Little help diagnosing stumble? UPDATE: Fixed w/ New Dist.

[dremu]

Feels like the battery going dead, my headlights and dash lights dim out almost completely and the starter feels like its struggling hard to turn the engine, but once it manages to rotate the crank once or twice it starts right up. I just noticed a little bit of corrosion on the battery cables near the terminals too, gonna have to investigate.

Bolded for truth. Corroded cables can drive you nuts; I had a truck that wouldn't start at all. Dome light came on, dash lit up ... until I turned the keyd it, and then the lights all went dead (and the solenoid wouldn't even click.) Wait a couple hours, the lights would come back on. The battery negative terminal was corroded enough that it would pass a slight amount of current for the dome/dash lights, but as soon as you tried to pull a heavy current through, it would heat up and block the connection. Cleaned and tightened the connection and voila, it runs fine.

Anyway, yeah, make sure your grounds are good, though if the lights are dimming there's definitely current getting to the starter. Might check the battery under load, too, and watch the alternator voltage for under/over, just to be sure.

-- A

 

[diesel4me]

I've had cables that look perfect not pass enough current under heavy loads like cranking a cold engine fisrt thing in the morning--or one thats hot and heat soaked a few minutes after a short stop...the stock GM cables are sometimes aluminum & copper combos and not pure copper,and I have replaced many with 2 or 1 gauge copper cables and noticed a big difference from the decades old originals...faster cranking,no "hesitation" and fighting to get past the compression stroke and brighter headlamps too....after buying bigger new battery and a high torque starter didn't help--I was told a hi-torque starter needs a large battery with more plates to work right and I believe it...along with good cables to get those amps TO the starter.......................................................................................................................................................................................................The 400 small block I had in my '77 GMC always cranked over hard after you shut it off and let it sit a few minutes,like when you stop for coffee or a burger..had to either wait until it cooled some,then it would spin over normally--or risk killing the battery...I tried a new starter,heat sheild and finally a battery,still did the same dam thing...I wondered of a head gasket was going in it ,and letting coolant seep in just enough to hydro-lock it some,as it sometimes blew some smoke after it started --after I replaced both cables with thick welding cable and new terminals it stopped doing the grunt and groan routine.........................................................................................................................................................................................................I thought maybe the timing was to blame ,I did get it to start easier before replacing things by swapping the vacuum advance to manifold vacuum (which I thought would make it worse,not better,because instantly it would get even more advance and tend to kick back more if anything--but it helped!)....a trick I found that let it start most every time if it was binding and grunting,was to leave my key off and crank it over with the push button (my anti-theft discount device to get 10% off car insurance ) and after it spun over normally I'd turn the key on--saw that trick at a speedway,when high compression engines with lots of advance wont spin over well from a "dead stop" if they had spark...