TR4/4A Fuel Pump just checking before I snap off the lever.

[jimstr4]

My motor was reconditioned a few years ago along with a repair kit for the fuel pump.
I added a fuel filter in the line pre pump. The pump wouldn't pump so I loaded the carbie bowls and it started and ran.
So I removed the pump, undid the cover and reseated the diaphragm, it seemed to be making the correct sucking noise so I reinstalled it.
The previous time I removed it I'm fairly sure that I managed to slip the lever under the cam as it wouldn't pump until I removed it again and turned the motor until the cam lobe allowed me to slip it on top.
This time I decided to check the pump by hand rotating the crank. The crank turns two revs for one of the cam, for one crank rev the pump primer handle is immovable and for the second there is a bit of movement. Given my previous experience I have concluded that even if I have slipped the lever under the cam, the lever cam wont bend or break the lever.
Would that be a reasonable conclusion? My research says that the primer lever will be immovable for a period of each rev but I didn't realise that it was for half the time.
Is that normal? They must pump for a very small part of each engine rev.
I suspect that the pump can't pump handle the fuel filter.

Jim and the 1962 TR4

 

[TR3driver]

The camshaft only makes one revolution for each engine revolution, so that part is normal.
But on my original pump, the lever never gets locked, it just doesn't do anything when the lever is lifted by the cam. So that part doesn't seem right.

 

[Geo Hahn]

The camshaft only makes one revolution for each engine revolution,...

I know what you mean.

But... is it really possible to fit the fuel pump with the lever under the cam lobe? I have never paid a lot of attention to that, just stuck it on there - but I cannot quite visualize how this could happen.

...They must pump for a very small part of each engine rev...

Yeah, if you watch as the fuel pumps out of a detached fuel line you'll see that is a pathetic series of squirts, not an impressive flow.

 

[TR3driver]

Seems like all it takes is having the cam lobe pointing up, and tip the pump the other way as it goes into the hole. It's really crowded back there when doing it on the car, so its easy to tip the pump. For me there was something obviously wrong as I couldn't get the pump to go all the way into place. But I've heard from others where it either fit or they didn't notice the problem.

 

[jimstr4]

Thankyou for the replies.
Hmm, I can't ever remember the lever getting locked in the past. I will have to remove it again. I too thought that it just didn't do anything when the lever is lifted by the cam.
I'll make sure that the lobe is pointing down this time.
I thought that it would be difficult to remove and reinstall due to the rear bolt being near the firewall but it wasn't too hard with the use of a 1/4" drive socket with a universal joint.

 

[Geo Hahn]

...I thought that it would be difficult to remove...

I was helping a friend with his Italia (a TR3 in an Italian suit) and we discovered that fuel pump removal is an 'engine out' procedure. They just lowered that beautiful body over the TR3 engine & frame without a thought to clearances, at least in that area.

In the end he rebuilt the pump in situ by removing just the top half.

 

[jimstr4]

It must have been riding under the cam, now the lever never locks up and there's alot more travel.
Removing the top half sounds like a better option than removing the body.
Otherwise an electric pump might have been an option

 

[charleyf]

I learned the hard way that when you install the fuel pump with the arm under the cam you can damage a small node inside the pump and underneath the arm. That node on older pumps keeps the arm from going down to far and keeps the arm high enough to stay above the cam lobe during the installation. I do not believe newer pumps have that same feature.
Charley

 

[Geo Hahn]

...That node on older pumps keeps the arm from going down to far and keeps the arm high enough to stay above the cam lobe during the installation. I do not believe newer pumps have that same feature...

Interesting, perhaps one reason I have never encountered this problem (apart from dumb luck) is that I only use rebuilt original pumps.

 

[TomMull]

Interesting, perhaps one reason I have never encountered this problem (apart from dumb luck) is that I only use rebuilt original pumps.

I can't get my brain around this issue. I'm quite sure it's not possible with the pumps I've used. Perhaps someone has a picture of a later pump?
Tom

 

[charleyf]

Tom,
I should have explained further that the newer pumps appear to be made differently and the arm does not travel low enough to be a problem. While on the older ones the arm did travel lower but the node stopped that downward movement.
Charley

 

[TomMull]

Thanks for the explanation, Charley, but I think I'll remain mystified until I get back to the shop and can actually try some pumps on an engine. Tom