Ain't this a....

So fun story about testing out these theories last night. My buddy Russell finally gets back from his vacation, so he comes on over to lend a set of hands and eyes.

We make sure everything's ready, the key is in the gas cap and such, and he says crank it. So I crank and it fires up, and it even fires up really rough! FINALLY I can test the gas cap and fuel pressure theories!

As it's idling in a rough manner, probably at 600RPM, I run to the gas cap, turn the key, and twist it loose. It's now venting, and I hear no change in the engine. Alright, check tank venting issues off the list, or so I suppose.

We sat there listening to the engine struggle. It had between 3 and 5hg of vacuum, the fuel pressure gauge was wobbling between only 5-7lbs this time, but oil pressure, water temp were fine and I had enough fuel in the tank (6-8gal). To test further, we decided to give it some gas. He pulled back the throttle lever about 1/4" to bring the speed up to maybe 1500 then let it go quickly. But the engine reaction wasn't instant. It wasn't even close. It took about 1/2 second for the engine to register it was getting a throttle command, and then it would rev for how long you had the lever depressed. It was a weird phenomenon.

Russell has the wheels turning in his head and asks for a spray bottle of water. He has me get a spray bottle from inside, and while I'm there (about 20 seconds), I was told it 'kind of backfired and then died.' So the engine had been running maybe 5 minutes at this point, and was pretty warm, maybe even warmed up to the point that it had opened the thermostat, but I wasn't sure.

So he and I checked some lines, made sure the carb was seated tight, etc, but didn't end up changing anything because nothing seemed to be out of order. What's important to note was that we definitely didn't change anything here, and also the fuel pressure line held a residual 6lbs after the car was turned off. He told me to fire it up again, so I went around to the driver's door and turned the key. It started up fast and I cannot believe it, it now idled like a champ! [Edited by Moparts - Family Friendly Site - Keep it clean]. It seems warming it up and 'kind of backfiring' did something, though this has happened before, where it dies itself out or I kill it and restart and it seems to be fine, always more than 3 minutes after I'd started it the initial time.

While it's running like a champ, I still check out the vacuum areas for leaks. None. No noticable change in vacuum or RPM when I sprayed down the areas of the intake mating surfaces or the carb mating surface.

At that point, we were through with our tests. He had driven 6 hours yesterday, so I let him off the hook for last night. We did, however, decide to change the carb back to the Holley because a: the Edelbrock is his, and b: the Holley had been rebuilt and needed testing.

We got all the linkage and lines changed over and everything, and we just try to fire it up, not even bothering with the needle and seat levels, only changing the mixture screws. It took some cranking to fill the fuel bowls, but started up alright. I was, however, told to urgently shut it off right after I'd got done turning it on. It seems that, somehow, my secondary fuel bowl sprung a leak where it's plugged (see picture)



I've been a good boy, but now I just want to throw new parts at the car. I've diagnosed this thing up and down, and I'm running into opposite issues - first it'd fire up fine then when it got to a time where it was warm, it'd die. Now it starts up really rough and dies when cold, but fires up fine when warm

I guess today we'll go back to the Edelbrock carb to save diagnosis time and so I can replace the fuel bowl on the Holley, but according to these new updated symptoms, anyone think they can narrow it down?