FastKat

iTrader: (10)

I installed a Bosch 044 fuel pump about 6 months ago on my Jaguar LS1 swap. The pump makes a surging sound at random every second or two, almost like it's getting a little gulp of air or something. It's done this since the day I installed it. It does not matter whether the tanks are full or empty, or if one tank or another is selected. Under heavy throttle and/or high RPMs, the car will hesitate, almost like it's running out of fuel or the spark is being shut off just for an instant. If you keep your for in it, the car will jerk back and forth pretty violently. The problem got worse on my way home today... worse than it's ever been. It actually stalled a couple times while cruising, but started right back up.

Here's what it sounds like:

Normal Bosch 044 on youTube:
"Rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr rrrrrrrrrrrrrrrrrrrrrrrrrr"

My Bosch 044:
"Rrrrrrrrrrbrbrrrrrrrrrrrrrrrrrrrrrrrbrrrrrrrrrrrr rrbrrrbrrrrrrrrrrrrrbr"

I tested the voltage at the pump, and it's dead steady, reading the same as at the battery posts.

Here's a video link:

The pump is installed inline by the bottom of the tanks. The pump sits very low. There is plenty of fuel in the tanks. I have a 100 micron stainless steel mesh cartridge Trick Flow fuel filter that I installed with the pump. It's all 1/2" fuel hose from the tanks, through the fuel tank selector valve, through the filter, and to the pump. The inlet-side fittings are -8 AN. There is also an LS1 Corvette filter/regulator in the engine bay. The tanks have plenty of fuel. The pump and inline filter have about 700 miles on them.

What the heck is going on here? Any thoughts?

Old Geezer

iTrader: (3)

Selector valve flow insufficient, causing pump cavitation?
Insufficient/no tank vent?
Why is the filter/reg at the ft of the car?
What size return line do you have?

FastKat

iTrader: (10)

Thanks for the reply - I wasn't sure anyone would!

The selector valve is suspicious. It has 1/2" hose ends on all sides, but I'm not sure if it's 1/2" all the way through. It started acting up over the last month or so. It no longer completely seals the tanks. If my left tank is full and my right tank is empty, the tanks will level out over the course of a couple days. Suspicious.

I'm not sure about tank vents. I know it has some sort of vapor recovery system and a charcoal canister.

The filter/regulator is at the front of the car because that was the most convenient place to put it. I also thought that the close you got it to the fuel rail, the better.

The return line is either 3/8" or 5/16" - I can't remember. I want to say it's mostly 3/8" with one 5/16" hose at the regulator.

I posted the video on another forum, and they seem to think that the sound is the fuel pump starving for fuel. I guess that leads to cavitation? If that's the case, it should make troubleshooting a lot easier!

Old Geezer

iTrader: (3)

The Vette reg has a 5/16 return line port. One feature of the Vette filter is to mount it close to the tank, to reduce hose use, routing issues, etc.
The canister could be an issue, if it's been disconnected/lines plugged off. Usually, the canister acts as a "filter/vent" for the tank.
Get the selector valve issue corrected.

stevieturbo

It does sound like cavitation.

So the pump does have completely free access to a good gravity fed supply of fuel ?

Can you draw a schematic ?

FastKat

iTrader: (10)

The return lines were already in the engine bay, so I just went with that.

Now that I think about it, the charcoal canister is not hooked up to the engine. There is a line that's supposed to get vacuum with a restrictor in it, but I never got around to hooking it into the intake hose.

This is a good question. The pump is mounted level with the tank outlet... maybe an inch below. I feel like it's getting "gravity" feed, but I am wondering if that fuel tank selector valve is somehow impeding flow.

I included a schematic.

I picked up a clean drain pan tonight, and I am going to disconnect the hoses on the inlet side and start troubleshooting.

stevieturbo

What exactly does this selector valve do ? Is it a manual valve that opens/closes each tank when you switch it over ?

And how long are the hose runs prior to the pump, and what diameter ?

Again, The above goes back to the free flowing gravity fed supply.

EFI pumps like the Bosch do not suck, so any restrictions prior to the pump are never good.

Old Geezer

iTrader: (3)

From the drawing, you have the reg/filter hooked up wrong.
The single fitting end is the outlet, not the return.

FastKat

iTrader: (10)

The selector valve and the two return valves are electric valves that all work in unison with a switch on the dash. When the switch is off, the tank selector valve pulls from the left tank and the return valve to the left tank is open. When the switch is on, the tank selector valve pulls from the right tanks and the return valve to the right tank is opened.

The runs prior to the pump are all 1/2". There's probably about a total of 2 feet of hose when measured from either tank to the inlet of the fuel pump, maybe a little less.

I want to feel okay about the position of the pump because I put the new Bosch pump exactly where the old EFI pump was. I think Jaguar used Bosch as their OE supplier, but not the 044.

The drawing does not reflect the position of the lines on the regulator. I have it hooked up correctly. Stupid Da Vinci!

stevieturbo

I guess the only sticking points are the selector valve itself, and perhaps long hose runs prior to the pump.

For a simple test, you could clamp the hose from one tank, and run the other directly to the tank outlet.
1/2" ID hose should be ok even at 2ft length. What is the outlet size on the tanks ?

And with regards tank breather....for purposes of a test, just try it with the filler cap removed..
I'd assume both tanks would be vented either to atmosphere or possibly admitted to the intake via a purge solenoid, and charcoal canister.

FastKat

iTrader: (10)

The saga continues.

I drained both tanks and took apart the inlet side of the fuel system. The pre-fuel filter was caked with brown stuff, probably rust. Fuel would not pass through. The fuel tank selector valve, which has 1/2" fittings, was restricted down to about 3/16" inside the valve at both inlets. I cleaned the filter element and installed a free-flowing 1/2" brass tee, and the pump REALLY quieted down. The car ran great!

At the end of my 15 minute ride home, the pump got noisy again. I went and started the car an hour later, and the pump was quiet again. Hm. Did it cake up again?

I also had an issue on the return side. The fuel pressure was at about 67 psi at the rail. It's supposed to be 58.5 psi. I suspect that with the pump now flowing properly again, it was over flowing the return system. I replaced one of the return valves, which was also very restrictive, with a piece of straight 3/8" tube, and the fuel pressure came down to 61.5 psi. I did not have time to do the other side. There is a chance that I filled up one tank, and the pump sucked some air from the other side. Maybe that's where the noise came from. I really don't know.

I need to replace the other valve with a piece of straight pipe so the tanks drain more evenly.

GrantO

Did you ever fix the problem?

I just installed a brand new 044 and it's doing the same thing. Making that weird noise ever coupe of seconds like it's sucking in air and it cuts out under high rpms.

I have my pump mounted in tank with a new filter sock directly on the end of the pump and a fuel filter before the fuel rail. I also rewired it to the battery thru a relay so it's not a voltage issue.

Any help is greatly appreciated.

stevieturbo

Is it a genuine 044 ?

What type of sock ? These pumps do not like any form of restriction at all in front of them.

Rewiring through a relay is of course good, but are wire sizes, and is wiring from alternator to battery good ?
What voltage are you seeing at the pump throughout ?

GrantO

Yes it's a genuine 044

And this is the link to the sock I got http://www.jayracing.com/fuel-filters-c-2_14/bosch-fuel-pump-prefilter-fuel-sock-for-044-p-62.html

I ended up removing the sock from the pump and the filter before the fuel rail just to see and the pump seemed to be running a lot better but still not 100%

I'm using the stock hard lines and 3/8 rubber fuel hose from hard line to the rail in my car (non ls nissan). Could the hard lines be too restrictive?

And I'm getting ~12v at the pump when it's running with the car off. And ~13.45v when the cars running

stevieturbo

Sock looks reasonable.

Although 044's should already have a small screen inside them anyway. At least any Ive used in the last few years have had.

Is the pump mounted low enough that you arent sucking air ?


In tank and surrounded by fuel, they should be fairly quiet and with a consistent noise.

Aeration, or very hot fuel can sometimes make them a bit louder, or anything that causes a lack of supply to them

Old Geezer

iTrader: (3)

Did you CLEAN the tanks of the **** you found in the screen??
If there was enuf to clog a 100micron screen, then it's highly likely it's back, again.
Furthermore, if it clogged the screen, it also messed up the Vette filter.