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84 Fiero injector problem


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I have been trying to figure out why my pulse injector does not work. (4 cyl. iron duke)

 If I spray gas into the air intake, it runs fine.

 Every time I ask the question, all I am told is how to diagnose it, but no one ever tells me what is actually wrong.

 Can anyone tell me what they have done to correct their problem?

 

 On bended knee, thank you, Roger

 

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If the injector is not spraying any fuel, it could be anything from a defective injector, to a broken wire, to a bad connection, bad fuel pump, to a faulty computer, etc.  Lots of things can cause the problem.  Need to do some diagnostics, like Joe said.

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No one can tell you what is wrong without diagnosing the issue using the repair manual with flow charts, etc. It is methodical.    You will need a digital volt meter, test light and the manual to begin the processes of diagnosing injectors not spraying fuel.  

Edited by avgwarhawk (see edit history)
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The 84 Iron Duke has a Throttle Body Injector that just has one injector, if it gets clogged, it stops working.

That said it uses an early OBD called ALDL. Moates.net has a device that connects to a USB port.

Also there is a fuel pressure shraeder valve in the fuel line. You should have 35-40 psi. (Can check by pressing the valve with a fingernail shortly after trying to start, fuel should spurt. If not, the problem is lines, filter, pump, not the injector.

Finally I've replaced A Lot of Fiero fuel pumps. It is in the tank in the center tunnel of the car and need to jack up as far as possible. A lift is nice. Change the fuel filter at the same time.

 

ps Do you have a service manual ? Are online at Pennocks and include diagnosis charts.

 

pps if it fires when you spray gas, problem is in fuel system. Can check ignition by seeing if the tach jumps while cranking.

Edited by padgett (see edit history)
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1 hour ago, Roger Walling said:

I have been trying to figure out why my pulse injector does not work. (4 cyl. iron duke)

 If I spray gas into the air intake, it runs fine.

 Every time I ask the question, all I am told is how to diagnose it, but no one ever tells me what is actually wrong.

 Can anyone tell me what they have done to correct their problem?

 

 On bended knee, thank you, Roger

 

I had an Iron Duke that did the same thing. The ignition module inside the distributor was the problem. It sends a signal to tell the ECM when to open the injector.  But as others have said, without going through the troubleshooting procedure you are just taking a stab in the dark.  Throwing parts at it without troubleshooting the problem can get expensive.

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 I think that I have solved the problem.

 I have been looking at the electric system and padgett  on this site told me that it is probably in the fuel system.

 

 After consulting the manual, I found out that the oil pressure sending unit starts the gas pump when it is closed after receiving oil pressure so I grounded the sender (normally open) and with a test light, I probed the pump wires and detected low voltage with out the pump running, so I believe the pump is frozen and only drawing current.

 

 I ordered a new pump ($17.50) and will respond with the results when I have installed it .

 

Roger.

 

 Ps, I have done a few modifications on the car and the fuel tank could not be in an easier place to change the pump!

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Edited by Roger Walling (see edit history)
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Was going to mention that it is a pain to drop a Fiero gas tank and would only use an AC Delco but see you do not have that issue.

 

BTW the GM CCC sends a two second "prime" burst to the fuel pump that bypasses the oil pressure sender. also there is a green "prime" wire somewhere near the engine. Just apply power to run the pump (or not). I had dual quads in my Sunbird so added a prime button in the dash.

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2 hours ago, Roger Walling said:

 I think that I have solved the problem.

 I have been looking at the electric system and padgett  on this site told me that it is probably in the fuel system.

 

 After consulting the manual, I found out that the oil pressure sending unit starts the gas pump when it is closed after receiving oil pressure so I grounded the sender (normally open) and with a test light, I probed the pump wires and detected low voltage with out the pump running, so I believe the pump is frozen and only drawing current.

 

 I ordered a new pump ($17.50) and will respond with the results when I have installed it .

 

Roger.

 

 Ps, I have done a few modifications on the car and the fuel tank could not be in an easier place to change the pump!

IMG_0488.JPG

IMG_0490.JPG

DSCN1462.JPG

And it keeps social distancing too!

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2 hours ago, Roger Walling said:

 After consulting the manual, I found out that the oil pressure sending unit starts the gas pump when it is closed after receiving oil pressure so I grounded the sender (normally open) and with a test light, I probed the pump wires and detected low voltage with out the pump running, so I believe the pump is frozen and only drawing current.

 

 I ordered a new pump ($17.50) and will respond with the results when I have installed it .

 

Or, you could simply apply 12v directly to the pump and see if you get fuel pressure before replacing a pump that may or may not be the problem.

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 At joe_padavano's sugestion, I supplied 12volts directly to the fuel pump.

 There was no sound or pressure on the test gauge.

 

As to those many that have said in other threads that E10 does not dissolve fuel hose or destroy fuel pumps, let me wrap this fuel hose over your mouth and then tell me that again! 

 

 The hose came apart in my fingers (inside and out side pics of the hose) and notice the gummy stuff on the bottom of the fuel pump.

 

 I think that I made a mistake buying the $17 pump.

 I noticed that I had replaced the pump years ago and that one was not E10 resistant.

The new $17 one is probably not resistant also.

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Edited by Roger Walling (see edit history)
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  • 2 weeks later...

Roger, 

You need to do a systematic diagnosis and let us know the findings so we can help you.  Since you say that your car will run with gas poured into the throttle body, that would indicate that your ignition side of your car is fine.

 

That said and from memory the information that is needed to determine the cause of your no run condition are:

 

With a fuel pressure gauge on the schrader valve what is the pressure when you turn on the key? If it is less than 35 pounds but more than 0, then you have a bad pump.  If it is 0, then there is either an electrical problem in the fuel pump circuit or the pump is bad.  You said that you put 12 volts on the pump and it did not run.  That is a bad pump. I would guess that the car has between 125,000 - 150,000 miles.  That is the usual life of an original pump. 

 

When you get a new pump installed, look at the pressure at the port at the engine.  It should be in the correct pressure range.  The suggestions to replace the hoses & filter are good recommendations.

 

Let us know where we can help you. 

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