Fuel pressure drop after injector install.
Thread Starter
Instructor
Joined: Jun 2008
Posts: 138
Likes: 0
From: Bridgewater Ma.
Fuel pressure drop after injector install.
Yesterday I installed my Bosch III's from Jon @ FIC.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Yesterday I installed my Bosch III's from Jon @ FIC.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
Don't wory about the extra 6 psi on the pinch test...sounds like the regulator is doing its job.
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
Yesterday I installed my Bosch III's from Jon @ FIC.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
Install went perfect, until I performed a leak test!
Initially the system pressurizes to about 44 psi, then drops to 20 psi in 20 secs. (from 44to 10 in 1 min.) No leaks to be found anywhere.
I then perform a leak down test by pinching off the return line (when standing at the rear, facing the tank fill, the bottom hose that enters from the right side, correct?) the pressure then goes to 66 psi, down to 60 after 6 mins. I then manually bleed of pressure to 44 psi where it holds beyond 20 mins. I understand this points to a faulty FPR. I installed a new diaphragm previous to the initial leak test. So I removed and reinstalled the diaphragm just to be sure. Same results with return line not pinched, rapid pressure drop!
I dont think I'm missing anything, just looking for tips before I go and spend $120 on a new FPR assembly and pull the fuel rails apart
A couple notes,
The car is not running, I have the dist. pulled (replaced intake gaskets) and valve covers off, waiting for my valve seals to arrive.
Also, the FSM states that fuel press., with the return line crimped, should be 60 psi. I'm getting 66 psi ?
Thanks, Ron.
the leak test prior to starting the engine is to find leaks. the rail, injectors and lines are full of air, untill you pulse the injectors there is no way to get the air out unless you purge it through the schraeder using the release button on the guage if you have that type. It will act just like a brake system wiith air, you pump the pedal it holds pressure because you are compressing the air. release it and the pedal goes right to the floor/ try to bleed the air.. if you need me I am on my cell
770 842 0882
Jon
Thread Starter
Instructor
Joined: Jun 2008
Posts: 138
Likes: 0
From: Bridgewater Ma.
You have a leak in the system somwhere....I doubt it to be the new injectors. There is also a fuel pulastor module (just above the fuel pump in the tank) that have been problematic for other CF members and there is the checkvalve in the fuel pump itself that may have a problem.
Don't wory about the extra 6 psi on the pinch test...sounds like the regulator is doing its job.
Don't wory about the extra 6 psi on the pinch test...sounds like the regulator is doing its job.
ron
the leak test prior to starting the engine is to find leaks. the rail, injectors and lines are full of air, untill you pulse the injectors there is no way to get the air out unless you purge it through the schraeder using the release button on the guage if you have that type. It will act just like a brake system wiith air, you pump the pedal it holds pressure because you are compressing the air. release it and the pedal goes right to the floor/ try to bleed the air.. if you need me I am on my cell
770 842 0882
Jon
the leak test prior to starting the engine is to find leaks. the rail, injectors and lines are full of air, untill you pulse the injectors there is no way to get the air out unless you purge it through the schraeder using the release button on the guage if you have that type. It will act just like a brake system wiith air, you pump the pedal it holds pressure because you are compressing the air. release it and the pedal goes right to the floor/ try to bleed the air.. if you need me I am on my cell
770 842 0882
Jon
For the record, Jon phoned me a little over an hour after posting this thread. My problem is that until the car is running or the fuel pump is continually energized while bleeding the fuel rail, the system is air bound and will not hold a static pressure. Duhhhhhh!
I have a few more things to do before I can fire it up, probably within a couple weeks. I'll post an update.
Thanks again everyone! Ron
