No Fuel Pressure after installing new EGR Valve - Corvette Forum : DigitalCorvettes.com Corvette Forums

oifcombatvet · 01-24-2013, 01:05 PM

1989 Corvette L98 6spd 122,xxx miles

Installed a new EGR Valve today. Hooked everything up, vacuum lines, sensors, etc.

All it does is crank. I pressed down on the Schraeder Valve and it is just bubbling...barely. It will turn over but never fires. I can here the fuel pump turn on, fuel pump fuse is good.

I CAN hear a sucking/hissing noise while the fuel pump turns on when you turn the key. When the fuel pump turns off, the noise stops. It sounds like it is coming from the FPR/EGR/Under Plenum area. All vacuum hoses are connected from what I can tell.

I looked back over, and I found that the plastic hose that goes from the FPR into the plenum was on the wrong port. I switched the hoses to the correct ports on the plenum and it is still having the same issue.

Thanks in advance for the help.

XQIZT · 01-24-2013, 01:10 PM

First, Welcome to DC.

Odd issue you're having, as the EGR really has nothing to do with fuel delivery. You could rip out the EGR all together and the car would still run.

Since you had the plenum off to put in a new EGR, also check all your connections on the throttle body. Its possible you missed something there as well. TPS sensor, IAC connection, etc.

Also, the vacuum lines are old, make sure they're not cracked.

oifcombatvet · 01-24-2013, 01:14 PM

TPS and IAC are connected. I did find a broken vacuum line, it comes off what I believe is the EGR Solenoid and into a vacuum line that comes off the throttle body and follows down in the the driver side front bumper. I need a connector to splice it in with the other line.

I doubt that is my issue though. I can hear the hissing/sucking sound coming from the FPR/EGR/Plenum area and it comes on when the fuel pump runs right after you turn the key. Once the fuel pump stops, the noise stops and I have no fuel pressure.

XQIZT · 01-24-2013, 01:20 PM

Hm....so if you put a fuel pressure gauge on the shrader valve, it goes to zero as soon as the pump stops? Is the housing of the fuel pressure regulator cracked?

Other things to check: Is the EGR seating correctly on the base? All the runners nice and right? Possible you bumped the distributor out of timing?

oifcombatvet · 01-24-2013, 01:35 PM

Quote:

Originally Posted by XQIZT

Hm....so if you put a fuel pressure gauge on the shrader valve, it goes to zero as soon as the pump stops? Is the housing of the fuel pressure regulator cracked?

Other things to check: Is the EGR seating correctly on the base? All the runners nice and right? Possible you bumped the distributor out of timing?

I haven't hooked up my gauge because it's broken. When I push the Shrader Valve down with a screw driver fuel hardly bubbles out, not sprays like it is supposed to. I never touched the fuel pressure regulator when I replaced the EGR. I only had to remove the top portion, I didn't remove any of the runners.

The only thing I did to the FPR was unhook the line that came out from the port. After I installed everything, I pushed the line back on the port and back into the plenum.

XQIZT · 01-24-2013, 01:37 PM

Hoping someone else will chime in here. Gotta be one of those "coincidental" failures, since even with a poorly functioning (or no) EGR, the car will still start.

Something else is going on here.

grumpyvette · 01-24-2013, 02:06 PM

http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

http://forum.grumpysperformance.com/...+sequence#p404

READ THE LINKS AND SUB LINKS
(yes I know you would rather be skinned alive and boiled in oil) (force yourself you might learn a few new things)

oifcombatvet · 01-24-2013, 03:35 PM

Thanks for the information so far.

About 1 month ago I replaced the fuel pump, sock/strainer, fuel filter and fuel pump relay.

I will go back through the fuel system.

Any ideas on the hissing/sucking/shhhshhh sound coming from under the plenum area? It has a good seal as far as I know and all the vacuum lines are on the FPR as well as the EGR Valve.

The hissing/sucking/shhhshhh only is there when you first turn the key and the fuel pump kicks on, when the pump turns off, the hissing/sucking/shhhshhh does as well.

87vette81big · 01-24-2013, 03:46 PM

Quote:

Originally Posted by oifcombatvet

Thanks for the information so far.

About 1 month ago I replaced the fuel pump, sock/strainer, fuel filter and fuel pump relay.

I will go back through the fuel system.

Any ideas on the hissing/sucking/shhhshhh sound coming from under the plenum area? It has a good seal as far as I know and all the vacuum lines are on the FPR as well as the EGR Valve.

Its possible there is a failure in the Fuel Pressure regulator under the plenum.
Maybe a piece of debris is holding the fuel pressure regulator Wide Open and bypassing all gasoline back to the return line to gas tank.
Remove the Gas door again.
With a pair of needle nose vise grips or hose pinch pliiers, clamp the rubber hose shut on the return to the Fuel pump.
See if Fuel pressure holds to 41psi or more.
Try starting your Corvette.
If it starts & runs, problem in the Fuel pressure regulator.
Service & repairs required on it.

BR

oifcombatvet · 01-24-2013, 07:45 PM

Which line is the return line? I know there are three that all connect to the top of the sending unit.

Thanks.

87vette81big · 01-24-2013, 09:08 PM

Quote:

Originally Posted by oifcombatvet

Which line is the return line? I know there are three that all connect to the top of the sending unit.

Thanks.

The Bottom Right Rubber Hose section.
It actually crosses over the upper C4 Fuel module to the Bottom Left.

So Your other Left if confused.

I checked with a friends NOS C4 Fuel pump module I have here.
Custom Race In tank Dual electric pump I am building. To support upwards of 1,000 HP.

BR

TommyFox · 01-25-2013, 09:21 AM

Quote:

Originally Posted by oifcombatvet

Thanks for the information so far.

About 1 month ago I replaced the fuel pump, sock/strainer, fuel filter and fuel pump relay.

I will go back through the fuel system.

Any ideas on the hissing/sucking/shhhshhh sound coming from under the plenum area? It has a good seal as far as I know and all the vacuum lines are on the FPR as well as the EGR Valve.

The hissing/sucking/shhhshhh only is there when you first turn the key and the fuel pump kicks on, when the pump turns off, the hissing/sucking/shhhshhh does as well.

Could the fuel rail have been tweaked or an injector seal leaking?

oifcombatvet · 01-25-2013, 09:20 PM

I did not touch the fuel rail. I only had to remove the plenum when I changed my EGR Valve. I did not remove any of the runners. I can turn it over and it doesn't smell like gas anywhere, the back or the front. The only gas I got was the little bit that bubbled up from the Schrader Valve. The injectors were done w/ rings/etc approximately two years agol.

I did have my fuel pressure tested last week and it was 34-36.

I feel like the hissing is coming from something fuel related because it only makes the sound when the fuel pump starts up when you first turn the key. After the fuel pump stops the hissing sound does as well.

XQIZT · 01-27-2013, 12:07 PM

This "hissing" sound...does it stop instantly when the pump stops or is it a gradual slow down?

oifcombatvet · 01-27-2013, 06:05 PM

Quote:

Originally Posted by XQIZT

This "hissing" sound...does it stop instantly when the pump stops or is it a gradual slow down?

It instantly stops when the pump stops. I have had some family in town so I haven't had an opportunity to start working on it again. I'm just trying to figure out where to start.

I replaced the fuel pump, strainer/sock, fuel pump relay and fuel filter just awhile back.