1990 v6 starts then shuts down after 1 second

Du6

Du6

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Hi...I have a 1990 4Runner with a v6 engine. It starts no problem, idles for a second and shuts down right away.
I've replaced the airflow meter and the fuel filter. No change.
When attempting to start it the other week, the oil pressure gauge shot up and hasn't come back down yet. I think it's stuck. Oil level is within specs.
Any ideas what's going on?
Thanks very much!
 
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how many miles? also has it been sitting for a while? Or have you or someone else made any major repairs to the engine? My first thought was the fuel pressure regulator may be faulty. One way to check that is to take the vacuum line off and if there is any fuel in that line, the diaphragm in the regulator has ruptured and that can cause a starting/running issue, usually it would take a few tries to start but my ex had an olds aurora that would start then die and it was the FPR.

here is a picture of the regulator, you can see the hose connected to it, take that off and like i stated earlier, if there is fuel in the hose, replace that regulator and you should be good to go. Please excuse the extremely dirty engine...haha
fpr_zpsabdf06a7.jpg~original


hope this helps, and if not hopefully someone that is more familiar with the 3vze can chime in!
 
It has around 210,000 miles. The guy I bought it from had new (1994) heads installed, new radiator and battery. Since I've owned it (like 3 months), I've put in a new starter, replaced the Air Flow Meter and fuel filter. Next, I'm gonna look at the fuel pump and/or relay.
It hadn't been sitting. The seller said it was a daily driver from Escondido to San Diego. (About 80 miles round trip).
Tomorrow (today), I'll check the regulator.
Thanks for your help!
 
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I took that vacuum hose off and it smells like gas, but no gas present. I cranked it once to see if any came out. There was none. It's looking a lot like a fuel pump.
 
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I disconnected the power to the fuel pump and tried starting. It didn't even fire. So I know there's power getting to the pump.
 
Does it run smooth for the short time it runs, or is it not long enough to tell? It may be the fuel pump, sounds like a fuel related issue. You might try checking the fuel pressure, also I remember changing out my fuel filter and I had to crank down on the lines to get it to not leak and I had the same issue while it was leaking. So make sure there is no fuel leaking from the lines going to the filter. Other than that if you haven't already try a search in the forums to see if anyone else has had any issues or maybe try another forum. Hopefully someone else can chime in if they have had a similar problem
 
For the one second it runs, it's very smooth. No leaks around the new fuel filter. I'm pretty sure it's the pump, I just dread dropping that tank.
 
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Here's a video I made. Note how much fuel flows. I still need to pressure test, but the pump is looking OK so far.
It seems like it runs longer if the gas cap is off...weird. That may mean it's a pressure regulator issue? I'm pretty confused right now :-(

20130612165202 - YouTube
 
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bimmr2002 said:
how many miles? also has it been sitting for a while? Or have you or someone else made any major repairs to the engine? My first thought was the fuel pressure regulator may be faulty. One way to check that is to take the vacuum line off and if there is any fuel in that line, the diaphragm in the regulator has ruptured and that can cause a starting/running issue, usually it would take a few tries to start but my ex had an olds aurora that would start then die and it was the FPR.

here is a picture of the regulator, you can see the hose connected to it, take that off and like i stated earlier, if there is fuel in the hose, replace that regulator and you should be good to go. Please excuse the extremely dirty engine...haha
fpr_zpsabdf06a7.jpg~original


hope this helps, and if not hopefully someone that is more familiar with the 3vze can chime in!
Click to expand...
OK so I tried to take the regulator off the engine, but the hose connection (big hose) hit the manifold and I couldn't get it to come off. Weird? What's the deal with that?
 
Any chance you unplugged the plug that goes to the air box? Mine did that till I remembered that plug. Fired right up after.
 
sounds like a fuel issue or a major vacuum leak, however, as azshtr stated the plug that goes to the air box, that could be it. Just for shts and grins I went out and unplugged mine and it idles for a bit then dies, check engine light was illuminated. Not sure 100% if thats it but you may try and check the connection and make sure the pins are clean, and if the air filter was recently changed this is a good place to look. Hope this helps! Also, the video you took, it looks like you are getting sufficient fuel flow, hard to tell for sure but it looks good.
 
It seems to me that i's running off the cold start injector. After the fuel it puts out is gone, it stops because the pump isn't strong enough to supply the other 6 injectors. Hopefully that fixes it, because putting a new fuel pump in is a huge hassle. After all this dirty work, I want the truck to run!
Also in the video I shot, There doesn't seem to be 38-44 PSI of gas flowing.
 
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So, It wasn't the fuel pump, But I'm glad I have a new one back there.
Anyway, I found 2 hoses that go from the intake manifold to the power steering pump. Both of these hoses were disconnected in the middle with a very bad patch job and electric tape.
Would those hoses (connected to the "Air Control Valve" where the power steering pump is mounted) cause this problem?
Also, I noticed the EFI Relay gets hot. Substantially hot. I'm pretty sure I have to replace that relay.
Anybody think I'm on the right track?
It does seem to run longer before shutting down. Weird.
 
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normally with a big vacuum leak it either wont start or it will run like crap then die...I guess its possible that the relay could be getting too hot. Unfortunately my experience lies in newer cars with very few vacuum lines so my knowledge and experience with older cars is not vast, but we will keep trying to get your rig back on the road! Where are all the 3.0 guru's!? As far as the video goes, watched it again and it doesn't look like very much pressure but only a pressure test would really tell. have you tried checking the connection of the AFM? right above the airbox?
 
I did a temporary fix on the air control hoses, and switched them in case i connected them wrong. No change. Are the hoses special or can I use regular vacuum hoses for that?
(These are the set of hoses that go from the intake manifold to a valve located in the same place where the power steering pump is mounted.)

When I disconnect the connection to the AFM it shuts down immediately. With it connected, it runs like 7 seconds.

It has a new fuel pump and filter, so the pressure shouldn't be an issue. And I know it's pumping, because there was a leak at the fuel line connection to the pump. I fixed that and no change.

I put in a new EFI relay, It doesn't get hot and no change.

When it starts to stall, hitting the gas won't help at all.

I tore the dashboard out and there was no light bulb in the check engine location. I used another bulb, put the dash back together, checked for error codes, and there are none.

My head is seriously busted on this.
 
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Is there a reason the fuel pump would only run during cranking but not when the key is in the "run" position? Reviewing the video of the fuel pump operating, it's clear that there is no flow when the motor isn't being cranked by the starter motor...
 
OK Here's an update.
I opened the Diagnostic box and connected the +B and FP together. Alegedly, this is how one bypasses the COR and the AFM and runs the fuel pump on it's own.
Well, it ran for about 15 minutes with no problem. When i pulled the wire from +B and FP, the motor stalled and shut down just like before.
So, we know that the fuel pump is only pumping when the starter is engaged, and not when I take my hand off the key.
I also noticed that the EFI relay got hot again, but that didn't seem to affect anything.
I removed the vacuum hose from the fuel pressure regulator, and nothing changed. This is a concern.
Anybody know what this is about?
 
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