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Well ain't this just peaches and cream.

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Only when workin' on my own stuff, Tom.
 
Well, we're getting close. The engine starts right up and runs... and overflows the float bowls like crazy! I hadn't messed with the carbs at all, but I checked them anyway. Float adjustments seemed fine, valves seated well.

I have a suspicion I may have damaged the fuel pump when I put the engine back in, as the manual priming lever seems to be jammed. I'm not familiar enough with the system to know what the pressure relief is on the pump when the float valves are closed, but perhaps I've damaged this? I'll have to figure out how that pump works.
 
Seems unlikely, but I guess anything is possible. There is no relief valve as such, the linkage from the camshaft pulls the diaphragm down to suck fuel from the tank, and then a spring pushes it back up to push the fuel to the carbs. The outlet pressure is determined by the force of the spring divided by the area of the diaphragm. Should be around 2-3 psi.

If the flow is blocked by the float valves, then the diaphragm just stays down.

Note that most vacuum test gauges will read fuel pressure as well. Eg,
https://www.harborfreight.com/fuel-pump-and-vacuum-tester-93547.html
 
Floats sinking?
 
ekamm said:
Floats sinking?
Click to expand...

This was my first thought, as it's exactly what recently happened to my Spit. But both of them at the same time? Besides, they're right at the top when I open the chamber, and I don't hear any gas sloshing around in them.

It seems a bit of a coincidence to be happening now, right after I put the engine back in the car.
 
I had the same issue when I went from a single Strohmburg to dual SU's. I Put a inline fuel regulator and seemed to fixed the problem.
 
I'd be more inclined to check the bowls, float needles, float pivot pins and all for ethanol crud as the culprit.
 
DrEntropy said:
I'd be more inclined to check the bowls, float needles, float pivot pins and all for ethanol crud as the culprit.
Click to expand...

Yeah, I suppose I'll pull the bowl covers again and do a thorough cleaning. But why is my manual priming lever on the fuel pump stuck in the 'up' position? Coincidence, perhaps...
 
What if the plunger part of the primer were bent. Would there be a free flow position caused by that?
 
If you're using a newer replacement pump, I understand that the pivot pin is not staked in place and can move to the point of disengagement.
 
I know it's a concern on Spit engines, but didn't think it's really possible on a TR engine. But I'm going to pull the pump anyway, as there is definitely something wrong with the lever arm , even if it's not related. So if your thought is true, it'll shake out when I do that.
 
You may have hit the nail on the head, Andy. I pulled the fuel pump (boy did I like working on things better when the engine was out!) and the rocker arm was jammed too far down. With a little push it snapped back into place and everything worked again, including the priming lever. I took the cover off and inspected the innards. Everything looked in its place, and the pump worked on the bench just fine. When I put the pump back, I physically felt the cam inside the engine with my finger and made sure the rocker arm was above/in front of it. Now the priming lever works correctly, and I was able to prime the whole system by hand.

Also inspected the float bowl covers again just to be sure. The front valve seat wasn't as tight as it could have been, and the rear float lever wasn't exactly at 7/16", but I don't think either of those was far enough off to be causing the problem. Corrected them nonetheless.

Anyway, it's too late tonight to start her up again (The kid is asleep, and a three year old's sleep is first priority!) so I won't get to see if I've still got a problem until probably tomorrow afternoon.

I did get the Spitfire's carbs rebuild tonight too, so all I have left with that is to tune them and I should have at least one Triumph back on the road!
 
No... I'm watching one on ebay that's got 8 hours to go and no bids at $2. Looks like it's in need of TLC though. Might just spring for a new repro for $50. At least then I can rule out the fuel pump.
 
Ok, now I'm making a little progress. Still suspecting an over pressure situation somehow. I replaced the needle valve seats with some new ones from the rebuild kit for the spitfire that I didn't use. Now the float bowls don't overflow, but the bit of hose that connects the inter-carb fuel line into the rear float bowl just gets blown off from the pressure soon after I start the car. It's certainly not any trouble to order new connector hoses, but doesn't it seem like an awful lot of pressure to completely blow off even an old bit hose?
 
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