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General Tech Engine Trouble--Can't Figure it Out

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KVH

KVH

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Driving my TR4A for the past several days has been great. Car ran perfect. Today it went back to its old tricks I've been battling for two years. My engine just started to miss and chug, then totally shut off. After cooling down on the side of the road, it started back up for ten seconds, then shut back down. Each time it would finally catch and run, it would shut back down. I got home by the skin of my teeth.

I have a new distributor, fuel pump and coil. I have a new condenser. All tuning is perfect. My carb floats look good. I've got pressure in the fuel lines at the float bowls, so the float needle valves appear to be working fine. All my gas lines are shielded from heat, wrapped in heat shield, even under the car. I get spark at all plugs. I have 12 volts at the coil. Points and point gap look good.

Tonight, after getting home, I decided on a lark to just change out the distributor rotor. The car started right up and sounds great again. But I don't think that's the issue. I swapped the old one back in, and now the engine runs good with that rotor. Despite that, I've put the new one back in--it looks more like original stock with the little "elbow," and I'm more comfortable with it. The Moss catalogue warns of bad rotors causing misdirected spark and "ruining Sunday drives." The Catalogue says there may be "no spark" due to bad rotors. Maybe that's me--maybe the rotor reacts to heat? Or maybe that's all hype.

But I'm right back to my old problem: I can't figure out what's wrong with this engine. The problem "feels like" no gas, no fuel. Makes me wonder if my reconditioned POR 15 fuel tank is clogging up intermittently. In sum, I'm at a loss. Could it be my ignition key switch? Could it be the power wire coming off the solenoid? Anything relating to the voltage regulator?

Thanks for listening, and any ideas.
 
Could it be condensation in the dizzy cap. Used to get that a lot on the old minis. Possibly check inside the cap when it starts farting about.
Also fit some clear fuel pipe before the carbs see if is lack of fuel
 
It does sound like fuel starvation.
Check the tank vent pipe first.
Then, check for floating residue from the cleaning and POR treatment.
Good luck. :smile:
 
Does sound like a fuel issue. It could be small particles of scale or whatever coming from the gas tank where the POR did not quite seal? I have an electric fuel pump attached to the frame rail before the drivers side wheel well. I installed a fuel filter before the pump which I check periodically. This filter traps a visible quantity of black stuff and prevents it going into the pump and fuel line. Mind you I had cleaned out the tank as best I could but did not use the POR treatment so some residue is to be expected from my tank. Anyway you might want to put an inline filter before the pump and see what that traps. Hope this helps. Karl
 
I just went through a similar experience. I followed the fuel line back to the tank and found that I pinched the hose coming off the fuel pick up pipe. It would allow me to drive the car a short distance and then cut off...like it was starving for fuel. I replaced the shorter hose with one that was new and somewhat stiffer and longer to keep it from creating a vacuum in the line. The car now runs without any issues.
 
"Misdirected spark"? What on earth is that? Typical Moss technobabble.

Thanks to this kind of nonsense, there is a lot of silly worry about rotors. The rotor is just a piece of plastic with a strip of metal attached. That's all. There isn't much that can go wrong with it. I know, there have been bad designs that could cause problems, such as some I've seen where the metal strip was attached with a rivet, and no one at the manufacturer figured out that rivets are conductive. Another possible (but rare) failure mode is a crack, which creates a path for arcing. I've also seen cheapo rotors that wouldn't work because of incorrect dimensions. But there is nothing abstruse and invisible that can cause it to fail.

When someone replaces a rotor and the car starts working, it's probably because he's inadvertently moved a loose connection. So, that would be my first check: make sure all ignition wires are fully inserted into their sockets.
 
I think I’ll pull the tank. Fern may be right. This has gone on too long. Something is screwed up. But first, more questions:

Let’s say my ignition line at the solenoid has a bad connection (rust), could that cause the engine to sputter and fail? It would not seem so unless it was like turning off the key.

What else at the distributor would I check? The lines seem good and wiggling while the engine is running does nothing. I have 12 volts.

My battery cables are very dirty. I ignore that since my starter works fine, but is there a “constant current” requirement from the battery even while engine is running?

Thanks all.
 
Have you checked the spring loaded carbon button at the top of the distributor?
Make sure it’s complete and not cracked.
 
Here is an easy one to cross off. Check the low tension lead from the coil to the distributor. The wire has a habit of breaking at the the female connector from engine vibration. It starts intermittently and as the connection becomes weaker, heat from the engine manifests the problem.

I had this year's ago. 30 mins into a ride it would start to misfire. Got worse over the months and started happening after 20 mins. Then 10. I was pulling my hair out as you. Then it finally completely died and left me at the side of the road 1/2 mile from leaving my driveway. 2nd time I've needed a flatbed in 25 yrs!

No idea why but, that very afternoon I found the problem. Cut off the old female connector. Stripped wire, crimped on a new one - good as new. Total cost $-0- (tow was free with Hagerty Insurance!).

Not saying this is you problem but it's an easy check.

Keep us posted

Bob
 
What a coincidence! I just walked in from the garage and see some very insightful comments, particularly relating to "electrics," and more specifically, the low-tension lead and the distributor spring button. Actually, the problem I just found and fixed is a combination of the two. Before getting into the details, though, let me first say that in my "other" TR4, not this current problematic one, I did find a defective wire at the spade connector, plus + side of the coil. I fixed that, and that car runs great, but only after I needlessly chased down fuel issues for several days. Remember the saying, "The problem with your fuel is your ignition."

Okay, back to this car. What I finally noted was "arcing" from the low-tension lead between the lead and coil core, right where the plug wire from the distributor goes. Fairly constant. When I touched to wire, I sure felt it. I removed the wire from both the distributor and the coil, and made sure the connectors were in good shape. I reinstalled it, making sure it was properly seated, and I saw more arcing. I pulled the wire back off and replaced it with a new one I happened to have handy. I carefully seated it, and now I have no arcing.

I'm hoping this ends the opera. I'm sure my falsettos are getting a bit much. Seriously, I'm beginning to think that this annoying problem dragging on for two years has from the start been that coil/distributor wire. And, painful as this is to admit, I'm also not sure I ever had the connectors fully seated. The boots are so tight and immovable that I may have been misled into thinking I was properly connected, when only the rubber boots were connected.

Anyway, for now I'm up and running. If there's a lesson, it's once again that the problem with my fuel was my ignition. Thanks all.
 
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Great to hear. Yup, same wire - the little one coming off the (+) terminal on the coil.

Before I solved this I swapped all of the following with no success: cap, rotor, coil, points (was running Pertronix). Tested fuel pump. I even tested for water in the gas.

Crazy it was that one silly little wire.

Bob
 
Hope that works. You can often tell a lot about the health of your car's ignition by watching the engine run in the dark. You will easily see any arcing in the system, and it really jumps out at you!
 
Quite a few years ago I recieved a very good tip about that short white wire. Make your own wire and make it long enough to include 2 or 3 coils (about 1 to 1&1/2" each) in the line. This accommodates the shaking of the engine. I have done that and not had any problems with that wire on any of my TRs.
Charley
 
My drive today was not perfect. It was better, and not stalling, but I had hiccups and I'm not certain my "coil wire fix" resolved everything. I may have celebrated too early.

While checking things back at my garage, I found that my two forward spark plugs were fouled with soot--black carbon. The carburetor was running rich. The other carburetor is perfect.

I leaned out the mixture on my forward carburetor by 3 flats, then took the car out yet again. It ran quite well, but I still felt a few hiccups.

I pulled my plugs again, this time noticing they are two different brands. For a TR4 is that a huge mistake or just a matter of preference?

Any other thoughts welcome. Thx
 
Keep in mind, you might have a bad coil. A hairline crack could cause the arcing you saw.

There's really no way to test a coil. I hate to suggest that people randomly replace parts, as it's an inefficient way to solve a car problem. But with a coil, replacing it with a known good one is the only way to determine for sure if it's bad.

It also might be a good idea to do a full-up carburetor tuning. Make sure the timing and valve adjustments are right first.
 
In his first post: "I have a new distributor, fuel pump and coil. I have a new condenser".

As always, "new" doesn't always mean "works perfectly out of the box". Sad to say, but necessary these days.

TM
 
You can test coil, but most do not have the equipment. I had the same problem on other cars. If coil is hot (careful to touch for burns) replace. But, I also found loose connections or broken wires were the problem. Usually an easy fix, just aggravating. Fuel would present different problem, like backfire. Always go with the shortest problem first.
 
I checked my coil using the 5 tests in that old Lucas troubleshooting booklet. It seemed a bit rudimentary but I passed. Tested for loss of voltage, ohms, and spark—as I recall,

I have a beautiful new Flame Thrower Coil from Moss but I seem to recall someone saying it may not be a good swap. I also have a spare used one from Moss in a Lucas box.

My mixed plugs are Chsmpion and NGK.

Also, I’m wondering: Is three additional flats either way considered much on HS6 carbs? Should both carbs be open the identical number of flats? I think not.
 
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