Help diagnosing engine trouble

[Sturube]

I think I have a problem...the other night on the way home, the engine was hesitating a little at the stoplight, just a little stutter. Once up to 30 mph it seemed fine, until about 1/4 mile from home when it lost power. I managed to limp home goosing the pedal and shifting between 2 and 3 (stock 3 sp auto) and parked on the street. In neutral it was idling rough, and there was a burnt rubber or oil smell, making me think maybe tranny?
Anyhow, just went out to start it this AM, and it's running very rough like the choke's not working. I checked all the obvious - fluid levels OK, no vac lines off, but am not sure where to go from here.

Haven't had any problems before this, oil pressure dash gage was reading low and never got around to verifying whether it was OK, but otherwise nothing. It's a stock 302, about 80K on last rebuild I think.

Anything I can check without doing more harm than good, and with it parked on the street, I can't tear too far into it. Would it help to get a pressure gage and do a cylinder check?

Thanks for any input...

 

[raharr3]

Check your wires and vacuum lines. I just figured I would take a quick stab at it for ya. The only reason I think wires or vaccum lines is because of the smell you talked about.

 

[74bronc]

Do you have stock points or electronic ignition. This is a common symptom of points going south or the ignition module that decided to die on you. I would start there, after checking for obvious stuff like enough fuel getting to the engine

 

[dpmerrill]

It sounds like points to me as well. If you have points, make sure they are opening when the engine is cranked over.

Also, while you're in there make sure you can't turn the distributor by hand. I had a car that had the clamp bolt work loose, and it acted the same way.

 

[Bronco Ben]

is it possible your dist is loose? check that for one, and check and make sure you alt. is putting out, did the lights work well when it started all this?....other than what these other guys say, thats the only thing I can think of right off!
good luck
Ben

 

[Sturube]

Thanks for the input. I just today have had another chance to take a look and it doesn't seem good. No burnt wires, no missing or loose parts - dist is tight, etc. It still fires but runs really rough, and it is very noisy on the driver side, not quite what I'd call knocking, but don't know what to compare it to. Not sure if this is enough info for anyone to go by, but does it still sound like an ignition problem or something worse?

What do you think I should do next - compression test?

Thanks again for your help!

 

[a67and77]

Kind of sounds like what happend to me to the other day. I was driving around and then all of a sudden the problems you are having. Turns out one of my spark plug wires came apart and was sparking at the boot near the plug. made kind of a knocking sound and ran like shi#. Also had one of my plugs loose making the same kind of noise.

 

[SteveL]

66 and 77 hit my answer. i was gonna ask if a plug wire got fried on the exhaust. That would answer the smell and bad running.

 

[Sturube]

OK, finally had a chance to get back into it. I changed the plugs, it still turns over but sounds and runs awful. I checked the resistance on all of the plug wires and all are about the same. There's some discoloration on the porcelain - is that normal or a sign of arcing at the boot?
Tomorrow i plan on taking the dist cap off for inspection (electronic ignition) - any input as to what to look for or at next?
I hate having a non-running Bronco...

 

[67EB_in_619]

triple check your wires... checking resistance wont help if your problem is the shielding is letting the spark arc out...

You said it sounds worse on the left.. so one by one.. pull and replace the plug wires and see if it makes a difference.. if you hit one that doesnt make a difference, then whammo.. bad wire/plug/something in that cyl.

 

[feitctaj]

Try running the rig at night in the dark, preferably in the garage with the lights off. You may have what I had , a cracked porcelen. it was arcing to the head and acting just like yours is

 

[SaddleUp]

Also mentioned above. Don't leave out the obvious. Maybe the smell was a concidence and it is actuallu a fuel supply problem. Until you said you smelled something that would have been the first thing I would have checked. A plugged fuel filter would let just enough fuel through to run but would really suck when you tried to accelerate. If you can't find anything in the ignition or fuel then the timing chain could have jumped a tooth but you will want to eliminate the other stuff before diving into it that far. Also don't neglect the wiring going between the battery and the module and the coil. Could be a bare wire in there causing problems as well.

 

[74bronc]

what kind of electronic ignition is it? Is it duraspark? if so, i would change the module, just to rule it out after you have done the obvious stuff mentioned above like checking for craked spark plug insulator, arcing wire, fuel delivery etc. they are less than 20 bucks. if that isn't the problem, you have the old one for a trail spare. In the automotive repair industry, this is what we call "throwing parts at it"