91’ LC wont stay running (1 Viewer)

[OffRoadMedic]

The other day my cruiser started up as usual but then bogged down to a very rough jerky idle then died. I started it back up and my buddy was pointing at my MAF sensor saying “this thing is clicking!” I removed the silicone and took off the black cap to see that the spring that opens and closes the door was consistently and rapidly opening and closing. I disconnected the harness and fired it up with the same result. It will run for about 3 seconds before totally dying with no start unless it sits for a while. Anyone have any idea what it could be? If you have any ideas or see anything I should check, please circle it in the photo so I can take a look at it.

 

[60 toy ota]

You're saying the flap was opening and closing? Because it's air flow that opens it against the resistance of the spring which tries to keep it shut. There's no mechanism inside there that would cause it to open.
BTW, you didn't mess with the 2 screws at the connector, right?

 

[ppc]

That is not a MAF sensor. Your 91 uses a AFM or VAF sensor which contains contacts that run the fuel pump. I'm guessing you. damaged those contacts by trying to remove the electrical connector the incorrect way.

 

[OffRoadMedic]

You're saying the flap was opening and closing? Because it's air flow that opens it against the resistance of the spring which tries to keep it shut. There's no mechanism inside there that would cause it to open.
BTW, you didn't mess with the 2 screws at the connector, right?

Yeah now that you say that, it could have been because it was gasping for air so maybe that caused it to open and close. My intake filter is clean as well.yes I did that first thing to check if the sensor was dirty. Found out after I got home that’s a big no no so I soldered the 3 foil flaps back down as found in a YouTube video and still had the same results as before, before I undid the screws. That’s primarily why I didn’t mention it is because I didn’t think that I damaged the MAF sensor.

That is not a MAF sensor. Your 91 uses a AFM or VAF sensor which contains contacts that run the fuel pump. I'm guessing you. damaged those contacts by trying to remove the electrical connector the incorrect way

That is not a MAF sensor. Your 91 uses a AFM or VAF sensor which contains contacts that run the fuel pump. I'm guessing you. damaged those contacts by trying to remove the electrical connector the incorrect way.

I don’t believe I did. It’s acting the same way as it did before I even touched it. I just don’t know if it could be the pump itself or a bad relay.

 

[jonheld]

The first thing you should do is smack your buddy on the back of the head.

You can bypass all fuel pump logic by jumping pins B+ (pin 8) to FP (pin 1) on the diagnostic connector.
However, if you screwed up the AFM, this motor will never run correctly.

It also looks like there are dreadlocks of aftermarket wiring going on around the battery compartment and the additional positive terminal that appears to be hanging on for dear life next to the aluminum radiator is giving me chills.
I would be sorting that crap out right away.

 

[OffRoadMedic]

The first thing you should do is smack your buddy on the back of the head.

You can bypass all fuel pump logic by jumping pins B+ (pin 8) to FP (pin 1) on the diagnostic connector.
However, if you screwed up the AFM, this motor will never run correctly.

It also looks like there are dreadlocks of aftermarket wiring going on around the battery compartment and the additional positive terminal that appears to be hanging on for dear life next to the aluminum radiator is giving me chills.
I would be sorting that crap out right away.

View attachment 3895838

Ok I finally had time to troubleshoot. Upon jumping the B+ and the FP pins with the key turned to the ON position, there is a hissing sound from one of my fuel injectors. Could it be stuck open or be something else?

 

[Funner]

Look here

 

[OffRoadMedic]

Look here

View attachment 3899193

For what exactly? Brand new intake filter and all wires and hoses are connected and leak free.

 

[petegangies]

Yeah now that you say that, it could have been because it was gasping for air so maybe that caused it to open and close. My intake filter is clean as well.yes I did that first thing to check if the sensor was dirty. Found out after I got home that’s a big no no so I soldered the 3 foil flaps back down as found in a YouTube video and still had the same results as before, before I undid the screws. That’s primarily why I didn’t mention it is because I didn’t think that I damaged the MAF sensor.



I don’t believe I did. It’s acting the same way as it did before I even touched it. I just don’t know if it could be the pump itself or a bad relay.

repairing these with soldering is hit and miss, due to the nature of the pads on the board connections. So while you may have resoldered them, there is no guarantee it's worked, or that your VAF was good before this mishap. Have you tested it using the procedure in the FSM?

 

[jonheld]

Ok I finally had time to troubleshoot. Upon jumping the B+ and the FP pins with the key turned to the ON position, there is a hissing sound from one of my fuel injectors. Could it be stuck open or be something else?

The hissing sound is likely the fuel return line from the FPR. These types of tests and diagnostic procedures are all outlined in the Toyota FSM.

 

[OffRoadMedic]

repairing these with soldering is hit and miss, due to the nature of the pads on the board connections. So while you may have resoldered them, there is no guarantee it's worked, or that your VAF was good before this mishap. Have you tested it using the procedure in the FSM?

No I have not, I will look into finding a downloadable pdf unless you have one. Thank you.

 

[OffRoadMedic]

The hissing sound is likely the fuel return line from the FPR. These types of tests and diagnostic procedures are all outlined in the Toyota FSM.

Ok I will look into this. Thank you Jon, sorry for all the confusion. I am learning as I go.

 

[jonheld]

No I have not, I will look into finding a downloadable pdf unless you have one. Thank you.

Available in the resources section.

 

[petegangies]

No I have not, I will look into finding a downloadable pdf unless you have one. Thank you.

PM me your email, I'll send my 1994 one or download from the resources section on mud.

 

[OffRoadMedic]

PM me your email, I'll send my 1994 one or download from the resources section on mud.

I got the one on mud, thanks