. About a year ago, I decided to replace the original rubber brake hoses and found rust in the "silicone fluid!" That had been in there for probably 30 years, as the calipers were stainless sleeved By "Vette Brakes" and that is what they suggested to avoid Florida condensation and rust! I traced everything back to the Master Cylinder, which was the original 67 unit and found a layer of rust inside of it! Having rebuilt the MC a couple of times over the years, it was honed to the point where I was not comfortable reusing it, so I ordered a new reproduction. After getting the new MC in, It leaked. Found a bad machining of the rear outlet of the MC bowl. The unit was replaced a second time and finally all was sealed.
Due to some medical issues, I was unable to test drive the car until about a month ago. I expected the engine to be running poorly, having set for a while. Well, it blew out a lot of blue smoke and I found the carb flooding gas into the intake manifold. I taped on the float bowl above the needle and seat and it seemed to stop the flow. Restarted the engine and decided to drive around the block. At the first stop sign, the engine quit! I was able to restart it and turned the corner. When I went to shift to second gear, the throttle was stuck at 3000 RPM, so I continued around the block and back into my garage. When I got out and opened the hood, the whole top of the engine was bathed in gas! Why it never ignited, I don't know, but it was a blessing, or was it?
I took the aftermarket Holly off and rebuilt the bowls with new needles and seats. Figured all would be good. I also bought a transfer pump and started pumping the old gas out of the tank. That's when I discovered the whole inside of the original tank was coated in rust. A new tank has been installed, with a new, reproduction sending unit, which by the way is not working! Yes, I cleaned all of the old wiring connections!
I also changed the engine oil and filter, not knowing how much gas may have gotten past the rings and into the oil.
Yesterday I took the coil wire out and most of the spark plugs and cranked the engine over until I had good solid oil pressure. Today I put in four gallons, on top of the gallon and a half I put in to check the sending unit O ring, that should be about five and a half gallons of fresh non ethanol gas. Cranked the engine over again until the system was primed. The inserted the coil wire and fired the engine off. It ran for maybe thirty seconds before I shut it off to check for leaks. All was dry except for the gas coming out of the vent hole on the top of the primary fuel bowl.
I am using a 66-67 style front fuel bowl, so I can use the threaded fuel line, rather than a hose to the banjo fitting the carb would normally have. The float inside is a hard foam plastic one, not the brass tank style of the old Holley's . Yes, the brass were prone to leak and sink!
I guess the next thing, when we get back from a three week trip, is to order another rebuild kit and go through the whole carb again. For the sake of maybe lessening the frustration, I may change the fuel pump also, as I really don't know how old the one I put on about 8 years ago, when I rebuilt the engine, really is. It could be as old as the car!
Just more time and money to maybe get another ride in my car before I go in for neck fusion surgery June 27.

Bill

Just an FYI for everyone... please use small paragraphs with a space between them. I find a half screen of single spaced text essentially impossible to read, and I doubt I'm not the only one with this issue. Hit the enter key twice at the end of a sentence to start a new paragraph, and that will leave a blank line between the last and new paragraph.

Duke

[Mike T.]

[William G.]

Re: Carb Problem - So frustrating!

Mike, I have had this carb apart two times this spring. the fuel is coming out of the vent hole on the top of the float bowl, under the rubber flap that is supposed to cover it under hard acceleration. The fuel is not coming out of the vent pipes in the main body of the carb. The last time I had it apart, before replacing the gas tank, I installed a brand new Power valve and new needle and seats. The problem still exists, so it is either wrong fuel pressure, or I have a bad float. I don't think it is the float, as I inspected it and could not find any cracks, and it felt very light weight. Only other thing I can think of is the small wire clip spring that holds the needle valve to the arm of the float is somehow restricting the movement, or position of the needle, not allowing it to seat properly. I may find my old brass floats and put one of them back on! I don't remember them using the little wire to hold the needle valve in place

Bill

[Mike T.]