The Stovebolt Site Forums The Shop Area Engine Shop Consistent engine stall issue

Hello everyone! I currently own a 1955 1 ton, 1st series that I've owned for almost a year (my first classic truck, so please bear with me!). Since acquiring it, I've put on about 100 miles on it and it's been great! Towards the end of the season last year, I would notice that as I'm driving along at 40 - 50 mph, it would stutter for a moment and then would be fine. I took it to my first car show in October and on the drive home, it quit on my after 3 miles. After sitting for 10 minutes, it fired up (with the choke on). Made it another 3 miles, same thing. Luckily it was a local show and I had to do that three times to make it home. I parked it for the winter and got to trying to figure it out this spring. I assumed it was the carb, so I got a full rebuild kit and did my best at freshening it up (I'm new to carb life in the car world). Put it all together, fired right up and off I went. ran amazing, 3 miles down the road she died. When I try to turn it over it sounds like it's turning over very hard. Again, waited 10 min, pulled the choke and off I went. I can't seem to pinpoint the problem. If I start it up and idle it all day long, it won't stall out. Not revving up while idling, so I don't think it's starving of fuel. It's the exact same situation every single time, starts perfectly, drives 3 miles, dies. Any troubleshooting suggestions would be greatly appreciated!

BTDT. When the vehicles were new. The fuel line is metal and runs alongside the engine block. When the engine gets hot, the fuel in the line vaporizes and boom, the engine dies and won't start. Until it cools down some. Then it starts and runs normally. Here's how you confirm it. Run the truck until it does this again. But bring along a can of ether Or the stuff they use to blow out computers. When it does, jump out, raise the hood, and spray a specific section of the fuel line. Start with the line that's closest to sources of heat, like the thermostat housing. Then see if the truck will start. If it does, you've found the problem. (The ether cools the line very quickly and efficiently.)

The solution is to either bend the line so it's farther away from the source of the heat, or put some insulation around the line to keep the heat away from it.

A couple of suggestions, in addition to vapor lock addressed by Paul;
1) Be sure you have a vented gas cap.
2) You may have sediment in your gas tank. Heavy scale will plug the fuel outlet from the tank. Or you may have an in line fuel filter that is full of sediment and needs changing.

Good luck and let us know how you are doing,
Kent

The breath of knowledge in this group continues to amaze me.

How I'd do the suggestions above. When you go for a drive with Paul's suggested "quick cool in a can handy", leave the gas cap loose or off if the weather's good. If it doesn't die, then as Kent suggested you need to vent your gas cap or just buy a new one that's vented.

If the two test above fail to fix the problem and you've changed the fuel filter then disconnect the fuel line upstream of the fuel pump, use compressed air to quickly and briefly blow the line to the tank. Just a couple of short quick burst of air. Your're not trying to air anything up just move any sediment that may be plugging the tank's fuel outlet. Then go for another test drive. If it runs as it should, time to pull the tank and either clean it or replace it. If it's rusty with loose scale it's pretty easy to clean/coat/ seal the inside. I did same on my '70 Duster's tank 4 years ago using a kit from Eastwood and so far so good.

Good Luck,

RonR

Look down your carb right after it dies and see if you're getting a pump shot of gas from your accelerator pump. If you are, replace the coil.

Trash in the gas tank moving around before getting sucked up to the outlet and plugging the line. Once the truck dies the trash will move away from the line and it will start. Cycle will repeat until tank is cleaned or replaced.🛠

And one more; the "Disclaimer", this is what I might do, I don't suggest anyone else try it. Put a few ozs. of gasoline in a empty plastic water bottle. Go for a drive, when it dies, immediately pull the air cleaner and poor 3 or so table spoons of gas down the carb and see if it'll start. This will tell if the problem is fuel or ignition related.

Be safe. Good luck.

RonR

Check the wire between your distributor and the coil. I had a similar issue to you a couple of years ago, and it would periodically be very hard to start. I started going over every connection, and when I touched that wire, the slightest touch pulled it from the coil connection. Re-connected using a new wire nut and it stopped dying.

Thank you everyone for your prompt replies! Today I replaced the fuel filter with a plastic one so I can see what's going on. I took the truck for the usual 3 mile drive and stopped it before its usual spot where it dies. I popped the hood and saw that the fuel filter was basically empty. So I clearly have an issue between the tank and the carb. I noticed that there is something in between the fuel tank and the carb and I'm not sure what it is? It's located on the passenger side, down at the bottom of the engine. I'll try and post a picture of it. I'm guessing it's a blockage somewhere between the tank and the fuel filter. Any suggestions on how to clean out or remedy this? Thanks again in advance for all your help!

What does the "something " look like? Some form of canister? An old filter possibly? The only thing I know of between the tank and the fuel pump could be an after market filter. My guess is a dirty gas tank or a clog that goes away for a while. This situation is pretty common. Recommend pulling the tank and get it cleaned out.

"Passenger side bottom of engine" is that your fuel pump?

Yes, it appears to be the fuel pump after some more research. Should I clean out the fuel tank, lines and pump or should I just replace everything? If I should just clean it out, how would I go about doing that? Thanks!

Use the method all the old Sun machines had painted across the top in big letters- - - - - -"We test, not guess!"

Do a pressure, volume, and vacuum test on the fuel pump. There should be 3-5 pounds of fuel pressure at the inlet fitting of the carburetor, 10 inches of vacuum or more on the suction side of the pump, and both pressure and vacuum should hold for a few seconds after the engine stops. The pump should deliver at least a pint of fuel to a catch container in 30 seconds at idle speed. Failing any one of these three tests is a good reason to replace the pump. If the pump tests good, you've most likely got an air leak between the tank and the pump, or there's a restriction inside the tank.
Jerry

I had a similar problem when I first got my truck. It would run for a couple miles, then die. In the final analysis, I had rust and other junk in my fuel tank that were interfering with the diaphragm operation in the fuel pump. To resolve the problem, I just cleaned the fuel pump, and cleaned and sealed the gas tank. An old guy at a car show told me the best way to clean out the tank is to put gravel (not smooth rocks) in the tank along with water and shake it as vigorously as you can muster. After a bit of that and some rinsing, I used the POR-15 49239 Fuel Tank Repair Kit to seal it. I've never had a problem since.

I've used the gravel cleaning method, but I attached the tank to one of the drive wheels of my tractor with ratchet straps and spent a couple of hours running a bush hog in a pasture. The tank got VERY clean!
Jerry

I'm not convinced you're clear fuel filter has actually indicated the source of your issue. The reason I don't think that filter is a reliable indicator is because I have a clear fuel filter on my 216 and it's almost always completely empty. If I took my truck for a 3 mile drive and pulled over to check the fuel filter I guarantee it would be wet but empty. It's been that way for the last 11 years of daily, and often long distance, driving. Even though I had no issues that empty filter bothered me so I replaced the gas cap, the filler neck, the fuel tank, the fuel lines, the fuel pump, the carburetor, and that clear fuel filter. Guess what? That new filter is still empty when I open the hood, but it never starves for fuel.

What does your filter look like at idle?
If it's full at idle but empty after a drive then you are correct and you can ignore my post. If it's mostly empty at idle then I would ignore the filter.

While the engine is running, that volume of air in the fuel filter is under pressure due to the fuel pump. This volume of air cannot escape since it cannot reach the input end of the filter, so it is always present. It will not prevent fuel from getting to the carburetor.
Carl

A couple of other things. If the fuel pump checks out as good, you might have to delve a little deeper. You might consider undoing the fuel line at the inlet side of the pump and at the gas tank at the pickup. This can be messy but you blow a bit of compressed air in the line to see if it’s blocked. Blows fuel in the line out so put a rag on one end until is all blown out. If clear, you might have to go further. If the tank has a traditional pick up, it may have a sediment sock on the pick up tube in the tank. That screen can get clogged with sediment and does not allow sufficient fuel to pass to keep the motor fed. So you have to unscrew the pick up to check. While it’s out, look at the end of the tube and make sure it’s clear. These pick up tubes can sometimes get lacquered up in the ID of the tube to the point that the tube is partially obstructed and again, does not allow sufficient fuel to pass when running at speed.

So I finally received all my parts and got to work. I replaced the fuel tank, sending unit, fuel pump and fuel filter. I took everything apart, blew all the fuel lines out and assembled everything together. Today I finally wrapped everything up and took it out for a ride. I drove 20 miles without a hitch. I made it back home and decided to take it for one more run into town, which is 5 miles away. She fired right up and off I went. I stopped for a 10 minute break by the water and when I got back in to go home, it started and died 10 seconds later. After popping the hood, there was no fuel in the fuel filter. I pulled the fuel line coming into the fuel pump and it was pouring out, so no obstruction there. I pulled the fuel line coming out of the fuel pump off and it was pumping (very little in my opinion, but I don't know what's normal for that pump). So then I took off the fuel line from the pump to the filter and blew it out and it was clear of obstructions. I then took the fuel filter off (which was empty) and filled it with fuel and hooked it back up. Still it wouldn't start. last option, tapped the carb a few times and she started. So it was either dumb luck or something is obstructing the fuel from coming into the carb. I rebuilt it and it has a new float, so it shouldn't be getting stuck. Is there any suggestions as to something I may have missed when rebuilding the carb that would restrict the fuel flow or if there's something else I should look into? Thanks again everyone for all your help!

Finally I have figured out the problem (I think!)! I was browsing further down the forums today to see if there was anything that would trigger something I missed and I came across "Rochester carb not squirting" by treydrummer. After reading his OP, it was my problem down to a tee! I followed his instructions on how to clean out the jet off of the acc pump discharge (after I found it because it was so caked up) and took her for a 30 mile drive. I'm excited to say the drive was trouble free, lots of power and there's now fuel visible in the fuel filter. I cannot thank everyone in the forum enough for sharing all your experiences and suggestions. When I broke down yesterday, it actually was 200 feet away from a classic car show that's held on Wednesday nights in my town, which I've never attended. There were about 3 dozen cars at the show and over two hours of working on my truck to get it running, not a single person came over to ask what was wrong or if they could help. It was extremely discouraging to say the least, as everyone was staring at me as I was scrambling to figure out what was wrong. Everyone here has been incredibly helpful and without you I wouldn't have solved my issue. Thank you for that!

treydrummer's thread:

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1317554.html#Post1317554

I have found that in recent years, there are fewer and fewer classic/antique owners who are builders , but rather, buyers. I'd be willing to bet that whoever was staring at you struggling would have just been in your way had they come over to "help".
Carl

Ditto! It seems that most "restored" antiques belong to owners who might as well be screaming "Look at what a big check I can write!" I did a pre-purchase inspection on a resto-modded stovebolt pickup with a price tag of $60K- - - - -and a rack and pinion steering system that tried to lock up the wheel every 90 degrees due to incorrect routing of the steering shaft and the wrong design of U-joints between the fancy new steering column and the R&P unit. The seller got highly agitated that I included that tidbit of information in my report to the potential buyer.
Jerry

So the saga continues I took the truck for a run to the hardware store today and at 10 miles out of 14, she stuttered and stalled. I popped the hood, tapped the carb a number of times and it fired up. So I thought I had figured out the carb issue, but clearly all the bugs aren't out. Is it fair to say that with the last two stall outs, after tapping the carb and it starting up that it's a float issue? I've replace the float & needle as part of the carb rebuild, so it shouldn't be hanging up. Any thoughts or suggestions?

Thanks!

The tapping on the carburetor is a dead giveaway that the float needle is sticking. Time to pull the top off and see if you can figure out why. Good luck. 🛠

After further review, it's looking like the fuel pump isn't producing enough pressure to push the fuel up the line and into the carb, especially when the needle sticks in the carb. This would likely be due to a worn camshaft lifter for the fuel pump. Has anyone either experienced this or heard of a lifter wearing out like that? If that's the case, I'm looking at either replacing the camshaft or installing a small electric fuel pump. Any thoughts or suggestions are appreciated! Thanks!

Take off the fuel pump and see if the lever (lifter?) is good.

If the lever looks good, you might have a bad fuel pump?

Checking a fuel pump for volume, pressure, and vacuum was once a routine troubleshooting procedure. Now people just throw parts at a problem and hope something fixes it.
Jerry

So I got my hands on a fuel pressure gauge and hooked it up to the line. Just ran the test and I’m sitting between 3.5 and 4.3 psi, which is right in spec. After letter the truck sit for 15 min, I fired it back up and it was reading at 1.5 psi. Could it just be vapor locking? I’d be surprised if that was it after such a short period running. I’m thinking that installing an electric fuel pump would remedy that. Any thoughts?

Sounds more like trash in the the bottom of the fuel tank, intermittently plugging the flow.
THIS is very likely the number one "cause" of so-called "vapor lock" for most folks who believe that they have vapor lock.
An easy way to rule this out is to provide a temporary fuel supply to the fuel pump. A plastic fuel tank for a small outboard engine works very well for this.
I use one anytime I break in a new engine if I do not have a brand new tank in the vehicle.
The hose on these boat tanks is the right size for the fuel line heading to the fuel pump, and the squeeze bulb works nice to prime the pump.

Carl

Hi Carl,

Thank you for your reply. I just replaced the tank and sending unit with a new one, so sediment shouldn’t be an issue anymore. This is why I’m running out of ideas as to what could be causing my intermittent fuel flow problem. Thanks again!

I still say stuck or sticking needle and seat. Go through the carburetor again.🛠

So today I installed an electric fuel pump and it filled the fuel filter with ease with a cold engine. I started the truck and it ran extremely well. I took the truck for a run down the road and when I got back, the fuel filter went from 90% full to 90% empty. The truck hadn't stalled out at this point, so out of curiosity I took off the fuel line just past the fuel filter, leading to the carb and it instantly filled the filter and blew fuel out the end. So the line was pressurized between the fuel filter and the carb and it wasn't letting the fuel pump push any more fuel into the fuel filter. So my question is that if the bowl in the carb had all the fuel it needed, the needle closed the fuel coming into the carb, why was the carb taking the left over 10% in the fuel filter and running it dry, all while pressurizing the line that the fuel pump couldn't pump anymore fuel? I hope this makes sense? Thanks in advance for your thoughts!

What pressure is the electric fuel pump rated at? If more than 4-5 psi you may have to put a pressure regulator in line after the pump.🛠

Any chance the tank isn't venting properly?

Dennis

The pump is rated at 2.5 - 4.5 psi, which is right in spec for that truck.

I thought that too and tried running it with the cap off, but that didn't help either. It's a brand new tank, filler neck and cap. Is there anything else to check for proper venting?

Running with no cap is about as vented as you can get. Where did you install the pump?

Dennis

So I took it for a drive this evening to see if it would starve itself of fuel. After 11 miles, nothing happened. The only change I've noticed since the fuel pump install is that when I push down on the throttle, it now hesitates for a second and then the power kicks in. Not sure what that's about? Being off on vacation this week, I'll likely try and drive it everyday anywhere I need to go to see what the reliability is like. With everything that's happened the last few weeks, I hate to admit it, but I'm not feeling very confident. We'll see how things go. Any other thoughts or suggestions are appreciated! Thanks again!