About 6 weeks ago while driving down the road I came across THE car I had to have. upon stopping at the dealer I drove away with a 87 T-Top Camaro for $995. She got a small crack in the right corner bumper cover (nothing a Lebra wont fix :P) and a small dent on the rear. Other than that she's pretty much perfect. 1 week after buying it she died on me at 90mph and I couldnt get her to run. Thanx to the posts of everyone I read about, turns out my Ignition Module burnt out. Sure enough replaced it and been troublefree ever since.... pretty much and thats why i'm here. She has the 305 btw and I am a diesel mechanic so im in the ballpark of goings on

About 3 weeks ago I noticed she started running rich. VERY rich. So much so that sometimes U can smell gas and just wanna say thank god I didnt have a cig lite when I popped off the air cleaner :P Right now she averages 16mpg (with an occasional hard run up to 60 or up to 100 when passing. I had some muffler work done (flowmasters ) and the mechanic removed by Cat cause it was CLOGGED. Now she runs HELLA fast :P. Anyways back to topic. She has dieseled on occasion (like about once every 5-6 runs) and a couple weeks ago I just tagged 3rd gear @ 80 and she backfired. Didnt think much of it till my friend aways behind me said wow nice backfire! I SEEN the flame!..wow. She sputters a bit but nothing to serious. Well a couple days ago I went to pass someone (@530am) and she flat started choking in high 2nd. Didnt think it was gonna recover but she reluctantly did. Drove home that day (@ 4pm) and everything was fine. BTW I have had ZERO problems starting her. Fires right up without even being on the starter more than a second. This morning I fired her up to defrost the ice for about 5 min. Got in it and put her in gear. Started to give her gas and she died. Took about 10-15 seconds of continuous cranking to get her goin again. Then along the way to work she would sputter and choke at anything above 2500 hard pulling. I can leave her in locked 2nd and slowly climb to 55-60 np but anything hard and she sputters. Had to drive to a nieghboring city (30 miles roundtrip) and didnt have a lick of problem. Drove home this evening same way. Not a problem at all.
I'm used to working on 444 and 365 International diesels but this Quadrajet stuff is new to me. What should I look towards? I was thinking the carb but should I be looking somewhere else?

Thanx for any help

 

It seems like you have a combo of issues, and one of them is likely the
carburetor.

Start checking for vacuum leaks from any of the hoses connected to the
carb. If they are loose, or cracked, cut them back and connect them,
or replace as needed.

The carburetor likely needs a good clean and rebuild. Check the floats,
gaskets, and fuel pressure at the inlet. If you're seeing flames out the
tailpipe, it's dumping fuel for sure.

Have a look at the timing as well.

 

Yea, im pretty sure the timing might be off a bit.

How is the fuel fed stock on these? is it mechanical pump or electric? Im asking cause theres and Accel Fuel pump mounted on the inner engie fender and just curious if it could possibly be feeding TOO much fuel and forcing it through. I've heard it can happen.

Does the Carb get its main reading from the ECT? i know on our more modern 365, they START at the ECT and then make the calculations necessary for mix and timing on our diesels.

Already thought of the hoses. Everything looks good as far as I can see.

Carb DOES look a BIT worn and I do know the main gasket is leaking a bit. Found some rebuilt quadra-jets @ guarenteedcarburators.com for $218 but not sure of the quality :P

Ill run er down to the shop and see what the fuel pressure reading is. Had a bus break down tonight and had to drive 45 miles each direction and it was pretty cold where they were at. Didn't have a spec of trouble the entire trip.
So pretty sure theres something sticky or a sensor is going bad somewhere.


Thanx for the help

 

Don't quote me on this, but I believe `86 was the cross over point for
carbs to EFI. If your engine is original, the carb'd cars came with a
mechanical pump, and the others used an electrical pump.

Sorry, I'm not up to speed on 3rd gen. trivia. Of the four Camaro's I've owned,
I had two 2nd gens, then skipped to the 4th gen style.

I know somebody here will have that info and confirm this.

If there's an Accel electrical pump at the front of the car, it's in the wrong
place. Electric pumps want to push, not pull fuel. Move it to the rear of the
car as close to the tank as possible.

There should also be a fuel pressure regulator. Ensure the pressure does
not exceed 6 PSI or the carb will flood (that may explain the rich condition).

If you know the main gasket is leaking, then you can attribute that to some
of the performance issues.

 

Just thinking out loud here but the problems started after exaust mods. On the computer controlled Quadrajet the distributor is what runns of the sensors to adjust timing correct? no vacume advance. Would an O2 sensor off due to CAT removal mess up the timing enough to cause these problems?

 

Welcome to thirdgen.org.

All 3rd gen f-body carbs were computer controlled except some exports. The last year for the carb was 1987. That happened to be the year for a few changes, such as both in-tank electric and engine-mounted mechanical fuel pumps, roller lifter cam, center-bolt valve covers, and small-cap separate coil ignition.

Taking off the cat won't affect the O2 sensor. But, the O2 sensor can get weak so that the ECM thinks the mixture is too lean, so it'll tell the carb to richen up. It's also possible that the coil is weak, as the module and coil are known weak actors from the factory (other than that, the system is good). Proper timing is essential, so get that set properly (why would it be off, though? Did someone mess with it?).

Get rid of the pump on the fender. It's not needed, and as said, doesn't work properly where it is. It was probably installed because the in-tank pump failed, so you need to verify that - if it's dead, drop the tank and replace it (make sure it's not something stupid like a blown fuse).

I happen to have a freshly rebuilt '87 carb I no longer need (from Berlinetta #2). IF you really need one, I'll beat that price you quoted. I know it works well, passed both California and Colorado emissions tests with flying colors, started right up and purred like a kitten before I pulled the engine.

 

WOW, thanx a ton for the replies!

I scheduled at a reliable tuneup shop to have the timing checked out and a fresh tune up.

The only problem that developed AFTER removing the cat was the stumbling. The other 3 were already there.

Will check the fuel pump in the tank today AFTER verifying the fuse is good

Sure, interested in the carb. Never hurts to have a fresh one and was planning on buyin one anyways. Just leave me a private msg or reply to my email address. Might not be able to get back to ya until tonight as I gotta run into town and unjury rig the work I done last night and fix it proper lol

 

I would say your ignition timing is off, get a timing light and fool around with it ( it's very very easy and once you do it you will always know how) The deiseling your hearing is probably engine knock. welcome to TGO!

 

Dieseling (as we explain it to the DIESEL MECHANIC ) is typically from far advanced timing, or the throttle sticking open a tad. Or a vacuum leak can cause the same effect as sticking throttle.
Timing is one of those nice things that you can quickly check once, then cross it off your list. I'd guess the carb needs a rebuild.
That pump is suspicious. Does it have a part number on it? I'd want to know what it's pressure is at. If it was a high pressure pump (as you were thinking, it might be pumping in too much fuel) then it wouldn't run even close to as well as you say it is. ie. It'd bog and drown almost instantly, etc.

 

Fender mounted pump? Is the mechanical pump still in place on the block?

Is your Check Engine light working and have you tried to pull any codes off of it?

At risk of oversimplification, the E4MC varies the primary mixture by cycling the mixture control solenoid (MCS) inside the carb (you should hear it click with the ignition on). It varies the cycle time based on vacuum sensor and throttle position sensor (TPS) readings. The ECM re-writes these 'learned' blocks based on O2 sensor readings. Running rich could be caused by several different sensor failures, most of which will trigger a check engine light. O2 sensor could begin to fail and cause it and not yet trigger a light.

A mechanical problem with the carb could also cause a rich condition. There are several settings in the carb that could become 'off' as gunk and junk clog passages. Rebuilding the carb yourself isn't too difficult and will cost around $50 plus, depending on any electrical components that may need to be replaced (the TPS and MCS are inside the carb). Rebuilding it yourself will also help you become more familiar with how it works.

On the other hand, getting a known good carb at a good price has its benefits...

Be prepared to adjust the carb to your motor. You'll need a dwell meter and the 'special' tool used to adjust the idle mixture screws. Whichever way you go let us know and we can point out some good info that will walk you thru, or answer any questions you have.

 

Sorry been gone awhile. had to cancel my tune up grrr. havent done much since we've had some work issues and been putting in a ton of hours. Anyhoo, got some time tomorrow and gonna run the time light on it. Put in some carb cleaner and seems to have help the stumbling issue. Not near as bad but occasionally hits me.

Gonna chekc the fuel pump and timing tommorrow. Changed out my Thermo to a 180 and the dieseling has stopped for now. Dunno why from just changing out the thermo lol.

Anywyas, ill get back to you guys tomorrow with some results.

BTW tried the paperclip 6 to 12 jump and didnt get ANYTHING. Maybe I had something Ackbaswards Gonna try again tomorrow