I picked up my 84 Z28 a while back, It's an automatic and the engine got swapped for a 350 17k miles ago, the rest is unknown. I know it's still got the intake manifold, carb, and air cleaner from the original 305 H.O. So it's a E4ME quadrajet for sure.

I've recently had some issues with fuel and so forth, it seemed like a clogging filter so I pulled the stock filter and put a inline filter in, I made the mistake of putting a 5/16ths in though.... Now it's fixed and I've got the 3/8 filter with new line to the carb.

Problem: When I start it cold, it gets up to idle (set at 900 right now) and then starts to 'chug', drops to 750, then 500, then dies altogether as if it can't get enough fuel.

If I gas it when starting it starts, then has a hell of a time revving, then promptly dies, like the 'floor' fell out from under it.

Once it's warm for a while, it runs fine, idles about 900, drops to 600 when in drive.

It's overheating (220 with a new 195* thermostat) a little like it's running lean, but I don't know enough to diagnose it.

Ideas: Fuel pump is going out? Maybe from too small a filter putting too much stress on it? Carb is tuned badly? I don't know how to tune it besides idle...

Any help would be appreciated.

 

Is your choke working?

 

As far as I know, yes. My choke light comes on when I turn the key to run, I'm new to carbeuration so I'm ignorant of what proper choke operation is, can you enlighten me?

 

With the engine cold, pumping the gas once before turning the key should snap the choke plate fully closed. After starting, the engine will be on fast idle for 3 or 4 minutes until the choke opens and the idle speed drops.

 

Still working with it right now, a few thoughts.

1. When I set the key to 'run' I get a loud repetitive clicking or tapping noise coming from the engine bay.

2. I don't know where the heck my fuel pump is... I've got a few blocked off plates, one on the upper intake (egr?) and another on the passenger side, up front with 4 bolts in it. It's hard line up to the passenger side, then 3/8 rubber line to a filter then to the inlet on the carb. Can someone tell me where my pump is? Is there a possibility it was removed?

 

That's the mixture control solenoid, its normal.

It should be on the lower passenger side of the block, at the front just in front of the motor mount.

 

Okay then, my fuel pump has been replaced with another unit then, where it is I don't know, I'd have to jack it up to find it. That might be an issue...

Back to the choke, what's normal operation for a choke?

*edit* Information that might help: usually I've gotta floor the gas while cranking the engine to get it to start, is this normal?

 

No, it's not normal. Usually that's a sign of flooding, which could be due to a dirty needle and seat, or to your fuel pressure being too high. If you don't have the mechanical fuel pump on the block anymore, then it sounds like someone has been doing some butchery on the car.

 

I read that normal fuel pressure is about 6 psi, I'll go ahead and see about pressure checking the line to see if the pump which is there is pumping too high a psi, if there is one at all....

*update* disconnected the ignition and fuel line, had someone crank it while I watched the fuel pour into a container, it was flowing fast but steady.

 

Well, a few updates this morning. On the off-chance that my filter change dumped all the gunk on the old in-carb filter onto the seats or needles, I put some seafoam down in the carb, I'm giving it a few minutes to sit before I fire it up. I made a few discoveries in the mean time.

1. I crawled under the car and guess what I found, an electric fuel pump mounted back by the rear axle!

2. When I floor the gas, the choke doesn't snap completely shut, it's got a slight crack of room left. I can push it shut all the way, but the throttle won't do it. How might I go about adjusting that?

When I tested for constant fuel pressure yesterday it seemed to be doing fine, I can't judge it by eye but it looked about like 6-8 psi... Maybe I'm getting too much fuel and not enough air?

*Edit*
I just started the car, it smoked of course with the seafoam and all, but while I was checking the exhaust fumes I noticed something veeeeeery interesting.... The fuel lines down by the pump were leaking! Just a little, but it might be enough to rob me of my precious fuel pressure!

*Double Edit*
I found the leak was coming from the rubber lines going from hard line to the electric pump, then from the pump to the hardline again, both rubber lines were ruined. I pulled them and put in new line, it runs great now.

 

I think my problem is the same as yours. I can feed it a bit of gas while turning the ignition and it will start up. Then I can go a few feet or a block before it dies on me. But if I crank without gas it won't start.

I also noticed a gas smell the day before it started acting up. Must be a leak. I got a V6 firechicken.

 

Yeah, feels like I just had sufficient fuel pressure to start, but then the leak would cause me to lose pressure.

I'm still having lots of trouble cold starting, but it's not nearly what it was before. I believe it's just bad tuning on the carb, which is scheduled to be replaced so I'm not stressing.

 

Replace it with what?

 

Eh, the plan was to drop a edelbrock 600 performer on it for a mild-mannered economy little street driver...

But then someone offered me twice what I paid for it and $500 more than I'd spent on it, I couldn't pass it up. Just got back from signing the papers.

 

Well, now you have a little more to go out and get another one. . .

Just don't put an Edelbrock on it, please.

 

Haha, seems like everyone I've talked to hates Qjets. Everyone but the members of this forum anyways.

I'm thinking about picking up this Caballero I saw nearby, maybe drop a 350 in it... I'll see about a Qjet for it.

 

The people that hate q-jets are the same as those who refuse to understand them.

But, you missed the point. In your situation, changing the carb would cost more than fixing what you had, performance wouldn't have improved (the #1 misconception people have about improving performance on these cars), and fuel economy would go down (vs. what you can get with a properly operating stock q-jet). However, they aren't the best carb in all situations. If you are starting with no carb, then there very well may be a better choice.

On the other hand, I can't think of any situation where a Performer would be better than a q-jet.

 

It's the whole "properly operating" and "stock" parts that I can't quite seem to make happen. I'm not one to just quit on a project, especially if all it takes is knowledge to make it work, so I'd work that Qjet until it works. It's out of my hands now so I'm not too concerned with it anymore.

The general consensus I saw is that some people hate them because they're complicated, others know what they're doing and love them. If you're competent it's your best friend, if you're incompetent you'd believe they're junk. I see the difference, now my chance to really develop the knowledge is gone. At least until my next chevy 350...