Fuel pressure issues

[Pertneer]

I have one for you guys to help with. I seam to have a serious fluctuation in fuel pressure when idling. I replaced the fuel pressure regulator a no change. Do I need to replace the pump or is there another issue? See video.


Also If I try to rev it up it will die or almost die.

[Fraser]

My initial guess is you have a bad TPS, but...
Vehicle?
Check engine light on?
How do you know fuel pressure is fluctuating, are you using a gauge?
Oh, and I don't see a video.

[Pertneer]

No check engine light
Ford 5.0 in my Jeep
Yes I am using a fuel pressure gauge, the video is of the needle jumping around

Any suggestion on how to check the Throttle position sensor?

[wdln]

I'd just try replacing the TPS. The check engine would come on if the sensor was completely bad (open or dead-short), but it might not if it's just returning incorrect data, like if it always thinks the engine is idling regardless of how much you're hitting the gas. In that case, the computer might not know there's a problem with it. If replacing the TPS doesn't fix the problem, you can always just return it. (and I can see the video, Fraser)

[Fraser]

Hmm, apparently the video is not mobile version friendly?

Does "no check engine light" mean you don't have one, or it's not on? Is the engine fuel injected?

[CLBJeep]

I would have the same question as Fraser. How do you know it's fuel pressure? Could the fuel pressure fluctuation be a symptom of another problem, and the fuel is trying to over come that? Vacuum leak, timing, TPS sensor, IAC sensor (may or may not give CEL), or egr system issue. If you got the OBDII port, I'd plug it up and see if anything pops up.

[wdln]

Hmm, apparently the video is not mobile version friendly?

Might not be.

[Pertneer]

Hmm, apparently the video is not mobile version friendly?

Does "no check engine light" mean you don't have one, or it's not on? Is the engine fuel injected?

I do not have a check engine light, never took the time to hook one up.

Here is a link to video on youtube http://www.youtube.com/watch?v=InPKofILTe8
the video is HD maybe that is why it is not mobile friendly or maybe just because it is embedded on this site so maybe watching on youtube will help.

I do have another TPS on another motor that I can swap in to see if that works. I will give that a try and let you know.

[vlucdog]

I can see the video on my 4s iphone

[Fraser]

Like Clint said, if you have a diagnostic port, tap into it and let the computer talk to you. When we put a 5.0 in Mickey's CJ, we put the OBDII port under the dash which allows for real time data monitoring as well as diagnostics. Hopefully it's still a part of your wiring harness.

[Pertneer]

I got no trouble codes when I checked them. just '11' which means all systems are good.

Also it is not a obdII system it is an EEC IV system.

[CLBJeep]

Hhhmmm..... Let's try to work this problem backwards with a few more questions.

1. Does it do this all the time (i.e. engine idles badly both hot and cold)?
2. Is this a recent problem that occurred after after you did another repair? (maybe a hose is disconnected)
3. Will it eventually stall out, or continue to run?
4. If you mash the accelerator what happens?
5. Is there a strong smell of fuel when running?

[Pertneer]

Hhhmmm..... Let's try to work this problem backwards with a few more questions.

1. Does it do this all the time (i.e. engine idles badly both hot and cold)?
2. Is this a recent problem that occurred after after you did another repair? (maybe a hose is disconnected)
3. Will it eventually stall out, or continue to run?
4. If you mash the accelerator what happens?
5. Is there a strong smell of fuel when running?

1. Yes
2. Depend on what you call recent, it has not been started all winter and now has this issue.
3. Yes
4. falls flat on its face and dies
5. No smell at all. I did look over all fuel lines for signs of abrasions and leaks all the way to the tank. I just could not see on top of tank without dropping it.

[Fraser]

Did you try that other TPS yet?

[CLBJeep]

Might be a shot in the dark, but it happened to a friend here in TN. Check your intake for blockage. A buddies Jeep here sat all winter and a rats nest was built in the air box. It would start, but stall out and run like crap. I've also experienced a similar problem on a 4-cylinder car with a K/N air filter. Even though it was washable (and cleaned often), it was apparently clogged up pretty good. I could start the car, but had to keep my foot on the accelerator to keep it running. So, check the filter element as well.

[vlucdog]

I wouldn't be surprised to find the fuel filter full of what looks like jello, or petroleum jelly. This would be caused by Ethanol blended fuel. This is where I would start. This fuel doesn't last long, like maybe 3 months.

Bill

[Pertneer]

I wouldn't be surprised to find the fuel filter full of what looks like jello, or petroleum jelly. This would be caused by Ethanol blended fuel. This is where I would start. This fuel doesn't last long, like maybe 3 months.

Bill

I had the fuel filter off and I ran gas through it in both directions and it did not seam to run slow at all.

I did notice that the pump is a little louder today than it has been. I am leaning towards a new pump. With it being an inline pump mounted on the rear cross member. it a little loud any way, but never loud enough to hear over the exhaust even though I now can.

Might be a shot in the dark, but it happened to a friend here in TN. Check your intake for blockage. A buddies Jeep here sat all winter and a rats nest was built in the air box. It would start, but stall out and run like crap. I've also experienced a similar problem on a 4-cylinder car with a K/N air filter. Even though it was washable (and cleaned often), it was apparently clogged up pretty good. I could start the car, but had to keep my foot on the accelerator to keep it running. So, check the filter element as well.

I had the intake off when I changed the pressure regulator and saw no obstructions. I may need to clean the k and n filter though. It looks a little brown. I will let you know if it helps.

[CLBJeep]

Any updates on this?

Clint

[Pertneer]

Cleaning the air filter had absolutely no effect. I currently trying to locate a new fuel pump as the one that is in it is no longer sold or made as far as I can tell. It is not a stock unit and changing it too much may require running all new line.