Fuel Pump Issue

OK here is one I've been trying to figure out for a while.

Euro Ghibli SS. Short story. One of the original Bendix Fuel pumps began to have problems, it was running slowly and could not keep up with the flow of fuel needed for the engine. Other pump still runs fine.

Since the pumps are mounted pretty much next to each other and the are now over 40 years old, I figured the smart thing to do is replace both. As most people know Bendix no longer makes this pump but the replacement is now made by Facet.

Spoke with Facet representative, he recommended their 32 gallon per hour version of the pump. I installed these pumps, the car then had a very similar behavior as the bad Bendix. A 1/2 to 3/4 use of the pedal results the car accelerating then losing all power (not electrical power) then 20 seconds later power again. As if not enough fuel is reaching the carbs.

Spoke to Facet, and had the pumps exchanged for their larger capacity 45 gallon per hour pumps. Installed the two 45 GPH pumps, and the same problem occurs. Accelerate, engine loses power, wait .......... power comes back ........ accelerate power loss. Repeat. Much like a fuel starvation problem.

Reinstall old (good) Bendix pump car runs fine. Anyone else had such a problem? How about a rebuild kit for the Bendix pumps?

 

Have the same issue in my Kyalami with one pump. Replaced it with a new facet, same thing, still the same problem. Think it must be the fuel line, dirty tank or the valve in the connector piece that might pump back into the other tank. Tried various things. No luck so far.
Think there is also a fuel starvation thread where similar problems are discussed in a bora

Best
Dirk

 

Bendix pumps are not rebuildable, no kits, only filters are replaceable. The speed at which the pump "ticks' should tell the story. If the pumps are "ticking" very fast and do not slow down, you are not getting enough fuel. If the pumps stay at a slow tick while you are driving, but the car does not run well, it is probably not the pump. Does a full tank (tanks) of fuel affect the situation? You could have a pin hole in the pickup tube on one of the tanks and the pump is sucking air. Just some things to think about.

 

Dyke,
The car runs fine on one of the original Bendix pumps. (Remember Ghibli 2 separate tanks each with its own pump). Then when using the new Facet pump 45GPH, it seems to experience a fuel starvation problem after a strong acceleration losing all engine power. Then after waiting a 15 + seconds power will come back as if the pump can't fill up the filter bowl fast enough. Doesn't matter which tank I use, each has a brand new Facet pump, both exhibit the same problem. But the old Bendix does not. BTW I did replace the filters in the both old Bendix pumps.

Joe

 

Joe,

I wonder of you are not getting enough amperage to the new pump. The Facet pumps are internally different than the old pumps and may require more amperage.

An easy test is to run a hot wire directly from the battery to the Facet pump. Take the car for a drive and do the acceleration test. My money is that the problem will go away.

Ivan

 

A friend who is an airplane mechanic (and transcontinental Captain) was going over things with me.

A new theory (which we haven't tried as of yet) may be in relation to the adjustable regulator on the top of the bowl. That maybe that the setting for the Bendix is too restrictive for the Facet pumps?

 

Honestly, I do not think the regulator is the problem. If it works with the old Bendix, than it would work with the new Facets. What is the situation with the speed of the pumps as I mentioned in my earlier post? When the car is stumbling and running out of fuel, what do the pumps sound like? Fast or still slow and regular?

 

Can't really hear the pumps very well as they are in the back of the car, with all the intake exhaust, engine, mechanical and road noises. They really aren't as loud as the ticking from the old Bendix pumps, they kind of sound more like a fish tank pump.

Plan on putting a fuel pressure gauge on it after the regulator and being able to switch between the Bendix and the Facet.

 

Joe,

Did you try what I suggested of hot wiring the pump as a test?? I really doubt it is the regulator since it is working with the old pump.

Remember that electricity needs to run from the battery, through the ignition switch, through the switch where you select the tank and back to the pumps ... lots of places to loose amperage.

Ivan

 

Joe needs to test a lot of things on this car. He's known that for quite some time now.
So get to it already Joe.

 

There is a service kit available for Bendix pumps

AlfaStop - passionate about Giuliettas (vintage Alfa Romeo Spares/Parts)

 

Joe, have you tried to put the known good Bendix pump on the problem side? This will at least tell you if the pump is the culprit or you need to look for further causes.
My guess would either be the change-over valve or the electrical feed to the problem-pump.

Best,

Jack.

 

Yeah he's done that. Both sides work with the old Bendix pump and both sides do not work with either the Facet pumps he's tried.

I've been talking with him for months now about this. It IS pretty damn frustrating. But what he has not done so far is actually calibrate and measure things to pin point what is the problem and where. I hope he finally does that. Because unless Facet has produced a long run of faulty pumps then something is wrong elsewhere. He could also identify if they are now making bad pumps. Just by measuring the performance of the new vs old pump.

 

If the problem changes sides with the pump, there must be a problem with the new pumps or they don't get enough electrical juice.

The Facets may have enough delivery, but do they deliver the right amount with enough pressure?
How much power do they need to do so?

You may want to install a relay in the pump-circuit to avoid the losses in all the switchgear.

It's been suggested several times: hotwire the pump and see what happens.

Best,

Jack.

 

The one original fully function pump works perfectly no matter which side it's on.

Time to measure and document EVERYTHING or how else are you going to get to the bottom of the issue? He's done the swap out thing ad nausea now and I know how frustrated he is with this.

I mean we can guess but only measuring will identify the problem now.

Each one of the new pumps he has are more than capable of delivering enough fuel for that engine. If they meet spec.

Now it is possible that the old pump is capable of generating more pressure and that's needed to properly operate his FP regulator? Seems like a rather odd thing to me but that can be determined as well by measuring the FP before and after the regulator with the old pump and the new one. Then you measure the amount of flow in the same setup. You'll find something is wrong.

 

Veloceone: thanks for the note about the Bendix pump "service kit". Unfortunately, the parts supplied really only give you the filter gasket, as none of the other pieces usually wear out. The failure point in these pumps is the electrical components, and they are sealed in the pump and not accessible.

 

Bob,

I must disagree with you. It is a lot more fun for Joe to swap parts at random and see if he hits the target. See, this way he stays busy and out of trouble. Your suggestion of actually measuring fuel flow and pressure would surely indicate where the problem is ... and what's the fun in that! Heck, he could even put an ammeter and to see if the replacement Facet pumps pull more current than the original Bendix ... but that would be too scientific and that only a geek would do. I like Joe's approach much better .

Ivan

 

Yeah but you haven't been fielding the the phone calls Ivan ... LOL

Oh I kid but I'm also somewhat serious here too.
We all love Joe and he's one of the most ardent Maserati fans out there.
Ivan you really do need to come up to Le Belle Machinne sometime.
Mike and George C. need to return as well.

Honestly, I just want to see him get the problem fixed.
I have to admit it's a bit frustrating for both of us. It's NOT just the simple straight forward sort of swap it out issue.

But I've had far worse ones than this back when all this internet access and decent inexpensive test equipment wasn't as available.

Al least he CAN still drive the car perfectly.

 

Interesting that you mention this because a few years ago I had a brand new one of these exact same pumps as Joe is using fail after becoming impacted from a large amount of rust in the tanks.

I then rebuilt the entire fuel system.

I never looked into figuring out what exactly failed but I cleaned it, and tested it and it just would no longer meet spec so I got another. It did originally work fine for a while though. I assumed the plugging up by rust was what caused it to fail and at $85 I just ordered another.

I wonder what it was? The replacement has been flawless for about 5 years.

 

The plan right now is to reinstall the good bendix and one new facet, then a fuel pressure gauge after the regulator monitor the pressure of both under acceleration. Then do it before the regulator.

 

Joe,

Good start. The other thing to test is flow volume.

Connect a hose to the output of the regulator and the other end to a small container.
Run the Bendix pump until the container is half full, record how long it took. Run the Facet pump for the same amount of time and compare the fuel volume.

Ivan

 

Bring an extinguisher Joe.

That sounds almost as scary as the fool pressure test I did for the Biturbo all those years ago. You know the one in the manual where you hook up a pair of gauges to the boost and fuel pressure via long hoses out the front of the hood and then tape the gauges to the windshield for a test drive to see if the regulator maintains pressure above the boost level?

On decent leak at 20 PSI of fuel pressure and WOW! LOL

 

First test: fuel pressure after regulator: bendix - 7 psi at idle, 4 psi at 3000 rpm. Facet - 4 psi at idle, .5 psi at 3000 rpm. Adjustment of regulator does not effect the performance of facet pump.

Second test: facet fuel pressure at source - 4 psi.

 

Facet fuel pressure of .5 psi at 3000 rpm after regulator is way too low. Webers like to be at between 2 and 3 psi. This is a clear indication that the Facet's flow volume is not sufficient.

Try the same test but hot wiring the Facet pump directly to the battery.

Ivan

 

You shouldn't have 7PSI after the regulator, way too high. Where is the regulator? You should ideally be checking this at the fuel rail inlet.

Can you adjust the regulator to get it back in spec for the Webers?

But it does sound like the Facet pumps are bad.

So check the flow and document what's going on. Maybe they have produced an entire batch of crap pumps. That WOULD explain Art's earlier problem with his Bora.