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Going @#%$^@$ crazy here!

2639 Views 40 Replies 6 Participants Last post by  C J
I have a 1992 B2600i. It was given to me and I know about issues with the fuel pump on it's way out. And when I first got the truck there were no issues, other than having to pull over to vent the gas tank.
When the weather started to cool off but not yet cold, I could no longer just start up and go. It idled fine (1500rpm) but when I gave it gave gas it would drop down to 500rpm or so and when I took my foot off of the gas, it rose back up to 1500rpm.after maybe 15 min. or so, I could give it gas and it wouldn't die down and I could take off. I could put up with this for a while.
A while has passed and I can't take it, Now I have trouble even starting it. I have to pump the gas four or five times, take my foot off of the gas and then try to start it. It would catch but a no go. I then started to just leave the key fully turned to keep the starter running and it if caught, I'd let the key go. Id' still have to let it idle for quite awhile.
So, thinking it may be a thermal sensor, I'd let the truck idle for a bit and then turn it off. I was thinking that the engine compartment would be warming up the sensors. Sometimes it would work and sometimes, not! Since my truck is too old to do a OBD reading, I have to shoot in the dark.I took of the mass air flow and cleaned it with that spray stuff. Both ends were covered in a black like soot. I made sure it was clean and put it back on. My next thought was if the mass air sensor looks like this then what does the air filter look like? I went it to the auto parts store and had to order one. My next escapade will be to completely tear down the air intake system and fully clean it, including the throttle body and all. I have one question and I can't find the answer to it anywhere!!!!! Behind the air intake "pipe" there's a sensor coming out of it going into a black box and I found the name or "RESONANCE CHAMBER"!!!! Does anyone here have a clue what it's for and it's purpose????? Thank you for any and all help/suggestion that you may be able to contribute!!!!!
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Well, I am not mechanic but the resonance chamber on Subarus were on the air intake and did two things; they tuned the sound and did something to the air flow as it went into the intake. It is one of the items that Subaru guys who like to mess with their cars take off, it gives the engine a better sound according to them. It is also something that many people take off when they put in cold air intake systems.
UPDATE>>>>>>>>>> Today, I went ahead and replaced the water thermo sensor.. Having the engine already "warmed up" couldn't really tell much other than the fact that the idle is somewhat irratic. It doesn't really stay at one speed and tends to go way up and then down. I'll know more later or tomorrow when I really try a cold start! If this doesn't work, I'm afraid my next step is to replace the gas pump and sending unit. It'll cost about $180 but I just don't have the time, the place nor patience to test things. Really getting tired of this stuff!!!!!!!
Sounds like at this point you are just throwing parts at it. Have you considered bringing it to a certified Mazda tech?
You see, that's part of the problem. Had I had the $$ available, I would've done that in the beginning. Since I don't and probably never will have, I've turned to this forum in the hopes of saving me time and $$$$. I'm not just throwing parts at it as you say; however, I am replacing possible culprits only after doing as much research as I can and make somewhat of an educated deduction ax I can. All things pointed to the water thermo sensor. I'll just keep going down the list. Make fun of me if you like. I thought part of the reason for these forums were for people to get their heads together and try to figure things out. Am I wrong?????? I can ill afford to to simply throw parts and hope! I'm happy for you if you're in such a good place in I'm not and will never be! That's why I'm here!!!!!!
Dude, I am not making fun of you AT ALL. Just pointing out that in the long run, maybe purchasing all of those parts may end up being more expensive then just bringing it to a Mazda tech in the first place. And sure, forums like this are great for this stuff but if someone can't actually see and put their hands on an engine they are just guessing like you are. Technicians have advanced equipment that they can use to diagnose a problem that you might not have.

And don't be so sure that your financial situation will not get better, life can take turns and I hope it does for you.
UPDATE: I've replaced the spark plugs, plug wires, rotor, distributer cap. That didn't make a difference and later replaced the fuel filter located on the firewall. That didn't seem to help other than it didn't take as long to get it running to a point where I could drive off. Now the Temperature outside has warmed up a little and coincidently, my truck now starts right up and I can drive it immediately. Just too weird forbnt to comprehend!!!!!!!
So....something temperature related?
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