View Full Version : Is this the strange or normal?

11-11-04, 12:31 PM
Sometimes then I start up my car, a '79 coupe, it starts running at like 150-200 rpms, and the whole car shakes badly as it does this. If I put my foot on the gas then is begins to rev up slowly, but not in relation to how far down the pedal is. As it revs up the car shakes worse and worse until about 2500rpm when the car begins to run normally. Then I let of the gas and it idles normally. I have no idea what the heck is going on? Could it be the ignition system, carb? Another thing it does is when I gun it around 25mph it pulls like hell, then begins to fire slowly and unevenly like its getting too much gas, or not enough spark. It usually happens around 2000rpm and continues untill I let off the gas. Could the carb be feeding too much gas? Those two things have me completely stumped about what I should do. It usally has nothing to do with how cold or hot the engine is. Any ideas?

11-11-04, 01:32 PM
It sounds like a timing issue, or a bad/dirty carb. Ie, it's sticking, and just not working quite right. But no, that stuff is not normal.

Night Wolf
11-11-04, 02:01 PM
nothing like that happens with my '79...

she starts right up, on a cold morning, it'll idel around 1100rpm or so, then I kick it down to 600.... on a warm start up it idles at 600 or so....

I would also say timing/ignition/carb....

11-11-04, 02:45 PM
When was the last time you changed the spark plugs and stuff? Carberators can cause problems like that when they aren't adjusted properly or they need to be rebuilt too.

11-11-04, 03:30 PM
Choke maby? it doesn't matter if its hot or cold it always starts like that? then I would say carb and plugs a good test is to pull one of the plugs and see how it looks if you've got one of the chiltons manuels for you car then it should have a chart with pictures and explanations of what the problem is by the way the plug looks

barge master
11-11-04, 07:36 PM
That thing sounds like it needs a serious carb rehab. The low rpm and shaking to rev up sounds like a choke pull off not opening the choke.

11-11-04, 07:46 PM

Since you say this "sometimes" happens, I would be inclined to think it is carb related, but I have seen similar problems described with bad wires and/or plugs.
Running at 150-200 RPM will shake any engine. Do you actually have a tach indicating that low of an RPM reading, or are you just guessing?

With the engine shaking through the RPM range to 2500, I'm thinking it is more electrical than carb related. The bad wires/plugs would be more consistent though. If you're goning to throw some parts at it, before taking it to a shop, I'd start with the plugs, then wires. I don't know this engine very well, but how about the dist.?

11-11-04, 07:56 PM
That thing sounds like it needs a serious carb rehab. The low rpm and shaking to rev up sounds like a choke pull off not opening the choke.

I'm saying carb issues, you probably see a lot of black stuff coming out of the exhaust. Sounds like its time for a carb rebuild. the thing is its hard to find someone nowadays that knows how to correctly adjust the carb once its reinstalled. If you got someone then your go to go!

11-11-04, 10:58 PM
Ok, I do have a tach to see what its doing, I just rebuilt the carb, so that should be okay. It also did it when I had an alternate carb on there so its probably ignition. The timing is fine, I just timed it myself with a light. I have a 45,000 volt HEI coil, but I have OE replacement wires. The spark plugs are brand new. Would wires be the culprit of this? The wires really arent that old, maybe 600 miles on em at the most. The choke pull off is brand new. I'll check the timing again just to make sure but it shouldn't have moved. It shakes on the startup only occassionally. Once, I pulled into a gas station and got a drink. When I went back out the car wouldn't start. It didn't seem

11-13-04, 06:50 PM
try timing the engine at different rpm's. it may be a problem with the pistons not keeping up with the ignition, and then catching up when it's moving faster. maybe someone who knows more can elaberate further.

11-18-04, 06:45 PM
Usually what happens is I turn the engine over, it does a quick crank, then it stops. I try to turn it over again and it wont run. I tried to give it more and more gas, and usually that'll get it started. Just now it did that, but it didn't start. I cranked it over for like 30 seconds in 10 secon incriments. Finally I saw a flash on the ground and realized flames where coming out of the cat, big flames(I have no muffler). This got me to come in here and type this. An awful bunch of fumes started coming from the engine. Like gas but with a mustard, spicy odor. It made me leave. I have no idea what that was. I just dont know what it could be. Usually after I get her cranking over and up to speed the problem doesnt persist. HELP! PLEASE, FOR THE LOVE OF GOD ITS DRIVING ME CRAZY!

11-18-04, 07:07 PM
Oh another thing, could it just be flooded?

barge master
11-18-04, 07:52 PM
Man 7.0, I hate to sound like a broken record, but are you SURE that timing chain hasn't jumped? That smell is probably carbon incinerating from improper combustion. If the problem is still there with a different carb it's probably safe to assume the problem is ignition/timing or possibly valve related.

Check carefully under the dist. cap for cracks or carbon tracks. While you have it off, put a socket on the crankshaft nut and turn it in either direction till you see the rotor turn. Then turn it slowly in the opposite direction and note how far the crank rotates before the rotor starts to turn.
Obviously a new chain will be tight enough to turn it almost immediatly. If you can turn the crank more than 15-20 degrees the chain is probably worn enough to have jumped a tooth at least. I'm just throwing out that 15-20 figure, I don't actually measure it, I just know too much when I see it.

Now that I think of it, while the cap is off, look carefully at the wires going to the module and pick-up. There is a wire, usually green, that tended to break from movement of the breaker plate.
Try this stuff and let me know what you find. If this doesn't get you anywhere, it will be time to do compression tests and hook up a vacuum gauge. More on that later. Check that chain lash dammit! :banghead2
Good luck!!

11-18-04, 09:50 PM
'preciate it barge master. You've been very helpful. I will definately look into the timing chain thing. This time it was simple flooding. But there is no reason it should be flooded. If I turn over the engine for less that a second, the engine shouldn't get flooded. That doesn't make sense to me. I think the slow working up from 200 rpms is due to the fact that the gas can only burn so much at a time, therefore untill it unfloods itself by burning the excess fuel off it'll only rev very slowly. I dont know what could cause this from a little turn of the key. Maybe the fuel pump needs replacement, it could be gulping odd amounts of fuel down the carb during startup. I dunno. Its all very confusing for a flooded engine. I ended up taking off the carb. and emptying her out. Finally that got her started. There was a puddle of gas inside the intake manifold that I cleaned out too. Thanks again.

barge master
11-19-04, 06:17 AM
The symptoms you're describing do sound like an overdose of fuel, either from a carb problem or an improper combustion problem due to..... Have you changed the fuel pump since you put it on the road? I ask because I had put a new Federal-Mogul fuel pump on my 89 in the spring and the thing was flooding so bad the car would barely run. That pump was to replace the previous one which lasted 6 weeks. I finally got an AC-Delco and all is well. You might want to idle it with the air cleaner off to look for flooding. If your engine has an EGR, try plugging the hose and take it for a run. I doubt that's it, but it will eliminate it as a possibility.
These kind of things make me wish I was there to look at it myself. I kind of enjoy these brain teasers guys have posted, but a situation like yours gets hard to diagnose without seeing it.
Just remember to be patient and systematic. A lot of times you have to check a lot of dead end leads to find a problem, even if you're skilled and the car is right in front of you. People don't always understand that, they think mechanics have magic powers and are just trying to rip them off.

11-23-04, 06:17 PM
I know the timing is fine. Its at 23degrees@1600. I have a tach and a timing light so I know its fine. I checked it yesterday. I'll look into replacing the fuel pump though. The one I have on there is original, and although the car has fairly low miles it might be the problem. Timing chains are cheap and simple to replace so I might as well do that too. I am most likely going to sell my caddy soon :( so I can but an 85 chevy longbed with a 350. Therefore, I don't want to invest too much money into her before I sell her. If the problem is deeply rooted I'll let the new owners deal with it.

barge master
11-24-04, 07:04 AM
That's too bad you're gonna get rid of it. You might find someone on the forum who wants it. I'm sure the problem is fixable with a little investigation. :(