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fuel system check valve

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Old Oct 19, 2015
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sageport's Avatar
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From: larkspur CO
fuel system check valve

2001 ranger 3.0 starts and runs perfectly when cold 70xxx miles. When I restart about an hour after stopping it cranks 5 seconds or more has a rough start then runs normal. I tested with a fuel pressure gauge at the fuel rail and when I turn the key the pressure rises for about 2 seconds then falls quickly to 0 psi there is 70 psi when it is running I think the check valve in the tank has failed. I replaced the fuel pump (pump only) about 3000 miles ago. can you take the check valve apart to look for the problem or is it time for a new fuel pump & sender assembly?
 
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Old Oct 19, 2015
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You definitely have a leak in the system, but it shouldn't "start cold fine" if pressure is 0psi

Check valve is part of most fuel pumps, i.e. fluid can flow out but not backwards, it is just a flap on the pump's output tube.

Check fuel filter, on Ford's "returnless fuel system" there is a return line, but it is on the fuel filter.
Filter will have 3 hook ups.
one is for fuel pump other goes to engine
3rd is the return line going back to fuel tank, so there is a check valve in the filter housing.

Yes, '01 should have 65-75psi fuel pressure, and it should only drop to 55-60psi when key is off, and hold that pressure for months and months.

When you turn on the key the fuel pump will only run for 2 seconds, it is a safety feature.
But you can then turn off the key and turn it back on, repeat this a few times then try to start truck.
This should build up pressure so engine runs OK until you have time to change filter
 
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Old Oct 19, 2015
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From: larkspur CO
Thanks for the quick reply with that helpful information!! If the check valve is in the filter that sure beats pulling the "fuel pump & sender assembly" I'll
pick up a new filter, if that corrects my problem it sure saves me time work & $$$ I really appreciate your help.
 
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Old Oct 23, 2015
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From: larkspur CO
Originally Posted by RonD
You definitely have a leak in the system, but it shouldn't "start cold fine" if pressure is 0psi

Check valve is part of most fuel pumps, i.e. fluid can flow out but not backwards, it is just a flap on the pump's output tube.

Check fuel filter, on Ford's "returnless fuel system" there is a return line, but it is on the fuel filter.
Filter will have 3 hook ups.
one is for fuel pump other goes to engine
3rd is the return line going back to fuel tank, so there is a check valve in the filter housing.

Yes, '01 should have 65-75psi fuel pressure, and it should only drop to 55-60psi when key is off, and hold that pressure for months and months.

When you turn on the key the fuel pump will only run for 2 seconds, it is a safety feature.
But you can then turn off the key and turn it back on, repeat this a few times then try to start truck.
This should build up pressure so engine runs OK until you have time to change filter
I am yet to find a fuel filter with a built in check valve. The ones I have tested allowed a free flow of fuel in both directions. Do you have any recommendations? Thanks.
 
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Old Oct 24, 2015
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If the 3 port filter allowed unrestricted flow then system couldn't retain pressure, it would just bleed off on the return line.
A 2 port filter, of course, wouldn't need a check valve.

Fuel pump itself needs a check valve as well.

Fuel pump/check valve-------------filter---------------fuel rail(65psi pressure)
Return line-------------Check valve/

I am just guessing since I never took a Ford 3 port filter apart, the return line outlet in the fuel tank could have the check valve to maintain pressure.
But when you have a return line you do need a check valve or fuel pressure regulator on it or pressure will be lost when pump is off.
 
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Old Oct 24, 2015
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From: larkspur CO
Ill let you know what I find
 
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Old Oct 30, 2015
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I used a dorman connecter #800-055 to make a adapter to connect my fuel pressure gauge to the fuel filter outlet. when I turned the ignition on the pressure jumped up to 70 psi the fell right back to 0 psi. This told me the check valve problem was from there back to the tank. I removed the fuel pump assembly from the tank ( I lifted the bed with a cherry picker with the rear 2 bolts loose but not removed and put large wooden blocks between the bed and frame for safety). I removed the fuel pump from the assembly and tested the check valve in the pump with 70 lb. of air pressure and the check valve was leaking by. I applied pressure and released it a few times and then to my surprise it began to "hold" I'm hoping some crud flushed out. I decided to reassemble everything and install it back in the tank. With the fuel gauge still on the filter outlet I turned the ignition on and the pressure jumped to 70 psi then fall back to 60 psi and "held". The fuel pump would run about 3 seconds then stop. I hooked up the fuel line going from the filter to the fuel rail and put the fuel gauge on the fuel rail and the check valve held after several on & offs of the ignition. This fuel pump has less than 10K miles on it so I took the gamble of not replacing it. Time will tell and a failed check valve shouldn't be able to leave you stranded. This truck has deserved every penny I have spent on it, however I'm kind of "tight"
 
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Old Oct 30, 2015
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Reads like you got it fixed, good work
 
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Old Feb 28, 2016
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From: Atlanta Ga
fuel pump

Originally Posted by sageport
I used a dorman connecter #800-055 to make a adapter to connect my fuel pressure gauge to the fuel filter outlet. when I turned the ignition on the pressure jumped up to 70 psi the fell right back to 0 psi. This told me the check valve problem was from there back to the tank. I removed the fuel pump assembly from the tank ( I lifted the bed with a cherry picker with the rear 2 bolts loose but not removed and put large wooden blocks between the bed and frame for safety). I removed the fuel pump from the assembly and tested the check valve in the pump with 70 lb. of air pressure and the check valve was leaking by. I applied pressure and released it a few times and then to my surprise it began to "hold" I'm hoping some crud flushed out. I decided to reassemble everything and install it back in the tank. With the fuel gauge still on the filter outlet I turned the ignition on and the pressure jumped to 70 psi then fall back to 60 psi and "held". The fuel pump would run about 3 seconds then stop. I hooked up the fuel line going from the filter to the fuel rail and put the fuel gauge on the fuel rail and the check valve held after several on & offs of the ignition. This fuel pump has less than 10K miles on it so I took the gamble of not replacing it. Time will tell and a failed check valve shouldn't be able to leave you stranded. This truck has deserved every penny I have spent on it, however I'm kind of "tight"
On my 2001 2.5 stepside I get up to 90lbs and bleeds down and hold around 50 hooked directly to the pump outlet. All other lines are undisturbed. I then take a measure at the fuel filter outlet and cycle the ignition (no start) 3 or 4 times I can get it to @ 45, and it falls to 0. At the fuel rail and running it will hold 45.Giving me a 171 lean code. I disconnected the return to the pump line from the fuel filter and plugged the filter and now I got 80 or 90. I'll probably get a rich code. Its a new fuel pump but the guy who put it in didn't wash the tank. Well the truck has been sittin for @4 yrs. The gas is real dirty before the filter. I was wondering where I could get just the regulator and check valve.
 
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Old Sep 17, 2023
  #10  
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From: City, MN
Thank you @sageport for your debugging breakdown. I was having similar issues with my truck, it’s mostly a beater, but I’m fixing a ton of issues, and decided that cranking the engine excessively to wait for fuel wasn’t acceptable. Your method worked great for me, however I wasn’t so lucky to have a working pump after.

I ended up blowing roughly 40 PSI through the sending and receiving ports. And they both were leaky in the beginning, one of them stopped being leaky, and the other ended up having a crack in the tube. (I assume this is the original pump assembly, so time for another rock auto shopping spree. I’d rather trust a new assembly than attempt a janky fix)

My crack in the sending tube :((

The ports that are required to hold pressure. (To and from fuel filter)
 
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