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TR2/3/3A vapor lock?

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So a fellow club member loaned me his original AC fuel pump that he removed under suspicion of an oil leak. After I installed it, and made a new cork gasket for the bowl, I tested it by running the engine until the temperature was normal, then shutting it off, closed the hood and let it sit for 5 minutes. I also changed out the filter element. Here is how the AC pump performs on the warmed engine: https://youtu.be/QgvrkYOxTlQ The next time anyone tells me 'there's so much room under the hood, it must be easy to work on', I will know that person never changed a fuel pump on a TR3 while the engine was in the car.

I don't think either fuel pump is bad. I don't think the invisible fuel in my filter is a problem. -But I still don't know what to think.

While I was changing the pump, I removed the vice grips that were used as a clamp on the fuel line from the tank to be sure a constant stream of fuel was available by gravity. My old fuel pump glass bowl had a little debris in it, but nothing serious. The in-line filter also showed some signs of working, but not enough to clog it.
 
Glad you made it home. I did too.
I used to have a clear fuel filter just upstream of my TR6's fuel pump.
I don't remember ever seeing it full. With the engine idling or upon just returning from a drive, I don't even recall seeing it more than half full, usually less.
It made me wonder too, but I've seen so many people on the 6-Pack report the same thing that I don't question it any longer and to get my mind off it completely I now use a metal body filter that keeps it's contents invisible.
 
Looks normal to me.

TexasKnucklehead said:
...The next time anyone tells me 'there's so much room under the hood, it must be easy to work on', I will know that person never changed a fuel pump on a TR3 while the engine was in the car...
Click to expand...

A friend has an Triumph Italia - fuel pump replacement offers 2 choices: engine out or body off. He had to rebuild his with the lower half still attached to the block.
 
TexasKnucklehead said:
The next time anyone tells me 'there's so much room under the hood, it must be easy to work on', I will know that person never changed a fuel pump on a TR3 while the engine was in the car.
Click to expand...
Having the right tool makes a world of difference

 
I'm with Randall (and Justin.) It's been awhile, but experience has shown me that the above combo works in my '3. It's a tight fit, but it works!

BTW, the only fuel filter I run is the original screen in the glass bowl on the fuel pump.
 
If you mount a filter horizontal it will always and a day retain a large air bubble. If it bothers you, then mounting the filter vertical with the inlet down will get rid of it. It's like trying to fill a cup holding it sideways.
 
CJD said:
If you mount a filter horizontal it will always and a day retain a large air bubble. If it bothers you, then mounting the filter vertical with the inlet down will get rid of it. It's like trying to fill a cup holding it sideways.
Click to expand...

John, perhaps you missed my statement in post #7 where I changed the filter from horizontal to near vertical. I understand the analogy to the tilted glass. True, the bubble almost goes away completely when the filter is tilted. What "bothers me" is that the bubble is gone when the engine is cool, but reappears after it has been warmed up, and then disappears again as it cools back down. Actually, it doesn't bother me at all, but I can't explain why the filter appears empty (when the car is warm) and everything is working normally (and refills simply by cooling down).

One of the reasons for choosing a clear fuel filter is so I could see if I have fuel in the rare occasion the engine refuses to function. When I push the car to the side of the road, an empty fuel filter doesn't help me understand anything -if the filter is supposed to "look" empty anytime it is warm. When I'm on the side of the road, I don't want to wait 4 hours for the engine to cool completely down before I can see a full fuel filter. Knowing that my filter may appear empty when warm changes the way I might diagnose a stalled engine.

I still don't know why I stalled in traffic. But I'm not as worried about the bubble. The (made in Canada) fuel pump I have works fine, but it does not have a priming lever. It also does not have stakes holding in the shaft (like the original AC pumps have the shaft long enough to go thru the housing, instead of staked into place).
 
The amount of fuel you see in the filter is affected to a large extent by hydrostatic pressure...the fuel level from both sides of the filter, the carb/pump side and the fuel tank side.
You know the old saying about "liquid seeking it's own level"
Hydrostatic pressure eventually shows it's effect on the fuel level when the engine is not running and the residual fuel pressure has dissipated.
But for diagnostic purpose, if you see gas pulsating from an open fuel line at the carbs when you hit the starter, your pump is working.
If you really want to get scientific, measure the volume per 3 or 4 cranks (or seconds) that accumulates in a baby food jar when you know things are working right with the volume when you have doubts....but usually a few healthy pulsations is enough to convince me.
Here's where I learned to DX a problem with a fuel pump AND the value of a priming lever.
https://www.6-pack.org/j15/index.ph...0808-Hey-mdlrr-this-look-familar?limitstart=0
 
Full when cool and empty when hot...got me there!!

That would lead one to believe the bubble is actually fuel vapor boiling off. Once it cools below the boiling point it is condensing back to gas?? Maybe the gas blend has components with different boiling points, so only some parts of the fuel is boiling off?

That would lead you to believe the fuel may be right on the verge of vapor lock in normal operation??

Just rambling guesses...
 
When I was having the running issues with the first set of SU's that I installed, I was running with a glass filter just before the carbs. It would do exactly as you describe....run with a full filter and then over time, the filter would empty. However, mine would eventually stop and not continue to run (this was with the previously mentioned troublesome SU's that I had installed). If you recall, at one point I thought it was the fuel pump as well (because of the empty fuel filter) so I changed that for another fuel pump with no change. When I started looking at the possibilities of vapour lock, and possible sources, I made the decision to remove the glass filter before the carbs as I thought it might be soaking up some heat. I did all the other stuff like checking the fuel line routing and adding small amounts of insulation here and there along the metal fuel lines.
Since swapping out with the second set of SU's (and still running without the glass filter), I have had no issues with the car stalling out do to fuel starvation/percolation. I do have to say, I miss being able to see the fuel in the glass filter though.....I have the same glass filter on the TR6 and have never had any issues with it (knocking on wood now...)

Cheers
Tush
 
TexasKnucklehead said:
OK, this may sound a little crazy. I know at least one person on the BCF who constantly recommends removing the fuel filter. I tested my fuel pressure yesterday and noticed something I'd never seen before. The bubble of air in my in-line filter went away. The bubble was always about 1/2 of the filter. It seems I installed the filter perfectly level, and near the carbs such that some of it is higher than the carbs, and the bubble always filled the top half of the filter. I looked back through pictures until I found a picture where the fuel level can be seen, just after I shut off the engine, shortly after I installed the alternator.

So, I've been thinking about how air expands when it is heated. I looked up the Rayleigh-Plesset equation for bubble dynamics and found it much too deep for my understanding. But I can't help wonder if my bubble had an effect on my situation. In any case, I altered the arrangement so my filter is tilted, and the bubble is minimized.

My fuel pump provides over 2.5psi. The pressure is held to 2 psi for over an hour after the engine is shut off. I have often found the most complex problems require a very simple solution. And often the simplest solution is just a prayer. I wish I knew a way to simulate my car dying when I least expect it.
Click to expand...


Just out of curiosity, ( as my set up is very similar to yours, though I use an electric FP & pressure Regulator set to 2psi).
i put mine through your test. Started with the glass filter about 2/3 full. Took it on a spirited 30 minute drive, then let it sit at idle for 10 minutes or so & got the temp up. Checked the fuel filter & there was very little fuel to be seen, except a minimal stream in the bottom.

also I did a thermal check throughout the fuel line. Nowhere did it top 190, in fact it wasn't even to hot to touch, even at the closest point to the valve cover, with the ss jacket.

means nothing really, except it points out this fuel filter operates like yours does, so it may not be your issue.
image.jpg
 
So much to read here that I will just describe my problem and see if anyone has an explanation/solution.

My 59 TR3A runs fine in cool <90 F weather. A couple days ago we had 96 F temperature when I got stuck in rush hour traffic (and two accidents blocking one lane). The temperature climbed up to 230 F when the engine died. It would not restart even though it cranked okay. I checked the float bowls and both were empty. I have a new mechanical fuel pump and gasoline hoses; newly rebuilt SU carbs. I abandoned the car in a grocery store lot; came back at sunset (83 F) and the engine started right up and drove me home without incident.

Why would the float bowls be empty because the radiator was very hot? Gas vaporizing in the delivery pipe and venting out of the float bowl vent? I don’t have these vents directed into the air filters. Maybe that is why the engine died; couldn’t suck gas vapor in with the air.

Any thoughts? I’m going to retrofit a six blade yellow plastic fan and dilute my radiator fluid back to 50:50 antifreeze and distilled water. That should help. Maybe pu in a different thermostat.
 
You describe vapor lock perfectly. The prevention is listed pretty well in this thread, but it's all a matter of reducing fuel temp.
 
If you are prone to sitting in traffic with the engine running, you should consider an electric fan.
I use the yellow fan on the TR4s but just put a Hurricane fan on the TR3A.
Charley
 
This is helpful, guys. I bought fuel line insulation and cut back the antifreeze to 50:50’with distilled water. I see the yellow plastic seven blade fan in Moss Motors. But it requires a hub extension which requires removal of the front cowling and radiator to install. A friend has this yellow fan mounted backwards without the extension hub. That makes it a pusher fan rather than a pulled fan. I don’t want to remove the radiator to install a replacement fan. Any experience with a pusher fan??? Seems to me it would be nullified at speed on the highway.
 
The Yellow fan that TRF sells does not need a hub extension but you would probable have to remove the front cowling and radiator to fit it as there is so little room between the fan and existing hub. The Roadster Factory yellow fan needs to be mounted in reverse to give clearance to the radiator. Reversing the fan does not change it operation. It is still a puller fan.

David
 
Apart from originality there is no reason to run the fuel lie around the hot engine. You can swap the su tops on the float bowls over and run the fuel line on the bulkhead between the back of the engine and the battery. So it feeds the rear carb first. I did this with my su’s and now with my webers. Helps prevent heat dish into the fuel line.
 
TR3TR6 said:
I realize that you are probably not using webers, but this is what I used on my TR3 for fuel lines along with an electric fuel pump a fuel regulator and an electric fan. I never had an issue with vapor lock, over heating or fuel delivery problems after installing this setup no matter how high the outside temp was or how fast I was going.
Click to expand...
Same, but w stock fuel pump. And hotter than heck here.
 
Thank you, and others for all of this advice. With all your inputs, and my own research, I have come to a conclusion that there are no solutions to original equipped TR3A’s to solve over heating that do not require removing the front cowling and radiator. I did this 30+ years ago when I bought this car used and not running. It was a royal pain in the @$$, so I don’t look forward to doing it again. For all I know, all those bolts and captured nuts are rusted seized. So for the time being, I will live with the limitation on what weather (I.e. ambient temperature) and traffic I can drive this car reliably. I did check, and found that my antifreeze came as a 50:50 mixture with water. Maybe I’ll replace the thermostat, if that does any good at all.
 
Donald1107 said:
This is helpful, guys. I bought fuel line insulation and cut back the antifreeze to 50:50’with distilled water. I see the yellow plastic seven blade fan in Moss Motors. But it requires a hub extension which requires removal of the front cowling and radiator to install. A friend has this yellow fan mounted backwards without the extension hub. That makes it a pusher fan rather than a pulled fan. I don’t want to remove the radiator to install a replacement fan. Any experience with a pusher fan??? Seems to me it would be nullified at speed on the highway.
Click to expand...
If you flip the fan over, it doesn't change the direction of air flow. Think about it!

I have one of those yellow seven-bladed (I think...) fans bequeathed to me by a PO. The way he left it, you had to tighten the crank bolt down on the plastic, so it couldn't be torqued properly. I had to make a bushing to take the forces off the plastic. Not the greatest situation, but it will do for now.
 
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