off topic gasser question

[Jim P]

I know this is not diesel related but I know there are some good mechanics on here so here goes.

I am working on an old 83 caprice for a guy that guit along the road. He said it would idle but not take any gas.

I thought easy fix, new fuel pump and it would be back on the road. No such luck. I put on a new fuel pump, new fuel filter and checked the line to the tank for leaks or obstructions. I sometimes can get it to start but it doesn't even idle very well. If you try to give it any gas, it stalls immediately. Sometimes when trying to start it, it will make smoke out the carburetor. I am thinking that the timing chain has jumped a tooth. Does this sound likely? The car has 145,000 miles. It only has 3" of vaccum when cranking over.

Help guys, this easy fix turned into a real PITA.

[JohnHolt]

Timing chain would be what I would look at. They didn't last as long in those days than they do today.

[FirstDiesel]

Not sure if that year had it but GM used plastic teeth on the gears to make them run quieter. As the chain stretched it also chewed up the gear teeth until the stripped off or jumped a ton of teeth.

[catmandoo]

gm's great idea for quieter motor plastic gear teeth .ya know i've been drivin gm's for 25 years and i swear to god they have to have the dumbest engineers on the planet.gimmicks gimmicks gimmicks jeez just give me a 1/2 ton 2wd with a diesel for god's sake.what is the problem to easy to build or what.oh it's probably not professional grade!i drive 60,000 miles a year and i'll be damned if i drive a rough ridin 3/4 ton that if you really look at it is probably nothing more than a glorified 1/2 anyway just says 3/4 ton to jack up the price.

[EWC]

If you can get it running , a timing light should give you some insight on the plastic coating theory . You could also drain the oil and see what comes out .

What about a plugged cat conv ?

Start with the basics ( plugs , cap and rotor , compression test , etc ) and report back .

[Jim P]

I put new plugs and wires on it and it will start and idle but if you try to rev it up , it sounds just like it is running out of gas. If you are fast and get the throttle back to the idle position it will keep running. If you aren't fast enough it will quit and won't restart till you let it set for a half hour or so. Then it just fires right up. I checked compression in only one cylinder but it is about 120 psi. I also put a vaccum gauge on it and it has a steady 18" of vaccum at idle, so I really don't think it is the timing chain. I'm thinking it is something in the carburetor.

What do you guys think?

How would it act if the cat. converter was plugged?

Jim P.

[FirstDiesel]

If it starts and idles have you put a timing light on it?? If the timing is in the normal range without having moved the distributor then the timing chain more than likely has not jumped. If you've already timed it and had to move the distributor a bunch then it might have jumped teeth.

Possibly just like it is acting. Fine at idle but when you try to rev and pass more exhaust through it the engine chokes.

Try taking the pipe off the front of the cat. Soak the bolts with Rust Buster for a day or so before trying to remove them. Also another tip I was given for dealing with rusty bolts on something like a cat is to heat them with a torch and then touch a candle to them. The wax melts and wicks into the threads inside the nut and helps lube it.

[Jim P]

Unfortunately my timing light does not work anymore. I can't take the cat off because at some time the flange must have rusted off so somebody welded it right to the pipe. Exhaust does come out the tailpipe though. I am about ready to put some dynamite under the car and do away with this problem. :D

Jim P.

[EWC]

Try checking the accelerator pump . With the engine OFF , look down the throat of the carb while moving the throttle lever . You should see 2 small streams of fuel being ejected from near the top of the throats . This would cover the lean spot when you open the throttle quickly . This would also account for having to wait to restart ie choke cools down and closes slightly and then you can restart . If this is the case , remove the top of the carb and replace the rubber cup on the accelerator pump plunger . Usually they get hard and then don't seal against the carb body .

[GARY PAGE]

Help me out a bit I don

[Jim P]

The excellerator pump shoots two strong streams.

The engine is a 305 v-8 with a quardajet carburetor that is electronically controled somehow. It has a solenoid in the carb with two wires hooke to it. If I unplug these wires, it does not seem make any difference.

Jim P.

[EWC]

The 2 wires should be 3 on the right front , correct ? These run the MC sol . This is a 4 barrel and not a 2 barrel ? Quadrajet vs Dualjet ? Any codes ?

[Jim P]

Yes it is a 4 barrel carb.

It does have three wires in the right front that hooks to some of other switch or solenoid. This switch or solenoid is operated by the lever that pushes down on the accerator pump. There is also another solenoid in the left front that has two wires. This is the one I was refering to. It looks like it somehow moves the metering rods up and down to change the fuel mixture.

Jim P.

[EWC]

That's the TPS switch . The point you have to remember with ECM controlled vehicles is the engine has to be in good running order , like there was no ECM , before you look for ECM related problems . So you have 18" of vac and it seems to idles OK ?

If the cat conv was plugged there would only be almost like a whisper coming out of the pipe . Take anything loose , O2 sensor , exhaust pipe , check valves in the AIR pipes on the exhaust manifolds , anything to let the exhaust out . Does that do anything ?

Does the dist have a hose going to it for vac advance ?

[catmandoo]

if memory serves me correct 83 cars didn't have a vacuum advance but if it does check the wires on the pick-up coil in the distributor when the vac advance comes on it twists and if these wires are old enough it breaks connection and will die when it dies it loses vac and returns and will run again a way to check is if it does have an advance is unplug the hose and it should keep running.

[EWC]

That's where I was going with the vac question . Usually with an ECM you have no vac advance so the ECM will control the advance .

I do remember that the 83 305 had a running problem that was a PIA to fix but that might have been only in the trucks .

[Jim P]

Guys,

I can't remember seeing a vaccum line on the dist. but I will definitely check that out tomorrow.

The owner wanted me to take off the carb. so he can get it rebuilt. So we are going to try that.

I was just thinking, it could be lossing spark because even though it sounds like it is running out of gas when you try to rev it, the plugs are always soaked with gas when I pull one. We were thinking that the carb. was just doing strange things. I never really gave it a thought that it could be spark because it idles.

Jim P.

[whatnot]

I think a timing light would help a lot. Sears used to have cheap ones for less than $20.

[WAPATI]

The 83 fuel Delivery system was a piece of crap.

It was the first attempt to reduce emissions.

I can't remember the name of the part but it sensed the Barometric pressure to deliver the right amount of fuel.

I got cross ways with a service manager because he wanted to charge me for the part and it was suppose to be covered by the polution warranty.

Good luck.

[patrick m.]

the problem is most likely a weak ign coil, the coil will fire under the lite load of idle, but does not have the power to fire when under a load.
replace the coil, its in the top of the cap.

[cruzer]

I think PatrickM has got the answer. Either
weak coil or I've also seen same symptom in a bad distributor. You are probably not getting enough spark to fire air/fuel mix. Friend of mine had to replace the distributor the coil was OK. If the plugs weren't fuel soaked I'd say vacum leak.

[catmandoo]

also a culprit is the little carbon stud under the coil.and i have seen on cheap caps that there is not enough meat where the coil screws go so when you tighten them they stick thru and the rotor can arc on them causing missing and even not to fire.

[EWC]

If the plugs are soaked , there are a couple of items that could be causing the problem .

The charcoal canister is operated by a black vac sol that is above the water pump and to the right . This has 4 or 5 vac lines that run into it . These had a problem with allowing the fuel vapors from the canister to pass into the carb creating a very rich mixture that usually had black smoke pouring out the tailpipe . Take the sol off and if you see fuel running out of it , replace the sol . You should also remove the charcoal canister and try to feel how heavy it is . This isn't very hard to do as the canister is not very heavy whereas a canister that is saturated is very obvious .

If you do the carb rebuild , get them to seal the plugs on the bottom of the carb body . There are 5 or 6 that are used to seal the body after the machining is done . These will leak down over night and cause hard starting as you will have to crank and crank to fill the carb with fuel .

A stuck or collapsed float will also give you problems .

You may have weak spark but remember that the plugs are soaked with fuel . The spark energy will travel through the liquid to ground and not jump the gap as that is the easiest path to ground .

[catmandoo]

yea charcoal cans were good for goin to hell if you do the carb rebuild and the canister did go south it should have charcoal in the float bowl and when you get the carb kit there will be a funky little sponge thingy the looks like a rhinos butt this goes in the well in the throttle plate between all 4 barrels this seals the rear metering rod plugs which tend to leak quite often.

[Jim P]

Well guys I finally figured it out.

The rebuilt carb. didn't help any but your not going to believe what it was.

The distributor rotor had a hole burned through it under the spring in the center of it. The only thing that I can think of is that the spark must not have jumped through the hole at idle but when I tried to rev it up, the spark must have been hotter and it would jump through the hole and short out to the steel distributor shaft underneath the rotor.

Now I know why I have a diesel.

Jim P.

[GARY PAGE]

You answered some of my questions and the wet plugs spell ignition issues. That distributor is an HEI I think and they are famous for 4 things. First is a module located inside the distributor, second is the coil and carbon pickup, 3 rd the cap and 4th is the reluctor coil. Pull and HEI out of a small block Chevy and try it they all fit. If that works the move on. To make his like new will cost 75 bucks so if you got a donor to test that the way to go. If that works then rebuild his, the parts are cheap and it a 2 hour task or rebuilt is about $125. The HEI is a real good distributor up to 5500 RPM.