Fuel pump pulsator?

[kishy]

Hi folks. Been a while.

Sparing some of the context details, I'll ask this:

For Rangers with multiport EFI and an in-tank high pressure pump (let's say '93), is there a "fuel pump pulsator" mounted inline on the fuel line coming off the top of the fuel pump?

If there is: do we know of any ill effects that will come from not including said pulsator in the assembly?

 

[RonD]

No "Pulsator", not sure what that is

Fuel pump is on or off, has Battery Voltage or doesn't
Fuel pump power is controlled by the computer via the Fuel Pump Relay in engine fuse box, or under it, depending on year

1997 and earlier Rangers used a Return Fuel system, with a Fuel Pressure Regulator(FPR) on the engine's fuel rail.
Fuel pressure was maintained at 30-35psi with engine running, extra pressure(fuel) was sent back to the gas tank on the Return fuel line attached to the FPR.

In 1998 Ford switched Rangers to a Returnless Fuel system, so just one fuel line, earlier models during this change over had a Return line on the Fuel filter, later models didn't.
1998 and up Rangers used 55-60psi fuel pressure at the engine



As a safety feature, the computer only powers up fuel pump(relay) for 2 seconds with key on and engine at 0RPMs
This is to prevent an electric fuel pump from continuing to run in the event of an accident and a broken fuel line.
So engine at 0 RPMs cuts power to fuel pump.
You can cycle key on and off and pump will get power for 2 seconds each time you cycle the key.
When engine RPMs are above 400(engine started) computer turns on fuel pump power full time, no "pulsing"

 

[kishy]

Thanks Ron.

"Pulsator" appears to be a small passive valve thingy (for lack of better term), possibly similar to a pressure regulator in construction (???), which some vehicles use as part of the fuel pump hanger/sender assembly in between the pump output and the metal line that exits the tank.

The Carter pump I bought for my 2.3 EFI swap specifically points out that a pulsator may be present and to reuse it if so equipped. Also, RockAuto sells a pulsator for a 93 Ranger, so somewhere there is application data (good or bad) which says there "might" be one.

In my case I am using the sending unit/hanger assembly out of an 87 or 88 EFI truck, which are 2-pump trucks, so there is no "pulsator" on it and there never would have been. I am however just using that unit as a bracket to hang a pump on and will be using a single high pressure pump, so I would be subject to any design considerations for the trucks that came that way new...hence asking about the pulsator.

I don't know what the pulsator does, all I know is it appears to be something that exists.

My fuel system will be the 'normal' older return system via FPR.

 

[RonD]

"they" could be referring to a pressure switch that cuts or "pulses" power to fuel pump when pressure reaches a certain point, Rangers didn't have that

Ranger fuel pumps did have a Check Valve, this holds pressure in the system when key is off, so there is at least some pressure to start the engine after it sits.
The 2 second Key On run time only adds about 10psi

The Check valve was in the pump on the output, not a separate part

 

[tomw]

I think it may be an 'accumulator' that absorbs strong pulses of pressure from the fuel pump and smooths out the pressure that is allowed 'up the line' to the injectors. Later Ford models do have somthing of that sort on the fuel line.
If I have it correct, the only thing you risk by not having one is the possibility of more 'bumpy' fuel pressure.
tom

 

[RonD]

1998 and up Rangers had a Pulse Damper on the engine's fuel rail
At 50+ psi fuel pressure, when an injector opens and closes it creates a pressure wave in the fuel rail, with multiple injectors these pressure waves can propagate and build up.
Then when an injector opens it could be on the front or back of a passing pressure wave, so fuel pressure could be higher or lower, so the amount of fuel that flows out would be higher or lower, not great for setting air:fuel mix when flow is not constant.

Pulse Damper is just a rubber diaphragm at the end of the fuel rail, it absorbs pressure waves so they don't build up, it often has a Vacuum Hose attached, that's a safety measure, in case diaphragm should leak, fuel wouldn't drip on engine or exhaust

 

[kishy]

The purpose and function is beginning to make sense. Seems logical enough. I'm used to EEC-IV 5.0s which don't have this sort of stuff...

Doing some further digging here, I think it's an application data mixup and indeed the Ranger 2.3 does not have it, in 1993 anyway (and my engine/parts are a hodge-podge of 93 and 95 parts)

The (sole) pulsator RockAuto offers for the 93 Ranger 2.3 is a BWD FPP3: https://www.rockauto.com/info/232/232_BWD_pct_2FNIEHOFF_FPP3_2__ra_p.jpg

It supposedly applies to
1997 Escort, Mystique, Tracer
88-93 Mustang
88-94 Ranger, Tempo, Topaz
1988 T-bird
1995 Windstar
which is an unusual application list and probably resulted from bad data.

I then looked at a 90 Tempo 2.3 (OHV, not our OHC engines) and checked out what the fuel sending unit looks like. Some of them do come with a pulsator installed:
https://www.rockauto.com/info/203/E2101S-1__ra_p.jpg
https://www.rockauto.com/info/463/F1112A__ra_p.jpg
While some of them do not:
https://www.rockauto.com/info/43/HP10152B__ra_p.jpg

By comparison, none of the fuel sending units offered for the Ranger include one in the assembly (including the Motorcraft examples):
https://www.rockauto.com/info/41/150212_1__ra_p.jpg
https://www.rockauto.com/info/48/F57Z9H307FA-FRO__ra_p.jpg

So we can call that 'case closed' I guess.
My '95 engine with '93 engine controls and return-style fuel system will do just fine without the pulsator because even Motorcraft does not supply one in their replacement sending units.

 

[RonD]

Good info

Thanks