Hey fellas, I'm the first to admit I'm a carb-tard, so help me out here. I have a double pumper on my 390 FE in my '55 F100. Runs great for a little while then runs out of fuel. I have good fuel pressure and my electric pump works good (about 5 1/2 PSI). I'll just be rolling down the road and suddenly out of fuel. The thing is that it won't restart until I've let it sit for like an hour! I can poura little fuel down the carb and it will run until that fuel is burned up, but nothing more. Could this be a power rod or metering valve causing this? Certainly seems like time for a rebuild, but I'm interested in learning what's causing the trouble as much as I'm interested in fixing the problem itself. I like to learn so I don't have to ask the same dumb question next time!
Check your nedle and seat, there might be crud blocking them. If its one of the carbs that have filters in the inlets check those out too.
I should probably define my statement "Runs great for a little while then runs out of fuel." I fire the truck up, let it run for a minute or two, then back it out of the garage. I can drive anywhere from 3-10 minutes before this happens. Since it's cold I'm never on it hard, so I don't suspect I'm using fuel faster than the pump can send it.
Danny, thank you. I know the filters you're referring to, but I'm admittedly a carb-tard. I know what the needles and seats are, but I don't know how to check them... or even where they are...
Try running it without the gas cap, or when you open the gas cap do you hear any sucking wooshing noise? If the vented system is not vented the fuel will not flow. How fresh is this carb, did it work good and then not work? You need to be really detailed in your info if some one that is not there is going to diagnose the problem.
Do you have fuel all the way to the carb when it does this? If not check your entire fuel line for leaks or pinholes. If a fuel pump can suck air, it will, leaving you starving for fuel.
Sounds like the pump might be shutting down on you. If you do not have a fuel pressure gauge, one would help find out what is going on. If you have pressure from the pump to the carb, the problem is a filter or carb, if no pressure, the pump or pick-up. It could be anything mentioned so far. You just need to figure out where the problem is before tweeking everything.
Runs great cold * Stalls and won't start until cold* Will start on fuel charge into carb * Check the choke first Then check for why it might like it so rich like a vacume leak, off choke carb adjusting or tuning. Heat or time related fuel delivery issues. What's the fuel pressure after warm up and 3-10 mins drive?
I would also check to see if you are not vapor locking. Sounds to me like maybe the fuel line might be to close to the header/manifold and might be boiling the fuel. Once the line and header/manifold cool down, then you get fuel back up to the carb. Just my 2 cents.
Man, I had the same issue. Big, fat double pumper on a 390. Boggy, no mileage, stalled. A 650 vacuum secondary Holly made life worth living again! Hallelujah.
When the carb runs out of gas,does any gas come out of the squirters when you move the linkage? To check if you have fuel in the bowl,unloosen one of the lower bowl screws a little,fuel should run out. To me it sounds like a fuel pump issue or a blockage in the filter or line.
Where is your Electric pump located? I have ran across electric pumps mounted in the engine compartment to try and "Pull" fuel. Most if not all electric fuel pumps are a "Push" type pump. In the past I have moved them back by the tank and Walla, problem solved. CJO13
michev asks a great question; When the carb runs out of gas,does any gas come out of the squirters when you move the linkage? To check if you have fuel in the bowl,unloosen one of the lower bowl screws a little,fuel should run out. To me it sounds like a fuel pump issue or a blockage in the filter or line. If So...Its not the carb: 1. Check the filters IN THE TANK 2. Repace the Inline filters. 3. Clean the carb filters. 4, Check that the tank has a Vented gas cap. If it is still happening.......bet ya a dollar it is the regulator. You mention 5 1/2 psi. do tou have a gauge on it or is this what the pump is suppose to put out. Simple, just eliminate the "free" possibilities.then one the filters are clean . Replace the regulator. my 2 cents. Great luck. Definately a clogged filter <!-- / message -->
From what you've said, I gotta agree with some of the others and say that the most likely suspect from the info you've provided is the sock filter on the pickup in the tank. '55 F100? Yeah, might be a little crud rolling around in there that will fall off after you let it sit and let you suck enough fuel to get you down the street a ways before it plugs again. I agree with Michev & vrod64, check to see if the carb will squirt any fuel next time it quits. Bud
Original gas tank with filler neck just behind driver's door, down low on cab corner. Cap is vented, no whooshing sound. Originally I thought I had a fuel issue so I replaced the ancient electric fuel pump and filter. Same issue persisted, so I pulled the sender a few weeks ago. LOTS of shit in the tank. Dropped the tank, cleaned it inside thoroughly, and put it back in. Replaced the fuel filter again, same problem exists. I bought the truck about 6 months ago and it had some "issues" so I never really got to drive it, but I did drive it home that day, some 5 miles. I've finally worked out the "known" issues (mostly brakes) but now I'm working on sorting out the things the PO didn't tell me about. So this is really the first week I've been able to actually drive the truck around. I'll provide as much detail as I can, but carburetor tuning is still a mystery to me. Yes, I put a pressure gauge right at the "fuel rail" or whatever you call the two-into-one double pumper steel fuel thingy. Stays around 5.5 PSI when the pump is on, motor running or not. No fuel leaks either. The pump runs no problem and keeps fuel pressure at the carb. Vacuum leak, EXCELLENT thought!
Did you change or remove the little filters at the fuel inlets? I've had the same trouble and found the inlets have little paper or porous brass/bronze filters behind them that plug up pretty fast.. Take the fuel line off and unscrew the carb fitting that the line screws into..should be a filter in each fitting. Try blowing through the filter...if it's hard to blow, replace those filters.
Don't know if anyone mentioned debris in the fuel tank (rust, dirt, etc.). Opps, just saw that you did. Perhaps time for a new tank. Might still have crud that floats to the pickup, blocks it, then floats away when engine stops. Or maybe vapor lock. Best of luck on this.
Picked my Vette up from a body shop { car rolled back in garage, door open, bent the door and A pillar } anyway left the shop went about 1 mile, car dies, though I ran out of gas...... Got gas let her sit, finally get her started, go gas her up, runs fine all the way home. Next day driving to go to dinner, she dies, will not start, pull air cleaner off, finally get her started, baby her home, she dies in the driveway, pop the hood and gas is pouring in the primary...... So didn't run out of gas she was flooding herself.... Pulled float adjusters out and reset float level, good to go again........... If when she dies on you, move your linkage and if she squirts, you may be flooding too................
If you have pressure at the carb even when it Wont run....and it will run when you manually put fuel in the bowls through the vents, it can only be the needle and seat assy. But that being said, still doesn't really compute as Holly needle and seats dont jamb Sjur or anything after beeing run awhile. As said sounds like it could be vaporlock...is motor getting hot in this time period and there any kind of insulator or thick vasket under the carb?
Vapor lock is certainly a possibility, but I thought that vapor lock was more prone to happen on HOT motors. Fuel line leaves the tank, runs up frame rail on opposite side of exhaust, onto driver's side inner fender well, to fuel pump, then across motor to passenger side fuel inlet on carb. Hmmm... maybe the block itself is heating up the fuel line... Good thinking! I know this is way too much carb for the motor, but it's what was on it when I got it. Figured I'd run it until something else came up. I do have a Carter AFB 600 on the shelf but it was destined for the wife's '48 peekup. I could swap it easily enough to see if that cures the trouble though. No, no fuel from the squirters (that I can see) looking down the throat of the carb. This further underscores the vapor lock theory, doesn't it? On the driver's side inner fender well. Although I didn't mount it there (I did replace the existing one though ) I'd forgotten that this can cause problems. Thanks for the reminder, I'll move it down by the tank! No in-tank filter, tank has been cleaned out. I'll remove and clean the carb filters tonight. Cap is definitely vented. Fuel pressure gauge mounted in line, just before the carb stays at 5.5 PSI running or not, no regulator installed. No filter inside the tank. It's a stock tank with a simple steel tube that picks up from the bottom. Not to say it never had one, but I can't see that it did.
Check the float on the primary for splits/holes. Resetting the float level might only last a short time until the float sinks gradually again when fuel seeps into the float through the hole/split. And you reset the float and it's good again for another short time. Don't Ask Me How I Know...
Guys, thanks for all of the great advice! I'll tear into it tonight (or tomorrow night) and see what I can find. I'll post my edu-ma-cation here as it happens!
Take the fuel lines loose from the carb,filter and the tank. Blow air threw all the lines to make sure they are clear. Do you have a on/off valve at the tank? If you do,I would bet that's the problem.
If it never had a tank filter and you said it had tons of crap in the tank, first off put a bigass filter comingnout of the tank, before your pumps. I would do the simple carb seal after that since you have one. If it works with the new carb...time for a rebuild and clean and or get a vacuum secondary
I put a filter off a BMW on my fity three chevy that had issues fløyting a normal small filter. Its about 5 in hes in diameter and just as long...lots of volume to catch lots of crap before it clogs...
When it quits running remove the sight plugs on the float bowls and see if gas dribbles out when you rock the vehicle. You should get some fuel running out if not then check floats pump etc etc.
I ran a 650 double pumper for years.. The tiniest little crap can hang the needle and seat, even with a clean looking filter. You can loosen the lock nut and pull the seat out of the top of the bowl and blow it out. The best investment I ever bought for it was a set of reusable gaskets, and clear sight plugs for the bowls. Then you can see if the bowls have fuel in them, without pulling the sight plug screws. Just shake the front end (leaning over the fender) and see if the fuel level is low or, if the bowl is full. The needle and seat should be set to where the level is just at the bottom of the threads.
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