My '95 3.Slow won't start and I'm throwing parts at it

M

Maui Cruiser

New member
Ok the car in question: 1995 3.0 V6 Auto 3VZ. Sparks are new.

After normal driving for months - a few weeks ago I fired it up and when she went to idle for warm up, it puttered out and stalled. Again, this time with the gas pedal pressed for good measure it back fired, slammed the air flow door shut and stalled. Third try it fired up totally normally, drove into town and back with no problems. Next day, 4th try to get it going. Next day 10th try. A week later 20th, etc. All with normal driving conditions once started. Now she's stuck in a parking lot outside... Here's where I started throwing parts at it to see what would stick.

The fuel system: fuel filter, fuel pump, and reset back to old injectors (recently switched to 4-hole sprayers). Same problem.

Air system: Vane air flow, filter, checked all hoses. Same problem. Cut and rewired the connection to the VAF. Nada.

I'm stumped and need help! Why won't this thing fire up?? :wacko:

There's fuel pressure - it sounds like the cold start injector is getting the initial turn over... electrical to EFI? Fuse looks a bit old but works. I'm hitchiking to work and need this truck to run!
 
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Troubleshoot first, then replace parts.

You need air, fuel, and spark (and you need them in the right ratio). Then you need compression and timing. So start with the basics. When you know what you don't have when it won't start, then you can start looking at what components aren't providing it and why. Check for spark on each cylinder, bench test the AFM, open the fuel rail and check your fuel pressure while cranking, etc.

Have you tried pulling engine codes? Sometimes there's a code lurking in there that might point you in the right direction.
 
I've got all three and she's still shutting off

I can start it up, and with the accelerator pushed it rev's up high - and then two seconds into it - decellerates itself into a stall.
 
I'd ask the same question as Kevin, what codes are coming up?

Sounds like it could be any number of about 20 different problems, reading the codes would narrow it down to just a few things though.
 
Ok, I jumped the code system with a copper wire, and it just blinks forever. No cryptic codes, just constant blinking. What does that mean?
 
How's your catalytic converter? I don't know whether these trucks use a brick-style catalyst or what, but if it's broken/loose in the housing it could block off the exhaust and choke the engine out.
 
I'd vote for a possible ignition issue if you really have good fuel pressure.
Timing, quality of spark, failing coil, bad connector at distributor, coil or AFM.
I'd put a spark tester in line with the coil and see if you have uniform good spark.
 
Maui Cruiser said:
Ok, I jumped the code system with a copper wire, and it just blinks forever. No cryptic codes, just constant blinking. What does that mean?
Click to expand...

Constant blinking means no codes are stored at all, normally good, but in your case, not so much. And the gunk in the connector is dielectric grease to keep the terminals from corroding. I'd put some back in there if I were you, being from Honolulu, I know quite well just how fast things corrode from the salt air!

Here's a quick list of things to check, sort of in order:
1. check spark plugs, are they wet/black/dry/sooty
2. check for actual spark-hold to block while cranking
3. check timing, short the timing check in same connector as you read codes, set to stock numbers to make sure all is good.
4. test fuel pump by shorting the connector for b+ and FP, see if she runs
5. if 4=yes, check your fuel relays, if 4=no, check for pressure at fuel rail (you should be able to get a gauge from the local parts store)
6. check injectors wiring and spray pattern
7. check injector resistor pack (looks like this:
$_20.JPG
)

I know you said you changed out the injectors, and now I'm thinking you may have damaged the resistor pack if the other 4 port injectors were the wrong impedance. Might wanna check that one before you start screwing with the fuel rail and other stuff.
 
Flyin Hawaiian to the rescue -

#4 yes. Jumped FP to B+ and she runs normally. EFI fuse is malfunctioning. One copper wire and I'm back on the road. Ha!

Thanks everyone!
 
I was going to say, running for a second or two and then dying sounded exactly like a Circuit Open Relay issue, glad you found it. So just to follow up, have you isolated what the real problem was and fixed it, or are you running around with that test port jumped? The Circuit Open Relay is there to cut fuel to the injectors if the motor dies with the key still On. With that relay bypassed you run the risk of flooding the motor, or worse, burning your truck down.
 
The real problem is a broken EFI relay in the fuse box. Top of it looks beat up. Worth replacing.
I'm driving around with it jumped for now and going to the parts store ASAP to get a new relay tomorrow after work.
Will it flood if driven normally?
Will I start a fire by driving around?
 
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Not saying the EFI relay isn't iffy or not worth replacing, but I'm not convinced that's your immediate problem.

The Circuit Open Relay is a safety feature. Your fuel pump normally only gets power under two conditions - the key is in the Crank position, OR the key is in the On position and the ECU detects the engine running and powers the COR, which powers the pump.

By jumping those ports, you've bypassed the COR. If you were absent minded and left the key On for longer than a bit, you risk flooding. If you got in a wreck and the motor died and you weren't able to turn the key off, you'd risk a fire as the pump kept pumping. Not a huge deal in the short term, I just wanted to make sure you weren't going to leave it like that. :)

Incidentally, I don't think the EFI relay and COR circuits are tied together, I don't think jumping that port has any effect on the EFI relay at all? I'd bench test your COR and see if it's defective... if not, you might have trouble with your AFM or wiring, because that's how the ECU knows if the motor is running.
 
I was under the impression that my circuit open relay was my EFI relay. Now I understand there are two relay's in combination with the AFM. One in the engine compartment and one somewhere behind the glove compartment. I just read this...

(Originally Posted by fourwd1 - There are 2 relays that affect fuel pump operation, the Ckt Opening Relay (COR) and the EFI relay. If either relay is bad, the pump won't operate at all. There is also an interlock switch in the Air Flow Meter that controls power to the pump. For test purposes, you can bypass the interlock and COR by jumping the +B and Fp terminals in the test connector, located adjacent to the engine bay fuse panel.)

So: Since the bypass allows the truck to run while still using the EFI relay going: COR is the culprit? (I have already popped in a working AFM so that can't be it.)

Is that correct?
 
I'd agree with Kevin, sounds like the COR is bad. Just as a reference, here's a photo of the AFM's fuel pump switch:

closed.jpg

open.jpg


That's under the black plastic cover of the AFM. the FP/B+ does bypass BOTH this switch and the relay. Once you replace the relay, if the truck still doesn't run without the jumper, then check the flapper door in the AFM to see if that switch is good inside it.

Just thought I'd mention it, I replaced the AFM on mine with a Cardone1 unit from Rockauto and found that they painted it so badly that the door was stuck partially open and wouldn't close properly! They are not rebuilt very well at all, so if that's where you got your replacement AFM, and you're still having problems getting the truck to run, I'd cut the cover open and inspect the switch and clean the rheostat board inside (very carefully, like with q tips and isopropyl alcohol!).
 
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