DTC 33 and 34

[Warren96]

Last June I replaced the vac pump because it had a pulsing reading when hot. This year it started the same thing so i thought it must be another pump. Put the new pump on and the same thing, pulsing when hot. How can it be possible to have 3 bad pumps in a year? .....Am i missing something? ..... Anybody else have this problem?

[More Power]

The diaphragm in vacuum pump is actuated by an eliptical cam lobe on a shaft that is driven by the belt pulley, so vacuum tends to pulsate. The 6.5 vac pumps I've checked with a vacuum gauge all swung the needle in the meter about 2-3" while the engine idled, centered on about 19-20" of vacuum.

So, in my opinion, a vacuum gauge will show some needle swing at idle when testing a normal vacuum pump.

Jim

[Warren96]

First off let me apoligize for a mistype in my opening title, it should have read DTC32+DTC33 the EGR codes not DTC34. (Happy fingers I guess) These codes refer to low vacum in the EGR circuit. I think I checked all of the usual suspects, all the vacum lines have been changed, the wiring checked and the supply volts to the solinoids checked. And 2 vacum pumps had no effect. Both solinoids and the baro are the originals. The puter is programed to shut the EGR down (no vacvum) if it senses a fault. What makes this problem so hard to chase down is the fact that the codes won't set in the puter or the vacum won't go away in the vacum circuit unless it's a hot engine. I always have vacum in the EGR circuit when the engine is COLD. It's like the old which came first the chicken or the egg proverb. I'm at the end of my rope, anybody got any ideas for me?