The Stovebolt Site Forums The Shop Area Engine Shop Engine Bogs Down and Dies Under Load

58 Chevy with 235 Inline 6. I had driven the truck the previous 2 weekends to pick up some lumber, and it ran fine both times. Then two weeks ago I went for a third weekend trip to the lumber yard, and after backing down the driveway, I went to drive down the street and only made it about 100 yards before the engine died. It started right back up but bogged down and died again as soon as I started letting out the clutch and giving it gas. I coaxed it back to the house and up the very short driveway. The fuel pump, which I had rebuilt last fall appeared to be supplying fuel fine (thanks for the recommendation on where to go for that). It idled fine and would rev high in neutral no problem as long as I didn't smash the pedal down fast. My wife looked down the throat of the 1 Barrel Rochester carb with a bright light and said that she could see fuel squirt out when I revved the engine. The spark plugs had some dark deposits like from an engine running rich, and I replaced them. No change in the problem, possibly worse (died easier when I revved it in neutral). I don't think it was the gas, as I had used the truck the previous two weekends before this problem started, getting some gas in between those two trips. It has a pertronix ignition and doesn't sound like it is missing (other than bogging down and dieing under load), so I don't think the distributor/ignition is the problem (but what do I know?). The fuel filter, which I replaced with the fuel pump last fall, is a clear walled one and the filter material still looks pristine. Could it still be some debris in the carb reducing fuel flow and requiring a carb rebuild?

Any thoughts are appreciated.

There are two kinds of Pertronix systems- - - - - -the ones that have failed, and the ones that are going to quit soon. If you have a point-type distributor handy, it's a 15 minute swap for troubleshooting purposes. If not, it only takes a bit longer to reinstall the points, condenser, and original coil. Somebody really needs to market a roadside emergency kit which includes those bits and pieces.
Jerry

My guess is that the Rochester has a stuck power valve. Power Valve

I had the same symptoms which was the Pertronix that caused it.

Update:
I finally replaced the pertronix ignition and started up the engine. It ran a little rough, but I figured that could be due to sitting for 2 months. I drove it the few feet up the rest of the driveway and parked it behind the gate. The next day I took it out with the intention of a test drive and to pick up a new mattress and box springs. It was a bit rough when I started it, but I backed it down the driveway and it ran smooth in 1st, 2nd, and 3rd as I drove down the street headed for the store. Then as I turned onto a road at a stop sign (3rd stop of this short 2.3 mile drive), it ran fine until I shifted into 2nd. The engine bogged down and died completely. Worse than before. I coasted off to the side of the road and turned off the ignition. I decided to try to start it again and turned the ignition back on. When I hit the starter pedal, it barely turned over at all. Could it be a problem with regulator or generator? But then why would it have run fine for a couple of miles after sitting for 2 months without any recharge of the battery? The ammeter guage is broke, so I don't know what the charge/discharge status was while driving. How do I test the parts in the ignition system to try to find the problem? Could it be a carb problem and it was the time sitting not the pertronix replacement that brought it back to life until a carb problem reared its ugly head again?

One easy, quick check to see if ignition circuit or battery is to turn on the lights. If they are strong then don't need to worry about the battery/generator.

Dennis

What did you replace the Pertronix with?

Test the battery and generator with a multi-meter. Battery could have had one last start in it and was too dead to fire plugs or recharge.

Lumbergh - Just my thoughts based on your description that it ran fine for a bit, after sitting for a good while, but then bogged down/stalled after running.

This sounds more like a fuel supply loss issue than an ignition issue. It could be you have junk/debris in your tank that will naturally get drawn to the outlet of the tank and when there is enough of it, it can block your outlet screen. When the engine stops and suction on the outlet is removed, debris can drop off from the screen, temporarily restoring fuel flow until it gets drawn back when fuel flow resumes at engine restart/running.

An alternative fuel supply issue has to do with your tanks vented cap not functioning correctly. Maybe you recently replaced the tank cap with a repop (which are kinda well known not to vent properly) or your old cap vent has become clogged/obstructed. A non-venting gas cap will stop fuel flow after a period of time running as when the gas exits, air has to be allowed in to stop a vacuum from forming. With no or reduced venting, the vacuum created by the pump drawing fuel out to the engine will stop fuel from flowing to the pump/carb, starving your engine till it stalls.

The leave it for a while and it will restart/run for a bit description, sounds like the tank eventually sits long enough to allow air into the tank and temporarily remove the vacuum condition.

Perhaps an easy way to check if you have a venting problem is to release the gas cap from the tank and start/run the engine. If your engine starts/runs normally and doesn't stall/die, you've likely found the problem is your tank cap.

If that test doesn't resolve the bogging/stalling, you' ll probably need to further investigate your tank and fuel delivery system.

Temporarily (only) install a clear fuel filter, when it dies check if the filter is empty.

RonR

Don’t underestimate the issues with the current batteries. Batteries tested by a multimeter may read good 12.7 volts but as soon at you apply a load, they fail. This has fooled me more that I want to admit. Have someone read the meter when you hit the starter.

My latest failure was on my jetski, and my battery less than two years old, tested @12.7 volts. I tried to jump start it with a booster and the starter wouldn’t turn over. I went as far as removing the starter which isn’t an easy task only to find that the battery was bad. Two hours of work that wasn’t needed.

Get the battery tested!