whalepirot

Is injector sizing identical or did you buy larger ones? Largers will flow more, dropping the FP. Your comment about rough running may be another hint, until the ECM shortens the pulses, attempting to meter to the proper mixture.

Do you check FP with the vacuum line to the FPR disconnected?

Another thing that can cause the FP to drop so quickly, is a pinched (shorted) wire to any injector, causing it to 'fire" (open) whenever power is applied (key ON). That can be a bitch to find.

Did I miss some other reason you are changing the fuel pump and filter?

I also hope you changed the (inexpensive) O-rings IN THE FUEL RAILS, as leesvette suggested. I used a wee bit of grease on them, too, so they slide together with ease, meaning they are where they need to be, sealing the joints from gas leakage. There should be no odor of gasoline up there, when you're finished.

Bugly87

Thank you for the response whalepirot. I got the remanufactured Bosch III's from FIC. I believe that they are similar to the originals. Each time I checked the fuel pressure I did so with the vacuum. Line connected. I hope to assume that my injector connectors are ok since I basically took them off then reinstalled. I plan on changing the fuel pump and filter mostly because the car sat without much use for a while before I bought it 3 years ago and the parts were cheap enough. I did change out all of the o rings on the rail as suggested. I will say that I checked the fuel pressure with a friends cheap gauge from harbor freight before the swap and got the 40 PSI. I bought my very own cheap gauge from harbor freight when I tested the fuel pressure after the swap. The car starts fine..even when warm...which was not the case when I had a leak down issue with the original injectors. The car runs pretty good except for the minor hesitation when warm. I had no reason to check the fuel pressure but did so out of curiosity. Another thing I forgot to mention is that the car use to start immediately when cold...now it starts ok but cranks maybe 3 seconds long. I fear that I got a FPR that may not be machined properly. No fuel smell at all now when I start the car. Before the swap when warm I always had the flood condition and fuel smell.

Any other suggestions will be appreciated.

Kevin

cormorant71

muriatic acid

Bugly87

I'm here on my anniversary trip and am thinking of my injector swap. Just so I can be sure of myself...I check my fuel rail and injectors each time the car is running and I have yet to see any fuel leaks. Is it possible that my fuel pressure can still be leaking from the rail or the injectors even though there Is no fuel or fuel smell present? The car runs pretty much the same as before the swap. I guess I need to be reassured...I'll change the fuel pump, filter, and FPR but if I have to take it apart for the injectors I'll be besides myself

Any help will be appreciated

Kevin

Bugly87

Hello all...today was nice so I swapped out my fuel pump. Once completed I turned the key and saw the pressure gauge spring to life and go to 42 PSI. Then the drop in pressure. This time the pressure dropped but not as quickly..but drop to 0 nonetheless. I heard a click when the pressure dropped so I felt around the relay. I heard a click and the pressure jumped to 40 PSI. I remembered that I stripped the vacuum line to the rear of the plenum. It is connected but an obvious leak. Jiggle the line and pressure builds...relax the line and the PSI drops. So I believe that when I replace this fitting I will be back on the road. Does anyone know where I can get new fittings for this vacuum line...the one from the back of the brake booster to the rear of the plenum. I assume that I need the fitting that screws onto the back of the plenum and the fitting that goes at the end of the vacuum line

Any help would be greatly appreciated... And thanks for all the help along the way

Kevin

Bugly87

Ok..I was able to properly connect the brake vacuum booster line to the plenum. No change. Closer inspection revealed that when I jiggled this line I was shorting out the connector to the fuel pump relay..causing the fuel pump to constantly prime. I corrected this issue and I am back to square one. Turn the key and I get 42 PSI. As soon as the relay clicks off I lose pressure to 0 rapidly. Car starts after a few seconds and idles fine. PSI of 37. Car runs ok except for my hesitation when warm. Warm starts are good..maybe 3 seconds of cranking. Looks like I got a bum FPR. I will get a AC Delco FPR and replace in the spring. I also clamped off the fuel return line at the tank and shut the car off. The pressure still dropped rapidly. Also there is no fuel at the FPR vacuum line. Is there any other way to check the FPR? Thanks for any help,

Kevin

aklim

In the tank there should be a couple of lines and a vent. One going to the pump and one coming back from the pump. Clamp off one line and if fuel pressure doesn't build up the other is the return line. I forgot which is which. If you clamp off the return line and the pressure drops, inspect the circuit going to the injectors. Probably in the dampener or pump or injectors.

Bugly87

Ok I tried clamping the fuel return line again...I actually clamped each line, one at a time with the same results. I clamped the lines and turned the key. 42 PSI right away then a steady drop to about 12 PSI. It continued to drop to 0 but much slower. I then had the car running and clamped the lines. Shut the car off and the same scenario..steady drop to 12 PSI Then a slower drop to 0 PSI. The only other differences are that the car doesn't start as fast at first start up..but always starts after about 4-5 seconds. Warm starts are always good now. Also I notice that my MPG dropped from 12.8 to around 10 MPG. no codes at all. The injectors and fuel pump are new. If the FPR was faulty..shouldn't clamping the return line hold the pressure? There are no signs of fuel leaking anywhere. Any help would be appreciated.

Kevin

aklim

What did you replace the pump with? What did you do with the fuel damper?

Bugly87

Thanks for the response, Aklim. I purchased a new pump from Jon at FIC. I reused the old damper... Just to clarify...I had this rapid loss of fuel pressure just after the injector and FPR swap and with the original fuel pump. The symptoms are the same with the new pump. Thanks for the response and I appreciate any help. I can check the check valve but I assume it to be working as it seemed to be before the swap.

Kevin

aklim

I don't know. I heard many people did away with the damper. I did. Replace with fuel hose so it won't bleed back. You might have moved or damaged the damper.

Bugly87

I had about a half hour before darkness so I checked some of my plugs for wetness and fuel smell. I took the middle 2 plugs out on the drivers side and found them dry with normal wear for two years old. I then took the middle 2 out on the passenger side and found the same results. Reinstalled them, primed the fuel system twice, and gave 2 quick cranks and pulled the 2 out on the drivers side. Dry with no wetness or fuel smell. Did the same and pulled the passenger side. Same results..all were dry and no fuel smell. Reinstalled the and the car started right up. Drives fine. Can I assume that the drop in fuel pressure is not dumping fuel onto the plugs and into the motor? I didn't have time to pull all 8 but can I assume that if 4 are dry, that all 8 will be dry? With all that said where could my pressure be going?
Thanks again for any help


Kevin

aklim

Could be the damper since the injectors and the pump is new. Not many places left unless you have a damaged fuel pressure regulator. Is it coming out the other 4 you didn't check? Possible but not as likely. Check the FPR hose for gas.

Bugly87

I did not have enough daylight to check the other 4 plugs but I assume they are ok, too. The FPR is new also. Checked the vacuum hose to the FPR several times and it is dry each time. I may have to wait till spring to get to the pump again. Thanks for the response

Kevin

aklim

If Jon sold you the pump, maybe you can ask him about the check valve of the pump? I know I was chasing a FPR issue on my Holley Stealth Ram till they told me that it was the expected thing for the FPR to bleed down that fast.

Bugly87

Hello all,
Spring has arrived finally and I had time to work on my Corvette. The hesitation persists and I still have no fuel pressure. Took it to my shop and they determined that the pump was faulty. My electrical connections were also burned. I had the fuel pump assembly replaced. They also found that my EGR valve was faulty and was most likely the cause of the hesitation. They plugged the vacuum line and not the car runs like it should. My question is..should I have received a code for the faulty EGR valve? I never got a code. Should I worry about replacing the EGR valve? Will I notice any difference in performance? Ill change it out if I hear that it is beneficial to do so. And if I do swap it out, can I remove the plenum without removing the throttle body?

Thanks for all the help along the way..

Kevin

Cliff Harris

Only if you have done a coolant bypass. Otherwise the coolant hoses prevent the throttle body from going anywhere. I just take out the 4 10mm bolts and leave it hanging there.