OLE442

I installed a new fuel pump maybe 15 years ago on my 455. It has been sitting for a while and has probably less than 20 miles on it since then. I got it into my back garage in the lift bay a few weeks ago and I got it started up and it ran pretty good. Well, after it sits a couple days, it will turn over like it's supposed to but won't fire, although it will sometimes seem to want to. I take the air cleaner lid off and dribble a little gasoline into the front to barrels of the carb, put the lid back on and it fires right up and runs well and idles well? Could this be that my old "new" fuel pump is bad after sitting for a lot of time. If not, any other ideas?

Thanks,
OLE442

jaunty75

I don't think it's the fuel pump. The pump doesn't really get involved until after the engine starts, does it? I mean, the engine has to be turning for the fuel pump to pump anything, right? A cold engine back then was supposed to be started by completely depressing the gas pedal to the floor and releasing it. This gave a squirt of fuel into the cylinders and opened the choke. If it didn't start, the owner's manual said to repeat the process. I have a '78 Toronado that I usually have to pump the pedal on a few times to get it to start if the car has been sitting for more than three or four days. (If I just drove it yesterday, though, it will start pretty readily after a single pedal press.)

But what's a new fuel pump cost? $20 or $25? That's nothing. After sitting unused for 15 years, who knows what the condition of the fuel pump's innards is. Why mess around? If it were my car, I would have changed it already.

Fun71

I doubt it is the fuel pump. If it were, you would notice an issue with the engine running. There might be a crack or leak in a rubber fuel line that's basically an air leak and prevents the fuel pump from being able to draw fuel from the tank.

Vintage Chief

If after starting the engine it CONTINUES to run well, then it very likely is not the fuel pump since the fuel pump is delivering fuel to the carburetor and the vehicle's engine & the engine continues to run. Sounds, as you're suspecting, it isn't getting fuel to start the engine & when you dribble fuel into the carburetor it starts & continues to run. If it's been sitting a LONG time, good chance you have some fuel gum which has settled out in the carburetor fuel filter or clogging the fuel filter. I'd suspect the least expensive route first. R&R the fuel filter. Is there gum in the fuel filter? If so, change it. And, IMO, importantly - take it on a 20 mile drive then see how it performs - run some fuel through the entire system. After this simple treatment, I'd probably look to see if the choke is set correctly, then I'd check on some basics - distributor contact points & spark plug(s) condition. Engines do like to be run.

BillK

ole,
There have probably been a million posts now on carbureted cars not starting after a few days sitting because of the ethanol in the fuel causing it to evaporate faster. Its either that or your carb is leaking out of the "well plugs" which q-jets are known for doing. You should be able to see it leaking if that is the case by blocking the throttle open after you shut it off and taking a look after an hour or so. If there is fuel in the intake manifold then the carb might be leaking. More than likely its the fuel. My S-10 and my Wifes Riviera are the same way. Will start right up if you drive them every day but if they sit over the weekend or longer it takes a little cranking to get fuel up into the carb.

OLE442

I filled it with "no ethanol" stuff from a Marathon station around here.

I do think I'll check the filter though! The car did sit for quite a few years without running. I'll have to find a new filter for the Quadrajet before I do though.

OLE442

Vintage Chief

Many of us (including me) agree on using the fuel filter with the check valve. Here's a nice read on the fuel filter w/ the check valve.

https://classicoldsmobile.com/forums...barrel-136375/

VI Cutty

I have the same issue and have been trying to track it down for over a year. The car runs and drives fine once it starts, and starts easily for the rest of the day.

- I run gas with no ethanol, so unless there's something else in the formula these days I don't think we can blame it on that
- I replaced my fuel pump while I was doing my timing set last year. No difference
- I need to follow up on Bill's suggestion to check for my carb (QJet) leaking
- I also need to read up on that check valve thread

The engine cranking will operate the fuel pump of course...one pump per rotation I think. It strikes me that the delay in starting is due to gas missing from the float (carb leak) and possibly the fuel line draining back towards the gas tank for several feet...so we have to crank enough to get some gas into the float.

Anyhoo, my two bits for what it's worth!

Fun71

Here in Phoenix the summer temperatures get to 120ºF and all we have is E10 gasoline. I don't see drastic issues with evaporation during the summer months so It's hard for me to comprehend how it's a huge issue in areas with summer temps in the 80s-90s. Maybe the base gasoline here is blended to achieve a higher vapor pressure for the extreme temperatures and that limits the evaporation rate?

jaunty75

Maybe, but I think the more likely explanation is that this idea that E10 evaporates more quickly than pure gasoline is just an old wives tale that's often invoked to explain away hard-starting issues because it makes for a good story and means we can blame the dad-burn gummint for our problems.

As you note, gasoline blends do vary around the country depending on time of year and climate, but all of these blends are strictly controlled by the EPA with one of the main goals being to limit evaporation of the fuel. Besides, if anything was evaporating, wouldn't it be the ethanol preferentially to the gasoline as ethanol is a smaller molecule? With it being only 10 percent of the mixture, wouldn't there still be lots of gasoline left (90% of what you started with) even if all of the ethanol in the gas in the carburetor evaporated away?

And another thing. If the ethanol really were evaporating away, couldn't we all use this to make pure gasoline for our old cars in our backyards? Just get a kiddie pool, fill it with gasoline, and let it sit out in the backyard for a few days. All the ethanol evaporates, and, presto, we are left with pure gasoline. Siphon it back into a storage tank and use it in your car. No more starting or running issues. What could go wrong?

Fun71

That's exactly what the study in this publication concluded:

https://www.tandfonline.com/doi/pdf/....1994.10467294

Tests were performed to compare the evaporation rate of 10 volume percent (vol%) ethanol-blended gasoline (E10) with the evaporation rate of its base gasoline.

E10 lost more total weight to evaporation than the base fuel, but less gasoline. The increased weight was due to ethanol

jaunty75

Very interesting. Thanks for the link to the article.

OLDSter Ralph

X 2

Checking this wouldn't hurt.

This was widely believed about the 1966 and 1967 Quadrajets. Maybe Joe P can correct or clarify this.

joe_padavano

The well plugs have been unfairly blamed for everything from hard starting to swine flu.

The reality is that the 66-67 Qjets used sheet metal plugs like small freeze plugs that WERE prone to leakage. Starting with the 1968 model year carbs, Rochester changed to a spun-in thick aluminum plug that does not leak. In 45 years of working on Qjets, the ONLY one I've ever seen that leaked from the well plugs was a 1967 unit with the sheet metal plugs. Despite this, nearly every Qjet I've ever taken apart has some residual epoxy on the well plugs that some previous rebuilder was compelled to slather on. Ironically, this epoxy is always loose and peeling off - it certainly isn't sealing anything.

Whether one believes in the well plugs boogieman or not, there is a VERY easy way to prove if it is or is not a problem for your particular carb. Simply unbolt the carb from the motor and prop it up level on your workbench. Place a piece of paper under the carb. Fill the float bowl with fuel through the vent tube. Now let it sit overnight. If the well plugs (or anything else) are leaking, the paper will be wet and stained in the morning. If not, look elsewhere for your problem.

Lonnies Performance

If it runs fine after started it has little to do with filters, fuel lines or fuel pumps.
Fuel cannot leave the carb unless it evaporates, leaks on the intake or in the engine.

Q-jets do have a common problem with the well plugs letting the fuel drip into the engine. I have had to epoxy & re-peen quite a few over the years due to leakage. Most were in late 70's GM vehicles that I ran across.
(The best way was to drill & tap & insert a set screw.)
This also caused a flooded condition where you had to hold the accelerator to the floor to get it to start due to fuel leaking in the engine after letting it sit for a short time.
This was then offset by the carb being empty a few days later & being hard to start, and requiring extended cranking to get fuel back in it.

Obviously your car wants fuel to start as pouring some fuel in the carb helps.
Does is easily restart after a few hours? A few days?
I expect what you are experiencing on most cars that sit for a month or more.

In the age of fuel injection, we often forget what it takes to start an old car.
I routinely have to crank my old engines a few times, pump the accelerator, then repeat until it starts on any vehicle that sits for a while... this is all to get fuel back in the carb, which will then allow the accelerator pump to inject it in the engine as you pump the throttle.
I often do as you stated & give my cars a small splash down the carb to keep from killing the battery on anything that has sat for months on end. I don't like cranking an engine for 30 sec. to get fuel in it... dry starts are tough on tough internals.

joe_padavano

So YOU'RE the one who epoxied all my carbs...

Seriously, did you actually see fuel leaking, or were you simply going on the assumption that it's a "common problem". I have yet to find someone who has actually demonstrated fuel leaking out of the bottom of a Qjet with the aluminum plugs. I also have yet to rebuild one where the epoxy was still adhering to the plugs.

Lonnies Performance

Yes I have seen physical evidence of these leaking.
As stated above.. hard hot starts was a first sign. Then we removed the carbs to check for leaks.

Also I never used generic epoxy that you get from Walmart... as it comes off like you have seen.

I had a grey industrial fuel safe epoxy that resembled JB Weld. I forget the brand at the moment.
You could hit the area with a cartridge roll to prep the surface & then apply.
After cured it was likely stronger than the carb. I've never seen it come off. Still have a few from 30+ years ago.

When I was really tricking out a carb, I would drill & tap for an allen head set screw, installed with Loctite.

oldcutlass

Have you actually popped the breather and looked down into the carb while operating the throttle to see if there is any fuel spraying? Is your description of a couple of days like 2 days or is it actually longer.

Sugar Bear

Is the choke closing properly? Is the choke pull-off adjusted so that it doesn't pull the choke blade open too far?

OLE442

Thanks for the suggestions. I will pull the cover off the air cleaner and see if the accelerator pump sprays. I will also get a new filter with the check valve and install it since this one has been run very little over the last 15 years. I'll also look at the choke position as well.

I went out a couple days after the last lost and turned the key, let it crank a couple times and then hit the accelerator pedal and it tried to start, I turned the key off, waited a few seconds and repeated the process and it then fired right up so, maybe I was doing something wrong or just being too critical. At any rate, I'll do a few of the above items this next week. Right now, I'm taking it easy since I've been up on a ladder painting my barn and seemed to have really messed my back up a bit. Really bad yesterday but today is a bit better! Old age sucks! Having to be careful sucks even more....LOL!!

Thanks for the posts,
OLE442