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3.4 swap trouble. by 86fiero3.4
Started on: 07-04-2013 11:27 AM
Replies: 26 (427 views)
Last post by: fierofool on 07-06-2013 12:42 PM
86fiero3.4
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Report this Post07-04-2013 11:27 AM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
I got my 3.4 swap almost done. The engine runs for a couple seconds than shuts off. If you feather the throttle it runs a little longer.
Anyone have an idea on what it could be? Map sensor? It has no codes popping up.

Its a 3.4pr egr delete, and mild cam swap. Chip made my gmtuners.

[This message has been edited by 86fiero3.4 (edited 07-04-2013).]

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Report this Post07-04-2013 12:13 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
I would start by jumping the fuel pump on all the time and see what that does for you. Larry
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Report this Post07-04-2013 12:32 PM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
Agreed.

It could be that the cold start injector is giving the engine the fuel it needs for a bit, then it starves.

If the fuel pump is not running, check the ecm for rpm indication; if none, check the dist connections (where the ecm gets it's rpm info from). Also check the oil pressure switch which is a backup to the ecm.

If both of those check out, check the gourns on the ecm, injector fuses, and make sure the injectors are getting the solid +12 they need.

Chay
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86fiero3.4
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Report this Post07-04-2013 12:38 PM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
I deleted the cold start injector with the kit from tlg i believe it is.

I show RPMs during cranking and running. The injectors are pulsing. There is a ton of spark.

I guess i can try hard wiring the pump but it sounds like its running the whole time even when the motor stops it sounds like its on.

My aux gauges arent working they worked before the swap.

[This message has been edited by 86fiero3.4 (edited 07-04-2013).]

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trotterlg
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Report this Post07-04-2013 12:42 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Either spark or fuel goes away when it stops, so you have a 50-50 chance of figureing it out the first try. Larry
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86fiero3.4
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Report this Post07-04-2013 03:16 PM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
Im just stuck as far as know what to check instead of replacing guesses and them not work.
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Report this Post07-04-2013 09:52 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniEdit/Delete MessageReply w/QuoteDirect Link to This Post
Did you power the fuel pump through the ALDL fuel pump port? This will keep it running continuously as a test.

You can also hook a timing light to the coil lead to dist wire and check for spark.

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sardonyx247
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Report this Post07-04-2013 11:48 PM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
check your fuel pressure. make sure it has pressure around 43ish, and that it holds when the key gets turned off.
It could also be a dirty injector.

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phonedawgz
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Report this Post07-05-2013 11:04 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Electrically unplug your MAP sensor and then try to start it up.
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86 toy
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Report this Post07-05-2013 11:13 AM Click Here to See the Profile for 86 toySend a Private Message to 86 toyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have been helping him with his car.. the fuel pump runs as it should and is brand new.. when you start the car it will run for a short time then it will try to stall but if you play with the throttle you can keep it running but it will continue to clear up the try to die again.. we need to get it to hold a steady rpm to break in the new camshaft..

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86 toy
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Report this Post07-05-2013 11:17 AM Click Here to See the Profile for 86 toySend a Private Message to 86 toyEdit/Delete MessageReply w/QuoteDirect Link to This Post

86 toy

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quote
Originally posted by phonedawgz:

Electrically unplug your MAP sensor and then try to start it up.


This will be the next thing we try.. thanks
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carbon
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Report this Post07-05-2013 11:30 AM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Reset the IAC and make sure the throttle body minimum air screw hasn't been tampered with...
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86 toy
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Report this Post07-05-2013 11:54 AM Click Here to See the Profile for 86 toySend a Private Message to 86 toyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by carbon:

Reset the IAC and make sure the throttle body minimum air screw hasn't been tampered with...


It does this even when your holding the throttle off idle trying to keep rpm at 2000
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carbon
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Report this Post07-05-2013 01:34 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 86 toy:

It does this even when you're holding the throttle off idle trying to keep rpm at 2000


Oooo... that sucks. Nevermind then.
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Slowbuild
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Report this Post07-05-2013 02:20 PM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
Can you post a video of it?

I'm curious about the way in which it dies off. Does it kick (misfire...timing), or smoothy die (fuel), or just cut off (no spark).

You said feathering the throttle helps a bit...add throttle helps, or off the throttle helps, or pulsing helps?

It really sounds like a fuel issue...Have your had a pressure gauge on it while running/dying? Perhaps a bad reg or something blocking the return?

Are you running the stock intake? Just wondering because it you have the 3.4 it's easy to use a stethescope to hear the injectors clicking. Probly not the issue as it's not just 1 cylinder, but worth a check if the other stuff is fine.

If you have a scope I'd check the ecm injector pulses as well. It could be bad injector drivers in the ecm, but probably not, as it does start in the first place.

It could be tune. Can you drop in the stock ecm prom and just try it at idle to see if it runs at least sortof ok? the a/f won't be right, but at least you could try. Do you have a scan tool on the ecm? If you get data the prom should be ok (IE inserted right and functioning to some extent) at least.
Chay
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Report this Post07-05-2013 02:39 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Next time you start it try running an unlit propane tourch into the intake and see if it keeps it running, that may give you a clue as to what is going on. Also, if the eprom has never been known to run an engine, I think I would switch back to a stock one. Larry
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86fiero3.4
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Report this Post07-05-2013 08:00 PM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
So after trying some of the stuff here i think its a fuel issue. The rail has no presure after the motor stops.

Anyone have a fuel rail with the regulator? Mine wont come off.

Cheap or free would be awesome.
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Report this Post07-05-2013 08:33 PM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
Maybe you have done this, but before thinking about the rail, how about a fuel flow test. And check/replace the filter. and check the return line (blow through it, it should be easy!


Regs do screw up, but I'd check the other stuff first.

Sorry if you said you have done this already!


Chay
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Report this Post07-05-2013 08:39 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniEdit/Delete MessageReply w/QuoteDirect Link to This Post
To get the fuel pressure regulator off you need the "tamper-proof" torx bit. You may be able to find one locally. The Fiero Store sells them too:
http://fierostore.com/Produ...d=263&nq=0&p=1&sz=50

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Report this Post07-05-2013 08:54 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does it look like this thing?

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86fiero3.4
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Report this Post07-05-2013 09:37 PM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
The filter is brand new and the lines are clear as far as i can tell.

Id rather get a rail that someone knows it works than to buy the regulator....
Considering they are like $80 for a piece of rubber and a spring.

I have the bit to do it but they wont break loose.
i was going to replace it before i assembled the motor but decided it wasnt important.... Silly me.

And no thats not it but thanks.

[This message has been edited by 86fiero3.4 (edited 07-05-2013).]

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sardonyx247
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Report this Post07-06-2013 07:26 AM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
instead of free parts, how about some free advice?.?
to test the reg and/or fuel system, hook up the pressure gauge and turn on the key(not start), should get about 43 psi for about 2 sec then prob drop a couple of psi and then hold. If the pressure does not hold, turn off the key for min 15 secs, pinch off the return line, turn on the key, should get higher pressure, if it holds now and didn't before, it is the reg, if it still doesn't hold psi then it is a check valve in the pump or the line in the tank to the pump.
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fierofool
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Report this Post07-06-2013 08:07 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
The ECM runs the fuel pump at first ignition ON. It pressurizes the fuel system. When the START circuit is energized, the responsibility for the fuel pump is handed over to the Ignition Control Module. The ECM gets busy with other things and doesn't know whether there's fuel or spark. You could still have spark but no fuel.

Check the 4-wire connector that plugs into the ICM. Unplug it and look into the end to see if all the connectors are evenly seated into the connector. Several times I've encountered a connector that's been pushed back into the connector and has lost contact with the pins of the ICM. This is usually the 2nd one from the right side of the connector, as it sits when plugged into the ICM.

I have a fuel rail with regulator from a 3.4, which is identical to the Fiero fuel rail and regulator except the cold start injector was deleted by the factory. If all other diagnostics fail and you think you may need it, email or PM me.

Correction: The two fuel rails I have may be from 2 different year 3.4's or one could be from a Fiero. One looks like the Fiero fuel rail except the cold start injector is located at the end of the fuel rail rather than in the middle. The other doesn't have a port for the cold start nor does it have the part bolted on top known as the Fuel Block. Fuel lines attach at a different angle on the two rails. I can send you pics of the two for comparison if you want.

[This message has been edited by fierofool (edited 07-06-2013).]

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86fiero3.4
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Report this Post07-06-2013 11:52 AM Click Here to See the Profile for 86fiero3.4Click Here to Email 86fiero3.4Send a Private Message to 86fiero3.4Edit/Delete MessageReply w/QuoteDirect Link to This Post
Well i figure a different rail on hand is a good idea incase it is the problem. But thanks guys

Edit. Where is there a check valve in the tank?
the line from the pump itself (rubber hose in the tank) to the assembly (metal lines in tank to the filter) and the filter to the rail is all new and clear.

[This message has been edited by 86fiero3.4 (edited 07-06-2013).]

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Slowbuild
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Report this Post07-06-2013 12:05 PM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have to tell you that the fact your lines are new etc is not a way to troubleshoot. It assumes that everything is good; assumptions are the root of frustration.

Disconnect the fuel line at the rail and place it into a suitable container, observing all safety protocols. Jumper the fule pump at the aldl and make sure you are getting good volume. Do the fuel pressure checks above. Let us know the results.

When you sdaid you show rpms, was that at the tach, or on a computer etc connected to the ecm? The tach means nothing. If it's from the ecm, when it sees engine rotation it should continue fuel pump operation.

Did you try to jumper the fuel pump on, then run the engine as suggested above? What were the results?

Chay

[This message has been edited by Slowbuild (edited 07-06-2013).]

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Report this Post07-06-2013 12:11 PM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fierofool, any chance that is a Camaro/Firebird fuel rail? Seems to me I have one of those too...

Anyway, the reg should work.
Chay
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fierofool
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Report this Post07-06-2013 12:42 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
The one without the cold start injector came from either a Camaro or a Firebird 3.4. I bought one of each. The Fiero fuel rail has the cold start injector, but its port is located at the end of the rail. The P22 shows it located at the center of the rail. It does have the same fuel block mounted on top as shown in the P22. That's where the fuel lies attach. The Camaro or Firebird rail fuel lines go directly into the fuel rail. I can't post pictures here from my phone, but if you're interested, I can send one to your email.

The regulators on both the Fiero 2.8 and the Cam/Bird 3.4 are the same part number.

[This message has been edited by fierofool (edited 07-06-2013).]

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