95 b4000 starting issue

[95bajaguy]

goodmorning everyone,

I am having a issue with my 95 b4000 (4.0) that is getting worse and worse. after sitting overnight it has trouble starting up the next morning. this is a every day thing. whenever i crank it it will sputter a bit and idle low for about 5 seconds then it will return to normal and run great. remember, tbis is ONLY when its cold. I live in South Texas so it doesn't get cold enough to cause problems. thismorming however it sputtered and bogged for about 2 seconds then i got a backfire and it died. after trying again i finally got it going. it has a new fuel pump and relay. fairly new spark plugs. i know alot about my truck but i am stumped here.. if anyone has any tips or ideas of what could be causing this, it would be much appreciated. like i said it is getting worse and worse.

thanks and keep on truckin

 

[RonD]

Reads like you have a slow pressure leak in the fuel system.

Not a fuel leak but a pressure leak.

'95 should have 30-40psi of pressure at the fuel injectors 24/7 even after sitting for few months.
There are 3 things that can leak pressure, beside a broken fuel line which you would smell
1. Fuel pressure regulator, FPR, has a spring inside the holds the fuel Return line valve closed when engine is off.
2. Fuel pump has a Check valve inside it that closes when pump is off.

3. fuel injector is leaking

Easy test to see if this may be the problem is to build up pressure before trying to start engine.
For safety reasons Ford only runs the fuel pump for 2 seconds when key is turn on.
It won't come on again until engine RPMs are above 400, engine started.
That 2 seconds is only about 10psi pressure.

So turn on the key, count to 3 and turn it off
repeat 2 more times
And then start engine
If it fires right up then you are losing pressure when engine sits.

You can test if it is the FPR or fuel pump, by clamping off the return line.

You would notice a drop in MPG if it were an injector leaking.

 

[95bajaguy]

Reads like you have a slow pressure leak in the fuel system.

Not a fuel leak but a pressure leak.

'95 should have 30-40psi of pressure at the fuel injectors 24/7 even after sitting for few months.
There are 3 things that can leak pressure, beside a broken fuel line which you would smell
1. Fuel pressure regulator, FPR, has a spring inside the holds the fuel Return line valve closed when engine is off.
2. Fuel pump has a Check valve inside it that closes when pump is off.

3. fuel injector is leaking

Easy test to see if this may be the problem is to build up pressure before trying to start engine.
For safety reasons Ford only runs the fuel pump for 2 seconds when key is turn on.
It won't come on again until engine RPMs are above 400, engine started.
That 2 seconds is only about 10psi pressure.

So turn on the key, count to 3 and turn it off
repeat 2 more times
And then start engine
If it fires right up then you are losing pressure when engine sits.

You can test if it is the FPR or fuel pump, by clamping off the return line.

You would notice a drop in MPG if it were an injector leaking.

thanks, ill update you tomorrow. i have to wait till morning to start it anyways

 

[95bajaguy]

thanks, ill update you tomorrow. i have to wait till morning to start it anyways

well i tried the cycle 3 times then start methid and it was alittle better. still started alittle rough but not near as bad as yesterdays episode. work is kicking my ass and i dont know where to even start if it is a pressure leak

 

[RonD]

If you can't smell fuel leaking anywhere then there is the fuel pump or the FPR.

I read in your other post about this, that you installed a new fuel pump.
Did you do the work yourself, or did a shop do it?

Maybe connector at the top of the tank has a leak, because of the time it takes for pressure to bleed off, assuming that's the problem, it seems to be over 6 hours then you may not notice or smell a leak on the top of the tank.

I guess next step, if is starts "sort of" tomorrow, with multiple key on/offs, would be to get/rent a fuel pressure gauge.
On the fuel rail under upper intake is the Schrader valve, looks like a tires air valve because that is what it is, it may even still have the cap on it just like a tires air valve.

Gauge just screws on like an air pressure gauge, and you can use an air pressure gauge as long as it is the screw on type.

Engine running pressure will be about 35-40psi
Shut engine off and pressure will drop to about 25-30psi
Then just let it sit and see if pressure is dropping over time.

If it is turn key on and off a few times to build it back up.
Then clamp the Fuel Return hose, the hose coming out of the FPR.
You don't need to mash it just clamp it snug.

If pressure holds replace FPR
If it still drops then..............new fuel pump or assembly is leaking