1986 Camaro 5.0l 305ci 5 speed manual: Gets too much fuel, not sure why.

Asked by Jan 18, 2015 at 10:06 AM about the 1986 Chevrolet Camaro Base

Question type: Maintenance & Repair

Alright, so provided there's no character limit on these questions, this is probably
gonna be a book, so bear with me! About a month ago, I was driving home from school
at about 3:30 on a dry, sunny (but cold, it's winter in Maine) afternoon. I noticed that
my car had been low on power that morning, and was really suffering when I left the
school, but I just assumed that it was because I hadn't let it warm up. I got about 5 or
so miles from the school, and as I was pulling away from a stoplight, the engine
almost refused to rev up... Now, normally, I can rev the nuts off the thing and dump
the clutch and she'll roll smoke off both tires until I let off... I tried that, just for giggles,
and it barely chirped one tire... So needless to say, i got about halfway through second
gear and pulled over, it just refused to go any higher than that... I popped the hood,
checked for any disconnected electrical or vacuum lines... I found nothing... So I
figured "screw it, what the hell", I jumped in and tried to drive away... As soon as I let
the clutch out the slightest bit, it stalled and I couldn't get it to start again... Now,
here's the confusing part... After the tow truck driver brought it to my work (which is
right next door to my house, very convenient), I gave the car about 10-15 minutes to
cool down and do it's thing... Then, I decided to try it again... I pumped the gas once,
cranked it over and it fired right up like it always did! BUT, it ran fine for only about 2
minutes... then, it gradually started to lose power, and eventually stalled after some
idiot (me) decided to try frigging with the throttle... It's been about 5 weeks now, but
every time after that, if you try starting it, it just cranks and cranks and cranks... If you
pump the gas 5 or 6 times, and hold your foot on the floor, it'll kick the starter out and
"run"... It's not a healthy kind of running, but it fires on it's own... If you can jump from
the driver's seat to the engine bay fast enough and finesse the choke and throttle, it'll
ALMOST idle... All this leads me to believe it's a fuel problem... I replaced the rotor
and cap the week it died, figuring maybe it had weak spark... That wasn't the
problem... I rebuilt the Rochester Quadrajet (Quadrajunk) carburetor about 2 weeks
ago, and that made no difference... Now, I'm not sure if I did that rebuild correctly... I
followed the instructions as best as I could, but I'm a 16 year old high school kid, and
that's the first carburetor I've ever rebuilt... It's running EXACTLY the same as it was
though, so I'm somewhat confident that I rebuilt it correctly... I'm pretty much out of
ideas here guys... If anyone has any idea of what it could be, I'd love to hear them...
Any help or suggestions would be greatly appreciated!!

1 Answer

56,775

A couple of things come to mind. First and for most is the automatic choke. It's electric and was troublesome from the get-go. Will it run if you hold the choke plate open by hand? The choke coil is heated by a tiny electric heater inside the choke coil housing. They ALWAYS burned out after a few years of use. The other thing that comes to mind is carburetor icing. This occurs in cool damp weather. Your Camaro was originally equipped with 2 systems to combat carburetor icing. The first and most visible is a "thermac" air cleaner assembly which pre-heats air going to the carburetor. Using a vacuum motor on the snorkel the air coming in is maintained at about 100°F under all conditions. The second is a heat riser system which uses an EFE (Early Fuel Evaporation) valve on the right (passenger's side) exhaust manifold. When cold the valve is closed and directs hot exhaust gases up and around the base of the carburetor to warm the throttle plates and further eliminate ice forming on the throttle plates. When you pulled the carburetor for the rebuild you should have noticed a channel running around the front part of the mounting spot on the intake manifold. That channel always gets clogged up with carbon and needs to be cleaned out. As for the carburetor rebuild, since this is your daily driver, send it out to be rebuilt. The Rochester Quadrajet is one of the most complex carburetors ever built. It has over 100 parts and, since your Camaro is an '86 model, it's computer controlled. Whatever you do, do NOT buy a rebuilt unit at the local auto parts store and turn in the old one for the core charge. I can guarantee it WILL be wrong! Carburetors have specific model numbers for specific vehicles. Rebuilt units are lumped together in aftermarket cataloging and are very rarely correct. I work at NAPA and personally won't sell a customer a rebuilt carburetor. I direct them to a rebuilder who will rebuild the old one. I'll sell the kit only but not the whole unit. HTH. -Jim

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