Fuel pump noob question single pump Walbro/TI no venturi outlet

[Cory S]

dr


Do i need to adjust the regulator?

It never went lean WOT but FP would tank but still maintaining Lambda 0.78 even with only one pump on line .

I can't see why two pumps at 13-14V running wouldn't show the same base pressure as before....

I would confirm pump operation/plumbing etc. Check for proper gauge operation as well.

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[olaosunt]

2 pumps show same base pressure .
its just one pump that shows lower base .
Logs look fine so I am not too worried but and if it drops 2 pumps I will know now for sure . LOL

 

[Grimreaper]

A single pump shouldn't have issues hitting 50psi at idle. The stock pump did that no problem and that was at 60% DC too.

Maybe the bottom sock is compressed or partially blocked?

 

[olaosunt]

thanks i will ask them to check

 

[olaosunt]

Check valve wouldn't have any effect on running pressure. That's odd. Maye it's pumping through the other stopped pump.

.75-.78 is perfect IMO. How do the STFT's look?

A single pump shouldn't have issues hitting 50psi at idle. The stock pump did that no problem and that was at 60% DC too.

Maybe the bottom sock is compressed or partially blocked?

Only thing that has changed is no check valves .

I think what is happening when only 1 pump is running is the other 2 not running are bleeding pressure through without the valve .
Less of an issue when 2 are running and evidently from logs(-and butt dyno) non existent when 3 are running

Same reason you can’t run the 295’s in a triggered set up / secondary as it will bleed pressure when it’s not on .



And I will know now immediately if I drop 2 pumps !

 

[cbrtrx]

Only thing that has changed is no check valves .

I think what is happening when only 1 pump is running is the other 2 not running are bleeding pressure through without the valve .
Less of an issue when 2 are running and evidently from logs(-and butt dyno) non existent when 3 are running

Same reason you can’t run the 295’s in a triggered set up / secondary as it will bleed pressure when it’s not on .



And I will know now immediately if I drop 2 pumps !

You are correct it is the lack of check valves.

 

[Angrey]

Only thing that has changed is no check valves .

I think what is happening when only 1 pump is running is the other 2 not running are bleeding pressure through without the valve .
Less of an issue when 2 are running and evidently from logs(-and butt dyno) non existent when 3 are running

Same reason you can’t run the 295’s in a triggered set up / secondary as it will bleed pressure when it’s not on .



And I will know now immediately if I drop 2 pumps !

If there's no check valves and they're setup like the photo in this thread, the single pump is going to struggle because instead of sharing some of it's flow with a brother to run the siphon, the other pump isn't running, so NOW it's not only bleeding off all the siphon hose flow/work, but it's backfeeding through the other pump that doesn't have a check valve as well. If you run no check valves then you either have to A) run an in line check valve after the pumps B) live with grumpy startups because the fuel drains back through after shutoff and/or C) Keep the pumps completely isolated or isolate with a check valve because when it's not running, joined lines present a path for backfeeding.

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