I've been experiencing some engine trouble on my 71 hilux. On a normal day when the engine is cold it will run rough, it "hiccups" on acceleration. It will also turn off when I down shift from 3rd to 2nd, even with a warm engine. To keep the truck running when down shifting I keep the manual choke pulled partially, it is attached to the idle so it keeps the idle high. Some days I don't have any problems and the truck runs great. It will keep running at normal idle and does not run rough. Another thing is when I turn the ignition off the engine will keep running, I think its called dieseling. This evening I fueled up and drove ten miles to my parents, 45 minutes later I got in my truck to leave and it would not start. I had to crank it for a long time before it would finally start, it has never done this before. Earlier today it had been running really well so it seems strange. After I got the truck I replaced the spark plugs and wires, later I replaced all the vacuum lines and cleaned the carb out best I could with carb cleaner without taking it all apart.

With all that said, I am looking for some advice as to how I should tune the truck so it runs better and what other maintenance I should do. I could use any suggestions and advice.

 

Hey I guess almost no-one answers questions on here about the 18R motors and trucks since I asked for help days ago and only got one response. I don't know if it's because they don't know anything about these motors or what?

But since I am looking for help with one and I have some idea about what might be happening with yours, I thought I would at least give you a guess. It sounds to me like your problem is your carb-I'm betting either you have clogged jets or your fuel level is off. It shouldn't be dieseling and hiccuping unless the fuel mixture is out of whack. Spraying carb cleaner can only help a dirty carb when it's minimally dirty and sometimes it only dislodges crud and it gets stuck elsewhere in there. If you can get by without the truck for a bit I would pull off your carb and take it apart to make sure it's clean. When you do this I would take lots of notes/pictures as you take it apart so it's easy to get back together. You should check the float fuel level once you get it clean and back together. Today's fuel is REALLY bad for carbs and will gunk them up pretty quick unless you use fuel stabilizer. Best of luck. Oh and if you find out what it was for sure let me know as I am still looking for help with my 18R.

 

kinda had the same i did three things and it help

1.took the top of the crab off and bent the floats clean a bit this should be the problem but also tryed
2. bumped up the timing a tiny bit
3.i closed the mixture screw all the way the 1- 1 1/2 tun open but dont remeber where i left it you have to adjust timing and mixture to figured it out
The only problem is that i have a welded throttle adjustmest so still kinda have problems on holding a idle but no hiccup or dieseling
good luck buddy

 

71hans,
I am not sure of the validity of what I am about to tell you, but the advice came from a friend of mine who worked for Toyota 30 years before retiring. My truck has a 20R and was running rough when I first got it (there were many issues with the monkey who dorked around with the emission lines before I owned it, works great now). Anyway, this guy had told me to take the aircleaner lid off and get a rag and block the intake while you have the engine reved up like 2,00-2,500 RPM. Right before it chokes out take the rag off as to keep the engine running. I personally need more reason to choke an engine out like that so I asked and researched this technique. Apperantly, the idea is that it creates a high vacuum in the carb and sucks out the debris that might be causing issues such as this. I am not sure as the legitimate research shows nothing of this procedure. BUT, a guy (and I trust him) that works 30 years as a technician, there is probably an element of truth to this procedure.

I personally would rebuild that carb and then check out all the emission system, timing etc. Systematically go through as these older engines are simple to trouble shoot. Just have to be methodic about it all.... I would be curious when you get it fixed, what it was though! Please post when you get it figured out!

CHEERS! Bake

 

Thanks for the advice guys. not sure what I'll be able to tear into the carb but I'll let you know what I find. Any advice for a first time carb tear down, beside taking lots of pics and notes? does anyone have a diagram of these carbs on line that would help with the rebuild? Also, how do I adjust the timing? And, what it is the best approach to adjusting the mixture?

thanks guys

 

I'm still looking for a complete diagram-the ones I found in my manual are detailed but not the best. I will scan them tomorrow and put them up for you. Also I can't be sure they are the same as yours probably very similar if not the same-do you have the 8R or the 18R?

working on carbs: I dedicate a space (like a workbench or table) for the parts and use either zip lock baggies or muffin tins to keep the parts that came off together in the same place. You will need 'good' tools like proper fitting screwdrivers. Much patience is also key. Before you do this though I just realized you didn't say much about diagnostics on your ignition system. So you should do that before you get into the full monty on your carb.

You should inspect your points inside your distributor cap. They should be gray not pitted or black and you need to check the clearance as well. A quick check you could do is to pull a plug wire one at a time and see if one doesn't make a difference when it's disconnected. I would also check your plug wires resistance and your coils secondary resistance. I will check those values for you and post those with the carb images.

You adjust your timing by loosening the pinch bolt on the base of your distributor and simply rotate your dizzy (one direction advances and the other retards), but be careful w/o a timing light you get it out of wack so do this in small increments and check for improvement.

The mixture is adjusted using the mixture screw on the carb itself-it sits about 3/4 way down the carb body and points upward at about 45 degree angle below the throttle diaphragm. This is not a real likely candidate for your issue since it runs ok some times and not ok other times. Which leads me back to electrical or dirty carb.

Of course it could also be your valves. I know not what you wanted to hear but it remains a possible cause as well. Honestly now that I've thought about it I think it's in your ignition. Bad coil, bad plug wires, improper dwell angle, improper timing, points bad, condenser bad, resistor may be toast, unfortunately there are a lot of things it could be, fortunately if its ignition related it's all really easy and inexpensive to fix. If you don't have one already I would recommend getting a repair manual. The Chilton seems pretty good, and most if not all the ignition parts are available at Auto Zone or on Ebay.

 

its your e,g,r valve i had the same problem with mine and several hundered dollers later i changed it and man what a differance ..

 

Mercury man, Thanks for the detailed information. After I bought the pickup I had my mechanic look over the truck...one thing he did was check the points and did something to them, I think he said he filed them or something. In October I replaced all the spark plugs and wires. So I think I'm left with the carb or the valves...which I am hoping is not the case. This truck was sitting for about 20 years before I bought it....so I'm thinking a good carb clean needs to be done. Hopefully I'll be able to do this soon. Thanks again

 

Randy I can't be certain 'cause I don't have one, but I don't think that year Hilux had an EGR system.

71Hans no sweat, we have to stick together and help where we can or these old classics will all end up being melted down for scrap. Yea you can file points just gotta be careful to use a metal file not paper or cloth, but they are cheap to buy new. I am about to do my valves so I will let you know how that goes. I don't think they are too bad, just gotta buy a new gasket. It looks like they are a normal rocker arm setup that you just adjust using a wrench.

Don't just assume your ignition is fine because your mech looked it over. Things can always go bad and he might not be real familiar with these old motors anyway. Most of the checks are pretty simple and not $$. A simple vacuum gauge hooked up to your manifold can give you worlds of information about what's going on. If you decide to try it let me know and I will post the page that shows what the various readings (on the gauge) are telling you. I am still looking for a good Carb breakdown, when I find it I will post it.

 

yupp i didny know it was a 71 sorry guys

 

thanks again mercury man. The engine is the 8R

 

I was do some work on the hilux this evening and did some investigating in the carb issue. I found a couple of things that bothered me and wanted to see if you know it to be a problem. I took the air filter cover off and first noticed that the filter is getting black (I put a new filter on 6 months ago) and also the choke side of the carb or air intake is also black black. After taking the air filter mount completely off I noticed that the small tube that connects the engine top block and air filter together had some oil on it and also on the male end of the tube connection on the engine. I decided to run the engine and notice that it is putting out a very small amount (a drop in ten minutes) when the engine is running. I find it weird that oil is coming out of the tube on the engine because it is sucking in air. I am wondering if there is something wrong with my heads...it doesn't seem like there should be oil coming out of that tube and it seems wrong that the air filter is black (I can only assume that it is the oil that is causing this) and also the air intake on the carb.

Let me know what you guys think and if there is a problem I should get checked out soon.

Thanks

 

Have you checked your PCV valve to see if it's clogged? I have an 18RC and haven't worked on the 8R, but I believe they also had a positive crankcase ventilation setup.

The hose that goes from the air breather to the valve cover is there to provide fresh air in and there should be a PCV valve on the top of the valve cover which then has a hose running to the intake manifold which draws a vacuum in the cover. If it's clogged then that vacuum won't be there and the sucking going on at that breather hose will reverse-there will be oil sloshing around inside there quite a bit as your rockers work the valves and the oil system bathes the valve assembly. This could lead to some oil being thrown out that pipe and then it gets sucked into the greater vacuum created by your carb intake. Black color in there can also come from fuel being backfired and not burned. If it's oil it will smell and feel like oil, fuel won't be as viscous (more like powder).

If it's working right there is greater vacuum being drawn on the PCV valve (from the intake manifold) and the breather hose lets in fresh air from the breather.

Easiest way for you to check it would be to keep the breather hose off and start the motor then using your finger or some paper check to see if there is a vacuum being created there. No then remove the hose from the PCV valve and see if the manifold is pulling vacuum through that hose. Yes then your PCV valve is not functioning. You can try and clean it in some mild solvent, I would just replace it as they are only a few dollars.