Been watching this thread until I can't resist anymore. If a carburetor leaks down and the bowl empties between reasonable uses the carb has a leak and needs to be fixed, Your metering rods are obviously not sealing the bowl. You correct this by getting proper number files and refile the jets. I recommend you replace the jets (the size, ie 51, 52, etc is stamped on the face of the jet) and get new metering rods. There is no excuse for a carburetor to leak down if it has been properly rebuilt. The process is more than cleaning and new gaskets and float valves! Check the bowl on a stand with carb cleaner, none should leak through the main jets.

Leak down is not always the problem. Heat soak can evaporate the fuel in the bowl fairly quickly. With the hot dog house and nearly red hot massive OEM cast iron manifolds in summer heat it takes a long time to cool. This is where headers help a lot, also open up the engine box for prompt cooling.

Sitting for extended periods between starts in the summer can do the same thing.

If I ran the coach regularly and it was not in summer it would always start promptly. If the coach sat for several weeks in the summer the bowl would evaporate, especially after a hot shutdown. Took longer to start then.

As you suggest, if it is empty overnight in cool weather it is probably leaking.

I do not think I had trouble starting Nose, not real long crank times. The problem seemed to be a dead spot in the accelerator or after it ran for a few seconds it would die when cold. The rebuild seems to have fixed that, I believe the maladjusted float, the atomizer rod out of its seat and the accelerator pump were the cause.


The momentary switch is for, "just in case". I do wish I had done a leak down test before I reinstalled the carburetor. Oh well live and learn, been sitting for about a week tomorrow I will see how Nose starts.

Q-jets that need cranking to refill fuel bowls is normally caused by the rod plugs in the bottom of the carb leaking. I coat these with epoxy. This has always been a problem. Not only does it empty the fuel bowls, it allows raw fuel in the intake that washes the oil off cylinder walls.

quote:

Originally posted by Doorman:
Q-jets that need cranking to refill fuel bowls is normally caused by the rod plugs in the bottom of the carb leaking. I coat these with epoxy. This has always been a problem. Not only does it empty the fuel bowls, it allows raw fuel in the intake that washes the oil off cylinder walls.

I did not coat mine, thought they looked fuel tight, did not get to the Nose yesterday, big case of laziness, maybe today...

Ok. got off my lazy butt, and did some work on the Nose!!

First, it started in like 3 seconds or less after setting for a week and half! It did die and had to be started a second time started in like a second this time and kept running, dead spot is gone

Next the choke began to open pretty quickly and the 454 ran pretty smooth. the choke only opened like .75 of the full amount until the t-stat opened then the new PVS opened the new lock-out vacuum motor retracted the carb went off high idle and the choke fully opened. Whoopie!!!

Now all I need is a semi-warm day to crawl under the Nose and set the timing.

Still undecided as to what to do about the electric fuel pump safety shut off.

We may have 15 inches of snow this weekend, don't come back yet Steve!!!

Think I going to copy DannyZ and put in a lighted toggle switch for a safety fuel pump shut off. Can't wait to see if I have any fuel improvement and how it performs with the secondary part of the Quatra working! Look out all you speeders, Barth on the road!!! With the new LED headlamps you will see me coming and I will see you too!!

You could use a momentary switch. That way there would be no fuel flowing in case of a serious problem. You might be able to mount it so it is linkage activated at some point of pedal depression or with kick down. Another option would be to put on the left floor/firewall like a dimmer switch of my youth.

quote:

Originally posted by ccctimtation:
You could use a momentary switch. That way there would be no fuel flowing in case of a serious problem. You might be able to mount it so it is linkage activated at some point of pedal depression or with kick down. Another option would be to put on the left floor/firewall like a dimmer switch of my youth.

Hey Tim
Like SteveVW I could not find an oil pressure switch that was normally open. Then I could put in a momentary switch for starting if/when needed. I guess I could put in a double throw relay along with the oil pressure switch and bi-pass it with the momentary. I would have to have electric current to keep the pump off in an accident if the ignition was left on, but if I lost current the pump would not run anyway. Oh the complications of doing the right thing. Another problem with the oil pressure switch is I have to disconnect the fuel pump or the relay on the negative side and rewire for that set up. All that makes the toggle sound sweet!!

BTW I started the nose today, Started right up with a bit of pedal fluttering it did not die this time, all other was as it should be...whoopee!!!

The momentary switch would be the only power to the pump. No need for other connection unless you wanted to use a relay.

quote:

Originally posted by ccctimtation:
The momentary switch would be the only power to the pump. No need for other connection unless you wanted to use a relay.

The electric pump needs to run when the engine is running too and not run when the engine is off unless I want it to.

Use a mercury switch paired with a resettable relay. This would enable with the ignition and function until disabled by a problem. Hard breaking might break the switch but you would be in control to reset the relay. You would not need the electric pump for resuming travel but would be able to reset before need for maximum fuel consumption.
Hold my beer and watch this!

Echlin makes an oil pressure safety switch that has an open and closed side. It is a simple device and needs no relays, other than your existing starter solenoid. You can pair this with an inertia switch used in Ford Mustangs, and you put that in series with the fuel pump. The inertia switch is the last thing before the fuel pump. Doing this all the time, never have a call back.

quote:

Originally posted by Tom and Julie:
Echlin makes an oil pressure safety switch that has an open and closed side. It is a simple device and needs no relays, other than your existing starter solenoid. You can pair this with an inertia switch used in Ford Mustangs, and you put that in series with the fuel pump. The inertia switch is the last thing before the fuel pump. Doing this all the time, never have a call back.

I will check with NAPA and get that switch, all these ideas sound like they will work.

Hey got the switch N/0 0r N/C switches at 2 psi, funny NAPA could not get it even with special order, but they gave me a NAPA number and Autozone had it in the store. So now I need a decent day to crawl under the Nose and install it. I can wire it direct to the fuel pump, and install a momentary switch to by-pass it when I do not have oil pressure if/when needed. I am not sure what amperage the switch will take so maybe I will install a relay, I have some 80amp ones left over from my headlamp upgrade. Whoopie!!