Pressure problem

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  #1  
Old 12-06-07, 06:44 PM
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pressure problem

hey i have a 99 surburban i just change the fuel pump and the fuel filter in it. Now i have a problem with the gas pressure. i can go about 50-70 miles per hour for about 5 to 10 min. then the car get to jerking alittle bit then the pressure drop down to maybe 10-15 mile per hour even if i start the car up and wait about 5 to 10 min. And press the gas while it still in park i still have that problem with the pressure but it never shut off. I was wondering what might be the problem. Now when i cut the car off wait about 10 to 15 second and start the car up i can go about 50 to 70 again then back to the same problem.
 
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  #2  
Old 12-06-07, 07:10 PM
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Were you having the same problem before you changed the pump and filter?
 
  #3  
Old 12-08-07, 05:57 PM
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pressure problem

yes but not as bad as it is now.
 
  #4  
Old 12-08-07, 06:03 PM
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You're referring to the pressure. Have you checked the fuel rail pressure? Is that why you replaced the fuel pump?
 
  #5  
Old 12-13-07, 04:31 PM
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pressure problem

no! I change the fuel pump because the car wouldn't start
 
  #6  
Old 12-13-07, 04:37 PM
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Originally Posted by gamer4life313 View Post
yes but not as bad as it is now.
some people say i might need a tune up i never got one on the car.
 
  #7  
Old 12-13-07, 04:44 PM
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Did you change the fuel pump and filter yourself or did you have a garage do it?

I am wondering if since it got worse after the work, that debris got past the filter, or due to the fiddling, some chunk broke loose from in the line and made it's way to the rail and is now floating around somewhere up there.
 
  #8  
Old 12-14-07, 05:17 PM
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pressure problem

how do i check the rail to see if any debris in there and how to clean or get it out. Will that make the car lose pressure. i can ride for a lenght of time maybe 3 to 5 miles before it start acting up. then i have to turn the car off for about 10 second then start it up then i ok for another 3 to 5 miles.
 
  #9  
Old 12-14-07, 05:57 PM
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Your problem almost mimmicks that of when junk is in a gas tank and the debris or rag (as a practical joke by someone) gets sucked to the pickup screen in the tank and chokes off the supply until the car quits. Then when the car quits, the debris or rag settles away again allowing the person to start the car and go for a while again before it gets sucked to the screen again. Ad infinitum.

Or when a car has a rubber fuel hose off the bottom of the tank that would collapse from the draw of an engine-mount fuel pump (not your problem). Then after the car shuts off, the hose relaxes and you can start the car and run it for a bit again, til it collapses again, (Had car of mine do that in the 70's)

Or the same symptom if the evaporative loss system in the car is making it so you start pulling a vacuum, where air cannot get into the tank to allow gas to be pushed from the tank to the engine (you'd know this if you opened your gas tank cap cover after it shuts off and get a big whoosh rush of air trying to get into where you fill the gas.) (I'm not sure if this is a realistic malady on today's cars or not)

Your problem is like these, except with you, MAYBE (just theory on my part), if you have none of those problems, you have something similar flowing around in front of injectors or in the line. The coincidence of how your problem surfaced after you changed filters seems to point towards this possibility, IMO.

Perhaps a fuel pressure device if left on the car while running could catch a pressure shutdown in the act.

Will your problem do this if you don't drive it but just let it idle in the driveway for say 1/2 hour if need be, and see if it starves out then?

Open for other opinions.
 
  #10  
Old 12-15-07, 04:01 AM
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Couple questions. Why was the pump replaced? Did you use a factory pump? If I remember correctly, the fuel tank is in the rear on that vehicle. I think those are the ones that the baffles in the tank would break free and slosh around the tank, destroying the tank/sending unit assemblies. Did you happen to look into the tank to verify the state of the baffle?
 
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