C3 guy with another TPI question.
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
C3 guy with another TPI question.
Hi guys, here's what's going on with the TPI install on my C3. At this point I have spark, I checked my injectors with a homemade noid tester and with 12 volts direct, to make sure they are firing (clicking). When I pull the fuel lines from the front of the TPI, gas is present in the fuel in line but not in the return line. The spark plugs are also dry. What would cause the fuel to not circulate to the injectors?
Thanks for your help.
Zorro.
Thanks for your help.
Zorro.
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... Its either that or the fuel pressure regulator or return line are blocked .............
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Need to check fuel pressure at the fuel rail, 40# + - is required.
What fuel pump are you using? In tank, external?
If correct pump the pressure regulator may be farbared.
What fuel pump are you using? In tank, external?
If correct pump the pressure regulator may be farbared.
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Is their away to test the regulator?
Thanks.
Zorro
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
I think I see some problems....
You must use a late model C4 pump and have it wired thru the ECM with the relay and Oil press switch in the loop..The pump is probably not running.
Those injectors won;t even drip with less than 25 psi.. You need 40 to start & run.
The regulator won;t open up to send fuel if there is low pressure.
Have you got the TPI ECM in place?
BTW..the fuel injectors are HOT always...the "bank fired" circuit is operated thru the ECM by grounding.
You must use a late model C4 pump and have it wired thru the ECM with the relay and Oil press switch in the loop..The pump is probably not running.
Those injectors won;t even drip with less than 25 psi.. You need 40 to start & run.
The regulator won;t open up to send fuel if there is low pressure.
Have you got the TPI ECM in place?
BTW..the fuel injectors are HOT always...the "bank fired" circuit is operated thru the ECM by grounding.
Last edited by leesvet; Jul 30, 2012 at 07:56 PM.
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
I think I see some problems....
You must use a late model C4 pump and have it wired thru the ECM with the relay and Oil press switch in the loop..The pump is probably not running.
Those injectors won;t even drip with less than 25 psi.. You need 40 to start & run.
The regulator won;t open up to send fuel if there is low pressure.
Have you got the TPI ECM in place?
BTW..the fuel injectors are HOT always...the "bank fired" circuit is operated thru the ECM by grounding.
You must use a late model C4 pump and have it wired thru the ECM with the relay and Oil press switch in the loop..The pump is probably not running.
Those injectors won;t even drip with less than 25 psi.. You need 40 to start & run.
The regulator won;t open up to send fuel if there is low pressure.
Have you got the TPI ECM in place?
BTW..the fuel injectors are HOT always...the "bank fired" circuit is operated thru the ECM by grounding.
Zorro.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Sounds like the initial prime power is there, but the ECM can't ground the hot in start and run relay coil for the pump. recheck your fusible links, fuses, and grounds.
By the way, buy a manual for the TPI you stole from the C4 the engine came out of. the wiring diagram is worth it's weight in gold.
By the way, buy a manual for the TPI you stole from the C4 the engine came out of. the wiring diagram is worth it's weight in gold.
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Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Sounds like the initial prime power is there, but the ECM can't ground the hot in start and run relay coil for the pump. recheck your fusible links, fuses, and grounds.
By the way, buy a manual for the TPI you stole from the C4 the engine came out of. the wiring diagram is worth it's weight in gold.
By the way, buy a manual for the TPI you stole from the C4 the engine came out of. the wiring diagram is worth it's weight in gold.
Thanks
Zorro.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Accel 74745. The instructions tell you that it's for temporary use only but mine has been on there for at least 10 years.
http://www.amazon.com/ACCEL-74745-Fu.../dp/B000JJNPNQ
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
Yes:
Accel 74745. The instructions tell you that it's for temporary use only but mine has been on there for at least 10 years.
http://www.amazon.com/ACCEL-74745-Fu.../dp/B000JJNPNQ
Accel 74745. The instructions tell you that it's for temporary use only but mine has been on there for at least 10 years.
http://www.amazon.com/ACCEL-74745-Fu.../dp/B000JJNPNQ
Zorro.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Get a TPI manual from here to sort the pump wireing: Easy to read & follow.
http://howellefi.com/gm-tpi-products.html
Couple of thoughts:
Is there enough fuel in the tank?
Maybe disconnect both fuel lines, stick each one in a container & have someone cycle the key to test fuel delivery.
Poor delivery = pump, line, filter problem
Good delivery = lines switched, bad FPR, no 12v to fuel pump.
GL
http://howellefi.com/gm-tpi-products.html
Couple of thoughts:
Is there enough fuel in the tank?
Maybe disconnect both fuel lines, stick each one in a container & have someone cycle the key to test fuel delivery.
Poor delivery = pump, line, filter problem
Good delivery = lines switched, bad FPR, no 12v to fuel pump.
GL
Last edited by Churchkey; Jul 31, 2012 at 09:29 AM.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
There is a white electrical factory manual.
I went to a book store and was browsng through the automotive section when I found TPI/fuel injection manuals just collecting dust on the shelves.
I bought two different ones because they both explained the same things in different ways, allowing me to grasp what the one was talking about vaguely, and the other explained in great detail and vice versa.
On the 86 TPI, the lines are not the same size. I believe the larger one is the pressure.
If you have an adjustable fuel pressure regulator, try screwing the adjustment down to give more pressure to get it started. Then, when it runs, readjust when running.
How bout posting a pic of your upper water outlet, I want to install the TPI on my 57 Chevy pickup.
I went to a book store and was browsng through the automotive section when I found TPI/fuel injection manuals just collecting dust on the shelves.
I bought two different ones because they both explained the same things in different ways, allowing me to grasp what the one was talking about vaguely, and the other explained in great detail and vice versa.
On the 86 TPI, the lines are not the same size. I believe the larger one is the pressure.
If you have an adjustable fuel pressure regulator, try screwing the adjustment down to give more pressure to get it started. Then, when it runs, readjust when running.
How bout posting a pic of your upper water outlet, I want to install the TPI on my 57 Chevy pickup.
Last edited by coupeguy2001; Jul 31, 2012 at 10:09 AM.
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
From my 86 FSM
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/En...agram%2086.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
Do you have the ALDL port from 86 harness ?
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/En...agram%2086.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
Do you have the ALDL port from 86 harness ?
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
There is a white electrical factory manual.
I went to a book store and was browsng through the automotive section when I found TPI/fuel injection manuals just collecting dust on the shelves.
I bought two different ones because they both explained the same things in different ways, allowing me to grasp what the one was talking about vaguely, and the other explained in great detail and vice versa.
On the 86 TPI, the lines are not the same size. I believe the larger one is the pressure.
If you have an adjustable fuel pressure regulator, try screwing the adjustment down to give more pressure to get it started. Then, when it runs, readjust when running.
How bout posting a pic of your upper water outlet, I want to install the TPI on my 57 Chevy pickup.
I went to a book store and was browsng through the automotive section when I found TPI/fuel injection manuals just collecting dust on the shelves.
I bought two different ones because they both explained the same things in different ways, allowing me to grasp what the one was talking about vaguely, and the other explained in great detail and vice versa.
On the 86 TPI, the lines are not the same size. I believe the larger one is the pressure.
If you have an adjustable fuel pressure regulator, try screwing the adjustment down to give more pressure to get it started. Then, when it runs, readjust when running.
How bout posting a pic of your upper water outlet, I want to install the TPI on my 57 Chevy pickup.
I finally broke down and bought a fuel pressure tester today, my pump is putting out no readable amount, even after jumping the pump relay so the pump would run all the time. Time to pull the pump out of the tank.
Zorro.
Last edited by Zorro O; Jul 31, 2012 at 11:41 PM.
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
From my 86 FSM
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/En...agram%2086.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
Do you have the ALDL port from 86 harness ?
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/En...agram%2086.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
Do you have the ALDL port from 86 harness ?
Zorro
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
The reason I asked about the ALDL port, is because you can supply 12V+ to terminal G, which should keep fuel pump running until power is removed from G.
May help with diagnosis.
Doing the pinch tests of fuel lines, from the first link I gave you, will answer some questions.
May help with diagnosis.
Doing the pinch tests of fuel lines, from the first link I gave you, will answer some questions.
Thread Starter
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
It Lives! Pulled the fuel pump and found that my auto-zone fuel pump harness was falling apart. I put it back together reinstalled it and it still didn't work. Pulled pump again and found the same thing, plug for harness falling apart. Turns out with where the plug is mounted on the sending unit, every time I installed it (sending unit) the side of the tank rubs against it, and the plug falls apart. Eliminated the plug, turned the key and the car started!
Thank you all. Whenever I come over to the C4 forum with a question, I am overwhelmed by how helpful and welcoming you all are. With your help I am well on my way to a functioning C 3-1/2.
Thanks again.
Zorro.
Thank you all. Whenever I come over to the C4 forum with a question, I am overwhelmed by how helpful and welcoming you all are. With your help I am well on my way to a functioning C 3-1/2.
Thanks again.
Zorro.
