Need some ideas. I have a 1986 L98 newly rebuilt and almost stock engine, in a C3. I am having fuel issues. It started with some leaky rebuilt Bosch3 injectors. It would not hold pressure and leaked down right away. I Finally decided to just put a NEW SET in of the Bosch 3 exact fit from FIC and it holds pressure for a long time. Maybe dropping a few psi over 2 or 3 hours. Good. When I hit the ignition, pressure builds up to 38 psi and holds it. But when I start the car ( it is difficult to do probably because of low pressure) the highest I can get the pressure is 30 PSI. I have a stock AC Delco pump ( less than 3 hours on it) going into a 10 micron RobbMc filter gong a the Holley 502-501 adjustable regulator then the new 22lb injectors. Would I be correct in assuming the new pump is bad, internal leak maybe? Any ideas for replacements for an in tank pump? Thx.

 

I use the Racetronix RXP255E in my 86 Vert. No issues at all for the last couple of years. Might be over kill on a stock engine but then it's there if you want to "modify" .Drop in replacement.
I owned my first Vette (75 Coupe) while stationed at CAFB. Lots of good memories of Charleston.

 

Just a thought could there be a kink or blockage in the fuel line or under size it's self.
You say you build and hold but once started it drops to low for any kind good operation, so the Pressure is there at the pump but not the supply pressure & volume/flow at the other end under operation

I bringing up the undersized line's because you say it's in a C3 which was a calibrator car unless a 82

 

Put back the stock FPR !!!

 

Good thought but I have changed out the fuel line and return to the appropriate sizes. I actually made the orignal supply line the return, and added a new larger supply line.
Mr Jazfe I will check out the Racetronix and I am also looking at a Quantum 255. Yes a bit more than I need but this 5 year project has taken me places I never dreamed of when I started so who knows. And yes Charleston is great. I have lived here for 22 years and the growth is out of control. We just moved our business to our home because we were spending almost 3 hours a day commuting, to our shop right next to the Air Force base. Distance from home is 13 miles.

Thanks for the input to you both.

 

The stock AC Delco Fuel pump can handle quite a bit of horsepower all by itself. Read about the issues people have had with aftermarket fuel pumps on the Forum and you might agree to stick with Stock UNLESS you really need the extra fuel.

My C3 is making way over 500 hp and it runs fine with the 255 (liter per hour) Walbro fuel pump used in the C4's. It will work up to 600 hp in a normally aspirated system. The Holley EFI systems require 60 psi in place of the 43 psi our L98's would like, and if the pump can run my BB 427 with all of it's power it should handle a

Do what BlowerWorks suggested and replace the Fuel Pressure regulator first. Fix the problem and don't just throw parts at the Corvette. It is entirely likely that your FPR is not working properly anymore. That part would give you the issues you listed above.

I did have a Fuel Supply line get internally rusted shut after leaving it with oxygenated fuel in it. I could get the pressure right but not sufficient flow to make the Corvette work properly.

I took my 36' Boat that I lived on from Fort Myers, Florida all the way back to Northern Virginia by the Inter-coastal Waterway. Charleston S.C. had some of the most beautiful homes along that waterway! It was the best way in the world to really see and appreciate the East Coast going 10 knots on a 1500 mile trip. I spent more money on food than I did on fuel so it wasn't half bad.

 

I tried with the stock pump which is in the car now, and I am sure it is enough for my 43 psi needs. But the FPR is as new as the pump and there are no leaks at the fpr. Diaphram seems good as new. I will double check it though. My steel line is only for the return and I used new braided line for the supply. I can't figure out however, the fact that if I can't get enough fuel to reach the FPR how would changing the FPR back to stock help. Maybe there is a flow issue thru the braided line. Pleasue understand all of you that I am not ruling anything out, I am open to any and all thoughts. Just that since I have already thrown money at this set up using all new parts, I am trying to figure out which of the parts isn't working.
As for Charleston, I am fortunate enough to be able to earn a living making canvas and upholstery on all of the boats down here, and I get to work on the water as much as I want. I told my son to remember that people actually PAY to come and visit these sites, and we get to live here. Not a big deal seeing dolphins playing in our "office"
all the time. Thx.

 

Aftermarket FPR is your problem Q!Q!Q Read my white paper .............

 

will the OEM regulator give me the 43psi I need for the bosch 3 injectors? And where can I locate your white paper. Thank you.

 

It should, eliminate the FPR being the issue by crimping your return line. If you have pressure then, it is indeed the regulator.

 

That sounds like the first place I will start. thank you.

 

You also can just pull vacuum line from regular to boost pressure

 

The stock L98 reg with the stamped steel black top is good for some 30 psi or so.....at idle......not enough for some reason 43.5 psi is needed and the only way I could get that was with the silver aluminum reg top and a longer adjustable bolt soon as I hit 43.5 with my new 24 lbs injectors, it runs GREAT!!! I do have an LT1 induction on it though, HEI up top, and all that epa crap removed, except EGR valve on the side.....

 

BlowerWorks.net
Downloads
http://blowerworks.net/

 

Today I have been waiting for this storm to hit Charleston, so far not much going on. But I have pulled the vac line off and the pressure went up. Have not crimped the return line yet. And Mrvette your explanation of the FPR is what my understanding has been. The OEM won't go up to the 43.5, but might hit 38-40psi.max. I have more to check out in the next few days but will let you know what I discover. Thanks to all.

 

I have never had a TPI fail to get to 42PSI gage with healthy components. 1PSI seems to be within range of the BLMs to take care of .