mavidatt

Just recently had my 89 corvette swapped over to a carburetor and got rid of fuel injection/computer. Car is a 6 speed has a zz4 crate motor in it. Car was running pretty good, every once in awhile it would act up and stumble a bit, mostly before it was warmed up. But today took it out and drove it down the road aways and then pulled in to a car lot and it just quit on me right as i pulled in and then wouldnt start back. I could smell fuel, but dont see no leaks, and car shows it is getting fuel pressure around 7 psi when i turn the key over. I think fuel pump may be going bad, it has the stock fuel pump, which they said might not work cause it was controlled by the computer, but was working okay for the time being. Also the car cranks over when trying to start it but just dont fire up. Oh yeah and the other day i drove it and it ran a little rough on me, but did okay once it got heated up, but after i got home and shut it off it after fired on me. Not a car junkie dont know much about this stuff but this is what i know any help is appreciated.

pkazsr

If your Vette has the stock fuel pump it puts out about 65-80# of fuel pressure. Plus the pump is controlled by the computer at start-up and oil pressure switch while running I think!
Anyway IMHO you don't know what you have and I hope someone else here is more familiar with a carb swap to an 89.

Black89Z51

You need to change to an 84 pump and run a return type fuel pressure regulator. Check your ignition and timing. Backfiring cod be caused by ignition timing being off. Also since the computer controlled the timing advance you're going to need a vacuum advance distributor or mechanical advance.
I converted my 89 to Carb. Im running an MSD 6AL and Pro Billet distributor with mech. advance. Also running and 84 pump with a return regulator.

mavidatt

yeah it has a vacuum advance distributor on it now. I figured timing could be off, but it has been running, so timing was good enough to get it started and drive ok.

Black89Z51

Check timing and make the distributer clamp bolt is tight.

383vett

A car needs fuel and spark to run. Pull the air cleaner off. See if the accelerator pump squirts gas. If yes, check for spark while cranking. One of the above should be missing. If all works, your motor may be flooded. Check the float levels of the carb. When I carbed my 84, the underhood temps got so high the fuel would perculate and flood the motor.

project C4

What is the fuel pressure on an 84 pump ?

383vett

13 to 15 psi

project C4

Thank you,383.

Do you have a good source for one of those.

I guess Walbro is the best ??

I am debating doing this or just taking the fuel pump out of the tank and running a regular electric 6 psi pump outside of the tank.

oldalaskaman

I vote external pump and check your icm in dist.

383vett

When I carbed, I ran an external Holley blue pump mounted in front of the tank on the crossbeam. You don't have to worry about a return line. This isn't the right pump, but mounted here.

project C4

Very good... I will do the same.

That should be quite a bit cheaper to.

383vett

I removed my original pump from the tank, used braided fuel line with a sock clamped to the end as a pickup connected to the stock hardline within the tank. Bolt the tank top back up. Outside the tank, I used braided steel connected to the hardline out of the tank. Connect this to the input of the new pump. Connect the output of the pump to the fuel line going forward. Cut and paste after the filter to the carb and you're good to go. Plug the return line going to the tank.

project C4

Good deal. Thank you for all the info. You make it sound easy now. lol

looks like I am going to be able to use the factory hard line to the carb without any rubber. I just need to move the factory line and put in a #6AN coupler

oldalaskaman

took a better look

Keystring

I'm running the stock pump with a regulator.

No problems so far.



(Lines are getting changed to flex this year and regulator being relocated)

Not my install.. PO's.

Nathan Plemons

Gonna go out on a limb and say it is not the fuel pump. If it was a volume problem you would have problems under load but it would idle. Sounds like you are having much the opposite problem. I am betting on a float level or a heat problem as others have mentioned.

project C4

ZZ4 and a 6speed...sounds like a good combo.
Once you get the bugs worked out It ought to run pretty good
The zz4 comes with a performer intake on it so hood clearance is not much of an issue. 650DP holley and long tube headers.
355hp on tap for a fun mild combo.

Nathan Plemons

Looking good. The wiring could use some work yet but I certainly understand the "good enough to get it going" approach.

I helped a friend relocate the fuse panel to the back of his Eagle Talon. All the "extensions" are the same color. The running gag now is that any electrical gremlin must have something to do with the green wire.

What sort of air cleaner do you have to run to clear the hood?

project C4

This is not a "good enough to get it going approach" by any stretch of the imagination.
I am not even close to being done yet. In fact I am just getting started. If you notice the intake is not even bolted down yet.
I am just test fitting everything now.