Help with fuel injectors please

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

May 29, 2009

#1

• May 29, 2009

• #1

Hey everybody I am still having issues with my car not re-starting after it runs for like 5 minutes or more. It will usually start in flood mode though. What I noticed was when I took readings on my Fuel injectors I noticed 9 volts on injectors 7 and 8 with the key in the third position(Engine not running):no. All the other injectors had a reading of 0 volts which is what I expected. Correct me if I am wrong but the computer only sends 12 volts to the injectors at the proper time in which they should fire...... I'm guessing my computer is messed up and is keeping those two injectors open all the time and this is allowing those two cylinders to flood. Let me know what you all think.

 

donkey_punch

New Member

Jan 16, 2004

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northern****ingjersey

May 29, 2009

#2

• May 29, 2009

• #2

http://forums.stangnet.com/786710-my-stang-wont-start-after-warms-up.html

 

gtstangrunner

Member

Sep 21, 2004

61

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6

Litchfield Park, AZ

May 29, 2009

#3

• May 29, 2009

• #3

Well the Dizzy is brand new. I have spark also. The only way the car will start back up is if you place in flood mode(Hold throttle wide open before turning the key) which tells me spark is not the issue but too much fuel is. I put my fuel pressure gauge on and when the car has sat the pressure holds pretty good, but after it has ran it will drop pressure pretty quick as if the injectors are still open. Car has new dizzy, TFI, TPS, ECT, IAB. Please keep the suggestions coming guys

 

donkey_punch

New Member

Jan 16, 2004

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northern****ingjersey

May 29, 2009

#4

• May 29, 2009

• #4

"but after it has ran it will drop pressure pretty quick as if the injectors are still open"

do you mean once you turn the car off there's no fuel pressure?

 

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

May 30, 2009

#5

• May 30, 2009

• #5

When I initially start it up cold if the key is in the ON position it holds fuel. I start it and let it run a bit, turn it off then put the key back to the ON position it will not hold fuel well at all. This is when you have to put the pedal to the floor to get it to start. Why do you think I have 9 volts on injector #7 and #8, that really has me confused!!!!!!!! Thanks

 

donkey_punch

New Member

Jan 16, 2004

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northern****ingjersey

May 30, 2009

#6

• May 30, 2009

• #6

can you hear the fuel pump prime when you try to start it after letting it run?

also here a check list, i'm not 100% which one you fall under, but it is a good read.
http://forums.stangnet.com/6161267-post.html

 

99FiveOh

15 Year Member

May 20, 2006

2,051

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99

J-Ville, FL

May 30, 2009

#7

• May 30, 2009

• #7

I didn't see a new fuel pressure regulator listed in your replaced parts. Maybe the diaphram inside is getting stuck or something allowing to much pressure after shut down, then when you try to start the car it's flooded. Then it slowly moves back to it's normal position so the car starts fine later on.

I'm not sure on injector voltages, but I believe the computer grounds the injectors rather than send voltage to them, someone correct me if I'm wrong.

JT (Hissin) should have some input on this.

 

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

May 30, 2009

#8

• May 30, 2009

• #8

I have new Aeromotive adjustable FPR. You are right I just looked at the drawings and it seems the CCRM supplies the 12 volts to the red wire on the injectors and the PCM grounds them in firing order to complete the circuit and allow the injectors to fire. I am still confused as to why two of them only have 9 volts on them. I would be less confused if either all of them had 9 volts or just those two were showing 12 volts. According to the drawing all the injectors are daisy chained iff the same 12 volt source from the CCRM. I'm going to check my CCRM and see if I have accessory voltage and ground on all the correct pins for the EEC. Any other suggestions would be great. Summit tech support said it sounds like I have a short in my wiring???????

 

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

Jun 4, 2009

#9

• Jun 4, 2009

• #9

Update

CCRM pins all checked out ok. Pulled off my harness in the engine bay leading down to the EEC in the kick panel and probed the two pins for injectors 7 & 8 and they showed 1.6 volts. This tells me the problem is from that point to the computer itself. I checked to see if I had continuity with all the other pins and there was no continuity present, not even with ground. At this point I feel it's got to be the computer. Let me know what you all think.

 

99FiveOh

15 Year Member

May 20, 2006

2,051

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99

J-Ville, FL

Jun 4, 2009

#10

• Jun 4, 2009

• #10

It can be an expensive "what if" when it comes to the EEC. I'd say make absolutely sure it's not something else first.

 

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

Jun 4, 2009

#11

• Jun 4, 2009

• #11

Yeah, I have double checked and triple checked to make sure I was probing the correct pins and checking for shorts to other wires over and over again. I checked for a short to other wires(Continuity with the wires for injectors 7 & 8) like three times on every single harness and junction point in the car. I showed no shorts to other wires and no shorts to ground. Got a new computer coming from Checker for only $125 dollars. They are a piece of cake to install(Just one 10mm bolt). I sure hope this solves my problem because I really can't think of any other possible causes right now. It's weird the voltage that's showing is identical(Both show 1.6 volts). This really makes me think it's computer related.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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129

Jun 4, 2009

#12

• Jun 4, 2009

• #12

Mark is correct. The injectors receive constant 12V when the key is on and it's the ground which is modulated. If you don't have 12V to all your injectors with the KOEO, check the VPWR circuit for an open.

 

gtstangrunner

Member

Sep 21, 2004

61

0

6

Litchfield Park, AZ

Jun 5, 2009

#13

• Jun 5, 2009

• #13

Problem solved

Ok, here goes I had 12 volts to all the injectors with the key in the third position. The side that gets grounded by the EEC had 1.6 volts on it for injectors 7 & 8. I probed with my DMM and found the problem to be on the computer side of the harness. Checked for continuity between the wires for 7 & 8 and all the other wires in the harness. The check came up negative which meant there were no shorts in my wiring. Swapped EEC's and the voltage(1.6 volts on grounded side) on those two wires went away and the car starts up each and everytime with no hesitation. The car also pulls alot harder all the way through to redline. As of right now the oil consumption has been reduced as well. Thanks for all you alls help ok.