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zenith-stromberg carbs

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lotuslover

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On my Elan what is the correct fuel pump pressure? I can't seem to get them to pull fuel up thru the needle and seat.
 
Three to five PSI. Are you still using the mechanical pump?
 
Look for ~ethanol~ damage in the Strommies. The stuff will plug jets with green garbage and stop fuel flow after only a month or so.
 
Been there done that with the green slime. I just cleaned the Z-S and reset the float level at minimum spec.
 
Good diaphragms? Best to check 'em by holding them in front of a light source and stretching them a bit all the way around their circumference to check for pinholes.

As long as the fuel is getting into the reservoir and vacuum pulls the pistons up (dependent on diaphragms with no leaks), the thing should light off. I will assume you have disconnected the supply hose at the carbs and checked to actually see fuel being pumped out.

Some Q&A curiosities:

175 CD's?
Has it run with this same pump ahead of this issue?
Could the floats be somehow binding against the sides of the float bowl?
Could some vacuum take-off at the intake runner or carb bodies (vacuum port to the dizzy or brake boosters) have deteriorated so vacuum is diminished at the throats of the carbs?

Trying to think of any other things which might affect fuel delivery...
 
It is a new pump, I'll check all the vacuum outlets, most of those have been plugged by the PO. It does run when primed. Thanks!
 
DrEntropy said:
Three to five PSI. Are you still using the mechanical pump?
Click to expand...

I respectfully disagree with you. The correct pressure should be approx. 2.5 psi. If using an electric fuel pump use one that can supply a higher pressure and install a fuel pressure regulator after the pump that can be adjusted to 2.5 psi. That's what I've done on mY elan it runs so smooth at that pressure. I believe the pressure for Webers or Strombergs will be the same.
 
An SU diaphragm pump, or a Facet "low pressure" one will supply enough volume without pushing the float needles off their seats and no need for another device in the mix. I feed the set of dual Webers in the Spider and the Elan with SU or Carter low-pressure pumps. Never had a flooding or delivery issue.

Unless you are willing to go for a Holley regulator, a location to mount it and all that jazz, I say stay with the low pressure pumps. They've all worked for me on my personal vehicles whether running SU's, Webers or Strommies. I've put them on dozens of clients' cars as well.

What I ~have~ seen is those cheezy dial-a pressure regulators come apart to spew fuel all over the engine bay, one resulting in a toasty Alfa!
 
I have one of those pressure regulators on the car, haven't had any problems yet. I wonder how accurate the settings are? Never bothered to check it.
 
Hi Jody,

I have ZS's on my TCS Europa, and have the dial regulator too, made by a reputable firm, not the cheapie type, but never had a problem with it. I checked pressure from it upon installation, and it matched the dial. But check it just in case.

I had trouble at one time with Grose Jets sticking closed as I didn't wash them in acetone before installing them. As a second check, pull the diaphrams/pistons out and see if you can see the gas near the top of the needle jet. As Dr Entropy said, check the diaphrams, and I am running 2.5 psi on my ZS's, works great.

I had trouble starting my TC a while ago, and had to pull the starter to ensure it was cranking fast enough. Once I overhauled that, it seemed to start easier. FWIW, I also installed a starting circuit (choke) on the rear carb, and a CD ignition which also helped it to start when cold.

I hope this helps, Jerry
 
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