98 Expy lacks power
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98 Expy lacks power
I have over 187k miles on my 90 Expy 5.4L 4x4. Over the last few months I was experiencing occational hesitation when taking off from a start when the fuel tank was less than 1/4 full. I measured the fuel pressure at the rail and was getting 31 PSI and 40 psi with the vacuum disconnected. Always started with first crank. I read TSB 00-20-01 which discribed my problem so I replaced the pump with a Ford pump and replaced all the hoses connecting to the tank since they were dry rotted. Fuel filter only has a few thousand on it.
Now, I have to build fuel pressure by cycling the key at least three times before the engine catches. I am also experiencing lack of power in all gears. I've driven it about ten miles to bleed any air out of the system but there is no improvement. Any suggestions?
Now, I have to build fuel pressure by cycling the key at least three times before the engine catches. I am also experiencing lack of power in all gears. I've driven it about ten miles to bleed any air out of the system but there is no improvement. Any suggestions?
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Thanks. I'll measure the pressure and check out the regulator when I get home tonight. I suspect you're right on the pump. I bought the Ford pump instead of a cheaper knock off, for the reliability...
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I attached the pressure gauge and read 0 PSI prior to cranking the engine. With one turn of the key, I'm only charging the rails with 5 PSI. At idle, I'm measuring 29 PSI. At partially open throttle, I max out at 31 PSI. With the vacuum disconnected, I get 39 PSI. Little drop in pressure after a hour with the engine off. I'll check the pressure regulator o-ring when I put the old pump back in tomorrow.
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Well, a few years ago I blew the #4 plug on my way back from PA to AZ on Thanksgiving. I managed to retread the plug back in enough and replace the COP and limped the rest of the way home. Once home, I installed Time-serts in all eight cylinders. A much easier job had I done it when I hand the heads off. So now I'm home pulling my tank again to swap out the new pump with the old one. I suspect Alloro is right that I got a bad pump. To add to the fun, when I installed the new pump, I drove it to the gas station and put in 28 gallons. I spent last night borrowing every gas can in the neighborhood. How's thing up north?
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From: Billings, Montana
I had that happen on my 99 a few years ago, so I had the insert done, then I blew that out, so I had to get a new head. It started having some other issues this summer that I didn't want or have time to deal with so I sold it and bought a brand new truck. Things are going pretty good up this way. Hope your problem is a simple fix. You got alloro helping you with it and he really knows his stuff, so I think you'll have it running like new in no time.
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I just finished putting the old pump in and its running fine. Somehow the float is stuck reading full. Not sure how I did that. Maybe God is feeling sorry for me and He's giving me infinite mileage. I can live with it until I get the replacement pump. I learned a few tricks that keep me from having to completely dropping the tank. It would have been nice to have used the Madsonp ramp! What type of inserts did you use on your 99?
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Joined: Dec 2005
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From: Billings, Montana
I just finished putting the old pump in and its running fine. Somehow the float is stuck reading full. Not sure how I did that. Maybe God is feeling sorry for me and He's giving me infinite mileage. I can live with it until I get the replacement pump. I learned a few tricks that keep me from having to completely dropping the tank. It would have been nice to have used the Madsonp ramp! What type of inserts did you use on your 99?
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