high psi pump leak on 57

[Chris S.]

John

Thanks for the help today, i checked the screw size and all 5 10/32 screws are a 1/2 long. Anbody else have issue of fuel leaking on the bottom side of fuel pump where the pump mounts to fuel bowl? Any input would be great. I have checked the weep hole and i have no fuel coming from that area and the drive cable is dry.

thanks
Chris

[Charles M.]

Re: high psi pump leak on 57

Never had one leak there but have heard of double gasketing the pump.

[Jim L.]

Re: high psi pump leak on 57

Anbody else have issue of fuel leaking on the bottom side of fuel pump where the pump mounts to fuel bowl?

Over time, the mounting surface of the fuel bowl can become slightly warped, possibly due to the pump screws being over tightened. I often find "high spots" around the screw holes and, while not dramatic, they can be enough to keep the 1/64" thick gasket from sealing.

For a "quick and dirty" repair that doesn't require disassembly of the fuel meter, try double gasketing the pump. You could also coat the gaskets with a little sealer like Permatex #2 or #3, both of which are rated to withstand gasoline (but not ethanol enhanced gasoline). If you use sealer, let it dry for a couple of days.

Jim

[Chris S.]

Re: high psi pump leak on 57

Thanks for the tipper. i have the parts coming to try this.

[John D.]

Re: high psi pump leak on 57

Hi Chris, Almost missed your post here.
So now do you believe old JD here? .
As mentioned on the phone typically (key word) a 57 FI fuel meter bowl is quite sturdy and you don't often see warpage on the FI hi-pressure pump to bowl mating surface.
But on 58 to 65 FI's (except for the 59 '7300 unit) the die cast fuel bowls are warped when I see them 100% of the time.
The die cast fuel meter bowl doesn't have the guts-the strength of a 57 sand cast bowl. Then people have to tighten up the 5 fillister head screws as tight as possible which only tends to twist/warp the casting.
Read my article on "Surface Plates" in Vol 36, #1 of Vinnies Corvette Restorer.
Now don't forget some bubba could have gouged the hi-pressure pump itself using a sharp object like nice crowbar to remove it. Then you are in trouble.
Be careful using the Permatex though. I never use it on the pump area as I typically resurface the parts. But if you do use it make sure you don't get any shellac in the hi-pressure hole right above the 9:00 screw.

I see someone cheated and used all 1/2" long screws on your FI. I guess that's ok but originally here is the scoop. One of the fillister head screws is 10/32X1/2" and the other four are 10-32x5/8" long. The shorter one goes at the 9:00 screw hole.
Refer to the Corvette Servicing manual-the ST manual as we call it for good instructions on rebuilding a hi-pressure pump. But if you have no experience at doing so far the job out as the pumps are delicate and very pricey.
Now if the double gaskets don't do the job I might say your pump seal is leaking. Does your burg in MT have 10% crap ethanol? Are you using it in your '4960 unit? JD

[Chris S.]

Re: high psi pump leak on 57

hey JD,

The fuel i am using does not have the ethonal, i am going to try the double gasket once i get your stuff and then go from there. once agian thaks for the expert advice! if the pump needs rebuilt i will take your advice and ship it to someone who knows what they are doing for sure!
do you recommend tightening the bolts a certain way?

[Chris S.]

Re: high psi pump leak on 57

My package never came, the place where i bought the fuel said the fuel had no ethonal as well. Did you send it third day?

[John D.]

Re: high psi pump leak on 57

Chris, Slotted fillister head screws (5) hold the pump onto the fuel meter body. You ask do I recomment tightening the bolts a certain way.
Car owners say they can't install the pump while the FI is on the car. Well some say that. I use a long screwdriver to install the short screw at the 9:00 position and the one below that. The other 3 screws can be tightened using a shorter screw driver. That's about all I can say except to not overtighten them. Don't kill them. Don't forget the split lock washers. Refer to the Corvette Servicing Guide-ST 12 manual for great info on the hi-pressure pump. In fact its the only manual that features it. Don't waste your money on a separate FI book. All the info is in various Shop manuals that you can use on the whole car.
Manuals available right here from NCRS book store at a discount. Or your favorite Corvette dealer.
Don't forget to make sure both surfaces are flat before your install the two gaskets.
The only time I have been know to install two gaskets is when bubba screwed up the pump. I always resurface the fuel meter bowl. On the pump I use a good stone to debur it.
Last tip: You can install the gasket backwards you know. I can't explain here. Just study the pump and the gasket. Its quiet simple but for some reason not everyone pays attention. John

[Chris S.]

Re: high psi pump leak on 57

I was wondering if you recommend a star pattern when tightening the screws? Start at the 9 oclock spot then move over to the 4 o clock? Or just start and go clockwise or counterclockwise? Thanks for the other tips.

Chris