95YotaPU

Bear with me, yet another cold start thread. I 've searched and searched but have not found any threads that match my problem. Here's the background:
1995 Toyota Pickup 3VZE 4WD
270,000 miles; 5 speed

This truck will not start when the outside temperature drops below 60 degrees. Once I get it started and it gets up to operating temperature, it starts fine, It started all summer, even when it sat all night. Now that we are having some temperatures outside lower than 60 degrees F, I am having trouble again. If the engine cools off and the outside temp is below 60, it cranks but won't start. I bought it for a winter beater and since the temperature is starting to dip, it's not going to do me much good sitting in the driveway. I have tested and replaced the cold start injector time switch (CSTW) and cold start injector. The original CSTW seemed to read around 80 ohms regardless of the temperature. Both parts replaced were not new as I got them from a wrecked vehicle. The new to me CSTW seems to be in spec. I also replaced the coolant temperature sensor with a new one from AutoZone. It still won't start when the outside temp is below 60.
The only way I can get it to start when temp is below 60 is to heat up the sensors (CSTW & Coolant) with a hair dryer. If the temp is in the 40's it can take 15 or 20 minutes of heating before it will start. Today, I switched my routine and heated up the VAFM and eventually it started. So I am not sure if that was fluke or not. Even with the hair dryer it takes a lot of cranking to get it started. And it runs pretty rough for the first minute or so. Once the engine warms up it starts great. If the engine cools off to around the outside temperature, and it is below 60, it won't start. Above 60 degrees and it starts with little cranking.
I read where the CSTW needs to have a good ground. I used teflon tape around the threads. I did remove the new to me cold start injector from the intake manifold and put it in a baggie to determine if it was spraying fuel. The injector was still connected to the fuel line. I cranked the vehicle and the baggie had a very small amount of fuel in it. I know the injector only sprays fuel for a short burst during cranking, so I am thinking it is working ok.
I do have a couple of trouble codes. I think they were EGR and ECU. These codes appeared after I fixed a problem related to an earlier trouble code where the oxygen sensor wires shorted out on the exhaust. The oxygen sensor trouble code was cleared after I spliced the wires. A short time later the EGR and ECU codes appeared. The cold start problem existed before the EGR and ECU codes appeared.
I did check compression of the cylinders and all the cylinders were very weak. I discounted the readings because the truck runs and pulls pretty well once it is running. I checked them one at a time and I read where you should pull all of the spark plugs, then test compression. I hauled some firewood and it pulled pretty well for an old truck. Once of the cylinders leaked off pressure, so I am think I could have a burned valve. But I am unsure if that would cause the cold start problem I am experiencing.
I have exhausted my knowledge and research on this starting problem. I suppose it could be the ECU but I know those rarely cause a problem. And I have read where the EGR should not cause a starting problem.
Any ideas would be appreciated. I want to get this cold start problem fixed so I can drive it this winter and not get stranded. I hate to keep throwing parts at it but I can't seem to figure this out. I don't have access to a FSM.

scope103

First, get the codes. "I think they were ...." doesn't help much.

Your problem sounds like a CSI issue. The injector-in-a-baggie was a terrific idea, but the CSI should spray a considerable amount of fuel while cranking. Try to get someone to help so you can look at the injector. (You are correct; it ONLY opens during cranking. (and when also cold, and then only for a few seconds))

BUT: heating up the sensors to start it points in the opposite direction. If "fooling" the ECM into thinking the engine is warm lets it start, that suggests you have TOO MUCH CSI. That one is easy to check; disconnect the electrical connector to the CSI and try again. There is no real temp spec on the CSI, but 60° sounds a little warm to me for the CSI opening.

But in the end, "hard to start" can be anything at all. Low compression will make it hard to start, even if it will limp along once running.

95YotaPU

Thanks for your comment scope103. I have been worried that the low compression is the culprit, as that is not an easy fix, especially for me. That, in combination with a stuck or burned valve means an engine overhaul, which I am not in the position to do right now. When it cranks, it seems like it may only be hitting/firing on 1 or 2 cylinders. It has spark to all of the cylinders though. A couple of gear-head friends have watched it crank and their observation was that it seemed like it wasn't getting enough gas.
I know that a warm engine starts much easier than a cold one, so compression may be the problem here. It doesn't use oil though. And I wouldn't think just one stuck valve would make it that difficult to cold start.
I am going to test the CSI again, both before and after heating it up. Thanks for that tip. I have sprayed starting fluid in the cold start injector opening in the manifold and it didn't start. Seemed like it just flooded out. All the excessive cranking is not doing the starter any good, as I had to replace it in the spring when I bought the truck. Of course the previous owner didn't disclose this problem to me. I drove it home and the next morning it wouldn't start and he wouldn't answer my texts.

RAD4Runner

Second on warmed CSITS pointing toward opposite condition.

As routine maintenance items, I also suggest that you clean all your temp sensors so they sense temp accurately. AND (I believe this is often overlooked) make sure the threads on CSI timer switch and the thread on block where it screws into (here) are bare shiny metal so they make good electrical contact. That's how CSITS is grounded. Do not use teflon tape in attempt to make a good seal.

95YotaPU

It was 45 degrees so I tested the resistance of the CSTI. It was 79 ohms. Seems a little high but maybe it has to be below 32 degrees to show a lower resistance. Also I ran the trouble codes. The codes were 25 and 71. Could the 25 code be causing my cold start problem? The 25 code is "mixture control-continuously lean" or "Air-Fuel Ratio Lean" according to the two sources I checked for trouble codes.The probable cause is listed as "wiring, injector, H02S, ECT/VAF sensor, intake/fuel/ignition system, ECM." Which of these would relate to my cold start problem? Is the ECT/VAF sensor all part of the VAF assembly or is it a separate sensor?
Once again the truck runs and starts great once it reaches operating temperature.

scope103

That measurement sounds pretty close. http://web.archive.org/web/201411140...ne/97colds.pdf I'm just not convinced the CSI is your issue. As I said before, anything that makes the truck a little harder to run, will make it a lot harder to start. Low compression, timing off a little, sticky injector, all sorts of things.

To get ahead of things, pull the EFI fuse for 30 seconds to reset the stored codes. Then re-check the codes. Some of these could be left over.

I don't have much else to suggest. Maybe a block heater?

RAD4Runner

I'm out of ideas but I just saw this on original post.

Like I posted above, in order for CSITS to get good ground, bare metal of its brass body needs to have contact with bare metal of the manifold. NO TEFLON TAPE.

az1320

so? what happened?

bcraj1

Good morning. I have been researching a start problem on my 1988 toyota 3.0 V6 pickup. I ran across this thread on low temp start problems. I have the opposite problem. For some reason when the temp gets up I get no crank. It starts fine when cold even in warm or hot weather but after running for a time I cant start the truck. No starter engagement. I get a click in the cab on the right side behind the kick panel or under/near the glove box. Any ideas of compunients which are heat sensitive? I had started into the replace components methodology but after reading all the start problems in threads here I was hoping to get pointed in the correct direction.

RAD4Runner

Good move aborting the replace components blindly approach.

Please answer these couple of questions and we'll go from there. (Doing your homework and answering these two questions mean you are committed to working with us to fix your truck yourself)
1) When you try to start, does your starter solenoid (piggybacked on the starter motor) clunk energetically? faintly? or not at all?
2) Disconnect the connector from the starter solenoid (shown below). Connect the connector on the solenoid directly to the battery as your assistant tries to start the engine. Does this consistently crank the starter properly?
3) Do you have a multi-meter? ["NO" IS NOT AN ACCEPTABLE ANSWER ]

bcraj1

To answer your questions:

1. Not at all
2. By myself bit will try when I get someone here when this happens
3. Yes I have a multimeter

RAD4Runner

+1 on Multi-meter.
Please use that to check battery voltage, both at the positive post and at the connector (yes, there could be a difference in readings if you have poor connection there). with engine OFF and all possible loads on. Should not get too low.

Sorry... Actually no need for an assistant. Just jump that connector on solenoid to battery, to see if it clunks energetically and cranks the starter motor. Pls make sure you're in neutral.
Also, check if your starter relay clicks. IIRC, for your generation it is in one of the fuse blocks in engine compartment. When it clicks, you should be getting 12V at the connector^^^ on harness.

bcraj1

Thanks. Been tied up all day on the property. Spring and so much to do. How large a wire should I use to jump between the starter solenoid to the battery? I'll try to get this tomorrow.

Thanks

RAD4Runner

12AWG should be good. That's what I use for wire from starter relay to starter solenoid.

bcraj1

Thank you. 12AWG it is. I'll let ou know.

bcraj1

OK I used 10AWG and got an energetic response. 12V and 12V on the multi-meter but have not been able to get the truck in the fail mode to test in that mode. Would the starter relay be temperature sensitive? Again, this happens when the vehicle has been running 15 or 20 minutes. Last time it happened I timed how long before the truck would start and it was a little over an hour. Could it be a loose wire connection, wire to terminal fitting? I have checked for tight connections and made sure any spade connectors are fully seated.

RAD4Runner

When solenoid cranks energetically you you always get a crank, correct? IF NOT, it could be solenoid contacts.

Suspects are with question mark in diagram below.

Most likely suspect is the neutral safety switch. It could easily get dirt on it and ideally should only be a position indicator/signal/input device, not for carrying current needed to energize the solenoid. (I measured 12 amps on my first-gen). I suggest you check it. Volt check is best. measure the voltage across it when in neutral and someone is trying to start. Voltage across it should be almost zero if it is good. If not, clean it and repeat measurement.

IF YOU PROMISE TO ALWAYS START IN NEUTRAL, another suggestion is to make a test "jumper" wire with a momentary push-button switch. Connect A to battery and B to spade terminal on solenoid. Use it to start for a few days an observe if the problem occurs.

Alternative way to eliminate/convict the neutral safety switch, IF YOU PROMISE TO ALWAYS START IN NEUTRAL, you can connect the "jumper" wire across the neutral safety switch. Try to start but you get no crank, push the push-button. If it gives you a crank consistently, then it's the neutral safety switch.

Starter solenoid contact should not be less of a suspect; they are designed to carry that load and the relay is on a pretty hospitable environment.

Any connection or even a straight wire that has some sort of resistance is temp-sensitive. Its resistance would increase with heat.
mechanical parts like the solenoid plunger would also be affected by heat. It might need more power to move if hotter.

bcraj1

Thank you so much. Oh, one thing I have not mentioned is that this is a 5 speed manual. I noticed on the schematic the "?'s" were on the automatic. I will check the interlock ( Clutch starts with with the multi-meter I have a couple appointmen to in San Francisco starting tomorrow so I will get back on this when I get back to Nevada City. I love this truck and get complements and purchase offers everywhere I go. I just have this one little (well not so little) issue. You mentioned you used 12AWG from the starter relay to the starter I think I might go with this 10AWG and do the same.

RAD4Runner

That's why I always stress with other members to list model-year-engine-transmission in signatures. Saves time for everybody trying to help.

IF YOU PROMISE TO ALWAYS START IN NEUTRAL, for troubleshooting purpose, try bypassing clutch safety switch and see if problem persists. 10AWG is not needed but would not hurt and even better if you already have the wire.

bcraj1

Yes. I apologize. My first time using the forum. Sorry for the omission. I should know better. I see the information on your signature. I'll work on that also. I actually had a roll of the 10 in the bottom of my electrical box from I don't know when. I'll let you know how it goes.