My car was running great until I changed the fuel line. I added a new fuel line and a fuel shut off valve. I took the car for a ride and noticed that it wasn't quite running right. It's seem to have a little less power and as the drive got longer it got worse. I was able to get my car back home but it clearly isn't running well. I thought it was a spark issue that just happened to occur at the same time I change the fuel line but I have checked everything with the wiring and it seems OK. I have checked to make sure the fuel line is flowing good the tank is completely clean and there is no signs of any rust inside. I completely cleaned the carburetor and nothing changed. I changed the carburetor and another carburetor ran the same exact way. I have checked all four spark plugs and they're firing with bright blue spark. I have checked the compression And although I didn't have the best gauge I was able to determine it had close to 50 pounds in each cylinder. Any thoughts what I should do next?
Vapor lock? Enough gas in the tank?
To change the fuel line you most surely had to close the sediment bulb valve. Had you been opening and closing that valve before? You may have dislodged some dirt in the process.
Vapor lock is another good suggestion to check. Why did you change the fuel line in the first place and did you route the new one the same way?
If your car is a 26-27 coupe, tudor, roadster, or touring, the line should give you no problem if you run it down from the valve and bend in a large arc to the carburetor.
But if it is any model with the tank under the seat, you must have the lowest point in the line toward the middle and the line goes up at both ends. Another problem is having the line too close to the exhaust pipe. Where is your fuel shutoff valve located? Is it the one on the sediment bulb, or somewhere else in the line. Another possible problem would be the line is pinched at some location such as at a bend or at the end depending on what type fitting you use. Even if you cut off the line with a tubing cutter, it might be restricted at the end. The steel line is best. The copper line is a little smaller inside and could also cause some restriction.
One other thing to keep in mind is how full do you have the tank? The ones under the seat like at least 3 gallons or more for good gravity flow.
I changed the fuel line because the other one was a mess. Whoever installed it kinked the pipe and did a horrible job routing it. I didn't close the sediment bulls because I siphoned out all the gas until it was empty.
I checked to make sure the vent hole is open on the gas cap.
I took off the carb and opened the fuel on/off valve and the fuel is flowing strong and clean so I don't think there is an issue with the way I ran the line.
The gas tank is just about full with fresh gas.
Did you adjusted the needle valve on the carburetors while it is running ? You maybe be getting more gas with the new line.
I did adjust the needle, it went from bad to worse back to bad again.
If I understand correctly, you have good flow to the carb, as verified by removing the line from the carb and checking flow. Have you tried checking the flow by having everything connected and opening the drain on the carb bowl?
This is a remote possibility, but depending on the type fitting at the carb, you can restrict the flow if the fuel line extends too far inside the fitting past the packing.
You checked the flow and determined it's o.k. What do you consider o.k.? Did the line emit a stream of gas that immediately dropped off the end of the line at 90 degrees, or did it shoot gas out a bit further, with the stream traveling out in an arc? The latter is what you want.
Also, when you checked flow, was the new shut-off valve still in-line? Not all valves are created equal, some are very restrictive. The T-handle ones, for instance, can be very restrictive especially if they're not wound open to the end, which is a pain because it seems to take 20 turns to do it.
My guess is that, in the process of changing the line, you dislodged something that ended up in the carburetor.
How do the plugs look if they are black I would change them with a new or known good set that seem to fix mine when it runs crappy
So, I spent a bunch more hours working on the car and still have no luck. The car barely has enough power in first gear to climb a very slight, almost non-existent, gradual hill on my dirt road.
I have opened the fuel drain on the bottom of the carb and it runs out fairly well.
I had it running slightly better at one point but still not well enough to have much power. I decided that I would put on the old fuel line and see if it went back to running good. Nope, actually ran a bit worse now...
I don't want to change too many things at once, cause I'll never know what it was that was wrong. I decided that I am going to pull the sediment bowl off the tank and check it out just to make sure that it's clean. If it's clean, I'll reinstall the fuel line, and check it one more time for flow without the carb on. If it flows well, I would have to say it's not the issue...
Next, I may splurge and get a new NH carb (since I could use a nice new rebuilt one anyway). If that doesn't fix it, I'm not sure what I'll do next but perhaps I'll take a look at my coils. Maybe they are not working well... They were newly rebuilt when I bought them 6 months ago and have only used them a few times. I also just installed (and gaped) new plugs so those are all set for now. I pulled all the plugs and had them sitting on the top of the motor and turned it to Battery and slowly moved the hand crank to see if each plug was sparking. They were creating a TON of bright blue sparks and appeared to be working correctly.
Well I got a new sediment bulb today in the mail because I tried to take the one I had apart to check to make sure it was clean inside and I pretty much destroyed it trying to get it apart. Oh, Well....
Anyway, I put the new bulb on, along with the new fuel line, and hooked it up to the carb that was freshly cleaned. I also installed new exhaust gaskets (the glans type with the metal ring with the copper gasket) because the paper ones were leaking really badly. I thought that maybe an intake leak was the issue...
I got the car running again and it still seemed to be not quite running right. I used a screw driver to ground out each plug and I discovered that cylinder #4 doesn't appear to be affected when I ground it out. I guess that means it's not firing. I looked at the #4 coil and it is sparking very bright at the coil, much brighter than the other coils.
I checked the spark in the past with the plug out of the motor and it seemed like it was sparking fine but I wonder if it changes once it's installed in the motor...
Anyway, what does it mean that the #4 coil is sparking really bright on the top of the coil? Is this most likely the problem I am having with the car running very poorly with no power? Is it a simple adjustment to the gap on the top of the coil that should fix the problem?
Initially, I thought it was a fuel issue cause the problem started after I changed the fuel line a few weeks ago but now I think that it was just a coincidence... Any thoughts?
OK, if #4 isn't firing switch coils #3 and #4 around. If the problem follows the coil and #3 doesn't fire, that tells you where the problem is. If #4 still isn't firing after the switch, you know the problem isn't the coil. If the coil isn't the problem, then switch the non-firing plug with another one and see if the problem follows the plug. If the plugs check out OK, then move on to the timer and wires.
Bright spark at the coil points says the coil probably has a bad capacitor inside of it which reduces the point arcing to help the points have long life but it also affect the strength of the coils energy in sparking the plug. Laying the plugs on the block and firing them without them being under compression pressure as they normally are in the cylinder is a pointless test that proves very little. Almost any plug and coil will perform OK for that test. See if each of the coil wires will jump a 1/4" gap to the block by making up a paper clip or other wire gap that is exactly 1/4" wide. My guess is that coil number 4 will NOT jump that gap while the other coils probably will.
Did a bit more trouble shooting last night and determined that it is in fact a bad coil. Just so happens that the coil went bad at the same time that I changed out my fuel line and installed the fuel on/off switch causing me to think it was a fuel issue... What a pain!
Anyway, I'm borrowing a coil from a friend and will hopefully be back on the road this afternoon. Thanks to all those that offered up advice.
Good for you Michael !! I hope a new, good coil will fix your loss of power problem. Just goes to show you that most carburetor problems are electrical ;o)
Excellent Posting thanks I learn a lot reading the trouble shooting and the back and forth
Glad you got it sorted out.
I put the coil in it today and it was back to normal. We went for a ride (about 20 miles) and it was running good. Had a nice time but my wife (who is the one who wanted the T to begin with) was a bit nervous being out on the road with other cars. It's a bit tricky navigating even a little bit of traffic through town with stopping and going. It didn't really bother me, but then again, I was the one driving. It's always worse being a passenger...
Have you ever had your coils rebuilt? I'm guessing not. I'd bet you dollars to donuts that if you had all four coils professionally rebuilt, you'd think you put a turbocharger on the dang thing, assuming you have a working magneto.
I bought them off ebay last year and they were advertised as "professionally rebuilt coils". I am questioning how well they were adjusted, and am thinking of buying a "strobo spark" to be able to rebuild and test my own coils.
You can rebuild your own coils. Its easy.
Get the MTFCA videos about coil rebuilding and buy a Strobo-Spark coil tester for testing. A Strobo-Spark would have detected your intermittent coil problem immediately and is great for maintaining a Model T Ford.
When you said your points were sparking excessively, I just assumed your coils had the original capacitors. Sorry. I'm sure a new capacitor could also fail. Certainly sounds like that is the problem. Go ahead and get you a Strobospark and do them yourself. I haven't priced one lately, but seems like it was less than the price of having 2 sets of coils rebuilt, and you will always have it for future use. The videos Ron spoke of are very helpful. They are kinda dated now (Unless they have been updated since I bought mine), as the quality of points available now is much better than when the video was made and you will find that you don't have to do all the modifications one used to have to do.
Coil rebuilding videos: