The Stovebolt Site Forums The Shop Area The HiPo Shop Need to pump pedal 30 x to start

I have a SBC in my '40 with a Weiand intake and a Carter 4bbl carb, 600 cfm I believe.

Anyway, I need to pump the gas pedal at least 30 times to get it to start. If it's been sitting for any number of days, I'll just pour a little gas right into the carb.

It's got a mechanical choke, which is operating properly. And I've got the choke fully closed when attempting to start.

The truck runs great and accelerates smooth once it's running, just a pain to start.

Any ideas? Thanks!

Change the fuel pump. You've got a bad outlet check valve that's letting the gas flow back through the pump and it's having to pump the line full. BTW, the only thing pumping the pedal is doing is giving you some leg exercise. A dry carburetor doesn't manufacture any fuel by pumping the gas pedal.
Jerry

It's a mechanical fuel pump, I don't know how old or what manufacturer, but there is no return line, just the feed line from the fuel pump to the carb.

Steve - you don't need a return line for the feed line to go dry from the pump not holding pressure

Bill

I just assumed the problem was with the carb, but it seemed strange that there was no visible leaks or fuel pooling or dripping onto the intake.

I never suspected the fuel pump.

how do you determine if it's a fuel pump or the accelerator pump in the carb??????????

If when it has fuel in the carb (just after running) if you cut it off, pump the pedal once and see or hear it squirting fuel in the throat then it's working.

If the fuel pump is bad, or more accurately one if it's two check valves, then with the line removed from the carb bump the starter with your finger over the line and it either won't pump or won't hold any pressure after it does pump.

Sometimes to free a stuck or dirty check valve you can remove both lines from the pump and with compressed air blow in the inlet. Worth a try before removing and rebuilding/swapping it.

Grigg

I am on my third fuel pump and still have to wait until it pumps the carb full if I have left it set for more than 3 days.I agree that pumping is a waste of time. Just crank it for about 10+ seconds.

After letting it sit for a couple days, I just went out and pumped it a few times, and each time a steady stream of fuel came out of the primaries. Even after 10 or so pumps, it still shoots a steady stream into the carb.

So do you still think it's the check valve on the fuel pump?

try a single pump to the floor and hold it down, at the same time pull the choke and start cranking, that should start a well tuned small block .... and sometimes they like hotter plugs

Bill

If you have flooded it repeatedly, the spark plugs might be fouled so badly that it's difficult to start. A manual choke carb that's the right size for the engine shouldn't need to have the pedal pumped at all, just hold part throttle, pull the choke, and crank it until it starts.
Jerry

Even after sitting for a few days, I would think there would still be fuel in the bowl(s)...hell, even after weeks. Carb kits don't cost much, and neither do fuel pumps.
Assuming compression is good, ignition is the only other suspect. Plug condition can tell a lot. Points and condenser, if required, and cap, rotor, wires, plugs, timing...you know the drill.
SBC's are easy and cheap.

cm

A new hotter spark plug is the same temperature as the old colder spark plug: room temperature.
It might leave the plug cleaner from the last time it ran, but it won't help this time.

Just a follow up...

So It's been sitting since the weekend. I waited one day, pumped the pedal several times and had a good steady stream. So then yesterday, a few days later I pumped the pedal a few more times and after like the second pump it was kind of sputtering and by the third or fourth pump nothing was coming out.

So just so I'm understanding correctly, would you say that after four or five days of sitting, should there still be enough fuel in the carb to get a steady stream? And if there isn't, it is one of three things... the fuel is evaporating, the fuel is leaking down out of the bowl and into the intake, or the fuel is running back down the fuel line past the fuel pump due to a bad check valve in the fuel pump?

Does that sound right? So because there is little to no fuel left in the carb, I can rule out ignition, plugs, points, etc, as the cause for my hard start problems.

Like I said, I can drive it, and then shut it down and it starts right up. But sitting after a day or two, and I have to manually dump a little gas into the carb to get it to start.

Am I on the right track here?

Fuel isn't going to jump out of the bowl and back through the needle & seat into the fuel line, through bad check valves in the pump... and eventually get home to the tank.

Otherwise sounds like the question is is evaporating? unlikely.
Draining into the intake? possibly but I'm not completely familiar with that carb to know how it would happen (if it could?) and what to check or fix.

My first guess is starting technique, you may need to learn and adapt to the truck, because it's not going to adapt to you. Some folks have a knack for it and some don't, I know because my father and friends have had trouble starting my truck to the point they about kill the battery while I could then start it with a gentle push and one bump of the clutch. Or if I'd get there before they killed it I could start it so easy they thought the switch was off the whole time they tried it... it wasn't.
Please don't take it the wrong way, I'm only trying to illustrate that the answer may be familiarity with the vehicle and what it needs to start, a lot of that is by feel and sound when you try, not a predetermined set of instructions.

Grigg

Thanks Grigg. I've had a a few older cars, so I understand starting methods and having to adjust to different cars.

What I'm dealing with here is a truck that will start fine when hot, but after sitting a couple of days or more, it won't start at all because it is starved for fuel. Typically with old cars I'll close the choke completely, pump it once, hold the pedal to the floor or half way, and then turn it over. With this truck it just cranks and cranks. And after a couple of pumps there is no fuel coming out of the jets. So that's the best description of the problem. What I need to figure out is, why after a few days is there no fuel in the carb to start the engine?

yes fuel will be evaporating, but if you still get a few shots after a couple days, the problem is fine tuning, and as Grigg points out, technique - a small block should fire on the first or 2nd rev, could be the timing is a bit off or the plugs are fouling ot your frenetic pedal pumping is flooding it

has it always been this way? have you done an ignition tune since you got it back on the road? HEI or points? how much do you drive it? long trips or short?

Bill

It's been this way as long as I've had it, about two years now. I did a tune when I got it, about two years ago when I got it, but have put less than 1K miles on it since. Stock distro with points. Don't drive it nearly as much as I'd like, less than 1000 miles per year. Long and short trips.