Engine cuts then coughs and hacks before running again

I suspect a carb issue but I'm just not sure. I don't have the issue at idle or when I rev the engine in my shop. But on the road after about 5 minutes it cuts off then on, like a phantom flipping a switch back and forth. Clutch in it quickly drops to idle, but as soon as I press the accelerator it coughs and hacks, or does nothing. After a few seconds, sometimes about a minute, it comes back and I can get back up to speed. 5 minutes later: repeat.

I've checked the distributor and all wiring and everything seems ok. I put nearly a can of carb cleaner in the file bowl and let it sit for a couple of minutes before starting. It idles and revs ok in the shop, but every 5 mins or so on the road it repeats.

I've also refueled and put a can of seafoam in the tank.

In terms of use, I run her for an hour or two a week, usually on weekends. Always at about 50 mph in 3rd along a couple safe routes in the county (wide shoulders). Recently I spent lots of time (about 6 weeks) at idle trying to repair the alternator, which now works, but there was no driving during that time. Before that work she ran fine, shortly after I got back on the road my problems started, but not immediately.

Other work I've been doing is electrical, replaced switches and gauges and grounded everything properly on the dash.

Is it time to take it to my mechanic?

Regards,
Tim

 

make sure timing is set correctly and that the advance is working at higher RPM. Change points or at least run some fine emory paper between the contacts. Change plugs. Pay special attention to the plugs and their color then gap them correctly. look up what they should look like on a proper running engine. get a vacuum gauge and look up proper tuning using one. it will tell you a to about the condition of your engine if you read and watch the tutorials.

If it were me i would buy new cap, rotor, points, condenser, plug wires and plugs and install them all using FSM or doing a lot of searching here and the Buick sites.. I would then check and set timing correctly. I would then disassemble, clean and rebuild carb and then set with a vacuum gauge. I like this stuff a lot though.

 

I am thinking fuel filter or pump . crack in fuel hose . the garage test is see how much gas it can put in a coffee can . cranking (no start). and with what gas is in carburetor (running) ."must use caution when dealing with gas" , running out of gas above idle . when idling you said it runs good . low flow

 

:iagree: Is it worse under sustained load, uphill, etc? Change the filter, and blow out the line back to the tank, it may be crud at the tank end.

 

Don't forget that fuel filter in the top of the carb.

 

I hate working with fuel...but all the above makes sense, one thing at a time.

Regards,
Tim

 

I had that same issue a few years back. I removed the fuel filter from the carb top and just put in a large in-line filter in the fuel hose between the pump and the carb inlet. No problem since that change.

 

I've got 2 (3?) filters for fuel:
1) in the tank at the siphon end
2) on front of engine between pump and carb
3) ? In carb or right front of carb where fuel line enters carb?

I'll start at the carb and work backward. My reasoning is the clear filter can (2) always has fuel in it.

Regards,
Tim

 

I think in the tank the stock set up is just a screen. Need to look at the FSM. You might want to pull the tank just to check for contaminants or water anyway.

 

I removed the fuel line from the carb and the filter there had some dirt in it, but not enough to clog things.

I then removed the fuel line from the carb to the filter down at the pump. It must be the original as the rubber portion was near closed on the inside. That could definitely restrict fuel flow. While at it I removed the fuel pump and cleaned it, blew air through the fuel lines and then removed the tank.

I filtered all the fuel and no debris in the tank. While that was out I re calibrated my fuel sender to the gauge.

Tomorrow i'll put it back together with new rubber fuel lines, a new filter and a new gasket on the pump.

Regards,
Tim

 

Bad batch of gas? Or maybe water in the fuel tank from condensation.

When that happened to me, it turned out to be the fuel pump getting ready to quit.

 

Yes, even if that doesn't fix the issue, you can sleep better knowing all is good in those places.

 

All is back together but now it won't start. Acts like fuel starvation; a shot of starter fluid and she turns over but won't run for more than a few seconds. How long should I crank it to get fuel to the carb? I cranked for a few minutes.

if the answer is, "as long as it takes" I'd like an idea how long that can be. Should I have spare battery?

Regards,
Tim

 

What is the fuel pressure coming out of the pump? Have you done a volume test? Unplug the coil wire. Pull the fuel line from the carb and stick it in quart jar. Have someone turn the motor over with the key. You should see a good squirts and have about a pint in 8 seconds.