Technical 1946 59AB - Intermittent Stumbling Under Load

So, I have been dealing with an intermittent problem with my 46 Super Deluxe Coupe. Acting like it is running out of fuel. This happens when cold or hot, and with the electronic fuel pump on or off, and seems (i think its my imagination) to occur a lot when I'm going up a hill. Typically, this only occurs in 2nd or 3rd gear. And will, all of a sudden, either shut down, or sputter, even if I put it in neutral and rev the accelerator, it will be difficult to keep alive. I have replaced the gas tank. and all filters (there are three, one in front of the electronic fuel pump, one before the mechanical fuel pump, and one in the pump bowl. I just had the carburetor rebuilt. I also replaced the coil with a rebuilt Ford coil that looks stock but has modern innerds. The car had the same issue with the previous modern 6 v coil. The car starts when cold and idles perfectly. Only under load will this issue occur. Also, when I rev the accelerator when idling, I get a slight hesitation (which is why I had the carb rebuilt). Most times I can keep it running and it stumbles through whatever is going on, and then it will run fine again. Last night it quit on me in the middle of a local highway and it wouldn't not turn over. I let it sit for about 5 minutes and it started up and drove home OK, albeit still with the hesitation when goosing the gas. I thought about vapor lock, but this can happen after only 2-3 minutes of driving. It really is intermittent and I cannot think of a comon scenario that is "causing" it. I've been over this forum and others reading others with similiar, but not quite exact tales of woe, and I am wondering if the great minds here can give me a perspective. I have thought about the distributor, mine is a non-crab style, and is a real pain to try to get the cap off. Is this the vacuum brake? Is it the condenser? Vacuum leak? Should I try a pertronix for the distributor? ANY help is greatly appreciated.
Thanks!

 

Direct replacement tank? I’d be getting rid of the filters before pump, why 2? With a new tank things should be pretty clean, one pump, either the electric or the mechanical then a filter before carb, sounds like you may have other issues as well but sort one thing at a time

 

All of your thoughts (excluding Pertonix) is where I would start.

 

Do you still get the hesitation from idle when accelerating now that the carb has been rebuilt? Are you running a regulator after your electric pump?

Converting from the round style 59A cap to the crab style is simple and pretty cheap. When I did mine it was only a couple hours work and most of that was stripping and crimping the new plug wires.

 

This is just what came with the car. Tank was a Drake direct replacement. I plan to remove the filter before the fuel pump and the screen filter on the firewall. My guess is that the previous owner thought that tank debris was the culprit for the stumbling. Can't say I didn't think that too. There was a ton of crud in the mechanical fuel pump filter.

 

I'm not sure on the regulator. But I have had the same issue when running with the electric pump on as well as off. There is a half second when I press the gas quickly where there is a short delay in the motor response, but not every time. Just wondering if I should replace the entire distributor.

 

If you want the easy to use crab cap, all you need to switch is the cap, rotor, and the two spring clips. I would guess the old wires might be usable, but now is a great time to replace them too. While you have the distributor on the bench to switch the stuff, check the points for wear, corrosion, or pitting. Every old car owner should own a point file. Buy one and lightly drag it between the contacts to remove any schmutz.

 

The condenser would be number one on my list. I’ve seen them do some strange things.

 

Too many filters? The electric pump needs to be as close to the tank as possible. No filter on the suction side. These pumps are good for producing pressure but have lousy suction. The only filter I would use is one between the mechanical pump and the carb. If the pump has a sediment bowl, this is normally all you need if the system is fairly clean. Have you blown out the gas line from the mechanical pump to the electric pump? Disconnect the line from both pumps and blow back with strong compressed air. Then the line from that pump to the tank. Don't put pressure through the pumps. Are you using the original sender/pickup? It could be a clogged screen on the pickup tube? If all this checks out and fuel pressure is good, look for a sticking or leaking float. After that, it's probably an ignition issue. Coil break down, bad condenser, etc.

 

You are looking at fuel, but it could be ignition. It would be real nice if you could find someone with an ignition scope so you can see what the ignition system is doing. That way you can verify that the system is good or bad and identify the bad parts (no parts cannon).

 

Points and condenser is where I would start.

 

I'm with a couple other guys. Condensor. Years ago I had a 59ab in my '39 coupe. It would start and idle but wouldn't rev up. New condensor fixed it.

Dave

 

Thanks!
Points and Condenser ordered. Will update after installation.

 

Test the new condenser first, I have installed a NOS one that turned out to be a dud, dont assume it is ok.

 

I installed the condenser. It seems to run a little better. It still wants to stumble briefly when shifting into 2nd gear, usually, even when I rev match, it has just a brief hesitation. Only when the car is moving, never when idling. It did seem to run a little rougher than before. This could be because I attempted to remove the distributor cover the other day, albeit unsuccessfully. Wondering if I can tinker with the timing a little with the distributor on until I get it right. The problem is, it seems to be perfect when idling. I'll give the car another run tomorrow to see how it goes. Gonna also remove two of the three fuel filters and leave only the filter in the fuel pump bowl. I also looked into the records that the previous owner left with the car. In 2013 he replaced the points and condenser, and from the notes, was having starting issues. I'd really love to replace the points with a pertronix. I reached out to see if they had a negative ground set for my car, but they want a casting number that I cannot seem to locate before they can tell me whether they have a product. I am also thinking of getting a stromberg 97 after reading so many posts here about the power valves that don't fit on the 94 rebuild kits. I am determined to figure this out! Just wanting it to be a good reliable car. Maybe that is too much for an almost 80 year old car?

 

The good fitting power valves are available from the correct sources. Do a search.
Nothing wrong with 94’s just as good and reliable as the 97’s.
rebuilt carb. Who did this work. Exactly what was done with the carb.
Stay with the stock distributor. These can be rebuilt and run better than the pertronix. Do a search.
Work on one item at a time. Multiple changes make it impossible to diagnose.
Run an in-line filter before the carbs.
Timing??
Lots of information here on timing that year.
Do a search.

 

A Pertronix is the answer. It’s always the answer.



Before you buy one, read up on guys installing them with generators.

 

Never have worked on this vintage of flathead distributor. Does it have mechanical and/or vacuum advance? Are they working smoothly or possibly sticking or otherwise hanging up? Rusty or gummed-up advance weights or maybe weak or broken return springs?

Also closely check all wiring and terminals going to and inside the distributor. Any place where the wiring flexes can be a problem area. Check any ground wiring inside the distributor. Maybe consider making up some new wiring with good terminal connections to at least temporarily replace the existing wiring as a means of troubleshooting.

 

Yeah, how did I ever make a car run without a Pertronix. Surprised Henry Ford was able to.

Dave

 

Man, how could I have been such an idiot to wonder outloud whether a pertronix could help my vehicle's issue..... EYE ROLL.....

 

Idiot

Nice old ford.

I'm thinking intermittent is probably fuel. Not always.
Intermittent also suggests other things. Fuel delivery problem is either too much fuel or not enough. If bad enough, either can keep the engine from firing at all. As yours did.

First thing I always think of is dirt in the bowls floating around and clogging the jets any old time they want to.

Can an accelerator pump fail intermittently?

Is your choke closing?

 

Stumbling under load can also be caused by low voltage in the ignition circuit. Connect a voltmeter to the ignition switch or coil, go for a drive and monitor the voltage. It could be something as simple as faulty contacts in the ignition switch. I have dealt with this in the past...same symptoms as you describe. Good luck!

 

I finally caught the car acting up on video. Is there an easy way to get a vid on here?

 

Download to YouTube and post a link.

 

https://youtube.com/shorts/WnuxT8QPe9I?feature=shared

this video is while driving. Here’s the backstory. It was difficult to start. Took some serious pumping of the gas. And when I got in the car I noticed the choke was already pulled out. (Damn kids). So it started really rough and spit out some smoke and was idling ok. I backed out, put in gear and it started sputtering. I pulled choke and that made it worse. When I turned choke off, it was still sputtering and missing at about 1/4 gas. Next video will show just after starting.

 

https://youtube.com/shorts/flI88IWjprU?feature=shared

as mentioned above, this is about 2 minutes after a very rough start. My son was inside applying the accelerator while I filmed.

 

Finally this video is about 5-8 minutes after the first video above. Running just fine.
https://youtube.com/shorts/ujytfPi0S00?feature=shared

 

…..where did everyone go?

 

We are here…
I’ve seen many have provided possibilities for your problem but you haven’t given us feedback on any changes from these suggestions. The video confused me, was it after changes?? No changes made?

 

This is after condenser replacement. And removal of one of the fuel filters. I am trying to pick a path and go down it instead of scattershot attempts. The variability of the occurrence makes it difficult. After replacing the condenser, I drove it 2-3 times for 30 mins or so each time and it didn’t have an occurrence. Before taking off the distributor, I wanted to see if the sputtering rang any bells with the group, hoping some experienced member may have seen this before and direct me to a definitive solution. My plan is- distributor next. Points, etc replaced. Then I may look at a fuel pressure gauge. Following that, I’m going to go to wiring. The wiring is original with the exception of fog light and fuel pump wiring and looks to be in generally good condition. If I strike out with any really drastic wiring issues, I may consider a fuel pump replacement, as this one was replaced in 2013. May be ok. May be bad. Also still wondering if the stromberg may be a solution.
The fact that closing the choke triggered this is intriguing. Does this meant I made it rich and it started to misfire and therefore only point to a fuel problem?