Friend has a new to him 26/7 Roadster PU. Ran up and down the street a bit but now won’t run more than about 30 seconds and then dies. Seems like a fuel starvation issue. Maybe electrical. Called me for help. I cleaned the timer, looked OK. Car wants a little choke to start then fires right up but dies after 30 sec to a minute. Checked fuel flow from tank and it seemed fine. Two NH carbs, one brand new rebuild. Swapped carbs and same symptoms. Ignition switch a bit flakey so we wired around it. No change. Car runs, not great but runs solid and then just dies. Took carbs home and tried them on my T – after adjustment both work just fine with a smooth idle and good response. Brought the carbs, a fresh set of known good coils and a good Anderson timer over today. Also brought two more friends over that I go to when I get befuddled. There had been some signs of crud in the fuel tank and I didn’t like his filter so we used another paper element type that I’ve used on my 26 with no problems. Same symptoms - might run up to two, maybe three minutes and then just dies. Change coils and timer – runs smoother but no longer. Can make it run a little longer by playing with the choke. Must be fuel flow. Try blowing into the fuel tank while the engine is running to pressurize it, seems to help but how long can you keep that up? Next we take out the filter and run a straight line. No change. Ignoring the stock tank, we set up another fuel line from a funnel that we fill with fuel. It sits about the same height as the stock tank. With this setup there is no filter and only a very short piece of ¼” fuel line. No real change, starts and runs for about three minutes and then dies. As a long shot, we drop the exhaust pipe at the manifold to rule out restriction in the exhaust. Wow! Runs for 5 minutes and as we congratulate ourselves it dies.
It simply reeks of a fuel flow problem but we’ve exhausted what we can see as ways to improve the flow short of adding a fuel pump. That might help but would be a work around, not a real answer.
So fuel flow looks very adequate when disconnecting the line at the carb. Electrical seems good, engine runs smoothly with the fresh coils and timer and adjusted carbs. Have tweaked carb adjustments a bit for this motor but still within 1/8 turn from where they were happiest on my car.
Three pretty experienced T guys and one novice are running out of hair to pull. Any ideas where to look next?
" As a long shot, we drop the exhaust pipe at the manifold to rule out restriction in the exhaust. Wow! Runs for 5 minutes and as we congratulate ourselves it dies."
I'm thinking you were on to something here with the exhaust restriction..
Is the gas tank cap vent hole clear?
All the symptoms of a bad gas tank. Rust or deteriorated fuel.
Doug - we had hopes when it ran longer but it still died the same way. A couple of times until we decided it wasn't the answer.
Henry - vent hole is open and not an issue at all when we went to fuel feed from the funnel (wide open top).
Royce - yes, seems that way but the fuel is fresh (just a few days old) and no signs of rust or debris showing in the filter when we were using one.
My 27 Roadster never had problems with fuel delivery until I replaced the paper filler cap gasket with a nice, rubber O ring. The cap did not have a vent hole in it and by the time I took the car out some weeks later I had forgotten about having replaced the gasket. It would run ok then just shut down. After tinkering a while it started up and I continued the drive until it shut down again. This went on for a while and I checked all kinds of things until I realized it was due to fuel starvation. All of a sudden I remembered the O ring. Left the cap loose, finished the drive and got home fine. Drilled a hole in the cap and that was that.
I've since bought a new cap (most surely a faithful reproduction of the original cap with a price tag of almost 50 Dollars) and am looking forward to using it soon when my car gets back out on the road.
Make sure file line is not to close to exhaust and boiling the fuel. An Inline fuel filter can restrict the fuel enough to cause the problem you seem to have. Like Eric said the vented cap may be plugged. Leave the cap loose and see if this helps.
No problem with the cap - open hole in it and not even in use for a good bit of the testing. Fuel line is a couple inches from the manifold, about as far away from the manifold as you can get with a 26/27 cowl tank.
After several months I decided to drive my 1919 Roadster and it was a no-go. I had about 2 gallons of gas in it and after opening the cap I got a good wiff of bad gas. The usual varnish smell!
After draining the tank I noticed it was varnish smelling along with some rust residue. Fresh gas solved the problem but it was a reminder of using fresh gas.
So my question is does gas go bad only after a few months? Maybe the gas was 'old' to begin with. But it seems like it should have been good for a good while. I usually don't have much gas in my cars unless I am going to take a long drive.
I have original tanks in my 3 T's and they aren't without their share of minor rust so I guess I am lucky to have only a problem with bad gas. So for!
If the inside of the tank is coated with shellac from deteriorated fuel it can cause lots of trouble with the fuel inlet needle in the carburetor. You might not see anything in the gas.
Make sure that you actually have an inlet needle, not a Grose Jet. Grose Jets are particularly affected by bad gas.
More info here:
If it dies that quickly taking off a plug wire and holding it near the plug so it continues to fire the plug shouldn't be a problem. If it loses spark you're onto the real cause. If it dies while still firing the plug it's fuel.
Worked on a truck one time that owner had lost gas cap, he stuck a map in fuel filler hole, pulling it out tore off a piece of the map that Would covered the outlet hole. Ran great most of the time then all of a sudden shut off. if you let it set for a while it would start back up. Something in tank? Maybe use clear hose to see fuel flow?
I wholeheartedly agree with what Royce said above. On my '14 with a Holley G, 3 Screw Carb., I had nothing but problems with a Grose Jet. I've now changed it to the stock needle and seat available from R. G. Anderson.
My problem with the trouble as stated is the time it takes to quit. 3 to 5 minutes every time. Tank, carb & lines are out of the picture and it continues to happen. Nice try with the exh. pipe but that didn't cure it either. Do the spark test I mentioned. It'll eliminate one system or the other.
Have you opened the drain on the bottom of the carb and let it drain for a while to really judge the flow?
Have you checked for vacuum leaks? What manifold gaskets are they using? Has the sediment bowl been checked and cleaned? Have you pulled the gas pipe off the carb and checked for obstructions in the inlet. Had a carb that would run and drive but not very well, there was a large flake of something that would move over the hole to the float valve and block it off.
What plugs are they using?
Get rid of the paper filter.
So lets clarify what you did.
-Tried two known good carbs.
-Tried a different timer
-Tried different known good coils
-Bypassed the ignition switch (I assume now wired battery to coil box direct).
-Bypassed the entire fuel system
-Bypassed exhaust system
IMO, you really need to see what system you are losing when it shuts off---fuel or spark. Fuel usually stumbles a little bit before it shuts off, spark is usually instant--usually.
And I don't believe it was asked or mentioned, but can you restart it immediately or does it take a bit to get it started or does it have to sit before it will restart?
I hope you don't have a coated gas tank. I would never think of doing that, but there are those who do!
Yes and thank you for the quick summary of what we've tried.
Have not tried an immediate restart but have tried about a minute after it had died and it fired right up.
The only electrical component that we haven't changed is the coil box and while older wood it looks OK and I don't see where it would cause a sudden failure.
The plugs first used were Autolite, replaced with new Champions, no change.
Thank you all for the thoughts and ideas. I'm away from the car until Tuesday or Wednesday. Will let you all know what we find then.
It's a long shot, but swap in another coil box---even a temporary hook up?
You really have tried to eliminate most of the system. Only other thing on my mind is a shorted or semi broken wire.
The new NH carbs and the rebuilds commonly have Grose jets. I would place that at the top of my list given what you have done so far.
No Gross jets in this one.
I don't have a 26/27 coil box readily available. May try a distributor as a work around on the electrical side. If that solves it I'll recommend a Fun Projects kit for the coil box.
You'd change to a distributor when you don't know what the problem is? Without even one simple test that would take 3 minutes?
The paper element filter needs to go away.
Don't necessarily need a 26/7 coil box to test. Just wire any box up and hold it off to the pass. side of the engine if need be.
With a spare distributor handy and a but no convenient coil box, yes - I will test with a distributor. Car would go back to coils in a rebuilt coil box if that proves to be the problem.
The presence or absence of the paper element filter has made no difference in the symptoms. When I know there are some issues with the tank, like on my 26 coupe, I use and replace the paper element filter. Works for me. YMMV.
Any water in the gas with a paper filter will cause a shut down.
No indications of water in the fuel which is all fresh. No change in performance with or without the filter in place.
Swap out the carburetor and use your "remote" fuel supply. Maybe you've got good fuel flow to the carb, but not through it.
Just wondering how long you ran these carburetors on your engine?
Did you check the float setting in the carburetor?
Unhook the fuel line at the carb and let the fuel run into a quart jar and see how much it runs. You should have a solid flow for the whole quart jar. If it falters at any time you have a fuel flow problem. It should fill the jar in just a few minutes. I believe you have a fuel flow problem.
Ran them a full 10 minutes on my car. All nice and smooth once initially adjusted. Will measure fuel flow out through the drain at the bottom of the carb to get a flow rating that includes everything in the fuel system. That will be early next week though as the owner is out of town.
Follow up - Finally back at it and problem found and corrected.
This always seemed like a fuel flow issue even though it always seemed better than adequate. Well today there was great fuel flow to the carb but darn little out the bowl drain with the fuel valve open. Seemed significantly worse than prior days. Checked fuel flow at each connection and all seemed fine until we got to the elbow that takes the fuel line into the carb. Pulled it off and it was almost completely plugged with rust and crud. Seems it must have had that junk in it for a good while as the tank, screen in the valve bowl, and in-line paper filter were always clear.
Anyway, with the elbow cleaned out and re-installed, the car now runs great. Glad to have it done.
Thanks to Steve for providing the amusement and Ray & Jerry for expert assistance. We were all feeling a bit humbled by the experience but a T will do that to you if you aren't careful.
Glad you found the problem!
Ditto and thanks for the instructive follow-up.