TR2/3/3A Rough Running TR3A - help with diagnosis

[spineguru]

My TR3 is running a bit rough, but not consistently, which is giving me trouble trying to figure out where to go first.

It seems to be running rough when cold, particularly when accelerating under load. It is rough at lower RPM's and less so if I "get on it" a bit. So my initial tought was that it was running rich. The plugs are dry and brownish tan which I think look pretty good.

The car does not necessarily get smoother as it warms up, although it will run smoothly at times. Last night, for example, I took my to dance, and it ran rough on the trip there, but on the retun it ran pretty smooth.

However, near the end of the return trip, it ran very rough, even at constant speed (35-40 mph). It sounded more like a misfiring engine (perhaps a bad plug / wire / point?).

Anyway, I was think of adjusting the carbs (which I am probably not even qualified to that), but have always heard that the carb adjustment should be the last thing looked after ignition, timing, etc.

Lastly, jut to prove how confused I am, I even thought that maybe it was running lean (vs. rich), like maybe the filter was dirty, or something like that.

I guess the bottom line is the car is intermittently running rough whether it is hot or cold.

Anyone have any thoughts?

 

[kc_doyle]

If the plugs look good, IMHO I wouldn't mess with the carbs. Sounds like an ignition problem somewhere. But then what do I know. /ubbthreads/images/graemlins/laugh.gif

 

[Tinster]

Now everyone here knows Tinster has zero knowledge
of things electrical.

But if it was the Crypt Car? First thing I'd do
is buy a new coil and new plugs. See it that
makes a difference. Cheap diagnostic test and
you have nothing to lose.

Come to think about it. That's exactly what I did.
But then the dizzy gave out.

Tin

 

[Harry_Ward]

The colour of the plugs sound good to me so I would not lean out the carbs. Sounds either like no fuel to the carbs, bad fuel filter, dirty fuel pump screen, fuel pump not working properly. If no fuel filter or screen maybe junk possibly in the fuel line which is now in your float bowls. Could also be a sinking float in one carb. If not that then check high tension lead to coil for cracks and bad end connectors. If not any of the above points, coil, tune up time, etc. It could be a lot of different things which you will have to eliminate one by one.

 

[Don Elliott]

It might be as simple as sediment or other crud down in the bottom of your float bowls. Take off the tops, carefully fish out the float and wipe out the sediment in the bottom. If you have compressed air, blow them dry. To give it a test, fill the float bowls with a bit of gas - or reconnect it completely. I found this out in my TR3A back in 1963 after driving overnight 400 miles from Hamilton, Ontario to Montreal on a full tank of gas. Naturally by the time I got home (4 AM) the tank was almost empty and there were no gas stations open along the way. For a few days after this, it was hard to start till the rocking back and forth of the engine that wouldn't start because it wasn't getting any gas - well the shaking stirred up the sediment, bits of decayed old leaves, rust, etc. from my gas tank - and then it would start. After cleaning it all, it ran fine. When I did my restoration, I had the inside of my tank "slushed" with something like epoxy. Since 1990, I haven't had this problem again in over 94,000 miles because the interior of the tank cannot get rusty.

 

[trrdster2000]

Try running a fine file or fine sandpaper thru your points and while in there check out the low tension lead, they give you a fit when they are broken inside the cloth. Points tend to oxidize under the heat. Wayne

 

[bailee2]

Had a similar rough running engine due to a fuel problem on my TR3A late summer. It turned out to be the fuel filter. My (plastic) in-line filter was mounted vertically and would just stop gas from flowing when it either got clogged or some anomaly not understood by several good mechanics. Corrective action was to mount a new one horizontally which has shown no signs of reoccurence.
/ubbthreads/images/graemlins/crazyeyes.gif

 

[TNTriumph]

I have the same problem with mine I replaced the coil, fuel pump, spark plugs, and air filters. It ran good for awhile but then it went back to the same problem as before which leads me to think that it is the carbs. Let me know if you do anything and it helps.

 

[Gblake2613]

I had a simialr issues once. After much tinkering, it turned out to be a pin hole in the fuel line right under the tank. I replaced all lines and had the tank cleaned out while I had it apart. Fixed the problem.

You can test to see if you have a good strong spark by removing the leads one at a time while the engine is running. Hold the lead close to a ground source and see if you get a good strong arc to ground. This can help you isolate an electrical problem.

It really sounds like a lack fuel though. I'd start looking at your fuel lines, filter(s), tank, and float boals.

Greg

 

[spineguru]

Here is a bit of irony. After I posted this, my wife's Ford Expedition started running rough and hesitating at low rpm's on acceleration. A trip to the dealer, some computer diagnosis, and we have a winner. A new ignition coil and a set of plugs. Running smooth again. I think it is a sign from God, so I think I will start by checking the ignition side of things! /ubbthreads/images/graemlins/grin.gif

 

[billspit]

Hope you find the problem. All the advice above is good. But, check your throttle shafts and see if you have any wear in them. I could never get my old TR-3 to idle worth a dang until I replaced mine.

 

[NickMorgan]

I am afraid that I would vote for dirt in the fuel line. That would explain problems when cold when the engine requires a richer mixture and then intermittent problems after that. Electrical problems generally are more constant or more likely when the engine is hot.