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TR6 Newbie with a TR6 engine problem

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tr6ster

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I have a mystery going on in my TR6, and I would appreciate some advice.

I have a 74 with 70000 miles. I've never had any engine problems. The other day I put about 100 miles on it, I was going 70 on the freeway, got off at an exit and when I started again the engine was fine up to 2000 RPM and then would sputter and fight going over 2000. I couldn't go more than 15 MPH.

I replaced the spark plugs. I checked the vacuum hoses and they all look attached and ok.
The contacts on the distributor cap look a bit worn, and I plan on replacing it. The distributor points look ok.

A previous owner put a booster fuel pump on the line from the tank to the primary fuel pump. This pump comes on when the key is in the auxilliary position. I'm not sure why this was added. I checked the filter in the primary fuel pump and it looks ok. I haven't checked the fuel filter yet.

The carb damper oil pots seemed ok, there was oil and pressure when pushing the needles back in. I have never tuned the carbs in 6 years (15000 miles). The air filters are a little dirty, not clogged.

I am running out of ideas. Any advice on what to check next?

Thanks in advance.
 
Hey tr6ster...I've never been able to tell a lot from looking at a distributer cap or rotor. Points are the first things I check when there's a misfire, then replace the rotor, and if necessary the cap. I also try and fix or replace one thing at a time, so I know what cured the problem.(It also gets the engine good and hot, so it's a "joy" to work on).
I think electronic ignition will eventually solve a lot of ignition woes, but I'm "scared" to try'em.
Take care Bob
 
AND, if you've not touched the carbs in that long, it's worth taking a look at the diaphragms. One pinhole or tear can easily cause the symptoms you describe.

But making sure that the ignition system is as it should be, changing the fuel filter, and possibly checking and resetting valve clearances are all good things to do FIRST. As many folks have noted, 95% of carburetor problems are electrical. /ubbthreads/images/graemlins/grin.gif
 
I had something very similar happen on one of the first drives I took this year. Ended up having my car hauled home. The condenser failed. I had installed a new one and did not get 100 miles out of it. Replaced it and everything has been fine.
 
Some great suggestions. I'm going to try a new distributor cap, rotor and condensor, as well as fuel filter. $25 at VB.

Is it a big deal to pop the top off the carbs and check the diaphrams? Do I need to replace washers?
 
Hey tr6ster... be sure and get back to everybody with the resolution...adds to the pool of knowledge.
Take care Bob
 
Bob its not hard at all to take off the top of the carbs. Just be careful with the screws. They may look like phillips head but in reality they are something called posidriv. You can use a phillips xcrewdriver as a last resort but just be careful.
 
[ QUOTE ]
Bob its not hard at all to take off the top of the carbs. Just be careful with the screws. They may look like phillips head but in reality they are something called posidriv. You can use a phillips xcrewdriver as a last resort but just be careful.

[/ QUOTE ]

Dem Brits always have to be a bit different don't they?
This forum is great, but it has just cost me around $500 in new ideas such as looking at Miata seats, fixing a smelly fuel tank, refinishing my dash etc. Thanks!
 
Well I replaced the condenser, rotor and distributor cap, and now the engine will turn but won't fire at all. At least before it would start, just wouldn't run past 2000 RPM. The ignition spark plug sequence seems to be right, I guess I'll put the old parts back on and see if it'll run.

The condeser was simple, a holding screw and a contact screw (with a rubber washer). The rotor went right on and the cap seems to fit well. ???????????????
 
The order from top to bottom:

Nut, Rubber washer, Condenser lead, Black wire lead (is this the low tension lead you refer to?
 
OK...darkest before dawn! Check for spark at the coil wire. Place the wire within 1/8th inch, and try and start the car (DO NOT HOLD ON TO THIS WIRE...and don't ask how I know). No spark- check coil. there is spark, remove a sparkplug wire and try the same thing. If there is spark at the coil, but not at the sparkplug, the problem is inside the distributor ie. rotor,points, or condensor.
If there is spark at the plug, the issue IS probably fuel related.
There is a Lucas Troublshooting guide available, for less than 20 bucks...integral part of my travelin' toolbox.
Take care Bob
 
At 70k the motor might have jumped timing. Put the motor at TDC and see where the rotor is pointing. If its not pointing to #1 or #6 it might have jumped timing due to over stretched chain. Its not to common on motors with a chain tensioner, but its something to look at.
 
[ QUOTE ]
At 70k the motor might have jumped timing. Put the motor at TDC and see where the rotor is pointing. If its not pointing to #1 or #6 it might have jumped timing due to over stretched chain. Its not to common on motors with a chain tensioner, but its something to look at.

[/ QUOTE ]

Here is a dumb question- how do you put the motor at TDC?
Another dumb one- is 1 at the front or rear of the engine?
 
I would start with getting spark to the plugs first. Once you have that, we can move to the basic timing. Then we can spray starter fluid into the carbs. to see if it will start. With each step we eliminate potenial problems. Then we start getting into the uncommon problems, like the timing chain. Confirm all the steps you've taken so we can move you in the right direction. It's important that you have a manual for your car and that you're familiar with how things work. We're here to help.

Bill
 
I pulled the wire to the ignition coil and checked it with a voltmeter. When I put the key in Aux 5 volts showed up. When I tried to start the car it stayed around 5 volts (jumped around between 4 and 6). Shouldn't the voltage be higher? I then connected the ignition wire and pulled a spark plug wire and checked it on the voltmeter. No voltage when I tried to start the car.
 
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