Topic: 85 4Runner losing power at 3000 RPM

[r6006a]

First off, I'm new to this vehicle, new to forums, and not very experienced mechanically.  So I apologize ahead of time.

I just bought a 1985 4runner EFI.  One of the previous owners installed a header on it but everything else is stock.  After taking it out the first time and trying to climb a few hills, I started experiencing a slight loss of power at 2200 RPM (which I can accelerate through) and then a drastic loss of power at 3000 RPM.  The power loss is most noticeable in 3rd gear.

I've done some trouble shooting to see if I can fix it and I've had no luck.  I noticed a loud vacuum leak and found a hole in the flange where the header attaches to the block.  I tapped it and filled it with a pipe plug.  That fixed the vacuum leak but did nothing for the power issue.  I replaced the spark plugs and also cut out the catalitic converter and welded a straight pipe in it's place.  It's not throwing any codes and I'm beginning to wonder if the problem is electrical rather than fuel or compression related since the loss of powere is RPM specific.  As a side note, the fuel filter was replaced about 11K miles ago so it should be fine as the filters are supposed to be lifetime (or so I've read).

My brother in law and I also adjusted the timing to the proper specs per the FSM.

Any help from you guys would be greatly appreciated.

[H8PVMNT]

I think your timing chain has maybe jumped a few teeth.  My buddies '85 4runner was just like that and it was about 12 teeth off on the timing gear. Tried all kinds of tuning before taking it apart but nothing worked.  Just had to put the timing chain back right with some new guides and a good timing chain tensioner.

This symptom could be caused by the throttle position sensor being off, but I'll bet it's your timing chain...

[tineye]

I'd say timing chain, does it start, idle, and shut off fine?

[r6006a [OP]]

Starts, runs, and idles fine.  I'll take a look at the timing chain and see if that's it.  Thanks guys!