Alright so before I get reamed out by everyone saying check archives/stickies/ all these other posts…. I’ve looked at a lot of them for MONTHS. So I’m at the point where I may need some pointers or ideas to something I may have missed. So here’s some info and backstory.

1993 Toyota Pickup Base model 2wd 22RE. With about 1,500 miles on a fresh rebuild. Along with new cap and rotor,plugs, wires. Fuel filter and I had the denso fuel injectors rebuilt yes including the cold start injector.

truck was running flawless after the rebuild and right about the time the weather started warming up here in the PNW my truck started having the notorious starts fine when it’s cold but won’t start easily an hour later symptoms. Sometimes when the weathers real hot like this last week 100*F+ And the truck has sat say 8hrs, it’ll be hard to start as well, like 15seconds of cranking before it stumbles and starts.

So the diagnostics began,

I’ve checked

Fuel pressure at the banjo bolt at the CSI =42 on my gauge. and despite my fuel pressure being fine I jumpered the FP to B+ in the diagnostics port and that didn’t make a difference… could my fuel pump be bad anyway? The FPR appears to be working just fine as well…

i checked the cold start injector both at “cold” and “operating temp” it sprays when cold and doesn’t spray when warm.

I checked the Cold start time switch(the black one) in a glass with boiling water. And it measures well within resistance.

I checked the ECU coolant temp gauge(the green one) right next to the CSI time switch and it measured great as well.

I checked the AFM according to the FSM and it too measures within resistance as well.

I pulled the circuit opening relay and tested it for resistance and all seemed good with it, I even pulled the starter plug so I could physically hear the COR click when I turned the ignition over.

I checked my TPS and my settings are on the money.

I checked all of my vacuum lines and caps( my truck is EGR deleted so a lot of the ports are capped) and replaced what ones I thought were “bad” nothing crazy cracked or anything.

Anyway I’m still having this issue if anyone can throw out some more insight as to what it might be don’t hesitate to toss out your ideas because I’m determined to figure this out!

 

Some more added symptoms, it acts like it wants to fire up when it’s warm when I crank it over, like it’s got fuel (maybe too much?) Example is, I turn the key, it cranks and it fires for a brief moment I let off the key and it dies, it will repeat this process unless I continually crank it over for 10-15 until it fires? Maybe a dirty injector??

 

Sounds like vapor lock.

 

Sorry my rigs are EFI
but seems like a lot of folks like the Weber 32/36.

 

Thanks for the recommendation, I explained my symptoms to a coworker of mine and he said the exact same thing, today when I get home I’ll test out that theory. It definitely has a ton of pressure when I crack the cap when I go to fuel up.

 

My 92 was doing that. It was due a timing chain repair at the time.

I changed the thermal time switch, and the ECU coolant temperature switch during the timing chain repair. That fixed it, and it has not done it again five years later. I got lucky because I bought the Beck/Arnley thermal time switch, and inside the box was a genuine Toyota part.

 

I changed both of mine already, didn’t fix anything for me so now I have spare thermal time switch and ecu coolant temp switch haha. And I’m really confident in my engine builder that it has nothing to do with my timing chain. Being I’m only about 1500 into a fresh rebuild. There’s no funky noises coming from it etc. but I could be wrong, and I wrote it down to keep in mind.

im starting to think it’s my distributor pickup coil, I don’t see in the FSM how to test that unit but I’m gonna do some research and see what I come up with.

thanks for your response!

 

So I checked the pickup coil when I got home, underneath the black “heat shrink“ the white wire was cracked and exposing bare wires, still the pickup coil tested good per the FSM. But because I can’t let it stay that way I ordered a new pickup coil anyway. And I’ll save the old one as a spare after repairing that wire.

SO…. I went back to re checking things. and this is what I’ve found. The fuel pressure is fine, the cold start injector turns on when engine is cold, and doesn’t turn on when the engine is warm. However I decided to try to start the truck at cold…. Nothing, it just cranked and attempted to turn over. And all of a sudden I started to smell fuel. I haven’t noticed fuel before. Nor could I find where it was coming from. I let the truck sit for a few mins and I decided to unplug my cold start injector to see if maybe it was overfueling? 🤷🏼‍♂️
and it fired up instantly, at the bump of the ignition.

Has anyone heard of the cold start injectors becoming sticky/ stuck open?? The injector ohms out just fine. I’m thinking of pulling it and taking it back to my injector guy to have him test it for something internal? Any pointers?

 

That problem also plagues a lot of us 22R-E owners. In 2016 I thought I fixed it by cleaning CSI timer switch mounting and CSI wiring. However, it came back in 2019. It randomly happens upon first start in the AM and after parking for a few minutes.

I suspected that to, and to test, I disabled my fuel pump while engine is still running until it's starved of fuel and dies. I assume there would be no more fuel pressure to leak through the CSI. Tried this so may times but did not fix the problem.
Now I suspect that a certain combination of actual engine temp and what ECU water temp sender is sending to ECU (THW) that affects ECU signal to EFI system. Monitoring THW voltage and block temp when that happens may give us a clue. However, adventure gets in the way, and it eventually fires up after a few cranks AND it always fires quickly when cold, that I don't bother.
(Below is from 1988 schematic. PLEASE IGNORE STJ pin that does not apply to 1986.)

 

next time you smell fuel, pull the vacuum line off of the fuel pressure regulator (FPR). is it full of fuel? it shouldn't be. if it is, the diaphragm in the FPR is bad, and the FPR needs to be replaced. the symptoms are similar. excellent cold starts, fuel pressure within spec. poor warm starts. although will start when warm/hot if shut off and then re-started within half a minute.

 

i tried pulling the vacuum line and it has no fuel in there. So it appears to be working.

I’ve got my fuel pressure gauge hooked up currently.

when B+ is bypassed to Fp fuel pressure is at 42psi.

when truck is running it is at 34psi.

when revved to about 3500 to 4000 rpm’s fuel pressure rises accordingly.

So I turned the truck off and the gauge was at 34psi, but 5mins later the pressure rose up to 40psi.

now I’m waiting to see if it drops completely or what?

im also waiting on the arrival of a distributor pickup coil. The old one had a bare wire and I decided to just replace it. Well when I went to pull it I decided to check the gap(which I have never done before) it was at .035” now and the FSM calls for .008-.010”? I wonder if this is enough to cause my symptoms? 🤷🏼‍♂️ Sorry for the long winded posts, but hopefully if I ever figure this out someone can learn from this haha

 

looks like your pump and pressure regulator are just fine. your problem is elsewhere.

 

yea I’m feeling confident in it too. On to the next thing.

 

New pickup coil has not fixed the issue.

it is as if the truck thinks it is hot when it is actually cold but as far as I know only the cold start injector time switch and the ECU coolant temp sensor control that.

So I grabbed my Cold start injector time switch (CSITS) checked it for resistance and got 79.5 ohms. According to the LCENGINEERING website when checked straight across the terminals there should be a difference I. Readings on the CSITS. So I simulated this with different water temps in a glass and hooked up my ohmmeter.

And what I’m finding is that I’m getting a reading between 79.3-79.5 no matter if I put it in chilled water or scalding hot water it hardly moves. Has anyone ran into this issue before? I pulled a spare CSITS that I had laying around and it was marked “bad” with a sharpie which isn’t a good sign but it’s doing the exact same thing as this one.

I think I’ve found my problem…. But that’s an almost $200 part OEM 🥶🥶🥶 anyone got any cheaper options out there that way I don’t blow 200 on something that might not fix my problem?

 

that isn't your problem. the csi system does nothing once the engine has actually started. it only functions, by triggering the injector, when the key is in the "start" position AND when the ambient coolant temperature is below a certain threshhold. once the key is released from the "start" position to the "run" position, the csi stops firing. if your truck starts, the csi isn't the problem, unless the injector itself is leaking. that is simple to test. unscrew the two bolts that hold the injector to the upper plenum. gently pry the injector and hard line back away from the plenum until you can see just see the tip of the injector. start the engine. then observe whether the injector is weeping/leaking (it will have to be excessive for it to have any noticeable effect). not leaking? not the problem.

 

The cold start injector could be leaking too!

 

First thing in the morning when it’s cool out my truck starts just fine. So I would think if the CSI was leaking it would be hard to start after sitting overnight? Right?

 

Cold start injector is cold in the morning. Once it heats up like everything else in the engine, it could possibly be leaking when the engine is hot, but not so much when it's cold, or even none at all.

Next time it won't crank hot. Hold the gas pedal all the way down, and see if it cranks.

Also, on a no hot start. Pull a plug wire, and stick a tester in it, and see if the engine is getting good spark. Could be an electrical switch acting up when it gets hot. Seen it happen many times over the years.

 

did you read what i wrote?

 

thanks Wallytoo, you are correct, it doesn’t appear to be the cold start injector system.

im now going to run some more tests on my MAF sensor tomorrow the intake air temp sensor has grabbed my attention. When the ambient temperature was 84 out today but my rig had been sitting in direct sunlight all day long the temp sensor gave a reading of .957ohms, then I took it out of the rig into a shaded area in my shop where it sat a couple hours and I checked the ambient temp again at 84 but not in direct sunlight and it measured 1.970 ohms. And according to the chart in the FSM that would indicate my MAF sensor is bad.

the more heat I applied to the IAT with a hair dryer the lower the reading got as well. It dropped down into the “.5” range but never really dropped iinto an acceptable range according to the FSM.