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I have a 1988 Ford E-350 Motorhome with a 351 (5.8) and the C6 automatic transmission. I am trying to figure out how to fix an OBD1 Code 85. As near as I can tell it is a problem in the Canister Purge Circuit. I've replaced two other sensors that were throwing codes 32 (EGR Valve Position Sensor) and 23 (Throttle Position Sensor), but I cannot find any sensors in this circuit. The vacuum diagram lists a canister purge solenoid, but when I traced out the lines there was not one to be found, and everything looks factory to me. I know there is no canister purge solenoid on this RV. I just got done replacing all the vacuum lines between the carbon canister and the throttle body (they were badly dry rotted), and there is no canister purge solenoid. Maybe they put the wrong vacuum line sticker on my E350 at the factory...lol
Is this just a ghost code that I can safely ignore since my canister purge system is vacuum driven?
I have a manual for my 88 E150 and will scan through it to see if I can find anything that might help. I don't have any codes but I never have any pressure or vacuum built up when I take my gas cap off so I need to learn how that system works! I also read something about an engine running a bit rough at lower rpms due to a bad vacuum line in the purge circuit.
do you have a single fuel tank or duel tanks?
If it is supposed to be there as your vacuum diagram shows,, here is the wiring from the ecm.
There are a couple more pages on trouble shooting the circuit but it assumes you have a breakout box. As you can see though you are dealing with #31=Grey with yellow stripe, 37=R, and 57=R.
Your E350 is EFI correct or Carburetor? I am thinking by 88, all the 5.8s were EFI
If you don't have a Ford service manual, you should think about getting one as they are much more detailed then other aftermarket manuals.
Here is one. You might be able to find one cheaper if you shop around but they are getting harder to find. https://www.ebay.com/itm/1988-Ford-T...0AAOSwaMhZwYTh
