its been two months and no CEL25!!!

 

Guess I will continue my monologue. At the risk of sounding like the boy who cried wolf, I feel like I have fixed the CEL 25 problem.

I went back to the basics and checked the fuel pressure (even though I had put in new denso fuel pump about a year ago). When I checked the pressure without engine running, it was 29 psi. When the truck was running, the pressure was about 25 psi and stayed there when I raced the engine. The pressure did not change when I pulled the vacuum line off of the fuel pressure regulator (while the truck was running and no fuel was in the vacuum line). I then noticed that there was no fuel going through the return fuel line on the pressure regulator. So I had low fuel pressure as it was not getting high enough to flow through the return fuel line on the fuel pressure regulator. I put a another new pump in denso (part number 950-1150, the first fuel pump was a denso SX7239 ordered on ebay). Anyway, the truck now runs great, starts quickly on the first crank (even when warmed up) and the CEL 25 has not come on for 1 week. I guess the first fuel pump was bad...not sure if it was a knock off or what. I did notice that denso had a big fuel pump recall for newly manufactured toyotas, subaru, honda etc....

At any rate, I think the combination of getting a new fuel pump and new thermostat (with gasket) has my truck back to great running condition.

 

Well I did jinx myself. CEL 25 came back.
Maybe it's the chinese MAF sensor i put on. My old one had vane spring break. I bought used one on ebay (OEM, but 30 years old) and it worked for a while. Its resistances all check out but truck doesn't run well with it. Now I have chinese one on it. Runs good, resistances all check out, but getting CEL 25.

Question: where can you get a good MAF sensor? Its discontinued at toyota. All that I can find are old ones from junk yards and the new chinese versions.

 

I will jinx myself.
The code 25 problem is resolved. My thermostat gasket broke and my engine was not getting up to operating temperature. I put in new thermostat and gasket and no more CEL 25. Also the truck is running much better. Truck also starts on first or second try when hot (30 min after running).

 

Oh well, the code 25 came up again after about 3 weeks. Back to the drawing board.
sorry about the false info

 

Thanks much for taking time to post photo. Cornfucius say, "Picture worth thousand words."

 

This is picture from the interweb. Pleunum port is circled in black. The hose on the port goes to the power steering. My truck doesn't have power steering and a simple vacuum cap was on the port. The Cap cracked and was causing the code 25 CEL.

 

Would you kindly post a photo w/ arrow of your engine bay, showing where (exactly) this part is found?
Thank you.