The part you have the pencil is part of the shotlengthener.
Without a s/l a ECO (this applies to the 93, 97 & 98 models) produces around 55 psi. With a s/l it will produce almost 110 psi.
Explanation: When ECO 90s were first produced service stations serviced cars and truck, so the ECOs needed to produce air pressures above 100. After trucks quit going to service station and went to truck garages, ECO offered these units without a s/l.
This has nothing to do with black plastic piece. Since I cannot see what it is I can only assume it is a broken piece of a spacer. Spacers are plastic and are usually red, but this one could be black. Spacers were used to lower the maximum PSIs. I have a large bag filled with many different size NOS ones.
(How many of you know the ECO sold a 97 that was capable of producing 300 PSI [if you compressor went that high]?)
You need a service manual.
We have been supplying parts for ECOs since 1989 and we believe we have the larges inventory of parts available (they are not being made anymore, but we do make many of them). We also offer a mechanism rebuild service.
http://petrolianacollectibles.com/eco%2090%20parts.htmJack Sim
