Honez

Anyone had any issues with fuel leaking through the aux accel pump diaphragm over and over again?
Happened about a year ago and found it after failing a smog. Replaced the diaphragm. Truck is rarely driven. Couple hundred miles later, same problem except this time it started leaking through within 50 mile. Replaced again yesterday and happened again. Cheaply made parts or something else?

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1986 pickup, 22r, standard cab, 4x4, 107k

L5wolvesf

You are missing some info here - see my sig. Also don't know your location.

1 pic = 1k words. Pics of the pump diaphragm would be interesting to see.

Honez

Aux Accel Pump housing is marked in blue tape. diaphragm sitting in front of it.

Honez

While driving fuel leaks through the diaphragm and into the vacuum lines. Lousy idle and stumbles on deceleration. The diaphragm does not have visible holes. I haven't rigged anything up that would allow me to put vacuum to it and see where the fuel comes through. Don't know why the original lasted 30+ years but the last 2 lasted less than 200 miles.

L5wolvesf

So, I didn't state my request quite right - my bad. What I would like to see is the 2 or 3 prior diaphragms in one close up pic. So I/we can see where the break is occurring.

Honez

Sorry about that. That is actually the biggest part of the problem. I can't find a hole or tear. The original that lasted 30+ years was torn. The next two were not. The best I can tell is that the MAY be seeping or leaking around the brass cone in the center. I may just build a vacuum chamber that I can see through and test the two that I have and see wear the fuel comes through.

Honez

UPDATE: I put in a fourth diaphragm and had the same issues with fuel leaking past and entering the vacuum lines. As a Hail Mary, I ordered an OEM from toyota rather than the after-market I had been buying. It is working fine! The low quality after-market were the problem. Unfortunately the toyota diaphragm was $80.

To test/prove the outcome I made a glass vacuum chamber and placed fuel on one side of the diaphragm and vacuum on the other. Three of the four cheap diaphragms were leaking fuel at the center point where the brass center cups are pressed together through the diaphragm. I would assume that the first of the four would have leaked there as well but I throw it away before testing. In this case, cheaper was not better at all.

old87yota

Great news!

Toyota OEM parts are usually the way to go.