Fuel Line Component - What is it?

swingjunkie · Oct 29, 2014

1985 Ford Ranger - 2.3 EFI. Debugging low fuel pressure. This component is inline between the high pressure fuel pump out and the fuel rail on the manifold. It is not shown in the manuals that I have. See the attached photo.

I would guess a check valve, but I can't find any info. Anybody have good info? Looks to be OEM equipment and at 29 years of age is suspect. High pressure fuel pump is new. Still reporting 24 PSI on the fuel rail.

Thanks
Carl

RonD · Oct 30, 2014

Never seen that one before

I would blow in one end of the line and then the other end, check valve would prevent flow in one direction, if it is working.

The Fuel Pressure Regulator on the fuel rail is a check valve, and I thought the high pressure pump also had internal check valve

swingjunkie · Oct 30, 2014

I checked fuel pressure with this in place. It was reading 24 PSI. I removed it and replaced the line. Cut it open and it was a fuel filter, albeit very small, and gunked. I retested fuel pressure and got 32 PSI with this out of the loop. I also replaced the fuel filter between the tank and the pump. This made no difference in the fuel pressure. Is it worth while accessing the in tank pump to see if the fuel pressure can be improved?

alwaysFlOoReD · Oct 30, 2014

RonD · Oct 30, 2014

The 32psi will work, but at almost 30years old the screen/sock in the tank may need to be cleaned/replaced

tomw · Oct 31, 2014

Most fuel pressure gauges have a relief valve with a piece of tubing attached. Use the relief to measure fuel flow over a fixed time period. Collect the fuel pumped, and measure the quantity. Do some arithmetic.
If you can get a half-cup of fuel in 10 seconds, that's 3 cups per minute.... .75 of a quart per minute. More math says if you get 25mpg at 60, you need to pump 1/25 of a gallon per minute. (mile a minute)
I have an EFI 85 and have the factory 'canister' fuel filter mounted on the frame rail. Tried to replace it once, but the strap wrench would not budge the canister. Decided that if I crushed the canister, I'd never find a replacement ... and then what? Have a new filter element on the shelf.
The high pressure pump seems low on pressure. If the vacuum line is disconnected, or the pressure measured with the engine off, it should be higher. The VOLUME, or 'filter' won't make a difference as long as the pipes are full of fuel. It is NOT flowing any fuel when it pressurizes, so if it seeped into the rail, via the lift pump(through the sock) through the can filter, through the hi-pressure pump, at slow volume, it would not matter. Pressure is pressure, and volume is volume. It can show good pressure, but not flow ... then the filters come into question. But not at zero-consumption testing.
However, if the injectors are leaky, the pressure may be low, but it would run like mumble, too rich. Check the pressure, and leave the gauge attached for a minute or so. It should hold pressure for at least a few minutes. If it drops immediately, the check valve in the pump(s?) is be not working, or the injectors leak. It has a return line that I believe has a check valve back at the in-tank pickup which should hold pressure.
tom

swingjunkie · Oct 31, 2014

RonD,

I agree tank screen is likely carrying 29 years worth of gunk. I'm not sure I'm ready to dive into it just yet. Perhaps later in the year during the long evenings of winter.

Thanks for your response
Carl

swingjunkie · Oct 31, 2014

tomw,

Thanks for your reply. I see the logic of your calculations. I'll do some more reading on testing the fuel flow rate and give that a look.

My truck has a cover over the frame rail mounted canister filter which cannot be removed and the filter strap wrench would not fit into the space. There are two 10 mm bolts which attach the canister housing to the frame rail. I soaked these with penetrating oil for a few days and they came right out. Disconnected the four fuel connectors and slid the filter canister out of the protective enclosure. I then put the canister housing in the bench vise and the filter wrench removed the canister no problems. One caution here. Even after emptying the canister from each of the four ports I still got some gas dribbling out when removing the canister in the vise. Getting the new Oring in place took a generous application of vaseline. Again, replacing this frame rail canister filter did NOT further improve the fuel pressure. Still reading 32 PSI. The filter appeared clean, no noticebale debri or gunk.

You comment that "the high pressure pump seems low on pressure". Spec is 30 - 40 PSI. So I am on the low end of that. Since you've got the same engine, what do you read at idle?

The only other thing I can think of, to boost this pressure, is putting in a new intank pump or cleaning that intake screen. No idea how much of a boost, if any, this would provide.

Based on your other feedback regarding regarding pressure bleed, I ran a quick test to see what the initial prime pressure was and how fast that bled off. Here are my results

KOEO one prime cycle of the pump
Time (sec) Pressure (psi)
0 40
30 30
90 20
180 15
300 11

I don't have anything to comapre that to, so I don't know if that is reasonable. Again, I need to do some more study on testing fuel flow rate.

Tom, thanks for your reply and your ideas.

Mikel89us · Oct 31, 2014

That part in the line would be a muffler, or its fuel line equivalent. The newer motors have them on the rail. All it is, is a spring loaded pocket that dampens fuel pressure pulses from the pum/injectors firing, and keeps the fuel pressure more stable.

swingjunkie · Oct 31, 2014

Mike,

I cut this open after removing it. It was indeed a small fuel filter with a metal screen inside which was very gunked up.

Thanks for your reply,
Carl

Mikel89us · Oct 31, 2014

Hmm, never mind then. I have something similar on my car but its bigger, bit I know its not a filter. I assumed it would be the same thing.

RonD · Oct 31, 2014

Fuel pressure shouldn't drop by more than 5-8psi with key off, even over night or a week later.

You have a leak, could be FPR(fuel pressure regulator) on the rail, it has a vacuum line check it for fuel or fuel smell, there should be none.
If none then remove return line with key off engine off.
Turn on key then turn it off, no fuel should come out return line outlet on FPR, if it does replace it.

Only other check valve would be on the high pressure pump.

Leaking injector could be causing pressure loss.
Simple test:
Warmed up engine
engine off
key on
press gas pedal to the floor and hold it there
Crank engine, it should NOT start, it should NOT fire at all.

Key on/engine off/gas pedal to floor = cut off fuel injectors, leave spark on
This is a computer routine on all fuel injected engines, often called Clear Flooded Engine routine.

If your engine fires even a little during test you have a leaking injector(assuming FPR vacuum line was clear)

As soon as you release gas pedal engine will start normally, even while cranking.

If you don't get firing then pump check valve is only thing left.

swingjunkie · Oct 31, 2014

Ron,

Thanks for your suggestions. The FPR is a new Bosch, installed just before I bought the truck. No smell of fuel on the vacuum line.

I located the return line on the fuel rail, but it is tough to get to. I can't see or feel a retaining clip on this line, but it did not push off the rail easily and I did not want to force it. I am attaching a picture.

I'm taking Old Blue out for a test drive in the AM. I have not driven it since correcting the timing and getting the fuel pressure up to 32 PSI. With the engine warmed up, I will try your suggested "Clear Flooded Engine Test" with the understanding that I won't know if it is an injector, FPR, or high pressure pump which is leaking off.

The high pressure pump is new and installed just before I bought the truck, so I "expect" it is OK. If both the FPR and hig pressure pump are OK, I guess that leaves me with a leaking injector. My question on that front is how would that impact performance?

Thanks again
Carl

RonD · Oct 31, 2014

MPG would be bad.
Hard starts, could get a rich misfire, which will heat up the Cat converter and shorten it's life.

If you fail the Flooded engine test, so ID a leaking injector.
You can find out which one by checking spark plugs:
Cold engine, preferably has sat overnight
Disconnect both coils
Turn key on wait 2 seconds turn it off, turn it on again
Do flooded engine test again, crank for 20-30 seconds
Pull one spark plug from each cylinder, the wet one is from the cylinder with leaking injector.

tomw · Nov 1, 2014

If the pump is within pressure spec, I'd not worry about it. If the volume test is ok, again, don't worry about it. The pressure leakdown may not be ok, but it is not a huge drop within a few seconds. To make the pressure drop, even 10 psi, doesn't take a lot of volume when you consider how much of the fuel system is under pressure.
The rail, the injectors, and the fuel line back to the high pressure pump. All will breathe a bit when put under pressure, and when the pump shuts off, the components will retract as the pressure drops. I don't think there is a lot of expansion/contraction room / volume in the components. That means it would take a tiny leak to drop the pressure. Tiny. I cannot emphasize the word enough. Tiny. Little. On the order of drops.
When a liquid is under pressure, it cannot and does not compress. In normal physics, anyway. The pressure retained is from the container trying to regain its former shape/volume. In this case, its the above mentioned components. Lose a drop or two of volume and the pressure will drop quickly.
If you are getting good mpg, say 25mpg without trying a Mobil Economy Run, or an egg between your foot and the gas pedal, you are doing ok. If you have a leaky injector or check valve, it is not a problem unless the truck becomes hard to start. In which case, you can cycle the ignition a few times to build pressure for starting before cranking the engine.
I tried removing the U-shaped piece of steel protecting the canister filter, actually pivoting it on one of the bolts for access to the filter body. Got the strap wrench on, and it slipped no matter. As noted, was afraid of ruining it with any other wrench, so left it alone and put back together. Did you note any water in the canister when you changed the filter element?
tom

Fuel Line Component - What is it?

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