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Triumph TR6 - Loss of power

My 1970 tr6 just started to lose power around 3000 rpm. Like its not getting fuel. I checked the filter during idle and noticed no gas in it. should if be visible? Maybe the engine is starved at higher load.
Any suggestions?
M. Simmons

Your fuel filter should have gas in it. If not, you need to find out were the fuel is clogging up. Because of the weather change, have you verified if
your carbs are running rich or lean? You can check this by looking at your spark plugs.
Good luck and hope to see if anyone else has any ideas for you.


I verified there is fuel, but noticed that one of the vaccumn lines, the one exiting the rear of the distibutor is not connected to anything. Is this normal as it looks like is was just laying on the fire wall.
M. Simmons

I have seen similar things happen when the fuel pump is on its last legs. It runs fine as long as you are loping around, but open it up and it sputters, it sputters on up hills, but is fine on level surfaces or downhills, becomes more pronounced as the fuel level in the tank drops, etc.

As for the vacuum line at the rear of the distributor and operating on the assumption that your distributor has two vacuum units since it a 1970 model, that would be the retard side. Feel around for a vacuum port on the under side of the rear carb area. If that vacuum port is not plugged or connected in a sealed system, you will have a vacuum leak that will cause a lean running condition.


Being from the neighborhood, and somewhat familiar with Steve's car, I'm jumping in here to add that it has SU's on it and the vacuum retard shouldn't be hooked up. (first hand experience)
I think I'm joining in with Benji and Steve, fuel delivery (or lack thereof) being the culprit. Any debris in the fuel tank? Did you pull the inlet side of the fuel filter to see if there was any residue blocking it? Another thing....Where did you get your gas? Any chance of contamination there? We used to hear about bad gas quite often aroud these parts, maybe some water in the bottom of a tank?
Pull a couple of spark plugs, see what they look like. Still got my phone number? Give me a call.... we'll do an impromptu tech session! A couple of the other club members are pretty good diagnosticians! I get lucky once in a while, the other guys are just good.
Rod Nichols

Rod, you flatter yourself!

thanks Rod
it did occur after I filled up. Maybe it is the gas. I'll check filter again and plugs.
M. Simmons

I had the same symptoms and it turned out that a very fine rust 'silt' had accumulated in the plastic plug at the bottom of the fuel bowl. The jet actually protrudes down into the plastic plug that's set there. This rust powder had almost filled the plug and was restricting the fuel flow at the bottom of the jet. I cleaned it out and have had no problems in the year since.
I also put one of those clear plastic fuel filters (FRAM G2) at the fuel tank outlet. This keeps any rust dust from getting into and settling in the flat run of line that goes to the fuel pump. There was a build up of silt there too, but it was probably due to the car sitting idle for a decade while in the DPO's care.
This happened shortly after Hawaii mandated 10% Ethynol fuel. The crud could have been there all along, or maybe the new fuel set more of the sediment free and some of it was fine enough to get past the filter at the fuel pump inlet and into the carb fuel bowls.

Honolulu, HI
JB Fetner

I checked the plugs, they appear quite "black". Maybe fouled? Could this be the culprit?
M. Simmons

If your timing is off you will lose power as you speed plugs indicate your mixture is too rich...they should be a tan colour

Charlie B.

If your plugs are black, that means that your engine is running rich and is not starving for fuel. I don't think it's the culprit, but should be adjusted after you've found the real culprit.
The question we should be asking at this point is when you lose power at 3000 rpms, does this happen when you're accelerating while driving or when you're revving it up while parked? If it's when your accelerating/driving, I'd look at your fuel pump as with SteveP comments. If it happens when you rev it up while parked, I'd look at your timing and vacuum advance/retard. Advance in particular for power loss is at higher rpms.(This is assuming that you have a lucas 22d distributor like SteveP has described)
As for the fuel starvation issue, (which I don't think is your problem, but it was brought up on this thread as a potential issue) be aware, if Idaho is like Washington in that they put 10% ethanol (E10) in your winter fuel, the alcohol in the gas works as a solvent which breaks up the crap in your fuel tank/lines and clogs up the system similar to JB Fetner's issue.
Hope this helps you I've gotta go fix my Fred Flinstone brake system on my TR. Yabadabadoo!!!

Oops??? I just remembered, when my fuel pump was going bad, it prevented the carbs from getting enough fuel. Therefore, my sparkplugs were a whitish color. Being that yours are black, I think you need to look at your timing and vacuum advance rather than the fuel pump. Charlie B. I think your on the right track.


Well, I changed out the plugs and replaced the fuel filter as it did have alot of residue in it, probably from the ethanol. Still sluggish. Maybe the carbs are plugged with crap.
M. Simmons

I'd check out your timing before tearing apart the's easy and will tell you lots.
If the timing is off the car will not have any power as it revs higher under driving load.

Charlie B.

This thread was discussed between 11/03/2007 and 19/03/2007

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