Fuel system problem?? Need help before I go nuts!!!
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Fuel system problem?? Need help before I go nuts!!!
I have had starting trouble for awhile now.. first I replaced the fuel pump it was fine for three weeks or so.. Glad it wasn't the injectors.. OK Problems back it would seem to be injectors vehicle does this when the key is turned on the fuel pressure hits forty then hits zero within 20 seconds or so.. But if you pinch the feed and yes I said feed line the line on the top side of the pump mount that goes to the left and is alone where-as the bottom return has a breather line which goes the other direction next to it... When you pinch off the feed line the pressure will hold?? I put different injectors in it last week and the same problem?? So I am on my second fuel pump AC DELCO and it's doing the same thing..? Would the position of the strainer on the pump cause a problem? I couldn't remember exactly how it was when I removed the pump. :mad :mad :mad :mad :confused: :confused: :confused:
[Modified by Ericthewolf, 12:53 PM 9/12/2002]
[Modified by Ericthewolf, 12:53 PM 9/12/2002]
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (65Z01)
No change fuel pressure drops like a rock still. But even with new injectors it did the same thing
[Modified by Ericthewolf, 1:22 PM 9/12/2002]
[Modified by Ericthewolf, 1:22 PM 9/12/2002]
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Fuel system problem?? Need help before I go nuts!!! (Ericthewolf)
So fuel pressure drops with either feed or return line clamped off.
With the feed line clamped I might suspect the FPR; with the return line clamped the FP check valve might be suspect.
With both lines clamped (first the return and then quickly the feed) it would be the injectors. In this case there should be a serious gasoline smell from the plenum and most plugs.
With the feed line clamped I might suspect the FPR; with the return line clamped the FP check valve might be suspect.
With both lines clamped (first the return and then quickly the feed) it would be the injectors. In this case there should be a serious gasoline smell from the plenum and most plugs.
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (65Z01)
No when feed side is clamped it stops dropping. return side clamped it doesn't slow a bit just keeps flowing till it hits zero.
Safety Car
Joined: Feb 2002
Posts: 4,212
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From: Sun City West Az
Re: Fuel system problem?? Need help before I go nuts!!! (Ericthewolf)
No when feed side is clamped it stops dropping. return side clamped it doesn't slow a bit just keeps flowing till it hits zero.
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (ittlfly)
That was my thoughts too I just didn't understand the workings of the fuel pump. Only problem is I put a new fuel pump in a month or so ago and today just replaced it with another ac delco pump yet I am still having the problem. I was thinking that If the FPR is stuck closed however that if the fuel pressure gets too high then the pump opens on the feed side and dumps it back to the tank.. But I am no mechanic.. I went out and got a FPR but it was 130 dollars and I don't want to install it if it isn't bad.. I am perplexed..
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Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (Ericthewolf)
http://autorepair.about.com/library/faqs/bl013a.htm I just read this post but what the hell cuz I just replaced the pump with a new one.
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Joined: Feb 2002
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From: Sun City West Az
Re: Fuel system problem?? Need help before I go nuts!!! (Ericthewolf)
You can check your FPR by : key on , engine off which pressurizes the system. Check the pressure, key off and it should hold. In your case, pinch off the feed line after key off and then apply 10-15" of vacuum to the FPR with a pump.(like what you bleed brakes with) The pressure should drop at that point as you are now simmulating idling. Fuel pressure should drop about 7-10 psi. (and it should hold there).. If so, then you FPR is probably OK.
[Modified by ittlfly, 7:55 PM 9/12/2002]
[Modified by ittlfly, 7:55 PM 9/12/2002]
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (ittlfly)
Well the GM mechanics told me it is either one of three things 1: pulse dampener is leaking ( so I replaced it) didn't solve the problem 2: pump check valve ... It's new so I am going to skip to three and see what happens then back up to pump. 3: a leak in the line under the connection on the sending unit... So I am going to extend the feed and return lines and the electrical connection so I can run the pump in a 5 gallon pail and see where the fuel is back flowing to finally diagnos the problem and stop the insanity.... :confused:
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 883
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From: Duluth MN
Re: Fuel system problem?? Need help before I go nuts!!! (ittlfly)
I am suspecting a pinhole in the metal fuel line on the fuel sending unit itself but we will see.. Plus the pumps I have been getting are coming from checker auto parts and The GM dealer has informed me that they recieve rebuilt units not new from AC Delco.. If it's the pump I will return and suck it up and spend the extra money to get it from the dealer..