Power surges after 2500 rpm

10639 Views 27 Replies 6 Participants Last post by 1dieselman, Mar 9, 2009

Plywood

Discussion Starter · Dec 31, 2008

Well, I did a search and I can't find anything that is the same as my problem.

What happens is, at 2500 rpm, if I increase the throttle there is less acceleration than there should be, then at maybe about 2600 rpm, the truck will surge up to about 3000 rpm without a change in the throttle.

Seems like it happens only when the truck is warm, and maybe been on the highway for a while, but I also don't rev it that high when cold so I am not 100% sure of that.

I am guessing the IP or lift pump, but IP is the only thing that makes sense to me.

Has anyone experienced the same thing or have any ideas?

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WhiteGardens

· #3 · Jan 1, 2009

I posted about this problem in the 6.9 forum. "what does air do to IP"

Whenever I run a tank out I get air intrusion and the truck wants to take off like it's on crack.

The only other time I've had the same symptoms was when I had the steel line, running from firewall around the block to the lift pump, rot away and I was getting air through it.

Could be that you have a fuel line that is letting air in and doesn't present a problem until you get the lift pump moving fast enough to suck air.

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WhiteGardens

· #9 · Jan 7, 2009

I still think you have a leaky section in the fuel system between the selector valve to the lift pump.

It's not to big of a deal to replace it, so you might want to think about doing it.

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WhiteGardens

· #13 · Jan 9, 2009

Plywood said:
No I haven't.
Right now I am trying to decide what electric fuel pump to use.
I picked up some clear line, but it was 1/4 inch, and I looks like I need 3/16 which I haven't found yet.

You could rig up a little section of clear hose and just put in short sections to just see what part of the system is getting air intrusion.

Also, use a braided clear hose.

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WhiteGardens

· #22 · Feb 23, 2009

Dang, I was hoping it was going to be a simple fix.

What about your CDR valve, is it bad and sucking excessive oil in the intake ??

One thing to try is when it's hot, and your having the problem, try shutting the truck off, and pouring water on the ip to cool it down.

If you start the truck up and it runs better then potentially your IP is bad.

Someone chime in if I'm wrong on this technique.

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WhiteGardens

· #24 · Feb 23, 2009 (Edited)

1dieselman said:
NOOOO don't do that if you poor cold water on a hot pump you will ruin it.

I've always heard that you can use room temp water to do it and you're OK. Maybe I'm completely wrong though.

Here's one of the many debates on the topic

http://www.thedieselstop.com/forums/f30/ford-7-3l-idi-hard-start-when-warm-180133/ .

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