Dead Reckon

Alright, I guess this goes in "Engine"? I don't really know.

So my problem is this, sometimes the car does not want to start, or idle, it's fine after a little bit, takes longer when it's cold, my guess is the carburetor. What it does is, and this depends on how cold it is outside, but, when I try to pull off without the car being warmed up, it will sputter, even stall completely, just bog right out, it does not want to move. Furthermore, when this happens, I often get a red "BRAKE" light on the dash as though the parking brake is set, but the parking brake has nothing to do with it. Pumping the brake pedal makes this light go off for a while. Also, when it acts this way, it does not like to shift properly, sometimes it won't shift out of park for up too 15 seconds, and sometimes it won't shift between gears right, it isn't rough, it's just a delayed shift. Lastly, the car will often sputter, sometimes even stall when coming to a stop, regardless of the temperature of the engine or temperature outside.

So, is it my carburetor causing all this headache? Is it a vacuum leak somewhere? Both? A fustercluck of both issues combining into a larger issue? I have no idea where to start, but I'm hoping y'all could help. It's causing my fuel mileage to really take a nose dive when this happens, not including the times I've had to idle the car for 5 minutes just so I could get to work in the morning without stalling in an intersection.

To clarify, the red brake light comes on while the car is operational, engine running, seemingly fine sometimes, it's random as far as I can tell, but it happens even more when the car acts up.

A few details about my car

I have a GM Goodwrench base 195HP 350, with the original 1977 Q-jet with who knows how many miles on it. The transmission may have been rebuild, it's clean looking. The distributor cap, and rotor, as well as plug wires and plugs are new. I replaced the PCV, and that helped a lot with the idle when it's cold. This car has had many owners who have done quite a bit of work too it.

If you can help, I'd appreciate it, I need to sort this out, but it's such a wide range of issues that seem to be stemming from a single source, but I don't see how the carburetor could cause this many issues. But hey, it's a $650 car, I'm still chasing out gremlins, so, please help me exercise a few more gremlins from this car, thanks.

Gary M

Nice looking ride. You are on the right site. Don't get discouraged because these issues are probably small adjustment fixes. Other more experienced members will chime in.

MDchanic

Carb sounds like a good candidate, but don;t rule out an ignition problem, such as a bad HEI module.

First, though, I'd recommend rebuilding the carburetor and verifying that all of the vacuum hoses are intact and properly connected.

- Eric

turbobill

I had an Isuzu diesel once that when vacuum was lost to the power brake booster, the brake light would come on. I've never known an Oldsmobile (or any other American built car) to do this however.

That being said, one possible cause of a large vacuum leak is the power brake booster and/or the large vacuum line going to it (including the check valve on the booster where the line connects) from the intake manifold or base of the carburetor. Other vacuum leaks, mixture leaness, and retarded timing/inoperable vacuum advance are all causes of the syptoms you describe.

Speaking of vacuum leaks, I now have a 307 that has a vacuum leak at the intake manifold gasket. My problem is cold bloodedness and a high idle when warm.

Dead Reckon

Nah, no discouragement here, I bought the car knowing full well it has issues, but I also know when I'm in over my head.



Could you explain how a bad HEI module could cause this?



That's interesting to know, although you probably realize this, I should point out that GM and Isuzu have a long standing relationship, I see those Isuzu Chevy re-branded captive import cab over city trucks from time to time. So it's not surprising if some features move over. I do know there is an all together different light on the 80's B bodies that is orange with the word "BRAKE" on it. As in, your brakes have failed, it happened when my front brakes disintegrated on my '86 Custom Cruiser.

MDchanic

A bad HEI can deliver an intermittently bad spark that can get better or worse as the unit warms up and can cause rough running and poor power.

- Eric

RROLDSX

If I were you I'd buy this diagnosis manual. It will be more than helpful and is very step by step.

http://www.ebay.com/itm/78-GM-Diagno...366155&vxp=mtr

MDchanic

+1. That manual could be a big help for a late-'70s car.



- Eric

Dead Reckon

Damn! If only I didn't have to spend $45 on a alternator today, my car budget has been blown lately. That was gas money, a lot of it, I can run that car on a month for $50 worth of gas. Hundreds of miles... So yeah, my alternator had been flaky, dim lights, varying voltage when using the heater or air con with the lights on, ect. Put on another reman today 'cause this one had a bad diode, so that's fixed...

I'll check into that manual though. Thanks a lot, would be useful to have.


EDIT:

Even after the $45 chunk out of my wallet, I decided to go ahead and buy one for $9.99 and free shipping on buy it now, same manual, slightly better shape, no grease stains (yet). I hope this helps me solve my brake problem.

RROLDSX

Which issue did you get? Hopefully it covers to at least 1978. If it does I'm sure it will be very helpful. I received mine from a GM employee and it was the fifth edition covering cars from the 70's to early 80's. It should easily pay for itself. Good luck.

Dead Reckon

It's similar to the '78 year model manual MD found, but it's a '77 year model manual, so there are a few differences. I'm not sure if it has the answers I need, but it might fix some other issues I have. At the very least it should give me a better understanding of the brake and vacuum system so that I can start narrowing things down.

MDchanic

Hey, for ten bucks you can't go wrong.

- Eric

Professur

There's no copy of that on Wild?

Dead Reckon

No copy of the book on what? By the way, after I've received the book I can scan it and make it into a PDF if anyone else needs it.

MDchanic

WildAboutCars.

They have a wide selection of manuals to download for free, but they don't have any of these.

Kurt may be interested in getting a copy from you to post. You might drop him a line (I don't have his screen name at my fingertips here at work).

- Eric

RROLDSX

You'll be scanning till the cows come home. I'd scan a later copy. Like I said, my fifth edition covers the 70's through 1983. I don't know of versions after that. I've had this one i n the cupboard for 30 years and completely forgot about it until recently.

Dead Reckon

I've found out that, according too the manual, my brake issue is likely the combination valve, a part which lives on the inside of the frame just behind the front drivers side wheel. I cannot find a replacement part, but explains the constant "BRAKE" light on the dashboard, and the sometimes mushy or grabby brakes.

As for the rest, I have yet to diagnose that.

Dead Reckon

After spending quite a lot of time under the hood checking hoses, I found out that the vacuum advance hose was not hooked up, it was snagged so when I pulled on it, it seemed hooked up. I think I'm getting over 20MPG now.

So yeah, somewhat of a rookie here, but, I found it.. It just took a little while.

oldcutlass

Glad you found it and back in the saddle again.