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MG TD TF 1500 - Why Vapor Lock Now ??

4 weeks ago I changed the fuel pump in our TD.. The pump I installed is a new unit, not rebuilt,,, It seems to work just like an SU pump should,, ie., a few clicks when the ignition is turned on, and then a click when ever the bowls needs more fuel,, BUT, Since the new pump installation, the car has had “Vapor Lock” on a few on a “hot start” occasions,, Can any one give me an idea on why the car has this “Vapor Lock” condition with the new pump and not with the old pump ??? Nothing else was changed or adjusted,,, I just replaced the pump !!!!!!

SPW
Steve Wincze

Steve - I would suspect coincidence. The reason I say this is that the normal place for vapor lock to form is in the passage between the float bowl and the carburetor and the fuel pump has no effect on the fuel in that area. If your float bowls still have the tickler pins in them, try pressing the pins down when the vapor lock happens, expecially on the front carburetor. If you get a squirt of fuel out of that bowl (around the tickler pin) then that is what is happening. All of the fuels of today have a higher rate of evaporation (I don't know if that equates to higher or lower vapor pressure), even the ones formulated for summer use, which makes for easier occurance of vapor lock. I resorted to installing heat shields on our TD to combat the problem. I have templates, pictures and part numbers for this if you should ever think that this might be the route you want to go. Good luck - Dave
David DuBois

My carbs don't have tickler pins, is this a dangeous thing, seems to me not but I'm been away from TD's since 1966. Car & carbs are running good. I know I have a little air leakage at the throttle shafts but not enough to make bad running. Got all the parts and after the Battle of the Brits in Sep I am going to rebuild them (winter type project) The last SU's I rebuilt were the HIF6's on my Rover 3500 back in '85.
greg & Grimm
G.J. Cenzer

Greg - The tickler pins are one of those things that are nice to have in certain cercumstances, but probably best not to have since they provide an avenue for fuel to flow out of the float bowls before the level reaches the overflow tubes. This could be a fire hazard since the fuel coming out at the tickler pins will drop down onto the exhaust manifold. I have never had a problem with that, but when I get some time, I intend to remove the tickler pins and plug the holes. The only dange with plugging the tickler pin holes would be that if the overflow pipes get plugged, the float bowls would not be vented and could cause drivability problems.
Cheers - Dave
David DuBois

I thought I was fighting a vapor lock problem. But found out that there was a bunch of crude in the float bowls that sometimes was making its way into the carbs. Cleaned it out and have been running fine ever since. Of course, had to find this out on the side of the road from a Model T man.
Mike R
Mike Razor

Just got my S.U.s back from a cleaning...they didn't need rebuilding.
The mechanic said one float was stuck solid, and the crud in the bottom of the bowls was a bit on the thick side...not to mention stuff "growing" on the inside top of the float bowls.....
Now they are all spick and span....
g.b.lawson '53TD

What's the best way of removing this crud?

Soaking in a solvent like acetone?
Will

He used a parts cleaner and varsol... whatever it was it didn't harm the gaskets...
He also had compressed air which is a nice way to finish them off.
g.b.lawson '53TD

This thread was discussed between 27/07/2004 and 02/08/2004

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