Fuel Pump Noise

[michaellatini]

Hello all,

The fuel injection pump, second one tried, both make the same noise so, must be something wrong with my system.

This is a VW Karmann Ghia. The fuel comes from the tank via 1/2" id hose thru a 1/2" id 10 micron fuel filter to the pump, all flowing downhill. Pump sits on the floor of the pan in front of the firewall. Fuel exits pump thru, 3/8" id hose to the rear passing thru a 3/8" id 100 micron filter, all the way to the engine bay. Inside engine bay it' all 5/16" id lines to the fuel pressure regulator and returns to the tank thru 3/8" lines. It has a CB Performance, Fuel Tank Outlet Tee. In the FB video link (sorry, couldn't figure how to attach it here) attached the key is turned on 3 times to pressurize the system and you can head the noisy grinding sound in between the quieter sound.

The tank has 6 gallons of fuel, it is about 80 degrees and the pump is cold during the video. I have read about issues with pumps due to hot fuel, not the case and with air bubbles. If I start the engine the noise comes and goes as in the video idling. I have tried, 43 to 58 lbs of fuel pressure with no change. Pinched the return line a bit just before entering the Tee.

If you have any experience with a solution, thank you in advance.

Michael
https://fb.watch/lVCD8RCiEt/

[wreck]

I tried a similar set up and had cavitation issues . I removed the 1/2" filter and routed the return back into a Tee in the 1/2" tank breather pipe on the fuel filler ('69 Ghia) . The bosch pump is rubber mounted and the only time I hear it is when it primes .

[michaellatini]

Thank you, Wreck! Sorry I didn't see this sooner. Need to turn on notifications.

[raygreenwood]

Thank you, Wreck! Sorry I didn't see this sooner. Need to turn on notifications.

Wish I had seen this sooner too!

You state that the fuel comes from the tank and goes through a "10 micron" filter BEFORE the pump and then passes through a "100 micron" filter AFTER the pump?

Unless that is a typo.....the 100 micron filter should ALWAYS be on the inlet side of the pump. The 10 micron fine filter should be on the high pressure outlet side of the pump.

The inlet filter is only to catch "rocks"...large sediment to protect the pump. The fine filter goes on the putlet.

Virtually all roller cell pumps as well as vane pumps have much more capability to "push" fuel on the outlet side than they do to "pull" fuel from the inlet side. A 10 micron filter will starve the pump.

Ray

[michaellatini]

Your correct, I said it backwards. I did as you did. Removed the 100 micron filter and ran the return back to the filler neck as well. problem solved! A tiny bit concerned about, no pump filter. Really surprised how much fuel returns.

Thank you again. M

[Piledriver]

The 044 in my Cabby was starting to get a bit noisy after many years of DD service.
Setup: pump draws on a .5L recirc sump, with in-tank turbine feeder pump to sump with sock pickup, high pressure side CIS filter, recircs to sump.
(essentially factory CIS VW Cabriolet setup but with bigger fabricated sump)

I picked up a screw pump for a mercedes a few years ago, it's just a generic Chinese replacement I probably paid around $40 for.
(just wanted to try something different)

The screw pump works awesome, much quieter, runs at rock steady 85 PSI, has for years (currently has CIS-M meter on it with adjustable Deatchworks pressure regulator in place of the NLA and prone to leak Bosch regulators. (had 3 good Bosch regs stored, both leaked, diaphragms all leaked when tested)

The screw pump is much smaller diameter than the -044 and would probably fit in an in-tank setup without much effort.

The screw pumps are a better design and do not require a feeder pump... they have ~no issues sucking, unlike a roller cell, which cavitates if you look at it crosseyed.

[raygreenwood]

The 044 in my Cabby was starting to get a bit noisy after many years of DD service.
Setup: pump draws on a .5L recirc sump, with in-tank turbine feeder pump to sump with sock pickup, high pressure side CIS filter, recircs to sump.
(essentially factory CIS VW Cabriolet setup but with bigger fabricated sump)

I picked up a screw pump for a mercedes a few years ago, it's just a generic Chinese replacement I probably paid around $40 for.
(just wanted to try something different)

The screw pump works awesome, much quieter, runs at rock steady 85 PSI, has for years (currently has CIS-M meter on it with adjustable Deatchworks pressure regulator in place of the NLA and prone to leak Bosch regulators. (had 3 good Bosch regs stored, both leaked, diaphragms all leaked when tested)

The screw pump is much smaller diameter than the -044 and would probably fit in an in-tank setup without much effort.

The screw pumps are a better design and do not require a feeder pump... they have ~no issues sucking, unlike a roller cell, which cavitates if you look at it crosseyed.

Interesting!
Screw pumps are not something you commonly see even though they are not uncommon.

They are very much like a positive displacement pump in flow. Very uniform as long as rpm is constant.

Back in the 80's, you had two types of common high pressure pumps.These were the roller cell like the 044 and the pumps used on D-Jet, L-jet and digifant among others and the impeller or turbine style pump that was used on a lot of in-tank pump carb systems of American cars and was pushed to be used in some 80/90's fuel injection systems. The turbine/impeller pumps were not great in those days and I hated them.

They got much better over the years but in between we started seeing sliding vane type pumps for carbs which were much more reliable. In the interim , the turbine pumps got much, much better and more reliable and pretty much surpassed/replaced roller cell pumps in modern fuel injection.

There were always issues with finding good feeder pumps that would fit and work well with non in-tank set ups....meaning...feeder pump outside of tank as well as main pump. That screw pumps sounds like a better set up. Ray

[Piledriver]

Screw pumps are positive displacement pumps.

TI Automotive sells some killer screw pumps for the blown Chrysler motors and things like the Buggatis.
Their aftermarket screw pumps also work just fine on E85, and are half the size of roller cells and with >2x capacity.

Mercedes has been a fan for awhile, IIRC the pump I sourced was for a Crossfire. (Mercedes with Dodge badge)

[michaellatini]

Back again with the noisy fuel pump issue, plus!

5400 miles of driving with an occasional squawk from the fuel pump but, today was different. Yay!
A quick reminder, the fuel line from the tank to the pump is, 1/2" id. the pump is mounted inlet end down at a 45-degree angle up. I moved the return line to the filler neck as advised last year.

Today, the pump started whining with a surging sound to it, high to low pitched on and on. s Then it just quit! Sat on the side of the road for 5 minutes, restarted the car and drove home still somewhat noisy but, not as much. When I got back, with the engine idling I opened the fuel cap to see the fuel squirting into the filler neck from the return line but, not a steady stream. It was pulses of fuel, on and off for like a second each and continued that way.

Is this a sign of pump starvation, or something else?

Thank you for reading. If you have any suggestions... I am all ears.

M

[Piledriver]

Check the filters before tossing the pump, but I stand by the screw pump advice.
You did replace/check the pickup sock in the nice, clean rust free tank, right?

[michaellatini]

Thanks for the reply, Piledriver. I don't have a pump in the tank. It's gravity fed. I'll recheck the filter tomorrow. The tank was coated with some tank coating product before install. When I had a pre pump filter for a while it was absolutely free of any debris, to my surprise. I was afraid of removing it but, I did.

The most baffling part is the pulsing of the fuel from the return line.

M

[michaellatini]

I found the Crossfire pumps on ebay for $40. Can that be used outside of the tank?
Thank you, M

[michaellatini]

P.S. It says, 110 LPH at 43psi. I have the fuel pressure regulator set to 43lbs and need more when on the turbo. Will this not work?

[Piledriver]

I use it on CIS-M at 95 PSI. Rock stable. Your call.
Try to buy from a reputable seller or you'll get a $20 turbine pump with a blue stripe painted on.
The real thing doesn't care if in tank or inline. They pump great.
If in doubt buy a genuine TI automotive one for a Hemi...

I think I paid about $40 for mine 10 years ago, might want to aim higher $$$.

[michaellatini]

Cool! Thanks again! M