Hi guys,
been chasing down a miss/stumble and today i fitted an adjustable fuel reg from South Florida pulley as i thought i had issues with the stock reg.
With the stock reg i was reading 44psi at idle with the vacuum pipe off and 32psi vac pipe on, pressure didn`t rise with revs at all and even seemed to drop a little.
With the new adjustable reg i adjusted down to 39psi vac pipe off which went down to 30psi vac pipe on, again no increase in pressure with engine speed.
About six months ago i had a pipe blow off the Y piece to one of the fuel pumps in the tank and that i fixed and replaced the crappy clamps with jubilee clips, symptoms of that were the truck wouldn`t run faster than idle.

1. Do my pressure readings seem normal?

2. Is it possible that the other pump has blew the line off the Y and i`m able to drive the truck because this pump is the low pressure one of the two?

3. Is it possible that the fuel relays are bad? I`ve swapped them around to no change and even bypassed the resistor under the front bumper.

4. A mechanic friend has suggested i have a bent valve somewhere but plugs look fine, TR6ix installed as they came- 1.0 mm gap, is this right?

BTW, new cops and injectors haven`t effected a cure either

Informed ideas please

Thanks

 

^^^^

 

Sorry dont have an answer for you Mark but a couple of other suggestion and or possibility's.

Yes I guess it could be a Pump/Line Problem inside the tank
Could be a bad Fuel Filter (happen to me and caused stumbling/missing)
Could be a bad coil wire (happen to me and caused stumbling /missing)
Could be a bad/defective plug (happen to me and caused stumbling /missing)

The best thing to do is open the hood and pull each coil connector "one at a time", and find the cylinder that DOES NOT effect the way it's running, hence finding the troubled cylinder. Once you get it narrowed down to a particular cylinder, make sure there is no problem with the coil, wires, plug,
connector, etc (even swap the coil AND PLUG with another). Once you rule out the coil, connection, wiring, and spark plug unfortunately it would be time for a compression test / cylinder leak down test

Dont rule out a Spark Plug just because it looks ok, I have had at least 3-5 look absolutely perfect but when you turned it with the tip facing down "and tapped it" all of a sudden the porc would seperate. Turn it back unside down and it looked perfect again ; o )

 

Fuel pressure should rise with boost pressure. It may need to be under load to see this rise. Do you have a fuel pressure guage in the truck?
Jim

 

Thanks for the suggestions Rob, i`ll try pulling the coil wires tmrw.
As for the pressure gauge Topgun, no i don`t have one in the truck- i just hooked one up on my drive at home to the schrader valve on the fuel rail, i suppose i could tape the dial to the windshield as the hose is quite long.
I`ll try that tmrw too and report back

Thanks again guys
Mark

 

you need one of these
https://www.f150online.com/forums/sh...d.php?t=244111


maybe you crushed the y fitting or it came off again.

 

Too many of these threads don't get reported back on after people have found a fix:
Well, took the advice and pulled each coil connector and sure enough, found one that didn't make a difference to engine sound.
Turned out that particular cop was dead!
Last year i had one of my original cops go and considering the truck was approaching 7 years old decided to replace them all with some new but cheap aftermarket ones off ebay, am i glad i kept my old ones!
swapped the dead one with an known good old one and it ran a lot better.

Still not perfect and after changing fuel filter with no change decided to pull the bed and check the fuel pumps, all pipes were still on and the crappy Y fitting wasn't crushed, what i did find was that the pick up strainers were clogged thus causing fuel starvation and strange pressure readings.

Now she drives like she's supposed to and i'm happy again.
All is well with the world!