TR2/3/3A More Fuel pump questions.

[DavidApp]

Working on a TR3B for a friend. Trying to get it mobile again.

One thing I have noticed is there is a gob of JB weld type of stuff around the fuel pump inlet so I intend to fix that. I have a new pump and was checking the inlet pipe size. The bore where the pipe fits appears to be between 1/4" and 5/16"? Only about 0.020 smaller than 5/16". I was assuming that some pipe should protrude from the olive.
I know the double cone olives from the hardware store are too narrow to for a seal. I have the Enots type olive that has a flat section.
So the question is inlet Bore size after the thread and cone?

David

 

[charleyf]

Working on a TR3B for a friend. Trying to get it mobile again.

One thing I have noticed is there is a gob of JB weld type of stuff around the fuel pump inlet so I intend to fix that. I have a new pump and was checking the inlet pipe size. The bore where the pipe fits appears to be between 1/4" and 5/16"? Only about 0.020 smaller than 5/16". I was assuming that some pipe should protrude from the olive.
I know the double cone olives from the hardware store are too narrow to for a seal. I have the Enots type olive that has a flat section.
So the question is inlet Bore size after the thread and cone?

DavidView attachment 70798

In lieu of trying to measure the bore, I would simply state that the inlet tubing to the fuel pump is 5/16". The tubing normally extends in front of the olive by 1/16" or greater. Which leads me to believe that the bore starts at 5/16" and likely narrows slightly from there. Of course the outlet pipe is 1/4" tubing.
Charley

 

[DavidApp]

Thank you Charley.

They have made the inlet a metric size. I will drill it out to 5/16 for about 1/4"

David

 

[charleyf]

Thank you Charley.

They have made the inlet a metric size. I will drill it out to 5/16 for about 1/4"

David

I have never seen a pump that needed that treatment. I have seen pumps from where I believe came from England, Italy, Canada and I believe India.
For the cost of an olive, I suggest you try it the way it is before modifying it.
Charley

 

[Graham H]

I found the pipe fittings were an od size and thread, it took me ages to find something to fit and seal but can't remember what I did in the end.

Graham

 

[TomMull]

I'm not sure that the pipe needs to go in beyond the olive, if that's the question here. I've had the olive even with the end of the pipe and no issues.
Tom

 

[DavidApp]

I found the nut at an auto parts store. It is 20 TPI Inverted flare nut for a 5/16" tube.

David

 

[TomMull]

David,
I have had the hardware store nut work but that connection is quite sensitive. You have a much better chance of success with the special nut that has an extension beyond the threads as can be seen in the picture. Click on this link: TUBE NUT
Also insure that there is no dirt or damage to the pump bore.
Tom

 

[TomMull]

After thinking about this, the suggestion above is for the 1/4 outlet not the 5/16 inlet tube. I m quite sure the standard nut will work on the inlet side. You probably know that by now.
Tom

 

[DavidApp]

Seems both the inlet and outlet are the same thread size but have different pipe sizes. 5/16" inlet 1/4" outlet so they use the same nut size with a different hole for the pipe.

David

 

[TomMull]

Yes, that is correct. It may (or may not) have something to do with the little extension an the end of the 1/4 inch one. Standard compression fittings are sized by tube and thread size so it is fairly easy to find different tube sizes with the same thread size.
That said, I've found my TR fuel pumps to be prone to leaks so I've resorted to the big three (now the big six or more) sources for the fittings.

The other part I've had trouble with is the screen for the sediment bowl. Since it has no edging, I suspect that it allows a very slight seepage around the gasket. The seepage leaves a slight odor and is only perceptible by running a piece of clean towel around the bowl after the car has been sitting. I plan to run some sealant around the edge of the screen to see if that cures it (or shows that the leak is elsewhere).
Also seems that I've seen a plastic screen with an edge on it listed for another British marque but haven't been able to find it again.
Tom