Ares

Hoping this is easy for you guys. I thought I heard an air leak in the engine bay to a '85 toyota pickup I just bought yesterday. I ended up tracking it down to a unit unit that sits on top of the valve cover in the back. Its got 2 ports. A vacuum tube goes into it from the intake, drawing air, but no hose attached to the other port. Anyone know what hose is supposed to be hooked up here and where it should go? I'll see if I can get a picture soon for you. Thanks

pcmentor

Are you talking about the A/C idle up valve or the EGR Modulator? Each have more than 2 ports. Also the A/C Idle up switch has two ports but is on the middle of the valve cover.
Which part in this drawing? Or could you mean the PCV valve?

Yoda

Welcome to Yotatech!

Ours has a vacuum valve that connects to the fuel pressure regulaor. Look at the firewall end of the fuel rail. Should be a small "can" with a nipple/hose that should go to a vac valve.

A picture would help us to help you.

Ares

Here is a picture



I thought the can was the charcol canister?

pcmentor

This looks like the A/C switch. Does the truck have A/C? There should be a metal valve with 2 or 3 hoses coming out of it at the middle of the plenum. This has an adjuster on it that you turn to adjust idle when A/C is on. Your part probably should be connected to this valve. This is a drawing of it. P/S is for power steering. Also what colors are the wires?








Yeah it's the Fuel Pressure thingy only on 4wd's!

4Crawler

iTrader: (3)

ON the back of the valve cover is typically the VSV for the fuel pressure regulator:



http://www.4crawler.com/4x4/CheapTri...ine_Pix/9.html

It can be eliminated as follows:
http://www.4crawler.com/4x4/CheapTri...ne_Pix/10.html

Ares

Ok, now be patient with me here, this is my first toyota truck, I'm coming off of AMC Wranglers here.....

So the truck does not have A/C, and to my knowledge no p/s either. I haven't looked if it has a ps pump, but based off how it drove, thats just my assumption.

Now the VSV, I assume there is only 1.

Its currently hanging below my intake manifold/T.B. I believe its only hanging by the wiring, nothing else connecting to it, but I'd have to look. The truck is at home and I'm at work. So these two items should be connected together?

But, as I look at your picture 4Crawler, the hose I'm missing is this one



What type of issues would this be causing. Right now the engine is making some pretty horrendous noise as very specific throttle positions, and has absolutely zero power, but I think these are unrelated to this issue .

I will take a closer look at the vsv and valve unit guy when I get home today, and I'll find out what color the wires are too. Thanks again guys, sorry I don't have more info on hand

4Crawler

iTrader: (3)

Same VSV, only present on 4WD models for some reason. I got rid of mine years ago. See the web page above for a description. You need some sort of vacuum feeding the fuel pressure regulator, as shown in your diagram above. Mine is direct connected to the intake. Without proper vacuum, you get too high a fuel pressure at low engine load and the engine runs way rich and bogs down until you get up to higher RPMs and loads on it. At WOT, you would have no vacuum at the FPR and full fuel flow, but at idle, you need way less fuel so less fuel pressure.

Ares

Ok, makes sense. On your bypass you just simply cut out the VSV from the circut along with its partner unit in that picture it looks like? Easy enough.

I will check to make sure the FPR is #1 hooked up to a vacuum and #2 hooked up to the right vacuum. I have a feeling the PO who rebuilt this engine didn't exactly know what he was doin.

Thanks for all your help so far, I'll be sure to let you know if theres problems here when I check it out. This has been a very rough and unpleasent begining to the Yota 4x4 life

4Crawler

iTrader: (3)

Yep, replace an electrically operated VSV, it's connector, and two sections of vacuum hose with one piece of hose. Simpler, cleaner and it works just fine.

Ares

Sure enough, the FPR was disconnected from the vacuum. It didn't fix the power issues i'm having, but at least its a start.

Thanks for all the help!

4Crawler

iTrader: (3)

Might try resetting the ECU (pull the EFI fuse or disconnect the battery for a few minutes). ECU will have "learned" how the engine was running with the high fuel pressure and resetting it will make it re-learn with the new setup. Might help and can't hurt anything.