crazymjb

For the past 6 or so months my truck has been taking a few more cranks than it should to start. When it finally does I see a faint trace of black in the exhaust for about 4-5 seconds and the mixture smells rich. No CEL and it seems to run fine after that.

The truck is 1996, OBDII, and has a manifold injected 350 small block. Any guesses? It has an automatically adjusting distributed ignition.

Thanks guys,

Mike

Will Y.

First thought is to check it for a weak/dying battery.

The extra cranking time results in more fuel being dumped into the engine before ignition > unburned fuel through the exhaust.

csmeance

black smoke is an indication of oil burning, i think. How many miles on this beast and what grade of gas is used? if anything lower than 93, put sme seafoam in the gas tank, the oil (500 miles before oil change is due) and if you want, some in the vacuum intake line. This will clean up all the gunk and carbon buildup that robs gas mileage, performance and reliability. Check the battery and the spark plugs to make sure that they are in good condition as well.

GreenMonster

Black in fuel, blue is oil...

Excessive cranking can be traced to a weakening battery, timing being off, or just from the engine getting tired (slight loss of compression over time).

If it's the battery, you'll find that out quick enough once it gets cold here come november/december. One morning the truck just won't start. I guess you could try jumping it with another car, and if she fires right up, you know the battery is getting weak.

With new fangled electronics, I don't know if you check the timing with a timing light anymore. Most of you people won't know what a dwell meter for checking the point either

You can do a compression check on the engine (remove spark plugs and use compression tester). I'm not sure what "good" compression is on your motor (I don't recall if you have the 5.0L or 5.7L in that truck).

crazymjb

Black smoke (and the smell) is an indication that it is fuel. I thought it was possible that it was a weak battery but being cheap I figured I would wait until it doesn't start. Also, on occasion it starts right up. I suppose I will give the jumping while starting a few tries just to look for a difference. The alternator is relativly new as is the battery. The engine only has about 90K on it now. My friend is looking at a similar truck with 160K on the engine and she starts right up.

I will try running some seafoam through it and report back. Where can this stuff be purchased?

Also, sometimes on the highway, very rarely, I will give it more gas and it will start to rumble as if the mixture just took a shit, and I will have to let off on and hit the gas pedal again.

Lets see... So far the following has happened 3 times, I will go to start it and it will make a really loud slam and run rough for 15 or so seconds.

I have the 350 (5.7L) Vortec engine, these things are supposed to be relatively bulletproof, however the factory engine had an apparent manufacturing defect the previous owner(mechanic) found, thus forcing them to replace the engine under warranty (they wanted to repair it but I guess he offered to meet them half way).

Mike

SiGGy

Battery: Take it to advanced auto parts and have it stress tested, do not wait for winter :duh

Compression check: you compare the compression of all of the cyl(s) they should all be similar to one another within 5-10%.... you don't have to know specifics.

I'd check the fuel pressure (pump), injectors, fuel filter, ignition (coil packs) and pickups, and O2 sensors.

p.s.

It's a dwell/tach/meter but no cars use points anymore as you know; but the meter still has it's uses. And yes you can still use a light it just won't do you much good on new vehicles as the computer sets the timing But it would tell you what's going on at least.