Plays_with_Toys

I swear this sounds like my truck when it still has a cold engine... I am not sure how the rich cycle works though. Have you checked your distributor cap/rotor?

What kind of smell is coming out of the exhaust? Maybe its running really rich, and you when you floor it, you're in essence drowning the engine, because its already getting too much fuel and you asked it for more?

jimbo74

well started trying to track things down today, it is not the coil....
i changed the fuel filter: did nothing
tried t ocheck the fuel pressure: didnt read on the guage... what is the fuel pressure supposed to be for my truck?
doesnt seem to be a clogged up exhuast, i cut the muffler off, and nothing... then loosened up the collecter to downpipe flange, it got super loud, but still acted the same way, so doesnt seem like a plugged up cat.... also disconnected the ECM, that didnt do anything either.....

jimbo74

i am thinking it hopped a tooth on the cam? could this be it? i hope it is, it should be easy to find and fix... jsut a note, imy timing used to be set at around 5* with adjustment both forward and backward... well today checking it out, i cant even get the distributor near 5 degrees, lowest it will go is like 12* and the highest is somewhere around 30*, looks like it might have jumped a tooth... will bust it down in a little while and examine

kyle_22r

12* and 30*? yikes! time to pop that dizzy out of there and reset it...nothing too hard. rotate your crank to 8* BTDC on the #1 compression stroke, point the rotor straight up and down, shove it in and it should move to about a 10:00 or 11:00 type direction. easiest way to check that you're right is to then pop the rotor off and line up one of the teeth on the star with the little "line" on the pickup in the distributor. i've been running my motor this way since i put it together and i haven't even gotten around to timing it yet.

never heard of a distributor jumping on one of these motors...but the way it sounds is that might very well be your problem, and it's definitely worht a shot.

also when you say your carb butterfly is stuck open, which one is it, and is your engine hot or cold when its doing it? when the engine is warm the passenger side(primary) choke flap should be open

jimbo74

i wasnt talking about jumping a distributor gear tooth, i was talking about jumping a crankshaft gear

but sounds feasible... if it appears that this doesnt fix my problem, then next in line is fuel pump and carb..... hopefully one of those will fix it?!
i have a old carb from the junkyard engine i got.... except it has clipped off connectors, i will rewire it if i need to though..... and i can get a fuel pump to test at the junkyard if needed.... whats the pressure of the fuel pump line? it didnt register on my friends guage....

kyle_22r

i'm having fuel pump problems right now...i'm only getting 1psi right now and my truck cuts out under loads...

should be anywhere between 2.5 and 4.5psi i think.

carb wiring is easy, just 4 wires. red wire and solid black wire(little solenoid with a black wire and a black/white striped wire coming out of it) are hot with the ignition on, the striped wire is a ground, and the purplish wire on top i have no idea. you could probably splice them into your connector

jimbo74

hmmm.... ok well i jsut tore into my truck.... want to check some things.... when the no 1 cyl is @ tdc and the crank pulley timing mark is @ 0* , the little locating nub on the camshaft should be @ the 12 o clock position right?

Ganoid

Keep in mind that your crank shafts goes around 2 times to one rotation of the cam. Im not sure on the nub thingy since i run a 3.0 but be sure you are not at TDC for the Exhaust/intake stroke. You need to be at the TDC where both your valves are loose with no tension on them (closed). Ideally for a rough estimate you can look at the TDC mark on the crank, make sure the valves are closed then make sure the dist is pointing to the #1 spark plug wire. If all that is correct then you are as thay say "In the ball park"

If you are too far out of the ball park it wont run at all. Reading the posts above I would just check the cam timing and set the ign timing at an idle to factory specs. As long as the valve cover is off you may as well set the valve lash too. From there I would start looking at the carb. I highly doubt its fuel pressure as carbs just use the pressure to keep the bowl full. If it was fuel volume then you would run great for about 30 secs then the power would fade away until you backed out of it and let the bowl fill again (essentially running out of gas). Im no expert on that model and year for sure but if you think you have a throttle plate stuck open then I would start there for sure. Both plates should "appear" to be completly shut at an idle or when the truck is off. The low speed primary (assuming its a 2 barrel) may be open just slightly to allow for idle air but again it will appear closed to you looking in.

If you are getting backfiring then its safe to say you have a lean condition or well.... reasonably safe. If you can idle fine and your idle to 1/3rd throttle response is ok then I would say the primary circuit is fine also. Carburators care about throttle position just like EFI since throttle position = engine load, The carb usually wont give a crap what RPM you are at for the most part as that has very little indication of engine load.

If you have both butterflies shut at idle and you are only having problems above 1/2 throttle then I would look at the main jet in the secondary specifically. Im not sure if your carb has vacuum seconadry or mechanical? If its vacuum then you may want to look at the vacuum actuator as well.

Do some more digging and get back to us Im sure this thing can be soloved.

Ganoid

Just looked through some of the posts again. Your ignition timing may be the clue. Some one mentioned vacuum advance but it could be thought of as vacuum retard if I remember correctly. If you do Indeed have a secondary valve stuck open at lower speeds then you should have very little vacuum in the manifold and the distributor would go ahead and advance the timing accordingly as if you where putting the coals to it.

When the distributor sees lots of vacuum (engine running but throttle closed,idling) it retartds the timing back to what ever point you have set it at 5 deg I think you said? When you start to open the throttle you let the air in and let the motor breath and in the process reduce the vacuum present in the intake manifold. The vacuum advance on the distributor sees this and lets the distributor start advancing the timing up to what ever the max is for the distributor. Your timing at WOT is what ever your base timing is set at + the amount the distributor will advance it. Some distributors use vacuum + a spring some use vacuum + centrifigal advance some use computers and im sure there are some other methods I have forgot about as well.

Dont be afrade of the carb. Thay are complicated as hell in theory but mechanically thay are very simple once the factory has done all the hard work in setting up all the base lines. Look at the carb linkage and try to figure out how the primary (small) and secondary (larger typically) valves or butterflies open. Im guessing that in 1985 toyota was using vacuum secondarys. If you think the secondary is hanging open then it may be a broken vacuum actuator or line. Remember that lots of vacuum is only present when the throttle valves are closed so bearing this in mind it stands to reason that a vacuum secondary much like the timing is pulled shut by vacuum and opend by some sort of spring when there is a lack of vacuum and the throttle linkage is past a certain point. Use a zip tie or somthing and tie it shut but make damn sure you dont mess up any of the other linkage in the process. I have no problems throwing out ideas to manually rig throttle valves shut but under no circumstances should you EVER rig one to stay open.

You can also look at where the vacuum connections are on the carb. I was looking back over what I wrote and forgot that there is indeed another principal that could be used to run secondarys and distributor advance as well. If the lines connect to the mid to upper section of the carb then its likley the vacuum in those lines is increasing as engine speed rises due to the venturi affect created in the carb. I havent played with a toyota carb so I have no idea wich principal thay run on? Maybe you should check the 4x4wire.com boards? most of those guys (including me) have been around a while and tinkerd on plenty of carbs. Most of the crowed here seems to be oriented to newer vehicles that are EFI.

Just some ramblings and some theories to think about when your trying to trouble shoot this critter. Remember vacuum from mid to top section of the carb increases with engine speed while anything at the base of the carb or intake manifold will lose vacuum when the throttle is opend. Look at where the individual lines go for the secondary and the dist advance and determin what thay need to do thier job based on where thay are connected.

sheesh I feel like I wrote a novel.... where is the spell check?

jimbo74

if i screw up the cam timing by it being off a whole turn it wont run @ all correct?

jimbo74

ok... it works now..... hmmmmmm ... any got a picture of what the timing chain guides/tensioners look like? the reason i ask is what happened was it appeared that the chain jumped a tooth... well actually about 3-4 teeth... meaning something aint right...... might be time for a timing chain.... and new steel guides..........

the tensioner doenst appear broken, however the left one looks like it pivots on only 1 bolt... and this doesnt quite seem right to me.......

jimbo74

ok looking around the net... and LCE has metal chain guides... jsut the 2 chain guides are $80...... engnbldr.com has a whole kit with only the "driver" side metal guide for $65.....

is there anywhere else to get both metal guides, and keep it cheaper then $80.... i would also want to replace the actual timing chain as well, and i know i will need a water pump gasket and a little rubber band oil pump gasket as well

Plays_with_Toys

Not sure about your questions.... but you got it running properly again?

jimbo74

yup it runs again... what happened was the camshaft basically jumped a couple gear teeth and made itself have like 40* of advance timing... my truck didnt like that and ran like crap (surprised it ran at all)

i was looking down the front cover, and it appears my driver side chain tensioner is broken.. looks like it only has 1 hole..... and you cant secure stuff with one hole... so i think the otehr hole has snapped off... time for replacement....

let me ask: should i get a new chain, gaskets, and the LCE 2 piece metal tensioners? or should i buy www.engnbldr.com 's kit with a metal drivers side tensioner? or use stock plastic yota? im trying to stay as budget minded as possible, but will spend the extra money for longer lastingness and quality

jimbo74

also i see a conversion kit that is $500 for a dual row timing chain

however there is a standard set of dual row that is a lot cheaper.. is this the same? or no? the only difference i see is that the conv kit has a largerincluded cover and the otehr one doesnt... would the new cover be needed? also it says about the guides being "metal backed" does that mean part metal? or are they fll metal?

kyle_22r

as for the pivot thing, the hole on the passenger side guide is elongated so there's 2 positions it can be set to. however it definitely shouldn't be moving!

jimbo74

no it was the one on the driver side that had what appeared t obe 1 bolt holding it in.... i think its broken.....

the lce stuff had 2 bolt holes, mine clearly doesnt

jimbo74

does anyone else reputable make the guides also?

kyle_22r

i'd go with engnbldr's stuff, price is right and it's good quality. i have the same ROCK parts he sells in my engine.

jimbo74

ok doa makes them... how are they? i have heard their stuff is cool, but they are a pita to deal with...