Initially when I bought my 72 Toro, it would take 1 pump of the gas pedal, and about 3 seconds to start on a cold start after sitting for over 24 hours.

Now it takes a constant pumping of the gas (15, 20 times) while cranking the starter to get it to fire. Once fired, she runs great, and starts back up perfectly for the duration of the days use, until sitting for another 24 hours or so. No lag in throttle or sputtering; only problem is that first initial start up.

Would this be attributed to a bad accelerator pump in the carburetor? All my rubber fuel lines are new. Starter and solenoid are new. Battery is new.

Any takers? This is a 455 base model with Rochester factory carb and no mods.


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Did you look into the carb, as you pump it, and see if it is squirting gas? .Have you taken the fuel line off at the carb, and turn the engine over, and see if pump is pumping gas? Does the fuel filter need changing? Also check the carb bolts and all vac lines.

 

fuel filter is new, and the Carb is getting fuel. Like i mentioned, its just the initial start up after sitting overnight that is difficult; after that, it runs like new. I ordered a carb kit for it, and will rebuild the carb next.... i was told possibly just needs accelerator pump replaced?

 

If it runs ok warm and doesn't hesitate the accelerator pump should be fine. Before doing a carb rebuild remove the air cleaner lid on a cold engine and post a photo of the choke blade. Next depress the accelerator once and post another picture of the choke blade, it should have snapped shut. If not it will start hard. A non-closing choke blade is due to sticky/binding linkages or a bad/misadjusted choke thermostat.

Good luck!!

 

thanks, I'll give that a go and see what happens. Thanks!

 

 

ok. I checked the choke blade and it's working as it should. I started the car and watched the blade slowly open as the car warmed up, so I don't think it's the choke blade or thermostat. It's as if it's losing fuel prime to carb when it site a while.
Would the accelerator pump be the cause if the seal isn't holding as it should? Even though car performs well under load?

 

With the engine cold, hold the choke blade open, pump the throttle linkage at the carb while looking down the throat of the carb. If two nice streams of fuel squirt into the carb the accelerator pump is good.

If the accelerator pump works ok I'd try lightly pinching off the rubber supply hose to the fuel pump overnight and re test the slow start condition.

Smell the oil dipstick for gasoline contamination.

 

no gas smell from dipstick; but I do have a question about the accelerator pump test.

If its losing prime to the carb, and I do that test cold, wouldn't I get no gas spraying since the fuel would have drained off? I'm assuming the accelerator pump is working, because the car runs great and drives fine under power, but I've been told that If the leather seal on the accelerator pump has been exposed to air it will crack or shrink, causing the carb to lose prime (father in law has a '70 Torino GT and something like this happened to him I guess)

Fuel pump is obviously working since it eventually gets fuel after cranking a pumping the throttle furiously, and works perfectly afterwards until it sits overnight. So i guess what im ultimately asking is would the carburetor lose its prime if there was a slight leak in the accelerator pump seal?

 

A few questions.

What type of fuel are you using? Modern ethanol will evaporate out of the carb fuel bowl sometimes as quick as overnight. Try a different brand of gas or better yet non-ethanol.

Did you get the correct fuel filter with the anti-drainback valve, and is it installed correctly?

I don't know of a leather accelerator pump seal that's been made since the 70s. A new kit will most likely have a neoprene one.

Have you replaced the rubber sections of the fuel line? They may be sucking in air thru pinholes which will cause hard cold starting.

 

The accelerator pump diaphragm leaking would not cause a fuel drainback.

 

it does have the correct fuel filter installed. Drainback valve i do not know about, but it hasnt been touched since ive owned the car and the car was starting fine until a couple weeks ago, so I am assuming it is fine.

I replaced the fuel line hoses in the front of the car, and by the fuel tank, and also have a new OEM gas cap so it's definitely venting correctly. I have not touched any of the lines going to carb; they all look fairly new and the carb itself looks like it's had a rebuild in recent years because it's in great shape with zero discoloration or corrosion, and everything seemingly works fine.

I run normal pump gas, but always premium and I add a bottle of SeaFoam every couple tanks. I think they run 7% Ethanol here in the State of Washington.

This problem wasn't a problem until very recently. I replaced starter, belts, and power steering hoses. The fuel lines at front under the AC compressor were leaking through pin holes, so I replaced them. The rubber fuel lines at the tank were soft, so I replaced them as well. Car ran fine after, until one day, it just didn't.

 

Would a pinhole in the carb rubber line cause drainback? Small enough to allow air in but not let fluid out? I haven't detected any leaks anywhere.

 

Noted. Thanks. I won't know until tomorrow if the accelerator pump is working correctly or not. I'll check and let you guys know. You guys are awesome with your accumulated knowledge and a great help; thanks! I definitely appreciate it.

 

If while looking down into the carb and operating the throttle you see 2 solid streams of fuel spraying, it is not your accelerator pump and the fuel bowl is not empty. Are you sure you're getting spark when the engine is cranking? Hook up a timing light and see.

 

Yes. A small hole would allow air in and the fuel could drain back to the tank. Any small fuel leaking out could evaporate and leave no visible wetness.

 

A couple things.

Firstly, do not keep smashing the pedal. There are 3, and only three, ways GM directed to start these things.

1. Cold engine. Depress once, slowly release. Crank engine with foot off gas, release key when started. Repeat if necessary. Blip throttle after it's running for 30 sec.
2. Warm engine. Depress pedal about half way and hold while cranking the engine.
3. Very cold weather or sat for several days. Depress pedal 2 or 3 times, then, with foot off gas, crank till starts.

Please confirm car starts correctly when warm. Get it running, go for a drive, come home, shut it off, then restart in half an hour. Then, please confirm that the car starts correctly on the next day. Then, please confirm the car starts right after 2 days.

If all this is good, and it takes a long time to start after several days, you are getting fuel evaporation and or drainback and this is normal. My quadrajet cars take @7 seconds to start when they have been sitting for a while. I don't mind this as it distributes oil and the starter can handle one 7 second crank.

 

Absolutely starts and runs as it should when warm. And it used to start off one pump of accelerator prior to very recently, as you described. Currently, it absolutely will not start unless pumped thoroughly while cranking now. This is only while cold, after sitting for a 24 hour or longer period of time. Once it starts, it runs and restarts with no issue. Drives perfect.

It's definitely getting some sort of fuel drain while sitting. I will check carb hoses tomorrow morning and see if I find anything. There are no noticeable leaks as of right now, so I will probably just replace the sections of rubber hose that go from hard lines to the carb. Carb seems to be working as it should, as per the various instructions I've recieved from this forum (you guys are great, by the way; thanks).
At this point, I'm starting to feel like I've got an air leak somewhere between pump and carb thats large enough to cause the drainback, but small enough to not allow fluid out.

 

 

Drain back can be ruled out by adding fuel directly to the fuel bowl through the top of the carb using a small plastic squeeze tip oiler bottle.

The accelerator pump has its own well/reservoir so it could squirt fuel even if the float bowl went empty.

 

Reason I ask is it is very tempting to smash the pedal during the time the fuel pump is pumping up to the carb and filling the bowl. Like the Bear says, maybe fill the fuel bowl once after a few days' sit.

 

Yes, filling the bowl from the vent and seeing how it behaves can rule out a lot of problems.

I follow the procedure in the video I posted (step on gas once to close choke, then crank engine) and with the bowl fully empty (after sitting), all it takes is about 5 seconds of cranking before it starts and goes into high idle.

 

One other thing to do is look around the base of the carb a few hours after shutting it off, look around on top of the manifold and see if the gas has pooled anywhere. It could just be the gasket has started to fail and the gas is evaporating. If that is the case I'd advise to get it repaired asap, the gas could catch fire from a hot manifold. As the others have mentioned and which I have always done is one pump to the floor with the gas pedal which sets the choke on a cold start and if it's been sitting for a days or even weeks crank it 3 to 4 seconds wait a few seconds then crank a few more and it always starts. Continuously cranking is a good way to kill a starter. Let the fuel pump fill the bowl back up, the pumping action does nothing.
Btw, beautiful car, love the color.

 

went through all lines, found nothing.

Oddly enough, I followed your instructions exactly, and it started up perfectly. I guess i was pressing pedal too fast initially, and just wasnt patient enough on a cold start. Either that, or while checking and tightening hoses (also replaced fuel filter and did plug wires), i inadvertently fixed whatever drainback issue i was having....

Thanks!