90 replies to this topic

[blue_sniper_fox]

My truck set for about 2 weeks, I go to start it and it sputtered then died. I have a half tank of gas, 60psi on the fuel rail, she'll run as long as you feed it through the throttle body. I took the throttle body off and checked the injector hoses and they seem to be spraying a good mist. I'm not sure if its the correct pressure or not. I have a new fuel pump, new plugs, wires, button, cap, MAF and just about everything else you can think of to be new. So now I'm stumped, so if anyone might have an suggestions I'd really appreciate it.

[Bobbing]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

[blue_sniper_fox]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

[rustyg]

it's the check valve in the fuel pump bleeding back to the tank, replace it with a Delco unit and you should be good

[blue_sniper_fox]

it's the check valve in the fuel pump bleeding back to the tank, replace it with a Delco unit and you should be good

I've only had this fuel pump maybe 2 months? Could it have possibly went out again?

[rustyg]

Possible, or there is a leak somewhere.

[TZ]

check the spark plugs

[blue_sniper_fox]

check the spark plugs

Those are also new, Bosch Platinum 4s and she runs fin as long as you feed it down the throttle body?

[Bobbing]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

The Fuel Pressure Gauge's needle will drop 5 PSI only and remain steady for at least one full minute.
In a system where the Fuel Pressure Regulator or Fuel Lines are not leaking.. the pressure should hold steady (not dropping to zero) for about 5 minutes.

CASE 1: The Fuel Pressure Gauge's needle DID NOT drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that the Fuel Pressure Regulator and the other components that are part of the Fuel Injector Assembly are NOT BAD.

CASE 2: The Fuel Pressure Gauge's needle DID drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that there is something leaking inside the Plenum. More than likely, it'll be the Fuel Pressure Regulator

[blue_sniper_fox]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

The Fuel Pressure Gauge's needle will drop 5 PSI only and remain steady for at least one full minute.
In a system where the Fuel Pressure Regulator or Fuel Lines are not leaking.. the pressure should hold steady (not dropping to zero) for about 5 minutes.

CASE 1: The Fuel Pressure Gauge's needle DID NOT drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that the Fuel Pressure Regulator and the other components that are part of the Fuel Injector Assembly are NOT BAD.

CASE 2: The Fuel Pressure Gauge's needle DID drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that there is something leaking inside the Plenum. More than likely, it'll be the Fuel Pressure Regulator

Ok the regular is about the only thing on the fuel system that I haven't replaced, that and the injectors. I was going to get both and then start with the regulator and see if that solved the problem. If not I was gonna go with the injectors, I may just pick up both and see if the regulator was the problem then if that fixes it I may go ahead and install the injector since she is an 02 with 120k miles. I know it might be a waste but I might as well go ahead and do it since I have the extra cash and it might save some headache later on down the line.

I appreciate all the info guys and I'll be sure to post back with the solution when I finally figure out what it is.

[Highrider24/7]

Hey maybe its the fuel pump relay???? If you change the regulator and it still does the same thing possible fuel relay?

Edited by Highrider24/7, 25 October 2011 - 03:21 PM.

[OCwrencher]

If you replace the injectors with an MFI upgrade, it comes with a new fuel psi regulator. If you plan on doing it in the future, you might as well do it now so you're not buying parts twice.

Even though you say your pump is only 2 months old, if you didn't use AC Delco or Delphi you can't rule it out. I've seen cheap pumps go out in less time.

Rule out the relay possibility quickly by swapping out the relays in the box for another one already there. Or you can use the fuel pump prime circuit and it will keep the pump on continuously while the ignition switch is in the run position, to eliminate the possibility of electrical issues. The prime circuit is the tiny square metal contact to the left of the fuel pump relay, if you're looking at it from the fender side. Energize it with +12V using a jumper wire and an alligator clip on the pos bat terminal.

What's your static fuel psi? (Engine not running) Use the priming circuit too keep the pump on for a little longer, so you can monitor it and make sure it isn't dropping off by itself. Ignition 'run' only primes it for 2 secs, enough time for normal operation but not diagnostics.

Keep us updated...

Edited by OCwrencher, 26 October 2011 - 12:43 PM.

[Highrider24/7]

I cant agree with OCWrencher anymore about the Dephi fuel pumps compared to other aftermarket pumps. If you use anything else besides Delphi or AC Delco it is possible to fail and will set you up for failure. And yea switching the Horn relay to the Fuel Pump relay is an easy test to make sure you rule that out its not the relay.

Please let us know what you think

[blue_sniper_fox]

Ok I jumped the pump across with the jumper wire and it holds 60psi perfect. So my pumps good and I have no leaks up to the fuel rail.

Also what is the MFI upgrade? My truck is an 02 and the only thing I can find is about a CSFI to MFI upgrade???

[OCwrencher]

Ok I jumped the pump across with the jumper wire and it holds 60psi perfect. So my pumps good and I have no leaks up to the fuel rail.

Also what is the MFI upgrade? My truck is an 02 and the only thing I can find is about a CSFI to MFI upgrade???

Yeah that's what I was talking about. Sorry, should have said MFI conversion. You can search and find a lot of info about it all over the net. Basically converts the poppet style valves over to individual electronic injectors.

[blue_sniper_fox]

Ok I jumped the pump across with the jumper wire and it holds 60psi perfect. So my pumps good and I have no leaks up to the fuel rail.

Also what is the MFI upgrade? My truck is an 02 and the only thing I can find is about a CSFI to MFI upgrade???

Yeah that's what I was talking about. Sorry, should have said MFI conversion. You can search and find a lot of info about it all over the net. Basically converts the poppet style valves over to individual electronic injectors.

Oh ok yea everything I've done has brought me to replacing the injectors. So as soon as I can I'm going to get that done and I'll post back and let you guys know if that solved the problem. Hopefully it does because I can't find any other reason on why she isn't starting.

[blue_sniper_fox]

2 weeks and still waiting on my parts to come in from GMPARTSDIRECT.....wish I'd went ahead and just got them from the dealer.

[OCwrencher]

That sucks. I never ordered anything from them but thought about it many times. Good to know for the future. Have you contacted them and asked where your shit is?

I got my MFI upgrade from Advanced Auto, then had them price match it to Summit Racing cuz they had the best price. Saved me well over a hundred bucks and had it the next day. Sorry for the late info, doesn't help you now

[Bobbing]

Central SFI to MFI Conversion Instructions

This procedure outlines the steps required to replace the existing Central SFI Fuel System with a new MFI (Multiport Flexible Injection) Fuel System. Be sure to use the appropriate year and model Service Manual for proper disassembly and re-assembly procedure(s).

Important: Cleaning the CSFI injectors is the preferred repair. The CSFI unit should not be replaced until cleaning has been attempted. If the vehicle should return for the same repair, then the CSFI unit can be replaced with a MFI unit. If the vehicle is out of warranty, the customer should be given the option of which fix to pursue.
V6 Engines

Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
FIGURE Figure 1©



Object Number: 900020 Size: SF
Click here for detailed picture of above image.
(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
Remove the Fuel Meter Body bracket and discard. Install the new bracket as shown in Figure 1.
FIGURE Figure 2©



Object Number: 900019 Size: SH
Click here for detailed picture of above image.
(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
Position Fuel Tubes of MFI Fuel Meter Body as shown in Figure 2. Tubes must be oriented away from the fuel pressure regulator end of the fuel meter body.

Notice: The number 3 Fuel Tube must be positioned behind the number 1 Fuel Tube to eliminate interference with the Upper Intake Manifold plenum when installed. See Figure 2.
Insert the MFI Fuel Meter Body into the Fuel Meter Body Bracket on the Lower Intake Manifold being careful not to bind the Fuel Tubes. Make sure that the number three Fuel Tube is routed in behind number 1 and 5 Fuel Tubes as shown in Figure 2. Push down firmly on the fuel meter body locking it into the bracket.

Notice: Use caution when inserting injectors into lower intake manifold to be sure the correct injector is being placed into the correct hole. Injectors should not be removed once they have been installed. Removal of injectors from the intake manifold may cause damage to the retaining lugs on the injector.

Important: The Injector holes are numbered on the Lower Intake Manifold. The injectors are numbered on the side of the Fuel Meter Body.
Insert the number 3 injector into the correct Injector hole in the Lower Intake Manifold first. Install the number 5 injector next and then number 1. This sequence must be followed correctly to prevent interference of the Fuel Tubes. Injectors 2, 4, and 6 are then installed.
Insure that the electrical connectors of the injectors are positioned so that they do not interfere with each other and are pointing towards the center of the Intake Manifold. If necessary, rotate the electrical connectors inboard.

Notice: Lack of lubrication will make installation of the Upper Intake Manifold plenum difficult and may cause damage to the O-ring.
Lubricate the Fuel Meter Body Upper Manifold O-ring (orange in color) with clean engine oil.
Inspect the Upper Intake Manifold plenum gasket and replace if necessary. Reinstall the Upper Intake Manifold plenum following the procedures outlined in the Service Manual.

Important: Lubricate the Fuel Inlet and Return Lines with clean engine oil before inserting them into the Fuel Meter Body.
Make sure that the Fuel Line Retaining Bracket is properly oriented with the tabs down.

V8 Engines

This procedure outlines the steps required to replace the existing Central SFI Fuel System with a new MFI (Multiport Flexible Injection) Fuel System. Be sure to use the appropriate year and model Service Manual for proper disassembly and re-assembly procedure(s).

Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
Remove the Fuel Meter Body bracket and discard. Install the new bracket.
FIGURE Figure 3©



Object Number: 900021 Size: SF
Click here for detailed picture of above image.
(1) Cyl. 2, 4, 6 and 8 tubes
(2) Fuel Inlet
(3) Cyl. 1, 3, 5 and 7 tubes
(4) Fuel Pressure Regulator
Position Fuel Tubes of MFI Fuel Meter Body as shown in Figure 3. Fuel tubes 1, 3, 5, and 7 are oriented toward the fuel inlet side of the fuel meter body. Fuel tubes 2,4,6, and 8 are oriented toward the fuel pressure regulator side if the fuel meter body.
Insert the MFI Fuel Meter Body into the Fuel Meter Body Bracket on the Lower Intake Manifold being careful not to bind the Fuel Tubes. Push down firmly on the fuel meter body until the tabs snap into the bracket locking the fuel meter body in place.



Object Number: 900022 Size: MH
Click here for detailed picture of above image.
(1) Cylinders 6 & 8
(2) Fuel Pressure Regulator
(3) Cylinders 2 & 4
(4) Cylinders 5 & 7
(5) Cylinders 1 & 3
Orient the fuel tubes to coincide with their corresponding cylinder. The fuel tubes are numbered on the side of the fuel meter body and the corresponding cylinder number is cast in the intake manifold.

Notice: Use caution when inserting injectors into lower intake manifold to be sure the correct injector is being placed into the correct hole. Injectors should not be removed once they have been installed. Removal of injectors from the intake manifold may cause damage to the retaining lugs on the injector.

Important: The Injector holes are numbered on the Lower Intake Manifold. The injectors are numbered on the side of the Fuel Meter Body.
Insert the fuel tubes into their corresponding holes in the intake manifold. Install tubes for cylinders 1, 3, 6 and 8 making sure that the injector electrical connectors are facing in toward the center of the manifold.
Insert fuel tubes for cylinders 2,4,5, and 7 in the same manner.

Important: When installing fuel tubes, it is important that the tubes are oriented properly to provide minimal interference when installing the upper intake manifold plenum. Intake holes for cylinders 2, 4, 5, and 7 are closer to the fuel meter body. It is necessary to cross tube 5 over tube 7 and tube 4 over tube 2 as shown in Figure 4.

Notice: Lack of lubrication will make installation of the Upper Intake Manifold plenum difficult and may cause damage to the O-ring.
Lubricate the Fuel Meter Body Upper Manifold O-ring (blue in color) with clean engine oil.
Inspect Upper Intake Manifold Gasket and replace if necessary. Reinstall the Upper Intake Manifold plenum following the procedures in the Service Manual.

Important: Lubricate the Fuel Inlet and Return Lines with clean engine oil before inserting them in the of the Fuel Meter Body.
Make sure that Fuel Line Retaining Bracket is properly oriented with the tabs down.

[blue_sniper_fox]

That sucks. I never ordered anything from them but thought about it many times. Good to know for the future. Have you contacted them and asked where your shit is?

I got my MFI upgrade from Advanced Auto, then had them price match it to Summit Racing cuz they had the best price. Saved me well over a hundred bucks and had it the next day. Sorry for the late info, doesn't help you now

Finally got my stuff on Tuesday, they don't have a way to contact them other then email and even then they said they couldn't give an estimate on when they could reply to that.

Is there a phone number to call and place an order?

To keep our prices as low as possible WE DO NOT CORRESPOND BY PHONE or offer phone ordering services.

All correspondence through our firm is by email only so we can document all transactions and conversations.

We will be able to help you in every way by email at Email Customer Service or CustomerService@GmPartsDirect.com.

THE FLOW PARTS DEPARTMENT IS A SEPARATE ENTITY. THEIR COUNTERMEN ARE NOT ALLOWED TO GIVE PART NUMBERS OVER THE PHONE! PERIOD! WE CANNOT BE HELD RESPONSIBLE IF YOU CALL IN TO THE DEALER AND OBTAIN ANY PART NUMBERS OR INCORRECT INFORMATION!

Please note all correspondence is required by email for accurate records and future training purposes. We strive to operate a secure customer friendly web site. We do not process orders in any manner other than our verification procedure on our website. We are serviced through a secure server and will not jeopardize our or your transaction history.

That came directly from their site. Yea I will give that it saved me $200 sum for a GM part then going to the dealer but given the fact it took forever I'd went ahead and ordered from the dealer. All in all my total was like $300 sum for the injector, new bracket and gasket sets.