shag67

I'm hoping someone can give me some guidance. 91 4-runner with the 3.0 VZE. Drivin down the road and it just dies. Get it towed home and head out for a new alternator and battery just in case. New alternator, no change....new battery, no change. I run out and get a coil, again no change. I'm reading the threads at yotatech and people are talking about the battery wires (negative and positive) and the brain. I want to use my multimeter and start looking for a break. (It's just not getting spark....it cranks over fine) How do I do that? What do I put my multimeter on (AC?) (Ohms?)...exactly where am I to put the test lead in terms of wires or connectors? Where would I start? Where do i go from there? Much thanks.....and I checked all the fuses....and I also shorted the E1 circuit to pull codes and it just blinks

wrenchmonster

How have you verified that you're not getting spark? What does your distributor cap and rotor look like? What do your spark plugs look like? Have you checked the hall effect sensor in the distributor? When did this problem start and was it running fine before or has it been slowly getting worse? Avoid throwing new parts at the rig and learn to diagnose the problems. Pick up a Haynes manual, and it will take you through some of the basic testing you need to perform.

shag67

You're right on...I got my buddy coimn out to help verify that I'm not getting spark by holding the plug against the engine block....Yes, now I've been going through the haynes manuals and going by the book. It's easy to get lost on these threads and chase a lot of improbable dead ends. My hunch wth the whole thing is that it's not spark but fuel. Assuming it does indeed get spark I'm going to go through the fuse connections for the fuel pump, if they check out then buy a fuel pressure gauge and see f that's the problem....switch out the fuel pump (after checking electrical connections at the pump first)....it's just a hunch but i feel that's the deal. Then return all the hardly used parts....put my old ones back in and get back on the road...Thanks!

shag67

PS....answer to your questions are new Dist. Cap and rotor look great, Fairly new plugs and wires...everything was running great and just died and cannot get started, no prolonged period of deteriorating problems. Gut instinct ...the fuel pump crapped out or possibly just a bad connection to or from Fuel pump. This truck has been kinda pain recently and therefore My daily driver and most dependable vehicle for the last 6 months has been a 66 volvo amazon i bought for $3000. It kicks butt. I had a ford escort that had the same symptoms as the Yotaa and after baffling my mechanic and I for quite some time problem turned out to be the brain (ECU)...I am a big fan of cars without brains

scope103

Don't do that. Who do you think ends up with your "lightly used" (!?) parts you try to pass off on the kid behind the counter? The folks on Yotatech, among others.

Before you start buying parts (alternator, battery, coil, fuel pump ....) at random, use your new book and do a little basic diagnosis. Check for spark by putting the inductive pickup from your timing light (they cost $20 -- how much have you wasted on parts so far?) on each plug wire. If the light flashes, that plug is firing.

A fuel pressure gauge is the best way to check for fuel problems, but they aren't cheap (around $75), or easy to use, and you MUST replace all the crush washers you removed to install it. So as a first cut, get a foot of 6mm (1/4") clear vinyl tube, and connect the fuel return from the fuel pressure regulator to a suitable container. Force the fuel pump to run by jumpering FP to B+, and you should get about 1/2 liter/min on the fuel return line. If you do, the pump is good (this doesn't test the fuel pressure regulator, but they are much less likely to be an issue.)

Charchee

Second on returning the parts you bought. Those costs are on you and don't need to be next guy's problem. Most electrical parts aren't returnable anyway. A new battery is almost always a good investment but I'm scratching my head about the alternator. Jump your FP and B+ terminals to verify that your fuel pump is working. Even a weak fuel pump should allow it to start and idle somewhat. Check your EFI fuse. Your injectors will not fire without power being supplied to the ECM.

Start with the efi fuse and then test the fuel pump and report back.

shag67

Yes...I'm starting now to go right down the list you've provided. Didn't mean to pass off used parts on fellow Toyota drivers, I just assumed it was definitely the alternator because this same thing has happened quite a bit throughout my car owning life and it was almost always the alternator...but you're absolutely right, I will not do that sort of thing in the future. I wouldn't want to get a slightly used possibly damaged part from the auto parts store myself...."do unto others"...and it's also just not good mechanics/diagnosis. Thanks for your help....just repaired the negative ground cable that goes to the battery. Key on and no sound from fuel pump. I guess i need someone to turn the key so that I can listen for a click from the EFI fuse (that's how you check if it's good?) and I'll start jumping the terminals you suggested to rule out the regulator. And check the pump. I never realized I can use my timing light to check spark...good to know! Thanks Again, -Rich

Charchee

EFI fuse is under the hood in the fuse box on that model I believe. Underside of the fuse box lid should show you it's location. In my 89 model, it's a 15A fuse but mine uses a different fuse setup. I still think it's a 15A. If you don't have a test light or multimeter, pull it out and examine it for a gap in the flat metal wire inside the plastic housing of it. Also look for evidence of heat damage around the prongs of it.

Start there and report back.

shag67

I didn't realize there are 2 fuses labeled EFI, one is big and round....I looked at the 15A one and it's not broken nor has heat damage on prongs. When it's light tomorrow I can recheck the circuit with my Multimeter but I think it's safe to assume that the fuse is good. Next step is to either jump the fuel pump and see if it's pumping...or buy a fuel pressure gauge which is prolly handy but not necessary for this operation ...maybe just go right into the fuel pump area (under pass back seat) and replace (after checking first with multimeter at electrical connection)...right? I say this because if I can't hear the pump working when key is on then it seems pointless to jump it or check fuel pressure.

Charchee

The fuel pump on these engines does not run unless there is air flowing across the mass air flow meter. When cranking the engine over or while it's running, air is drawn across it and it sends the signal to the fuel pump to turn on. You will never hear it without air flow across the meter. Jumping the terminals eliminates the requirement for a signal from the MAF and will allow it to run whenever your key is in the run position. You should be able to hear it then. You can also try and start the truck with it jumped. If it starts, you likely have an issue with the MAF. It will not run well at all but it should run. Don't leave the jumper in permanently. If you had a fuel leak and it were to ignite, the fuel would just keep pumping and you will have a much worse problem.

Also, that fuse may not be burned but it may not be receiving any power at all. You have to check it with the meter or test light in order to rule it out. Check it on both sides. Needs power in and out in order to rule out the electrical circuit upstream of it.

red90toyota

does that year 4runner have an access panel under the rear seat to get to the fuel pump? If it is easy to get to you could unplug the fuel pump, put a meter on the wires normally powering the pump, get someone to crank the truck over and see if you had 12 volts there. if you do, all your wiring and fuses and relays going to the pump are probably ok, if not you could start working your way back. while you are in there you could hook the pump directly to a battery and see if it runs. If it does not you would be fairly certain your pump was bad.

Charchee

Good idea but make that step two. Jumping those two pins and listening for the pump takes literally 2 minutes and you don't have to turn a single wrench. If you don't here it, test for voltage on B+. If you have it there, then head back to the pump and check it there.

scope103

The "big and round" thing is the EFI relay. http://web.archive.org/web/201204170.../2powersou.pdf

You're going to find this process a lot easier if you get a cup of hot chocolate and spend a few minutes sitting in front of the fire with your Haynes manual. Familiarize yourself with the basic systems, and do diagnosis before replacing parts. As several have pointed out, you can directly test the fuel pump by jumpering FP to B+. You use a multimeter (not just your eyes) to check fuses, because a) a fuse can fail near-invisibly, and more importantly b) you might not have power TO the fuse.

Several of the people making these suggestions HAVE replaced a fuel pump, and that's a job you don't want to do only to find out later you have a blown fuse.

shag67

Jumped the Fp to B+ and the fuel pump is not operating. Also double-checked the fuse box with multimeter. Removed the access panel in the rear and it only allows access to the fuel line in order to disconnect. To get to the fuel pump you have to drop the tank. You could cut a new access panel in there for the future (or not)...What a job! Now I see why diagnosis is so important. I found a good thread with pics and steps for removing fuel tank. I'm going to double-check my diagnosis, go through this thread again....reacquaint myself with the manual and probably end up dropping the tank to access fuel pump, double-check to see if it is getting power, see if it runs off battery and if need be replace with a new pump....Dang! Thanks y'all

bootscootboogie

iTrader: (1)

Put a new coil in it. Bet that baby fires right back up.

shag67

Already did that

Charchee

Now that's good work! Yea, if you can get to the connector, try running it off external power to be sure you don't have a broken wire between the tank and the engine bay before removing the tank. Toyota tanks are easier to remove than most of the others I have done in my day except for the one with badly rusted hardware. Just take it one step at a time and you'll get through it.

Oh, and by the way, if you don't cut a hole in the floor to remove it, make sure you buy a quality fuel pump and not some $20 carquest part. I have never had a OEM Toyota fuel pump go out on me. Not saying they won't but I know in my younger days, I replaced several with cheap aftermarket pumps and all but one time, I was back in there replacing the new one within two years.

shag67

Thanks for walking me through that and all your advice...I will spend the money on a quality pump. It's gonna rain here in Northern Cali but the sun will be back in 2 days. I found a good thread to follow for tank removal, I'm going to take it slow and check for a broken wire between tank and engine bay

shag67

For what it's worth...ended up being the timing belt. I did a compression check first (because its easier than taking the whole timing belt cover off) and it was zero. Took the cover off and the belt was shredded. Makes sense I suppose. My previous issue was that my harmonic balancer was slipping, which caused my timing to be almost constantly off (sometimes by as much as 180 degrees). This would have put unnecessary stress on a timing belt that has already had 60,000 mies on it...and wham! Car won't run. Thanks to Charchee for helping out. Be patient and use the shop manual, that's what I learned from this. Hope this thread helps someone else...

Charchee

Glad you got it figured out! These engines aren't as complicated as a lot of folks think. Most of the troubleshooting tests can be performed in less time that it takes to get to and from the parts store. I have the luxury of a good running 02 model and as well as a company truck at my disposal. My best thinking is done while I'm running the roads for work. When I hit a snag, I just leave it alone for a day and plan my next test. Doing one test every afternoon, I usually have my issue figured out by the weekend and knock it out on Saturday. When you're trying to get one going in a hurry, you can go down a bunch of wrong and expensive roads. Patience is the key.

Good work.