90 4runner fuel pump?

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I had been having random stalling acts with my 1990 4runner V6 5 speed.

315000km . At first a thougjht it could have been an electrical problem as it would stall and start right back up. But now that it has completely died it seems it is a fuel issue. I brought it to the local garage for repair, but the repair estimate was around $1000. $350 for a pump plus lines fuel filter labour and possibly sending unit. So I have decided I would tackle the repair myself as I have had the fuel tank off the truck before.

I was told that the truck would run with a purge.

When I turn on the key I can not hear the fuel pump...but then again I dont recall ever hearing the fuel pump run...probably cause I never tried listening for it.

I was wondering if I could run 12volts directly to the fuel pump connector located under the back seat. To ensure that indeed the fuel pump is the problem before dropping the tank?

I read a couple of post that stated there is a "T" connector on the older 4runners you could short to give power to the fuel pump ..is there a way to do this on this V6 90 4runner?

I see an EFI relay in the fuse box in the engine compartment, is there any other relays that turn on the fuel pump?

Thanks in advance. Cheers Jason

Reply to
computeks
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The fuel pump does not run if the engine is not running. I believe that it needs a signal from the crank sensor.

Yes, just make your connections at the pump FIRST before applying the 12 volts so that no sparking occurs in the vicinity of the fuel pump!!!

Conversely, if you have a meter, you should see 12 volts at the pump while you are cranking.

Reply to
Ray O

Ok ....I started removing the fuel tank. I noticed a broken wire that had in the past been reconnected with a crimp on. This broken wire is one of the three wires that go to the fuel pump. I reconnected the wire before I completely removed the tank...but it still would not start.

So I took off the tank. So on the top of the tank there is the sending unit with 2 fuel lines and two wires for the fuel guage right? Then another round piece with another fuel line coming out.

Then on the lower part of the tank is what I believe is the fuel pump with a connector and three wires going to it.

Right?

So how does the fuel pump connect with the fuel lines coming out of the top part of the tank?

I guess what I want to know is how to I get this fuel pump out. I guess I have to drill out the rivets? Does the sending unit have to come out too?

I tried applying 12volts to what I think is the fuel pump with the 3 wires...put it did not come to life?

3 wires.... power and ground and another for a signal wire (switch) ? How does this work?

Cheers Jason

Reply to
computeks

After I was told by the garage that I needed a fuel pump..I bought one on ebay. After removing the tank...I dont see these types of connectors on my tank.

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I dunno?

Cheers Jason

Reply to
computeks

Oh ok...so the pump is mounted in the tank on the sending unit? So what is that other part on the lower part of the tank with the 3 wires? Let me guess it is for the fuel guage. So the broken wire was doing what?

Im starting to make some sense of this ..I think.... :-)

Cheers Jason

Reply to
computeks

Update...oh ok...grrrrrr...I put 12volts to the fuel pump and the pump is functioning. I was able to pump a bunch of gas into a jerry can. So now what ? Bah-hum-bug... :-(

So I guess I need to see if 12 volts is getting to the pump? Can I turn the engine over without the fuel tank installed to see If I can get

12volts. I believe I did this before and was only getting 2.5 volts. But would like to try again.

Stumped...but learning alot about my truck...:-)

Cheers Jason

Reply to
computeks

Without a wiring diagram or looking at where the wire goes, but the possibilities are fuel pump, fuel gauge sender, and low fuel warning sender.

Reply to
Ray O

While the engine is cranking, the pump should be getting 12 volts. If you are only getting 2.5 volts, check the wiring and look for a crankshaft rotation sensor, probably somewhere around the front lower pulley.

Reply to
Ray O

Ok with more testing.....if I apply 12volts to the pump it works. If I put a meter on the connector that goes to the fuel pump with the key in the on position I get like @2.0volts...then when I crank the engine over the voltage goes to zero ? This is wth the fuel tank removed. On yes that broken wire most likely the low fuel indicator. Cause that quit working awhile back and the guage was functional.

Hmmmm...

Ray O you have been awsome thanks for your imput...you dont know it yet but you will be the guy who fixes my truck...:-) Well with my labour..I hope.

Where are all the certified toyota dooods?

Cheers Jason

Reply to
computeks

OK, if the voltage goes to zero when you are cranking, then either something is physically wrong with the wires, like a loose or bad connection or something is wrong with whatever is supposed to control the power going down the wires, like a relay or the crankshaft rotation sensor. I'd look for a loose/bad (colored green) connection or a bad/loose relay.

You're welcome, hopefully we can get the thing running! You seem to be a good listener and are looking for the right things, which is half the battle!

They're probably on vacation!

Reply to
Ray O

Well Ray O ...I think I might have found the problem. I went out and bought myself a Haynes repair manual...cause i needed to know where to look....

So turns out there is another relay " Circuit Opening Relay" located above the ECU computer on the passengers side kick panel area..I had to take the glove box and speaker off to get at it. Well It definetly had a case of the "Green Monsters" (corrosion)

This truck has a bit of a water leak when it rains on the lower passengers side windshield...rust rust rust...Canadain winters...The ecu was the first thing I inspected because of this water leak. The ecu seemed to be free of corrosion..but I didnt know there was a Main relay right above it that absorbed some of this water over the years.

I did a simple continuity test on the relay and it seemed fine with some scratching on the terminals. I could hear it click....so I scratched it up a bit more and put it back in.

So I put my meter back on the fuel pump connector and cranked it over...Well Well Well...I now am reading well 11volts while cranking....closer to what it should be to run the fuel pump.

I will have to get the fuel tank back on and see if this sucker will run for me again.

Will let ya know.

Cheers Jason

Reply to
computeks

Good news here !!!

I put the fuel tank back on.... and it started right up!!

I hope I have this problem beat !

I will have to clean up that relay a little better...or price a new one?

Then I will have to figure out a way to divert the water leak...

Yes I know I should fix the leak...easier said than done...:-(

Thanks again Ray O for all your input.

Cheers Jason

Reply to
computeks

Yay! Use some very fine sandpaper or emery cloth to clean up the contacts on the relay. If the contacts in the socket are green, you may be able to clean them up with one of those finger nail emery boards or a thin screwdriver wrapped with fine sandpaper that you work between the contacts. Invest in some dielectric grease to slow down the return of corrosion and moisture in the contacts.

As far as fixing the leak, bathtub caulk works well, and Backpacker Magazine rated Gorilla Duct Tape the best, even when wet!

Reply to
Ray O

Well...hmmmm.. I took the 4runner for a test spin..all seemed well. I was just about back home and it stalled again...grrrrrr.

Maybe I should get a replacement relay ..this one does look rusty..and I suppose I could open it up and check out the insides.

Cheers Jason

Reply to
computeks

Ok I opened the relay to have a look. Ohhhh...very rusty inside. Pretty much screwed and I am suprised it works at all.

I am going to get a replacement and will post my results.

This is got be my problem. I hope.

Cheers Jason

Reply to
computeks

...all except Ray it seems!...

Reply to
Gord Beaman

I think you're cooking with gas now Jason...11 volts is sure near 'nuff...hell, your meter could be out that much...good luck...

Reply to
Gord Beaman

I haven't figured out how to do newsgroups on my new Treo but I was able to do e-mail from camp this weekend!

Reply to
Ray O

I called toyota for the relay. They want $120 +tax special order. So I have ordered myself a like new used one for $20 shipped. 3 days.

Cheers Jason

Reply to
computeks

Just an update to finish this thread. I recieved the used relay..popped it in..and my troubles are gone. No more stalling. Yeah !!

Thanks all.

Saved myself serious $$$.

Cheers Jason

Reply to
computeks

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