iwilder

I have a 94 4Runner V6 SR5 automatic 3vz-e engine. It has 108,000 miles on it. I bought it new.

The problem is a loss of power. The car would start and run fine until you tried to accelerate. It would only go up to around 2000 rpm before it cut out. It doesn't throw any trouble codes

I put in new plugs, plug wires, distributor cap and rotor. I also replaced the throttle position sensor. It has a new exhaust system.

The first time the problem occurred I took the car to the dealer but the problem didn't reoccur so they could test it. I drove it for about three months until the problem occurred again. The second time It cleared up as they were testing it and they couldn't find the problem. After several months the problem occurred again. I had it towed to the dealership and the dealer said I had low fuel pressure and needed a new fuel pump. Cost about $1,300. I changed the fuel pump and filter my self. Saved around $1,000. The car ran fine for a week until I went on vacation in July. When I came back it had the same old problem. This time the problem cleared up for a day then reoccurred. The problem seems to occur after the vehicle sets for several days or more. The previous times it occurred were always on a Monday. I didn't use the vehicle a lot on weekends.

It seems that when it won't accelerate that the fuel pressure is low. There is only a very small amount in the return line to the tank. Cracking open the fuel line at one of the fuel rails sometimes will get it running again. I manage to get it running correctly again and I drove it to the dealership, they had it for several months and it never failed to start and run. After I picked it up the problem began again. Since then I haven't been able to get it to run correctly. I haven?t driven it since last fall. It now starts very hard as well as not being able to rev up. I'd like to get it running so I can use it this winter.

Any help would be greatly appreciated.

Thanks

Ike

Guardian_Saint

I assume a bad transmission?

iwilder

No its not a transmission problem. All the symptoms occurr while in neutral or park. Its definitely an engine problem. It appears that the 4Runner in thread "3VZE Problem Supries Suprise......HELP" has the same or a similar problem. I am beginning to suspect it may be a vacuum problem as I had what seemed like brake failure at one point when I tried to test drive it. The peddle was almost solid and little or no brake response. What would casue an intermittent vacuum loss? The symptom of breaking up and seeming to backfire through the intake at around 2000 rpm would make me think it is timing related but all that checked out fine. It appears to be fuel delivery control related. I will be doing some work on it this weekend I hope. I may know more then.

Thanks for your response.

Ike

BrownsfaninMN

Have you tried your fuel pressure regulator? The dealership will tell you that they'll have to remove your intake manifold to get to it (wrong), it is accessible on the top of your motor, however what you'll have to do is when loosening it you'll notice that it contacts your intake manifold. Just get a screwdriver and bend one of the fuel arms up less than 1/8" and you'll be able to easily remove... Autozone gets $70 for one, bend the new arm up a bit and reinstall, bend back down once you get it installed and tightened. Also, I forgot to mention, you'll have to take the 2 bolts that hold your throttle cable support off (totally easy, right out in the open) and just move out of the way. If I can do it, anybody can...

nate V

iwilder

I believe we have the same problem here
Definitely not the tranny I have a 5 speed..so cant be that
Like you I replaced the Cap, Rotor, Plugs, Wires, TPS, Coil, 2 new o2's, and a new cat,

I had mine plugged in and it said code 21 o2 sensor, sensor circuit, or ecu

If you replace the fuel pressure regulator let me know if it works because I have not done that yet.

Also may be clogged cat......just a guess I know my o2's aren't sending the right signal to the ecu for some reason most likely a broken wire somewhere This is the direction I am heading with mine Hope this helps and maybe we can help each other with this prob. GOOD LUCK

nate V

Try changing the furl pressure regulator and report back with your results?

I would be very interested if that changes anything for it is something I have not done yet...

OR

Try changing the brake booster....could be your vacuum leek as well

rowdy235

fuel pressure regulator
fuel filter
fuel pump

my suggestions

iwilder

I thought I should reply to this as i started the thread. i haven't had a chance to work on the 4runner as i have been building a new shed. I need to get all the stuff out of the garage so I can get the cars inthere and possibly do some work. I read a post on a web site where the author permanently jumpered the B+ and Fp terminals to by pass the MAF and that seemd to solve a similar problem http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump. I have done this to check that the fuel pump was working but not when the engine was running. I have the fuel filter out at the present time so I can't check this. I have a fuel pressure gauge but getting an adapter for the 14mm fuel line is a problem.

The fuel pressure regulator could be a problem but I have low pressure or nonexistant pressure not over pressure. There may be more than one thing going on now as the symptoms have changed. It no longer starts easily or idles well at all.

I will keep the group updated

Thanks for the suggestions.

Ike

iwilder

I have been doing a little more work on the 4Runner and have some new information. I hooked up a pressure gauge and I am getting about 25 lbs. max. This builds up very slowly and decreases to about 10 lbs. when I rev up the engine. The engine will die at about 2500 rpm. I don't get any voltage across the +B Fp terminals. Jumpering them doesn't seem to help. I don't believe that the jumper is working. Anyone have any idea what is going on or what it will take to change out the diagnostic check connector as there may be a problem there if I'm not getting any voltage.

Any tips on how I would go about checking the voltage at the fuel pump connection with the engine running? I don't have any voltage there when I jumper the +B Fp teminals.Will try a few more things tomorrow.

I actually got the car to start a idle but not smoothly. I wanted to move it across the drive way nearer the garage. When of course i was driving with the hood up but that isn't a good excuse for running over my battery charger. I expect I will be needing a new one.

Thanks in advance

Ike

iwilder

The saga continues: I fixed the diagnostic coonnector so that I can jumper the +B - Fp connectors. Now when I jumper the connections the fuel pump turns on as it should. I am now getting 40 lbs but it builds up slowly. When I turn the engine over the pressure drops immediately to 10 lbs and the engine slowly stalls. The drop seems to occur even before the engine fires. If I leave the key on it slowly builds back up to 40 lbs. If I shut the key off with the pressure at 40 lbs it remains there for at least an hour. I really need to see if I am losing voltage at the fuel pump when the pressure drops and if so what is causing it. I was under the impression that jumpering the fuel pump at the diagnostic port would by pass the MAF and the vsv and what ever else controls fuel flow.

If anyone has any ideas I am open to trying anything.

Ike

iwilder

I am keeping this going hoping someone will come to the rescue. I tried looking for vacuum leaks to no avail. I removed the +B to Fp jumper and the fuel pressure improved. I am now getting 40 lbs at startup and around 30+ at idle. The engine will now idle fine but when I step on the gas the fuel pressure drops rapidly to about 10-15 ibs and the engine wil misfire and cutout. So I still have a fuel delivery problem. I have decided to remove the tank and check the fuel pump which has about 0 miles on it but there may be some thing wrong there. A plugged filter on the pump or something. I have drained the tank and removed the bolts but am having trouble with a stuck fuel line fitting. Sprayed on some penetrating opil and will give it a try later today. It is a new hose/fitting I put on the last time I had the tank out, but the other end of the fitting is original 1994. I really can't explain why the fuel pressure improved on its own.

I tried removing the vacuum line from the fuel pressure regulator with no change. Closing off the fuel return line got the pressure up to about 60lbs. but didn't help with the engine missing and cutting out when I reved it up. So I don't think the regulator is a problem. Does anything else control fuel pressure? If you have any experience with a similar problem or have any suggestions let me know.

Thanks,

Ike

iwilder

I've done some more work on this rig and found out a few more things.

I have/had a problem with the VAFM. When I finally got the vehicle idleing I found that the slightest movemet of the vane in the VAFM would cause it to stall. The VFM tested fine. I took the top off the VAFM and found that the E2 connection was loose. I tightened this up and the engine no longer stalled when I touched the vane but would stall if I moved it any distance.

I blocked off the fuel return from the fuel pressure regulator. This gave me higher fuel pressure (55 lbs) but didn't prevent the engine from stalling when I opened the throttle. Opening the throttle caused the fuel pressure to drop to around 10 lgs.

I static tested the EFI relay and it tested correctly but when I checked it for continuity with voltage the switch was still open so this is a problem. I pulled the tank to check the fuel pump but haven't had a chance to bench test it yet. Hopefully this weekend.

I haven't been able to find the circuit opening relay. it is supposed to be under the kick plate on the passengers side. I removed the glove box and found two identical black relays side by side. These are above the ECU. Both are number 90987-04002. Which I believe are AC or blower relays. The don't look like the relay shown in the service manual. I know others seem to have found this relay but I need some help.



More later. Thanks,

Ike