79 toyota pickup problems

timing-belts

#1

thank you to all the advice i got on my earlier question. I have a 79 toyota pick up, that will not run. the engine turns but does not start. It has spark, though not the best should start. The carb is old but there is gas in the engine when i try to start. compression in all the cylinders is fine. A friend thinks maybe the timing chain jumped a tooth. Does anybody have experience with this? I cant find the bright link on it so im having trouble knowing if that is the problem. ANybody got any other ideas on what it could be?


#2

If the timing chain has jumped a tooth, you’ll not have good compression. You can safely rule that out.

Has any work been done on the ignition system? Is it possible that the distributor cap has been reversed? Normally they’ll be asymetrically designed, but I have to ask.

Will the engine fire with starter fluid?

Regarding the gas in the engine when you start, is the choke closing? When you twist the accelerator linkage pulley, does the accelerator pump spray fluid into the throat of the venturi?


#3

I seem to recall a problem with the EGR port on some 20R and 22R engines. They would develop a severe vacuum leak and prevent the engine from starting but they would always stumble and almost run when fuel was poured through the carburetor. Also, I believe that the 1979 used the old point type distributor to trigger an electronic igniter which could give some strange symptoms. Look in the distributor for points and recheck the spark with a plug gapped out to .075.


#4

You will have good compression with a timing error of one tooth off sadly…it takes a few more degrees of timing variance to affect the compression test.

If you havent checked the distributor cap and rotor they are good things to check…and IF you have an IGNITER…I would try to test the truck using a know good one…not sure you will find one in a yard as these trucks are getting scarce…but the igniters do fail often and while you have spark, it isnt hot enough…I have replaced many an ignitor with good results…and having the same symptoms as you. They go bad often. I am fairly sure you have an electronic ignition system on this…NO? You might be able to scare up an ignition module from a corrola or other Toyotie that is close to your year…a new ignition control module will be pricey new…over 200 bucks. But Toyota used the same mod in many different cars…I believe that module has the ignitor within it… If not electronic…thenyou have points to check. I dont think it is a standard old ignition…pretty damn sure its electronic

Also do a TDC check for the distributor…get it to TDC and pull the cap off the distributor…where is your rotor pointing? Then correlate that to which wire it will hit next…make sure that wire is on the #1 plug. Make sure ALL of your wires are on the right plugs in the correct order, you can look up the firing order online as well as cylinder numbering…VERY IMPORTANT Also pay attention to how close it is to hitting that #1 plug wire thru the distrib…needs to be right there…

Trying to squirt gas or start fluid in while cranking will be a good test too…what is the result of that? Other than that…the cap, rotor, wires, plugs…I’d go to the IGNITOR…DEFINITELY… Seen many a failed ignitor that had spark but wouldnt run…The coil would be the next suspect.


#5

I obtained a used igniter for my '79 4X4 but never did need it. If you are not getting a really powerful spark, I would suspect first the magnetic pickup device inside the distributor - I think Toyota calls it a signal generator. It takes the place of points in the earlier distributors. Some makers call them pickup coils, electronic control modules, etc. Mine did fail. I was 350 miles from home but fortunately parked outside a parts and service place. They diagnosed it pretty quickly. The part was about $95, IIRC - aftermarket, not genuine Toyota.


#6

If you are getting spark you are already past the magnetic pickup. It is now in the coil/ignitor arena to amplify the spark.