• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR4/4A Out of the blue - started to loose power

Share this page

Eeffoc

Eeffoc

Freshman Member
Country flag
Offline
Hey everyone, I am in need of your help

Up until recently the car has been running not bad, accelerates through all the gears just fine, then gradually at highway speeds I started loosing power.
Now the symptoms of power loss has gotten much worse, I can accelerate through 1st and 2nd (shifting around 3500 rpm) but when I get to 3rd and around 3000 rpm I can do no faster and the rpm's go no higher and it sounds like I am running on 3 cylinders or starving for fuel.

  • The car starts fine with a little choke when cold and will idle fine with no choke shortly there after
  • There is an occasional pop when listening to the exhaust - like it is missing
  • I've been using the highest octane fuel I can get
  • Carbs are ZS
  • Mechanical Fuel pump
  • Electronic ignition

So far I have done/checked the following:
  • Set the static timing
  • Checked the plug wires - they all measure between 2.8-3.2 K ohm and are practically brand new
  • Checked the cap and rotor - they look practically brand new
  • Checked the fuel pump bowl (it's clean)
  • Checked the inline fuel filter and it is clear
  • Checked the fuel pressure with the priming lever into a pan
  • Thought it may be vapour lock but this is happening at the start driving before things get really hot
  • Checked the coolant
  • Checked the oil
  • Checked the carbs to see if they are balanced (they are pretty close)
  • Checked the dashpot oil
  • Checked the pistons to see if they move freely and drop quickly and they do
  • Checked the mixture by lifting the piston - not sure if I got this fully figured out but the RPM doesn't drop right away (maybe after 3-4 sec)
I haven't pulled the plugs out yet but I had replaced them a year ago

After looking at the plugs I'll have run out of ideas on what to check next

I need help
Thanks
 
Maybe replace the coil if you have one laying around.
 
I'd try replacing the coil. Curious, is anyone telling you you're blowing a cloud of smoke when shifting from 1st to 2nd, or 2nd to 3rd? Are you sure there's no sticking of those carb pistons? I don't have Z Strombergs, but after first thinking mine weren't sticking, I saw they were at the very upper end of the travel range. Zero problems ever since I fixed that problem. Did your problem follow any recent engine work?
 
What exactly indicates you are losing power? The engine starts firing erratically ("missing") at high rpm under load? The engine starts firing erratically ("missing") at high rpm *not* under load? The engine is slow to accelerate at high speeds? The car acts like brakes are too tight and get even tighter at high speed?

If the engine is "missing" only at high rpm, whether or not under load, I join the "replace the coil" camp.

Tom M.
 
Get rid of the electronic ignition. Install new cap, rotor, points, plugs, coil, and condenser. We can go from there if it isn't then fixed.
Bob
 
KVH said:
I'd try replacing the coil. Curious, is anyone telling you you're blowing a cloud of smoke when shifting from 1st to 2nd, or 2nd to 3rd? Are you sure there's no sticking of those carb pistons? I don't have Z Strombergs, but after first thinking mine weren't sticking, I saw they were at the very upper end of the travel range. Zero problems ever since I fixed that problem. Did your problem follow any recent engine work?
Click to expand...
I'll double check the carbs, I'll be pulling the pistons out and cleaning them but they were moving very freely. No recent engine work and just today I had a friend follow me for a bit and he had mentioned that there was a hint of blue smoke. Looking into a new coil as well now

Thanks for the assistance
 
NutmegCT said:
What exactly indicates you are losing power? The engine starts firing erratically ("missing") at high rpm under load? The engine starts firing erratically ("missing") at high rpm *not* under load? The engine is slow to accelerate at high speeds? The car acts like brakes are too tight and get even tighter at high speed?

If the engine is "missing" only at high rpm, whether or not under load, I join the "replace the coil" camp.

Tom M.
Click to expand...
The car acts like it is bogging down, it starts out fine and accelerates like normal then things get sluggish... I'm not explaining myself very well, I'll see if I can post a video of what is going on
 
bobhustead said:
Get rid of the electronic ignition. Install new cap, rotor, points, plugs, coil, and condenser. We can go from there if it isn't then fixed.
Bob
Click to expand...
I'll look at getting these parts ordered and give it a go and see what happens.

Thanks
 
sp53 said:
Sounds like the timing is not advancing as you pick up RPM.
steve
Click to expand...
I thought that as well but after I set the static timing I put a timing gun on it and increased the rpm's and the timing mark would advance. I suppose it could stop working while driving though.
 
Eeffoc said:
I'll double check the carbs, I'll be pulling the pistons out and cleaning them but they were moving very freely. No recent engine work and just today I had a friend follow me for a bit and he had mentioned that there was a hint of blue smoke. Looking into a new coil as well now

Thanks for the assistance
Click to expand...
Can you verify that blue smoke? Is it a hard puff when shifting at about 4000 RPMs? Separate thought—has that electronic ignition historically worked well at high speeds and rpms? About those carb pistons, the give-away for me was that they were sticking at the upper limit. Finally, you mentioned missing. Do you have missing every single time you reach higher RPMs, or is it something only occasional?
 
Is the tank vent clear?

From what I am understanding, the engine does well in 1st and 2nd, but then bogs in 3rd and 4th? If so, I would concentrate on fuel delivery. Ignition would bog at higher RPM in all gears. The engine uses more fuel as the gears go up, making fuel delivery the likely cause.
 
Hamish is spot on. If you do NOT use fuel injection lines back at the tank, they can swell shut and strangle the flow.
also at the pump ONLY fuel injection grade hose. The quality of fuel line has plummeted in the last 10 years.
MAD DOG
 
Sounds like fuel deliver to me now. I once had an electric fuel pump with a regulator and it did the same thing when turned down too low.
steve
 
I've ordered some parts, while waiting for them to arrive I'll try out the other suggestions.

I'll update my progress as things change.

Thanks everyone
 
Back
Top