The Stovebolt Site Forums The Shop Area Engine Shop Suddenly, no power!

I put a newly rebuilt carb on my '48 half ton (216, 6 volt system) recently. Checked the points, set the timing, and all was good. Last week I was enjoying a ride along the Hudson River on a great road, doing about 50, when suddenly it felt wrong. The next hill I came to was a struggle to get up. On hills I normally go up in third with plenty of power I was now downshifting to second, then first on a steeper one. I limped home and parked it. I tried to drive it today but barely made it up a very slight incline to the street. I'm not much of a mechanic. What am I looking at here? Timing? The new carb? Demons?

Recheck your points setting. May have closed up on you.🛠

All I will add is, it is not the carburetor. "Its never the carburetor." Check the points and associated ignition parts as Martin recommends.
Even if it turns out to be the carburetor, they are difficult to diagnose and taking them apart is tedious. Save that for last when troubleshooting engine problems. You need to check everything else which can cause an engine to not run right first.
I cannot tell you how many times that I have not listened to my own advice, and tore the carburetor apart for no good reason, only to end up finding that the real issue was caused by an easy to test component unrelated to the carburetor.
It will help if you can describe more specifically what the engine sound like when it fails to do what it is supposed to.
Carl

Make sure the rotor is seated on the top of the distributor, then recheck the point gap like Martin says.
Carl is right usually the carb gets the blame, you didn't use teflon tape on the fittings did you on the fuel line?

More information. When I tried to back up the driveway it bogged down and I had to let off the gas, rev it up, and try again. It took several tries. It backfired twice.

It started and idled like normal. It's when it's under load that everything goes south.

No Teflon tape anywhere on the vehicle.

Thanks to all for the advice. I'll check the points and rotor later this week, but if the rotor was off or the points closed, would it start?

As to the points... if they closed up entirely it would not run at all. If they are too far out of adjustment it will act just like you have described.🛠

Tom,
You asked about timing. I would recheck that, as well. My COE ran smooth, but seemed to be losing power, maybe not as severe as you describe. Turned out the clamp on the distributor had loosened and the timing became too advanced.
Kent

I have had points wear down due to dusty environment causing engine to peter out, easy fix when figure it out(not my vehicle).

Ed

Lightholder, I recently had to deal with a loose distributor clamp. The person who fixed it really tightened it down good. I wonder if that may have broken the clamp...

For me, sometimes it is the carb. I experienced fuel starvation at speed going up hills. Found the small filters inside the carb and the main fuel filter clogged from bad gas I picked up on a road trip. The car would buck and sputter. Engine would ‘catch up’ on down side of hill.

"It's never the carb"....well, except when it is.

I had a Rochester recently that I was not aware that the choke spring was broken, which allowed the choke flap to slowly close while I was driving the truck. One minute I would be driving along, and the next, my power was cut by 75% and it was puffing a little black smoke out of the tailpipe.

Of course, as many here will say, running a proper test and diagnosis is key, but never rule out the carburetor.

I checked the points and they weren't closed. They were a bit open, so I reset them to .18. It ran very slightly better, but still way low on power. The clamp holding the distributor is tight, so it hasn't moved.

The good news is that I found a great shop near my house that works on old vehicles, so I'm taking it there next week. I'll report back on what they find.

Again, thanks for all your inputs!

Tom, we would really appreciate the follow up report. It will certainly help those with the same problem in the future. Thanks

So sidetrack slightly from this thread, but I did read a comment that was interesting.

Are you not supposed to use teflon tape on the fuel line threads? I believe I used some when I put my new fuel pump on last year. If that is not smart, I may go back and scrub it off.

And yes Tom, please follow up, we'd like to hear what the diagnosis was.

Teflon tape is just fine as long as you are careful when you wrap it not to get any close to the actual movement of fuel. It will break down and foul up the tiny passages in the carburetor. Others will say never ever use it. It’s your choice.🛠

I once experienced problems similar to yours, loss of power, would not pull up any incline, backfiring, bucking etc. However it would idle fine. Had to tow it home. Turned out to be rust/sediment in the tank, that had moved into the entire fuel line, filter and carburetor. Water in gas would probably do the same. Try a little fuel dry treatment first.

Otherwise known as alcohol.

Ed

Update: The shop didn't take the truck in until last week, but although I don't have it back yet - due to some other work I'm having done (gas gauge and bleeding brakes) - here's what they said about the engine. The timing was way off and the valves way out of adjustment. It was overheating because of a bad thermostat. (They put in a 195 degree thermostat. I'm not so sure that's what the truck needs, though. I had a 180 in it and it ran fine until two weeks ago with the needle right in the middle of the gauge.) Anyway, he says the truck is running great and strong on the hills.

The guy working on the truck seems to really like it. Maybe I can sell it to him. With my poor mechanical abilities and my father having passed a few years back (he was a '50's era mechanic), it's probably time for me to pass the truck on to a new owner.