Fuel system upgrade and problems

[67 Coronet Conv]

Hi everyone, upgraded my fuel system today to remove a home made fuel rail on my 67 coronet with a 440 with 870 Holly Street Avenger.

Here’s what I upgraded
Installed new Carter Fuel Pump M6903
Installed new Comp Cams push rod with chromoly tip, mine was measuring at 3.05”.
Upsized fuel line from pump to fuel rail from 5/16” to 3/8.
Installed new Summit Fuel Rail which required me to remove the inlet filters and springs from the carb fuel bowls.
Running a 3/8” plastic fuel filter inline from pump to fuel rail.

When I go start it up, fuel was pouring out of the fuel bowl vent (?)in the front, see photo. Car started and ran rough and turned it off when I noticed fuel coming out. I can hear fuel run down the intake too.

Any idea what I screwed up and how to fix it?

Thanks
JP

 

[pnora]

What is your fuel pressure? Either its to high or you got debris stuck on the needle and seat.

 

[67 Coronet Conv]

7psi. I’ll check for debris.

Thanks!

 

[fourgearsavoy]

7psi. I’ll check for debris

Look closely at the O-rings on the needle and seat. If they look good and are still soft just put a little lube on them and reset the floats. Make sure you check both bowls.

Gus

 

[67 Coronet Conv]

Look closely at the O-rings on the needle and seat. If they look good and are still soft just put a little lube on them and reset the floats. Make sure you check both bowls.

Gus

Thanks, was thinking I probably need to re adjust the float level. Would removing the carb inlet filters have any effect on this?

 

[fourgearsavoy]

Thanks, was thinking I probably need to re adjust the float level. Would removing the carb inlet filters have any effect on this?

Yes the fuel line might have had some debris in it and it just went into the needle and got stuck. I would probably have a few new needle and seat assemblies ready to go so you can get it back together right away.

Gus

 

[Aron Gleason]

To add to what's been said, I'd drop the fuel pressure down to 6 lbs.

 

[MWbirdLOVER70]

To add to what's been said, I'd drop the fuel pressure down to 6 lbs.

Sounds like added pressure not letting N/S set also and debris. Careful setting float height when running for fuel dribbling and fire issue. Holley used to have screw in sight windows for sale but I see these days they’re already installed. Just be cautious

 

[DanielSlocum]

i learned the hard way that fuel pressure actually drops as underhood temp goes up. just the opposite of what i had thought it would do.
years ago i learned this with my nos system. i had a safety pressure switch to shut the solenoids off if fuel pressure dropped below 5 psi.
needed to set pressure higher [cant remember how much] with the hood open to prevent the system shutting down during a hard run.

 

[Aron Gleason]

Thats funny, I've never experienced a drop in fuel pressure from underhood Temps rising. As long as the fuel system is good there's no reason the fuel pressure would drop.

i learned the hard way that fuel pressure actually drops as underhood temp goes up. just the opposite of what i had thought it would do.
years ago i learned this with my nos system. i had a safety pressure switch to shut the solenoids off if fuel pressure dropped below 5 psi.
needed to set pressure higher [cant remember how much] with the hood open to prevent the system shutting down during a hard run.

 

[Dave6T4]

Those filters you removed may have restricted pressure a bit. Without them, pressure at the floats increased, and overpowered them, causing flooding.

 

[DanielSlocum]

Thats funny, I've never experienced a drop in fuel pressure from underhood Temps rising. As long as the fuel system is good there's no reason the fuel pressure would drop.

then perhaps it dropped for some other reason? a friend of mine had the same thing happen though.

 

[BSB67]

i learned the hard way that fuel pressure actually drops as underhood temp goes up…..

needed to set pressure higher [cant remember how much] with the hood open to prevent the system shutting down during a hard run.

What was your evidence that it was from temperature?

 

[DanielSlocum]

opened the hood on a hot summer day after driving a considerable distance; looked at the gauge there and noticed the pressure was lower than where i had set it previously.
as i said....my friend had the same experience with his car. it so happens that he was riding with me that day and made the suggestion after i had made a failed nos test run.
we were on our way to the drag strip on a test and tune day. i proceeded to make a good nos run at the track. previously..... the nos system had been surging;apparently due to low fuel pressure allowing my safety pressure switch to open and close rapidly. thats all folks.

 

[67 Coronet Conv]

Update-adjust the front floats and got the car to idle. Then when it warmed up idle speed jumped up to 1100rpm, backed down the idle screw with no effect. Gasket on the needle seat assembly is old and hard, so thinking that might be letting fuel by thus increasing RPM. I’ll replace the gaskets and see what happens.

 

[BSB67]

Fuel does not increase the rpm, air does.

 

[67 Coronet Conv]

Fuel does not increase the rpm, air does.

Hmm, I got to look at it more. When pull down on the throttle assembly it will decrease RPM, so something is making it open up more…..

 

[Aron Gleason]

Hmm, I got to look at it more. When pull down on the throttle assembly it will decrease RPM, so something is making it open up more…..

Vacuum leak