View Full Version : TR2/3/3A TR3 Fuel delivery problem

09-05-2009, 02:29 PM
Having trouble with fuel delivery on a TR3.

I'm stumped as I can find no issues with the pump but it will not move fuel when running on the engine power.

I replaced the fuel pump when getting the Ol' girl going. I've driven many miles with no troubles. The other day I was stranded on the side of the road with what seemed to be fuel starvation. I cleaned out the fuel bowl of some trash and used the hand pump to fill the filter bowl and float chambers. The engine started and ran until running out of fuel again when the float chambers empty. I'm getting no fuel flow at the carbs with the engine running but I am able to use the hand pump and get plenty of flow.

Could there be an issue with the diaphram in the pump? Vapor lock of some kind? Maybe a problem with the cam lever not moving the diaphram enough to move fuel?

Anyh ideas or similar experiences out there??


09-05-2009, 03:09 PM
There's a pin on the side of the pump that holds the cam lever arm and link lever inside the pump. The pin may have come part way out or might be gone entirely. It's supposed to be held in by two retainting clips, but I seem to recall reading about them being inadequately peened in place and falling out on replacement pumps.

Geo Hahn
09-05-2009, 08:44 PM
I too have had that pin fall out. As noted the originals were held with circlips or such, repros sometimes used a press fit.

But based on your symptoms I would suspect one of the check valves may have fallen out. I have had that happen too. If a check valve is gone it may just be possible to pump using the priming lever but not get sucessful pumping under running conditions.

The check valves were sometimes swaged in place with a couple of peens -- on other pumps they are held by a little butterfly-shaped piece secured with a screw.

Check valve operation can be confirmed (w/o disassembling the pump) by a 'suck & blow' test though I have only done that with the pump on the bench.

09-06-2009, 12:26 PM
Duke, we all have stories.

My TR4 began stalling back in the 70's when I needed to get to class. Engine would just quit as I was driving, and I didn't have the money to do anything but tinker and complain.

I'd pull over, disconnect the fuel line, blow into it, suck on it, and if I was lucky it would run again--though twice I left it on the side of the road and hours later it just started again.

I knew about that lever pin even back then, and it was firmly in place. I eventually "gave up" and just replaced the fuel pump, but then I stalled again a few days later.

That weekend, totally frustrated, I drained the fuel tank, looked in with a flashlight and found a 12" piece of wood that had been floating around with plenty of other prankster debris.

My car ran perfect from that day forward.

My message for that symptom is to check your pump, of course, including that pin, but be sure your tank isn't clogged and obstructed. You need solid steady flow to the pump. Maybe a no-brainer, but I get agitated again just thinking about it.

Don Elliott
09-06-2009, 01:07 PM
I had exactly the same problem with my 1958 TR3A on a 1550- mile trip from Montreal to VTR in Valley Forge PA and back. I put it down to the 10% ethanol that is in all gasoline in USA but I never had this before in Canada. I always buy my gas at Shell here in Canada and back then I assumed that Shell Canada had no ethanol. While in PA I removed the outlet pipe just at the exit of the fuel pump and the pump would pump like new.

I suggest you do this to check your pump before pulling it off the block.

But my float bowls would remain empty when I would re-connect tye outlet pipe from the pump. It would start like you if I filled the float bowls. After about an hour the problem would seem to disappear, so I would carry on till it happened again.

Randall Young suggest that I change the 50-year old feed hose as the ethanol might be affecting the inside of the old rubber. I have the banjo fillings on mine so I took it to a hydraulic hose shop and they made me a new one. I put it on in 2008 and started to add 4 oz of Marvel Mystery Oil to every tankful of gas.

Since then I've had no issues, even when I filled up in Vermont at a Shell pump where there was a notice that the gasoline at this pump contained 10% ethanol.

09-06-2009, 09:25 PM
I have seen new AM pumps have the arm too short to reach the cam, also a worn lobe will stop you dead.Always remember the old AC does NOT SUCK, it wonts to push fuel that comes to it,take off the primary line and watch the gas gush out of it...now clean up your mess.If the gas did NOT gush you have found the problem.
MD(mad dog)