Wannabetruckguy

I recently purchased a 1984 Toyota pickup 4x4. My friends owns an 83 and told me it would be a great first truck for me. The engine was rebuilt a little under 50,000 miles ago but other than that everything else is stock. I had a few questions I was wondering if anyone could answer for me.

1. It backfires when you get on the gas, about 3-4000 rpm's. I was told so many different things by so many people who "knew" what the problem was. Anybody know what it could be? or how to check?

2. It seemed to not want to stay alive today and it was recently transported to the city I live in when doing so it came up 500-1000 ft. in elevation, we are now at 4900 ft. From what I read this is more than likely the jetting. Is there a safe way to tune the jetting? The only people I know won't touch it in fear of not being able to get it to start back up or making it to lean and burning a piston.

I am fairly mechanically inclined i.e. being able to fix things, but my knowledge of trucks and engines is fairly small; so please take it easy on me.

xxxtreme22r

backfiring issue sounds like an ignition timing issue. Which would certainly cause your other issues.

For elevation change you may or may not need a jet change. Very hard to find on stock aisin carbs BTW.

What you might want to mess with is the idle mixture setting using basically what the weber carb guys call a lean best idle procedure. But I highly recommend you have a shop do this if you are not familiar with carb tuning.

500-1000 ft elevation change really isn't that much. I travel to and from work at about the same elevation change. I notice a bit of a difference but nothing like you describing at all.

Best info on the net about your carb. http://www.bluebassdesign.com/boonin/carb_faq/

Wannabetruckguy

So for both issues I'm at the mercy of a shop mechanic? :X

I understand the basics of tuning a carb. You tighten/loosen a screw that dictates how high/low the needle gets before stopping either allowing more gas and less air or less air and more gas, for the most part right? What I don't understand is a friend told me if I leave it too lean I can burn a piston, is this true?

As far as the timing goes is there a way to check or should I just take it into a shop for that one?

xxxtreme22r

As far as the idle mixture screw goes, it meters how much outside air the carb brings in in relation to how much fuel is sent through the jets.

Don't get the idle mixture screw mixed up with the idle speed screw. They are two different things.

Too lean of a fuel mixture causes high combustion temps in the cyl which can burn a hole in a piston.

Timing can be done yourself, just get yourself a timing light. One that is meant to clip onto a plug wire. Most if not all new timing lights are like this.

Timing procedure is listed in the FSM (factory service manual) in which you can download here: http://www.ncttora.com/fsm/

Wannabetruckguy

I went out and bought a timing light for 50 bucks and long behold the timing was set to 5 when the FSM says it should be set to 12. Turned the distributor and good bye backfire. If it wasn't for you xxxtreme22r I would still be dancing around like a money with my thumb up my ***. Thank you.

I was wondering if you might be able to help me with one more issue:

I replaced the spark plugs and the old ones were black. From what I understand this is probably from it running too rich? The carb is old and rebuilding seems a little out of my league so I was thinking about upgrading to a weber. Are Weber"s worth the money? I was told i would be looking at a 10-15 hp increase because of the better air flow is this true? On the weber website there were a few different carbs with sizes ranging from 32-38 which should I go with? There were also "DGEV" "DGV" "DGES" and a few different letter combination no one seems to know what they are. Do you? Or is there a website to find out?

xxxtreme22r

whoa hold on there buddy, you got a carb'd truck, timing should be 0. EFI trucks are 5 or 12 I forget off hand.

Make sure you take the vac hoses off the carb and plug both of them on the hose side and then set your timing to 0.

Timing being off can mess with your fuel mixture. Not directly, but indirectly.

If you don't know carb's do not get a weber. Although they are great carb's, provide a little more power and throttle response than the aisins and just as reliable as a toyota aisin's are, they require alot of tinkering to get perfect.

Wannabetruckguy

The FSM says, and I quote, "Using a timing light, slowly turn the distributor until
the timing mark on the crankshaft pulley is aligned
with the 12° mark. Tighten the distributor bolt."
Is it supposed to be 0? It's a 22r not 22r-e.

So what should I do for a carb clean this one up and call it good? I just heard weber's were easier to adjust and one of the first things "most" do to a 22r engine.

xxxtreme22r

make sure your on the right page of the fsm and your not in the 22re section. I am almost certain it's 0 degrees. Page 351 of the FSM if you are using the 88 4runner FSM and page 295 if you are using the 85 pickup fsm. I would also like to add, once you reconnect those vac lines that your total timing should be showing 10-14 degrees advance. Don't mix those hoses up either.

This is assuming your 84 22r timing specs are the same as the 88. Different motor I know but.... Also check under your hood, if your lucky your emissions sticker and vac diagram should be on there. It will also tell you there.

I just checked both fsm's and they both say 0.

Wannabetruckguy

Well I suppose there would be another issue. What vacuum hoses do I need to unplug? I did the timing just as is, I didn't touch anything other than the distributor. In the FSM underneath what I quoted before it says, "Ignition timing: 22R 0° TDC (Max. 950 rpm)
(w/vacuum advance cut)" I ignored this because it contradicted what the step by step instructions were saying to do...
So if I unplug the vac advance which is what connects the carb to the distributor (right?) and reset the timing to 0 that would make it correct?

streetlancer

iTrader: (1)

xxxtreme22r is right. I just looked it up:
22r 0 TDC @ Max.950 rpm
22re,22rte 5 BTDC @ Idle

As for the carb look here:
https://www.yotatech.com/forums/f116...d-time-226236/
Not as hard as they say, trust me.
Maybe i should have posted that in the 84-85 section, it would appeal to a greater group.

xxxtreme22r

yes, if your not at operating temp, which you really should be, pulling both vac hoses off the distributor is the best thing to do. The one closest to the radiator side "top" is the actual vacuum advance. The other is to retard the timing a little on cold start.

now also the 0 degrees is with the engine at 950 rpm. You might have to turn up the idle speeds screw to raise your rpm a little as your normal idle rpm should be around 750 rpm. This allows the mechanical advance inside the distributor to advance the timing slightly. But this is 950 max not min. FOr good measure I have always turned the idle up, but you should be ok not doing so.

Just don't mix up those two hoses. And make sure you plug them. A screw small enough to fit in the hose will work.

Wannabetruckguy

Ok so after adjusting the carb, or at least trying to, I realized the idle mixture screw had been drilled into. So I ordered a new re-manufactured one. I have checked and checked for vacuum leaks (by spraying the vacuum hoses with carb cleaner.) When doing so the rpm stays at about 900 (where it is idling at.) Though it seems it is having a misfire because the whole engine rocks when idling at cold. Although when it warms up it puurrrrs like a kitten any ideas what could be causing this? Also what I suppose may be the bigger problem here is: Chilton says you are suppose to set the timing at 0 with the vacuum advance lines cut and plugged but when you plug them back in the timing is supposed to adjust to 13. The timing does not move in the slightest when plugging the lines or hooking up the lines. Any idea what could be causing this? Chilton's manual says check the "HAC" Valve but my truck is not equipped with one. Maybe the distributor? Anyone know a way to be sure before I throw more money at it?

xxxtreme22r

try taking a length of hose and hooking the advance side of the dizzy directly to the carb. Same ports as the old hook up. Which one I do not remember off hand. Just follow that metal vacuum rail from the outside port to the carb. You might have a vacuum leak in that rail itself like I did. I got lucky and was able to put a hose on a little further down as the leak was towards the end of the steel line. If this doesn't allow the vacuum advance to work then there might be an issue with the vacuum advance diaphragm in the dizzy. You just have to make sure you using the correct side (closest to the radiator)

Having that port drilled out just means somewhere along the line someone screwed with the idle mixture, not a big deal unless they were idiots and drilled right into the adjustment screw. As even the FSM says to be careful that there is not alot of room from the end of the plug and that screw. If they did that there is a good chance that the drill might have turned the adjustment screw.

You have to be very careful around that steel vacuum rail too as they corrode and any little movement of the tubes can cause a vacuum leak which is easily overlooked.

Wannabetruckguy

I did exactly that and long behold the timing jumped. Turns out one of the steel vacuum rails had snapped so I just Ted the vacuum line and my advance is working. One problem down...

Yeah someone had literally drilled INTO the screw its self and from what I was hearing you can't get those replaced so I ordered a new, or at least re manufactured, carb. Should be here in a couple days.

Ok so now the timing is set properly but the whole engine still shakes at a cold idle. Once it is hot, not just warmed up, about 15-20 minutes of idling it stops shaking and runs decently. Even at cold it drives ok and doesn't seem to have any power difference between cold/hot maybe a slight difference in throttle response. Any ideas on what could be doing this? The only thing I have been told is a miss fire in the engine.

xxxtreme22r

what rpm is it idling at when cold or at least trying to idle at? Is this when it's on or off the high idle cam? Mine is a little shaky too when it first comes off the choke and high idle. Does it seem as though the choke has been messed with?

Cold weather is not friendly on the best of carbs let alone a 20 year old one. My weber has only been on about a year or so and doesn't like to run when it's really cold out. Summer time didn't show an issue whatsoever.

My last 3 trucks were all carb'd and none of them liked to run in cold weather unless the engine was fully warm.

Could be a miss from it being too rich, but if that idle mixture screw was moved by the drill bit, probably nothing you can do about it. If I remember correctly turning it in richens out leans. If a drill bit hit it then it was turned in. Even an 1/8 of a turn can make a huge difference.

Wannabetruckguy

About 600 it's hard to tell because the needle jumps so much but just under 600 would be close enough. Well I mean I wont step outside if it's under 50 degrees unless I am on my way to work. So it hasn't been THAT cold when I have been working on it.

I have not checked for either of those... Should those be the next step?

The carb I ordered is "bench" and engine tested so I was waiting for that to get here but should I check those before hand?

Yeah when I replaced the plugs when I first got it they were black as night so I know it is running real rich that is why I was in there trying to mess with the mixture screw.

xxxtreme22r

idle is set too low, bring the idle up to about 750-800 and see if it still wants to act funny. Unless the idle creep up when the engine is fully warm back to 700-800 where it should be. Mine sits at about 500 until engine is warm and off the choke after about 5-10 minutes.