Hey everyone! This is my first post even though I read a lot of info on this forum.

 

Anyways, I just finished swapping a 1986 or 1987 engine into my 1981 4wd brat and got it running successful. The problem is it runs to good. It acts as if it's always being floored. I even got a fcproducts remanufactured carb on it. I have tried everything in my feable knowledge like adjusting the idle screw, holding my hand on the intake to see if it's getting air from somewhere else, adjusting the fast idle screw, unplugging vacuum lines, holding the valves closed and timing (althought it's hard when the engine won't idle). It seems like once it gets warm the problem is less but I doubt that has much to do with it.

 

Really, I'm not even sure it's the carb that is causing it and don't know what else to try! Any help would be greatly appreciated.

First off, welcome to the board! You already know that this place is chalk full of awesome (and sometimes not so awesome) information.

 

Now I'd like to drag your attention to the throttle cable. Make sure that its got a little slack in it to rule out the "too tight throttle cable" thought of mine. Also, check the linkages to make sure there's no binding going on and try bringing them to the idle position with your hands. Even though its remand, you could have a sticking throttle shaft which would cause this issue as well. If these both check out, look at the choke and make sure its functioning properly. One way to check the choke is to disconnect the wire going to it and hold it open with your hand (manually). If it still has a high idle after these few checks, we can basically rule out binding or the butterfly stcking open.

 

So now what you ask? If its remand and its none of these, next thing is the adjustments for the throttle adjusting screw and idle adjusting screw. Now this is coming from my '83 FSM for the EA81 and I could get it from my '78 FSM but it'll basically be the same thing. I'm also going to shorten it down and bit and make it so its not quite so technical sounding too.

 

1. While running, adjust the throttle screw to specified engine speed.

2. Adjust idle mixture screw until maximum engine speed is obtained.

3. If engine speed rises, readjust it to the specified engine speed with the throttle adjustment.

4. Repeat above steps until engine speed at best idle mixture is obtained.

5. Readjust engine idle speed to specification by turning the idle mixture screw.

The throttle cable has slack in it. It was the first thing I thought of. I messed with the idle screw/fuel air screw/throttle stop screw and none of them make a slight difference. But i'll try them in the steps you said. I think I just need to put a piece of cardboard on the intake so that its not redlining why I am making adjustments, don't wanna blow my new engine. Im wondering if it is a stuck needle or vacuum hose somehow pulling in to much fuel. Thanks for the reply!

disclaimer *i know more about Ganymede's soil composition than carbs*

 

vacuum leak? have you tried shooting some carb spray around in the engine bay?

Welcome to the board! Have you hooked up a vacuum guage to see if there is any vacuum when the engine screams on up to redline? If the vacuum is somewhere in the 15-20 inches as if it were idling, then you might have a problem with your distributor. One of the springs on the mechanical advance mechanism could be missing/broken.

 

Back to ideas on troubleshooting on the carb, I have gotten inproperly rebuilt carbs before. Can you verify that the float valve is cutting off properly and the fuel pump isnt just pushing fuel down the engines throat?

 

Good luck, hope thats springs some ideas

Thanks for the reply. I am going to test the floats today. The distributor could totally be goofed up, could I disconnect the vacuum tube going to the vacuum advance to test if there are broken springs? Or do I just need to take it apart to look inside and see?

P.S. One important detail I forgot to mention was - I had the old carb on it, and it did the EXACT same thing, which lead me to believe it was the carb b/c the old carb was pretty much obliterated and covered in gunk. But the new carb still redlines it which leads me to look somewhere else than the carb. . .

could you possibly be connecting

a vacuum line to the seconday throttle plate diaphragm

by mistake.

 

Both carbs would then do the rev to the max gig.

 

Note: I would have to go get one to verify the

secondary throttle plate diaphragm is external

on the EA81 HiTachi.

That could totally be it! Although I don't really know what a secondary plate diaphragm is - However, the vacuum lines Im just sorta plugging in all willy nilly, according to my manual. The problem is the manual only has like 1/2 of the lines in it. Good ol chilton. My friend who is much more knowledgeable about carbs is going to help me soon and i'll make sure to run that by him. Thanks for the reply!

good luck, I checked a couple I have

but

one Hitachi is for an EA71 - it's secondary is mechanical

 

the other I found quickly is for an EA82 and

it has the diaphragm operated secondary,

but it's connected internaly.

 

I'll keep digging, if I find the proper type I'll post

a picture of the seconday diaphragm.

 

I did see a picture on here recently of the unit in question.

Found it thanks to "Brown Muscle"

The part that is missing is the part you need to look

at. Funnel shapped thing .

How lame is that???

read up on it here

http://www.ultimatesubaru.org/forum/showthread.php?t=93320&highlight=secondary

Edited January 11, 200917 yr by Skip

Wow. So I figured it out. There was a silly one way check valve going into "selenoid valve 1" that was backwards. So happy/mad right now. Anyways, good info for future engine swappers!