Evap System Question

[Jason_25]

Could someone explain in detail to me how the evaporative emission system works on explorer 95 and newer?

Since my engine was switched out I noticed that one of the lines coming out of the valve (driver's side fenderwell) wasn't attached to anything and hanging loose. I noticed 4 lines running from the rear of the truck to the front. Are these all fuel lines?

I need someone to tell me where the lines running from the valve up front go to!

Thanks in advance.

 

[Jason_25]

Are one of the lines from the valve supposed to run to the throttle body?

 

[410Fortune]

Jason,

Not sure if your 95 is the exact same but if should be.
The feed line goes from the TB to the canister purge valve itself, then from the canister purge to the evap (chacoal) canister and then to the fuel tank.

The computer tells the canister purge to open, this foces air through the lineand purges the fumes built up in the evap canister back to the fuel tank.

You also should have a fuel return line back to the tank for all the gas that doesnt get used by the injectors.....

does that make sense?

This system should be outlines in any Haynes or chiltons......

 

[Jason_25]

410, that sounds right for 91-94 explorers. But for 95+ the system is very different, and the Haynes manual offers no diagrams, only a vague explanation

 

[410Fortune]

Okay I was wondering about that, I know they changed a bunch of stuff after 94, and I'm no good after that since thats all I have worked on......

Somebody here must know.......

Also whenever I have a question like this I will go to the dealer, locate a similar truck and take it for a test drive or just pop the hood, if you catch my drift. Man those poor suckers though they were gonna sell another car!!!
hehehehe

 

[Jason_25]

Here's a diagram I drew up. Does this look right?

Sorry for the poor quality.

 

[dogfriend]

I'm trying to make sense of this

I have a factory manual and a bootleg CD with Powertrain/Emissions but both are for a 97 Exp.

The description of the function of the Evaporative Emission System is 18 pages long. The basic function is exactly as 410Fortune describes it. The purge vapor flow is shown as entering the intake just upstream from the throttle body. The valve you are describing is known as either the EVAP canister purge valve or on the Vac diagram as the VMV (vapor management valve). You should have a Vac diagram on the sticker under the hood.

The part that may be confusing is that the VMV has 2 hoses that connect to the intake. One is the hose mentioned above that supplies fuel vapor, the second hose connects downstream of the throttle body to supply manifold vacuum to the VMV.

One warning: My manual shows one drawing with vapor supply going to port upstream of throttle body; others show same hose connecting downstream of throttle body. To me it seems like it should be as I described but it is possible that the two should be reversed

I know what 3 of the four lines are, but I can't figure out the last one. The first two are fuel supply and fuel return (both connect to fuel rail) One of the others is the vapor line coming from the canister. I believe that the fourth line may go to the canister vent solenoid, but I'm not sure. This would make sense if the canister vent solenoid is under the hood somewhere.

Hope this helps

 

[dogfriend]

oh yeah

I left out the part about the canister location. Its located right next to the fuel tank on the later Explorers. I think it was under the hood on early Explorers (like my 89 Ranger). My manual says that the later Explorers have two canisters, but I think that they are both in the same assembly.

 

[Jason_25]

Ok that all seems to make sense and I have hooked it up as good as I can.

What I need to know now is the large hoses from the VMW go. I know one goes back to the canister, and one goes to the fitting past the throttle body, but which is which?

 

[dogfriend]

top one should go to throttle body

bottom should come from canister

i tried to look for where the 4th line goes this morning but couldn't see it under the hood. I'm kind of curious, but don't have time to crawl under the truck right now.

 

[Jason_25]

Thanks dogfriend!

I think the 4th line may be the rear brake line, it's cramped in there so it's hard to tell.

 

[dogfriend]

that may be correct about the brake line, because the schematic (vac diagram)implies that the canister vent is located near the canister at the rear

the thing that is weird is that the picture of the fuel line assy in my manual shows 4 lines. You would think that they would call it the "fuel line/brake line assy" instead