[oldguy829]

This problem comes and goes.
Only does it about once every 3 or 4 days.
Usually when accelerating around 30 miles and hour. Once or twice from a dead stop. Once just cruising along. Yesterday at about 10 miles an hour when making a U turn.
Bogs as if it is runinng out of gas. One or two seconds and everything is back to normal. I can't get it to do it on purpose.
It's a caddy 500, stock intake, Quadrajet. I'm fairly sure it is fuel, not electrical, but I'm open to suggestions.

 

[saitek5678]

saitek5678

Replace the fuel filter, this probably won't fix your problem but, do it anyway, unless you have already. Check for vacuum leaks,listen for a hissing sound, does the car idle good? If the car idles good and no vacuum leaks, I would say carb overhaul, about 400 bucks where I live. Have the Plugs , Cap,wires and Rotor been changed latley?

 

[oldguy829]

intermittant bog

Plugs, wires, cap and rotor are new. Idles pretty good. some days it seems to be a little bit rough.
No obvious leaks, but I'll check again. Fuel filter is a good idea, just in case. I hadn't thought about the spark advance. I'll check all that.
Frustrating to work on a car thats running good. Which it is everytime I pull it in the shop.
Thanks for the tips.

 

[carsavvycook]

Another thing to check, would be the fuel supply hoses for cracking.

I am thinking under a light torque, a cracked fuel supply hose could be sucking some air, and dropping your fuel pressure, and volume.

 

[saitek5678]

saitek5678

What year is it? If it has electronic ignition I would not worry about spark advance or "ignition timing". It has been out of date for decades to "check the timing" although shops would say they would do it to make a buck. Don't get me wrong, the timing has to be right but once set it will never change unless someone messes with it even then the engine computer will compensate

 

[saitek5678]

saitek5678

How many miles? I was thinking you may have a worn out distributer + timing chain and gears, one way to check is to take off the distributer cap and manualy turn the crank back and forth. Does the dist move according? if not replace the timing chain and gears.

 

[oldguy829]

intermittant bog

Sorry, It's an early caddy 500, mid 70's I think. Supposed to be rebuilt. Compression is consistant at 160 lbs. Has a clean, new looking HEI dizzy. Pulled vacuum on it and the advance seems to be working properly. Book calls for +8* timing. It is a lot stronger at 10*. Timing light shows no variations (like you get with a slack timing chain).
fuel filter was a little crapped up so I replaced it. Test drive was perfect. couldn't get it to bog any which way.... which means nothing. Lets see how it goes.

 

[oldguy829]

intermittant bog

Thought I would close this out. It always bugs me to follow a thread and never find out what the cure was.
This gets a little long, so bear with me.
Still had the intermittant bog, nothing helped. One day it wouldn't start. Dead battery. Charged it up, battery checked good. Charging system checked good. Then the fans kicked on. Turns out the new fans pulled so much juice the alt couldn't keep up at idle. It was a 10SI, about 65 amps, but only 30 at idle, It was slowly discharging in heavy traffic.
It has an idiot light, sure enough, in a darkened shop it had a faint glow. Never saw it while driving.
Installed a 12 SI alternator (97 amps, about 60 at idle) The difference was instant. Could I actually feel a performance boost?
I now believe the alt output was so marginal that in specific situations, it just starved the ignition. Have had the new alt over 6 weeks. Have not had a bog at all.
Anyone else heard of this? Or is it all a coincidence?

 

[Argess]

I had that happen once, but it was a slipping fan belt. It would only slip when a lot more current than normal was required. So one day, on the highway, in the rain, with lights on and wipers running, car started to misfire after a few hours. Of course I pulled over to check things out. Bad msitake. Got back in and found battery was dead. Moral of story: Always stop at the top of a hill so you can jump-start your engine if battery is weak.

You dont' suppose your alternator was OK, but you had a v-belt varnished up and slipping? Oh well.....all is good now.

 

[oldguy829]

bog

Argess, no the alternator checked out bad. Thanks for the confirmation. I guess I thought it would run till the battery died and then quit. Had no idea it could run crappy, but keep going. In my case I didn't notice the correlation between when it acted up and when electrical draw was high.