VTXRider

Theres nothing wrong with the pump. It just doesn't get current due to the relay being bad. I was able to run it with the paperclip all weekend. I will probably try to track down a relay eventually but its just my toy and seems to be running fine. The paperclip was definately cheaper!

ayoung101

i'm not familiar with this part of my truck at all, so maybe i'm misunderstanding, but you are using a paperclip to jump the terminals where normally a relay goes? it doesn't work using the relay, but it DOES work by jumping with a paperclip? maybe i'm EXTREMELY over-simplifying, but doesn't that just mean you have a bad relay? i know on modern vehicles, if a relay goes bad, you can just pull it out and plug-n-play a new one in and you're fine. not sure about 20 year old toyotas, cuz, like i said, i'm not familiar with that part of my truck.

runnermedic

ok friends did you check the VAFM for proper function?
yep!!! VAFM controls the COP and it sends a signal to turn on or off the fuel pump.
in my case the VAFM doestn turn off the fuel pump when ignition is selected so the pump continues to run fuel alltime.
so check the VAFM take out the black cap and check the wires and terminals in my case 2 of them where splited and one was piece of material was in contact with other one.
that was the cause fixed and now is running great!!!!

scottydogg

Okay, here is a stupid question. What is a VAFM and where is it located?

runnermedic

sorry is not vafm is VAF
volume air flow meter
get the service manual there are the instructions on how to measure the connector!!!

VTXRider

You are pretty much correct. I just need to plug and play a new COR but it is a $90 dealer part or a day spent running around to junk yards. The actual jump with the paperclip is made in the diagnostic port by the relay/fuse box under the hood. By jumping B+ terminal to Fp terminal you bypass all the relays related to the fuel pump and send 12 volts to the pump. The purpose was to allow sevice techs to quickly and easily determine if the pump itself was bad without having to drop the tank...Or to allow you to get your rig back in the mud quick! Even if the paperclip works it could still be 1 or more of 3 relays. COR, VAF, or the ignition relay. In my case it did not pump while cranking or with the VAF flapper depressed so I determined it to be the COR.

VTXRider

VAF is located in the intake tube right by the air box. If you take the lid off the airbox and reach up the tube you will feel a butterfly valve. This is the VAF it sends a signal to the fuel pump to say the engine is running keep pumping fuel. If you turn the ignition on and press the flapper the fuel pump should come on. If not the VAF is bad OR the COR is bad. If it tries to start while cranking it but dies when you stop cranking it is probably the VAF.

BeniciaRT

I just went though this one with my 90 4-runner. The intake sensor has two functions and separate circuits. One tells the ECU how much air is coming through the intake ( like a Mass Airflow Sensor) and the other simple on/off switch tells the ecu the engine is running by the "door" opening just a little.

If the ECU doesn't think the engine is running, it shuts off the fuel pump. (It's a safety AND functional thang...) This keeps the fuel pump from just running when the key is on for no reason and also if the engine dies, for whatever reason, including an accident, the fuel pump shuts off.

I ended up tearing mine up trying to check it, so I took it apart. (very brittle and the connector was NOT cooperative!)

This is the offending part:



Here is a picture I took and marked up JUST FOR YOU (Trying to make a good impression on my first post here...) (Sorry it is so large, but otherwise the details are hard to read...)




I forgot to put the note for the temp sensor, but that is the switch at the top and the black wires on the 3rd and 6th connectors. (counting downward)

So when I found a used one (Toyota wanted $850+ WTF) I found that switch was bad also! Not knowing this I did more troubleshooting to come back to this little switch as the culprit.

Try jumpering the two switch terminals at the airbox and see if the fuel pump runs. If so then that is your problem. That will also eliminate all the other relays etc. (i.e. this is where the "control" side of the circuit lives)

However, now it is time to see if you can get that part fixed...

scottydogg

Would it be safe to spray some electric contact cleaner on that? I am almost positive mine is dirty cause mine is just a hunting wagon and has been thru the ringer a time or two.

BeniciaRT

Well, yes... But here is the catch. That part should be very pristine! To get that cover off, it takes a bit of diggin' out the silicone it is sealed with. That should still be intact. Once you get it open, getting a watertight seal again will be more difficult... Make sure to get all the old goop off both parts. It probably won't cause you any grief... It certainly is worth a try if it is already causing you problems.

mac9968

I had trouble with the relay in the VAF. I ended up cutting the silicon from the top of the VAF to gain access to what looked to be a reed type relay. With the Air flow meter open and drawning air the reeds didnt not touch as they should in order to provid power to your pump. I hope this is making sense, and diffenately stuggled with is for a while. I was ready to replace the VAF, and figured I may as well take it apart, I am glad I did.

mac9968

redundant, must of post just after BeniciaRT

CHEEZBURGER

What does it mean when the paper clip gets really really hot?

Matt16

I didn't know that. Cool. I think this is how the cckscker who sold me my truck had it running because he'd screwed up the AFM by trying to pull out the plug-in socket. Lucky I had a spare.

abecedarian

A LOT of current is passing through the clip, likely due to a partial short somewhere.

Matt16

I'm assuming you jump the ports on the diagnostic box; wouldn't those all be part of circuits with relays and fuses? I'm quite surprised that they would get warm, as (a) a paper clip wouldn't present much resistance I would think and (b) relays, fuses?

CHEEZBURGER

It gets so hot that if I would have taken it out by hand it would have burnt me pretty good, I'm glad I licked my finger and touched it really quickly before I just grabbed it out of there

Jerbou71

well I dont think I have a fuel pump problum. My 92 4runner v6 was running fine till I replaced the air filter and then took the old radio out and put a new one in and then when I went to start it, it starts and runs for about 1 second and then shuts off. Every time I turn it over it starts and then stops. I tried jumping the spot under the hood to get the pump to run all the time and the same thing. How do I check to see if any codes are coming up? I replaced the steering colum on my 2001 silverado and this 4runner is acting the excact same way. The silverado I have to tow down to the dealer to reset the computer. Is this what could be wrong with My 4runner? If so how can I reset the computer? Any help well be thankful.

VTXRider

Sounds like a bad VAF to me. The fact that it starts when you are cranking it pretty much rules out the fuel pump. I would try jumping the B+ to Fp again. Make sure you are getting a good connection in the jumper box. If you can't get it to run jumped then I would investigate the pump. Check the voltage to the pump, if you are getting voltage but no pump then pump is bad but I suspect no volts due to bad VAF or random short. Physically check the wires that run to the pump for worn insulation which could cause a short. That's all I can think of. My money is on bad VAF. Any takers?

CHEEZBURGER

I'm no expert, but I would undo what you did to it, maybe you mightacould did something wrong