SolarGoldRaptor

Hi,

I have an issue with my Trans Am, she's really hard to start after sitting. It doesn't take very long, thirty minutes or so. The starter turns and turns with nothing happening. It takes several tries to get her to start.
If I stall or stop the car and start it shortly after, she fires right up.

My first guess is that the fuel in the carb goes away.

The oil doesn't smell like gas so I doubt it's an internal leak.

I rebuilt the carb myself and I'm sure I put everything back correctly.

Nearly everything is new or rebuilt, the car runs very well. I only have to replace the valve stem seals since she smokes a bit on start up. The fuel pump is one of the few parts I haven't replaced, but I do have a brand new one.

Do you have any ideas ?

Thanks

sofakingdom

iTrader: (1)

What does it do, first time you start it in the morning, after sitting overnight or longer?

naf

iTrader: (7)

You can check for fuel in the carb after sitting by pumping the booster and looking for fuel to squirt out into the primaries.

Another issue with a rebuild could be the installation of a new seat that has the slot in the side to replace one that did not. This slot, combined with a slight fuel leak, can allow the fuel bowl to drain back. Assuming any fuel leak you may, or may not, have is not great enuff to drain the carb on its own.

Not advocating against that type of seat, but it can compound a fuel leak issue. If this problem suddenly imposed itself upon your world after a rebuild...

SolarGoldRaptor

I can't recall for sure but I think the seat was just like the one I replaced. Gonna have to check that out.


Engine cranks, nothing happens even if I press the pedal, until what I believe is fuel finally coming to the carb and then it fires right up.

naf

iTrader: (7)

First verify that the carb is actually empty of gas after sitting.

RedLeader289

iTrader: (2)

Sounds like the fuel is just evaporating, especially since that's what it does after sitting overnight as well.

Try this: run it, let it sit 30 mins (or however long is needed), then turn the key to 'run' but don't start the car, just let the pump prime for 10 seconds or so, then give the pedal 2-3 good presses and see if she fires up.

SolarGoldRaptor

I don't think my car has an electric pump, I'm not hearing anything in the back, and there are no wires going through the floor like my '89 parts car had. It's a May 1984 model, I'm not sure when they installed the electric pump that year. But it was just a back up pump to prevent vapor lock

I tested yesterday and the booster just pumps air after sitting, no gas squirting in the carb.

naf

iTrader: (7)

Time to pull the carb off, fill it up on the bench and verify where it's leaking out.

Most likely the well plugs require sealing, with either epoxy or the drill/tap/insert method.

danryanm

Second and Amen. Fuel doesn't evaporate that quickly, so it is definitely going somewhere. Bench testing will be easiest and safest way to diagnose, lest you risk letting too much fuel get into your crankcase.

SolarGoldRaptor

Okay I drove the car quite a bit this week end, approximately 220 miles. I got a pretty decent gas mileage too with around 19 to 21 mpg on an average of 75mph.
But I was wrong, if I try to start the car after letting it sit for an hour or two, it's fine.
It only struggles when it sits overnight. Yesterday I had to crank the car three times for about 5 seconds to get the engine to start

midias

Is it a mechanical fuel pump that needs a few cranks to prime

RedLeader289

iTrader: (2)

^what he said^

Still a priming issue.

naf

iTrader: (7)

Carbs don't need to be 'primed'. The fuel bowls need to be full, or nearly so. The fuel bowl should not empty overnight. Best to fix the leak (likely well plugs).

RedLeader289

iTrader: (2)

Wasn't talking about the carb 'priming' but the fuel pump because like you said, carbs don't need to be 'primed' . But all pumps need to prime. And I've never seen a carbureted engine (new, old, anything) that didn't need at least 1 pump of the pedal to help it start up after sitting overnight(in regards to your statement about the bowls).

naf

iTrader: (7)

Pumping the throttle engages the booster pump within the carb which will spray fuel directly into the throttle bores. This is required because the airflow when trying to start is generally too low to pull fuel in thru the idle bleeds.

I assume that the booster pump is correctly connected to the throttle linkage because Solar stated that he had checked it. If the lever arm is hanging loose the motor will be difficult to start (and stumbly off throttle and the converter will try to stay locked).

SolarGoldRaptor

Should have taken care of the well plugs when I was rebuilding the carb :/ What glue should I use ? 2K epoxy ?

naf

iTrader: (7)

JB Weld is fine. After it's been cleaned really well.