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95 B2300 2.3L low fuel pressure at KOEO


poco70

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Location
seattle,wa
Vehicle Year
1995
Make / Model
Mazda
Engine Size
2.3L
Transmission
Manual
Symptoms:
Tough to start, if it does not fire on the first key turn, I have to hold the pedal to the floor until it starts.
A little hesitation when driving

Symptoms started after replacing the fuel filter and spark plugs and plug wires.

I have a problem of having 5 psi of fuel pressure when the Key is On and the Engine is Off.
When the engine is running, fuel pressure is ~30 psi (range in manual is 25-35 psi). If I had pressure when the engine is off, the pressure should drop by 3-10 psi.
When I remove the vacuum hose from the fuel pressure regulator, the psi increases by 10 psi (manual says it could be between 35-45 psi).

I replaced the fuel filter (had been sitting on my shelf for about 5 years) and had some trouble with the special pressure connector on the engine side of the filter.

I'm thinking the connector springs are sprung and the line is not making a good connection on the filter.

11/24/15 - update
I replaced the fuel filter today with a Motorcraft FG872. I didn't trust the other one and I suspected I had damaged the quick connect when I installed it. So I focused on the connector right away. And yes, I did push in a couple of the tabs in the connector; one almost flat.
Ford uses a quick connect coupling on the engine side of the fuel filter. Inside the connector are four stainless steel tabs. These can become bent during the removal process, bent enough as to not make a good seal when the new filter is connected.
The tabs can be bent back in position, very carefully using a large paper clip with the tip of wire bent into a sharp hook.

When I connected the connector to the filter I heard a distinct snap as it clicked on. I remember, NOT hearing that before. I feel pretty confident that it is fixed.

I was not able to put a pressure gauge on it and could not know by sight that it worked. So far, I've started it a couple of times, without priming with a key on, and it seems like the issue is not resolved.

2017: After driving it for quite awhile priming the pressure before starting I finally gave up on the issue and took it to a mechanic. He noticed a small kick-back and looked at the plug wires. One of the two #1 plug wires was not correctly installed. Anyway the #1 piston was not getting the double spark. It starts as expected now!

He did not have much of an answer to the question, " Why did the fuel pressure gauge read low?" other than he has not had good luck with using the pressure gauges on Fords due to the schrader adapter. Resolved.
 
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Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

RonD

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First DO NOT hold gas pedal to the floor, that turns off the fuel injectors.
It is a computer program to "clear flooded engine", all fuel injected computers have this program.
1. Key on
2. Engine RPMs 0
3. Throttle position sensor(TPS) above 4.5volts(gas pedal to the floor)

Computer enters Clear flooded engine mode, injectors are turned off

Gas pedal on fuel injected engine only lets air in, it should be called air pedal now, lol, the computer controls fuel flow, so pumping gas pedal while starting also doesn't do anything except throw off air mix the computer is trying to set for starting.

So with fuel injected engines just let the computer do it's job while starting.

Ford computers will only run the fuel pump for 2 seconds when key is turned on, fuel pump won't come on again until engine starts.
Fuel pressure should hold above 25psi for a few months, not days or hours.

So you are losing pressure, and it could be a bad connection at fuel filter, do you smell gas in that area or can you feel it when putting fingers around the fuel lines in that area?

For now you can get pressure back for starting by "priming" fuel system 3 times.
Turn key on, count to 3, turn key off
Repeat 2 more times
Each time fuel pump runs for 2 seconds you will add about 10psi of pressure
So 3 times should get 25-30psi
Now try to start engine, without touching "air" pedal :)
 

enjr44

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02 2X4; 08 FX4
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4.0 SOHC
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Automatic
I have a problem of having 5 psi of fuel pressure when the Key is On and the Engine is Off.
When the engine is running, fuel pressure is ~30 psi (range in manual is 25-35 psi). If I had pressure when the engine is off, the pressure should drop by 3-10 psi.

I'm thinking the connector springs are sprung and the line is not making a good connection on the filter.
When you turn the key to run the two seconds the fuel pump runs can/will raise the pressure about 10 pounds. So cycling the key three times as suggested should get you about 30 psi. With the pressure tester connected what happens when you cycle the key? Does it go up each time you cycle the key? Or does it stay at the low number? Does it go up and then drop back down.

I would think that if the connection was poor you would have a fuel leak at the filter. But, if it is leaking it will dump the pressure real quick. IDK; but, I would think 30 PSI should cause a leak you can see when the truck is running. Think of the leak you get from the rad with just 15 pounds of pressure.

If you have 30 psi when running the hesitation you are seeing may have something to do with the plugs and wires you changed. My rule is to do one thing at a time, so if something screws up I know where I went wrong and where to look (of course that "rule" doesn't help much now).
 

poco70

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seattle,wa
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1995
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Mazda
Engine Size
2.3L
Transmission
Manual
RonD and enjr44,
You both spot on! Thanks for the heads up about priming. I only got 10 psi when I primed it. But it sure helped to startup like it used too.

I also was not able to get the fuel line clip over the connector. I did not worry too much about it as it was not connected when I started the replacement.
I'm going to give that a shot while I wait for a new Motorcraft filter to arrive at the parts store.

I'm also going to prime the pressure gauge with KOEO and wait to see if it decreases.

There certainly is a pressure leak and I think it is at the filter. It starts after priming eight times.

2017: After driving it for quite awhile priming the pressure before starting I finally gave up on the issue and took it to a mechanic. He noticed a small kick-back and looked at the plug wires. One of the two #1 plug wires was not correctly installed. Anyway the #1 piston was not getting the double spark. It starts as expected now!

He did not have much of an answer to the question, " Why did the fuel pressure gauge read low?" other than he has not had good luck with using the pressure gauges on Fords due to the schrader adapter. Resolved.
 
Last edited:


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