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checked FPR, now won't idle at all


hiljak

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I was having a random "shudder" while idling in my 99 STS and have been trying to track it down. I replaced the plug wires and checked the plugs which appeared fine. I drove the car all day today (after chaning the plugs yesterday) and the shudder was still there. I decided to clean the throttle blade and check the FPR. I cleaned the throttle blade (wasn't very dirty at all) and reassebled the airbox. I then removed the clip that holds the FPR together to inspect. There is a black plastic washer and a green o-ring, both of which appear fine. After reinstalling the FPR, the car barley wants to start and WILL NOT idle unless I hit the gas. No codes except for the obious near stall or miss code. Also when the car dies, I hear a vaccuum hiss. I checked all visible vacuum lines and all appear fine.

Could the FPR be damaged from simply removing the clip? i was thinking maybe the ISC motor (had that give me problems on my 95) but I don't think this car has one. Someone help me please.

James

1999 STS 65k

1995 STS 127k

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I took the FPR back apart and noticed that the metal screen has a rupture in it (part of the screen is seperated from the plastic). could this be cuasing the problem? Seems like gas could pass through the screen anyway.

Guess I will buy a fuel pressure guage tomorrow. If anyone has had this problem, please reply. Thanks.

James

1999 STS 65k

1995 STS 127k

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Well, when I force he car to keep running by holding the gas, it seems like its being "held back", maybe starved for gas? At first I thought maybe the air box was restricting air somehow, but I removed the airbox completely and got the same results. I also noticed that while its running, the car smokes white smoke (not real thick) and smells of pure gas. I think it is either a fuel injector, foulded plug, or the FPR. Since it started right after I took apart the FPR, I will replace it first.

This sucks.

James

1999 STS 65k

1995 STS 127k

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Yeah, check the FPR. GM sells a rebuild kit. Use the search feature to find the part number. I remember posting it a few months back, but don't remember the part number off hand.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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I'm going to pull the one from my 95 STS and see if that solves it before I buy a new one for $70.00. When pulling the fuel rail to check for leaking injectors, do you have to let the pressure out of the fuel system first? Also, will they spray gass all over the engine?

Also, one other syptom is that even after I let the fuel pump run a few times, I get next to no fuel out of the schrader valve, just a little drips out. Shouldn't fuel spray out like its under 50 lbs of pressure?

And one last thing, I stubled across the post by Shaiden Kai about the hydrolocked engine as the result of spraying fluid into the throttle bore. I praying to god this is not what happened to me. The engine wouldn't run at all if this was the case though, right?

James

1999 STS 65k

1995 STS 127k

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I'm going to pull the one from my 95 STS and see if that solves it before I buy a new one for $70.00.  When pulling the fuel rail to check for leaking injectors, do you have to let the pressure out of the fuel system first?  Also, will they spray gass all over the engine?

Also, one other syptom is that even after I let the fuel pump run a few times, I get next to no fuel out of the schrader valve, just a little drips out.  Shouldn't fuel spray out like its under 50 lbs of pressure? 

And one last thing, I stubled across the post by Shaiden Kai about the hydrolocked engine as the result of spraying fluid into the throttle bore.  I praying to god this is not what happened to me.  The engine wouldn't run at all if this was the case though, right?

First of all, you checked the FPR wrong and may have damaged the seal replacing it. All you have to do is remove the vacuum hose from it and look for fuel leaking from the nipple. If there is fuel present it needs to be replaced.

When checking for leaky injectors you do not want to depressurize the fuel system. Just lift the rail with the injectors still on it and energize the fuel system by turning the key on. The fuel pump will run for about 2-3 seconds and pressurize the system. The injectors should not leak or spray. They will spray if you start to crank the engine.

If you press the button on the schreader valve after turning the key on, yes, you should get a strong spray of fuel. As you said it is under about 46 PSI. However since you are getting white smoke from the tail pipe (you could probably ignite it with a flame) your system may be bleeding down very fast.

If you engine was hydrolocked it would not run or even turn over for that matter. Hydrolocking is filling one or more cylinders with liquid. Since liquid is not compressable, that piston "runs up against a brick wall" so to speak and the engine locks up.

It sounds like your problem is self inflickted. Take another look at that FPR. Pay close attention to the O ring condition and seating. Also look for fuel from the nipple. If any is present it is going straight into the manifold unmetered and will cause a rich condition.

Let us know how you make out.

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One thing you said got my attention, you said, "Also when the car dies, I hear a vaccuum hiss. I checked all visible vacuum lines and all appear fine". Have you looked under the hood while its running to see if you can hear the hiss? It sounds like you have a large vacuum leak. See if you knocked the vacuum hose off the brake booster or broke the fitting, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Wow, I fixed the problem. I feel like such a moron for not noticing it last night. Well, it turned out to be a wire piched between the bolt on plastic houseing (thing with the screen on it) and the throttle body. It was ground the wire out which must have something to do with the idle control. fixed the wire and now it stays running fine. I still have the "shudder" though, and after driving it a few times, it takes a few more seconds to start (never did that before).

Thanks to everyone that replied. :lol:

James

1999 STS 65k

1995 STS 127k

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Wow, I fixed the problem. I feel like such a moron for not noticing it last night. Well, it turned out to be a wire piched between the bolt on plastic houseing (thing with the screen on it) and the throttle body. It was ground the wire out which must have something to do with the idle control. fixed the wire and now it stays running fine. I still have the "shudder" though, and after driving it a few times, it takes a few more seconds to start (never did that before).

Thanks to everyone that replied. :lol:

I would still recommend that you repair/replace the FPR since the screen is torn. Also, you might have lost the lower o-ring and that will make the engine run rich.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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