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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
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Toy-t100-3.4L-97-stan: I'm Chip,I have a '97 t100.Somes when

Customer Question

I'm Chip,I have a '97 t100.Somes when I start it,it starts but will not accel and even backfires. After a few tries it gets better and eventually runs fine.What will make it not work and suddenly work.I've looked for vac leaks and sprayed connectors, maf sensor and wiggled things. I can't pin-point the trouble. Can you help?
Submitted: 2 years ago.
Category: Toyota
Expert:  Juan Crespo replied 2 years ago.
Hi Chip. welcome to our site. The symptoms you describe point to a bad signal from the engine coolant temperature sensor (ECT). Has the Check Engine Light been on at any time? Have you had the system scanned for codes?
Customer: replied 2 years ago.

I changed the etc a few years ago. At that time, I had the system scanned and it pointed to replacing the etc. I did not have this situation that I do now. I have no code for you as my check engine light is not on. This situation first occured about a year ago as I was driving. I was doing 60 mpg and slowed to 30 mpg for town traffic. All of a sudden the engine seemed to stall so I pulled to the shoulder and tryed to keep it alive-keep it from stalling. All of a sudden the engine responded and all was good. I drove home-30 miles-and all was good. The next day, same problem it started but would no run. It started but not accelerate. After a time, it started and ran well. I drove it for months, having no confidence. Today, I started it and ran into choppy idle and no accel. I sprayed and wiggled and even exposed the cam sensor. The sensor seemed tight. OK. It rained last night. When I first started, it was choppy and no excell. As time went by and I looked at the cam sensor, my son started the engine and it idled but would not rev over 2000. I took a break for about 30 min. and started the engine. It ran normal. I had idle and excell. It as like a switch had been turned on. This is my situation. I can't understand. Is it the dampness? It's done this on a dry day also. Is it a wire connection? What wire ( color ) would cause this problem. What connection should I check?

Expert:  Juan Crespo replied 2 years ago.
This is one of those issues that can drive a mechanic crazy. You're on the right track thinking there might be a intermittently bad connection or failing component causing this issue. Unfortunately, the only way I know how to diagnose this type of problem is by using both a capable scanner plus a lab scope. Would you like me to opt out to see if another expert on the site has a different option?
Customer: replied 2 years ago.

The truck started and ran for me today but it idled at 2000rpm. It settled down to around 1000. By opting out are you deserting me. Can't you just ask around and get back to me.

Expert:  Juan Crespo replied 2 years ago.
I'm sorry you feel I'm deserting you because you don't have the necessary tools to work on this type of issue; that's not it at all. It's because that's the only way I know. All experts on this site login from their own location. For example, I'm retired and login from my home. I have no one to ask.I'll opt out and re-open the question so other experts can chime in. Please don't respond until another expert responds or the system will route the question back to me. Best Regards.
Expert:  Toyota Service replied 2 years ago.
Hello. Please allow me to assist my colleague Juan on this request.
This sounds very much like a fuel pump that is starting to fail.
The only way to check this would be via a fuel pressure gauge which is connected to the fuel system.
Normal operating fuel pump pressure is 32 PSI; measured at the inlet of the fuel rail.
If this vehicle was in my shop, the fuel pressure would be the very first thing I would be checking, as you have no check engine light on. The fuel pump, if bad (or going bad) will NOT set a check engine light.
If you have any questions, please feel free to reply
If you are satisfied with my input, a positive rating would be greatly appreciated. Thanks in advance