Fuel Problem?

[jclit]

After my car has been sitting overnight I need to crank the engine for about a minute or longer before it gets gas and starts. I rebuilt the carburetor, replaced the fuel pump, replaced the rubber fuel hoses at the pump and tank and it still does it. I borrowed a carburetor from a friend and still had the same problem. I have inspected the fuel line front to back and don’t see anything wrong with it (I can’t see all of it up to the right of the tank). I can’t smell gas anywhere after driving so I don’t think it is leaking.
Am I missing something?
Should I just go ahead and replace the fuel line anyway?
Any ideas?
Thanks for your input.
Jim

 

[wishuwerehere82]

It could be one or two things.

1) The fuel pump has a check valve in it that allows the fuel to flow in one direction(from the tank to the carb)
If it is bad, it will allow fuel to leak back down the line to reach the same level as the level in the tank. This could be several inches of elevation. It has to pump all of that length of line full before it starts filling the float bowl. It would also keep your fuel pump from pumping at the proper rate when you first crank it.
You might want to replace that pump, new or not.

2) The screws on the bottom of the carb that hold the base on, are not sealing the float bowls so that they drain overnight into the intake mamifold. The screws must be tight and sealed with thread sealer.
I don't think this is the problem because it would fire initially, then die until the carb fills.

Hope this helps.

 

[Vettehead Mikey]

Are you setting the choke before you crank the engine?

 

[pgtr]

The fuel should not evaporate out of the float bowl overnight and neither the pump nor the line are going to 'retain' the fuel in the bowl.

There are no screws that fasten the throttle plate to the main body of the carb that seal fuel. The bowl is a single piece and part of main body but more on that in a minute.

As VH Mikey said - look at the choke mechanism first - that's the easiest and a logical place to start.

If that is OK look at the float bowl. With age - there are metal plugs pressed into the bottom of the bowls at the factory that can fail and allow leaking down into the intake manifold. However if this leaks badly it can also make the car difficult to restart after it's warmed up and shut off.

But as noted above, I'd second looking at the choke before looking for a possible internal leak to the carb.

 

[jclit]

Thanks for the replies.

The choke is working fine. I used JB-Weld on the well plugs when I rebuilt it. It starts fine once it gets gas and will start fine all day long even when hot. Once it has started for the day all it takes is one pump on the gas pedal and it starts so quick I don’t even hear the starter. If I disconnect the fuel line at the carburetor before starting it for the day it is dry, no gas. Shouldn’t some still be in the line?

The carburetor I borrowed came off a Malibu with a 305 so it didn’t run too well but it still had the same starting problem the next morning. When we put it back on the Malibu it worked fine even a few days later.
I think I will take another look at the fuel pump.

Any other suggestions?

Thanks Jim

 

[Vettehead Mikey]

Is your accelerator pump gving you a good shot of gas before you start the engine? Hold the choke open and watch down the throat of the carb while you open the throttle.

 

[jclit]

No shot of gas. It looks like the Carburetor is dry also. I guess I need to pull it off again and reseal the well plugs again. I am just not sure it is all Carburetor related. After I tested with the other Carburetor (engine just running and fuel line full of gas) I put mine back on (it had no gas in it) and it started up with only a couple of cranks, not the long cranking like when the whole car has been sitting overnight.

Maybe fuel pump and Carburetor - I just hate to swap things out with no good results.

Jim

 

[wishuwerehere82]

It sure sounds like the check valve in the fuel pump is not seating properly, thus letting the gas drain back down the fuel line. Since swapping carbs isn't working, I would try the pump.
I have that problem on my 79 Electra. It starts at first, then stalls. After a few cranks, it re-fires.
Lots of gas in the carb, but nothing in the fuel line.
Only after sitting overnight and never when hot. 1 rev and it fires when hot or that day. But sit overnight, and it's back to stalling again. I have gotten used to it, but someday I will put in a new pump.

 

[jclit]

Thanks Pete
I think I will try another pump next week
Jim

 

[wishuwerehere82]

Good luck,
And I envy you for being in CA. this time of year. My Vettes have been in storage for a month and I really miss driving them. I used to camp near Marysville in the summertime and really enjoy northern CA. especially the mountains.

 

[JohnZ]

Are you using the fuel filter with the check valve?

Most Q-Jet applications use the fuel return line from the filter to ensure that there is no fuel pressure to the carb once the engine is shut off. Q-Jets depend on heavy fuel flow to keep the bowl full, as there's only one needle and seat to feed both the primary and secondary sides of the carb. They use a single large (.110"-.135") needle and seat, and with that much valve surface, it's hard for the float to keep the needle closed when fuel pressure between the pump and carb rises due to underhood heat-soak after shutdown.

Another issue to look for is if you use a "windowed" needle and seat like the stock GM one on the higher-performance Q-Jets, you should have the fuel filter with the check valve to prevent the fuel level from dropping in the bowl after shutdown; the "windows" are below normal fuel level, and as the fuel level drops and pressure rises as fuel evaporates, the needle and seat opens, and the bowl fuel flows back out through the "windows" and out through the return line to the tank. Then you have to crank and crank in the morning when you start it until the fuel level in the bowl comes back up.

Holleys have separate primary and secondary float bowls and two separate (and smaller) needle-and-seats, so they don't have the same fuel sensitivity as the Q-Jets.

 

[jclit]

Good luck,
And I envy you for being in CA. this time of year. My Vettes have been in storage for a month and I really miss driving them. I used to camp near Marysville in the summertime and really enjoy northern CA. especially the mountains.

This is Vet weather time for me. It is too hot in the Summertime past about 10:00 am or so (my A/C can’t keep up). Last night the low was 51 and tonight it is suppose to be around 50 or so. We do get freezing a few times a year. I put more miles on the car between September and May then the rest of the year.
Jim

 

[jclit]

John
Thanks for the reply
I don’t think I am using the fuel filter with the check valve. I think it is a simple paper element. Is this a special filter? I got the one I am using at Napa the same time I got the rebuild kit, just got what they gave me. Should they know what I am asking for if I just ask for one with a check valve in it. Sounds like that may be my problem. At least it is a simple thing to try.
As for the needle and seat, I don’t know. It is the set that came in the Echlin kit. Do you think that would be correct? Echlin seems to have a good reputation and I would hope the kit would be correct.
Anyway it looks like I have a couple more things to check out.
Thank you
Jim