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Fuel pump won't prime
Need help troubleshooting my 87 buick t-type. My car started just fine 6 days ago while installing me new carpet. Once carpet was put in, my car failed to start and I do not hear the fuel pump kick on which is in the tank. At the fuel rail, my pressure was zero so I pulled the fuel pump fuse and the fuse is fine. I then went to the fuel pump relay switch and when I inspected the prongs they were corroded with dirt and grime. After cleaning the prongs and connector, I checked the switch with my multimeter and determined there is no problem with the relay. When turning the key in the on position I still did not hear the pump prime the line, but I do now have fuel pressure reading around 40 at the fuel meter attached to the front of my fuel rail. If the fuel pump is bad why would I still have a fuel pressure reading of 40. Could this possibly be to a clogged fuel filter????? Any thoughts or feedback would be greatly appreciated!!!
Also, inside my car when the key is in the on position my scanmaster comes on and displays 2.1 then just goes out. I don't know why this happens but perhaps the car has to be running before all the information can be displayed. While trying to start, the oil pressure gauge will come on after a few seconds so I know the oil pressure switch in the car is working properly. Jamie Last edited by JAMIEPACURN; 12-15-2012 at 03:58 AM. Reason: forgot to add something |
#2
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Re: Fuel pump won't prime
***uPDATE**
After cleaning the fuel pump relay connections, the fuel pressure at the rail is reading about 15 now. Fuel pump still won't prime and car will not start!!! |
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Re: Fuel pump won't prime
Chances are that the carpet being disturbed is completely coincidental.
You can force the pump to run (on 86-87 cars) by shorting the open female BLACK electrical connector on the front driver's side of of the engine (behind the AC compressor) to 12V+. It may be possible to use the line for the hood light to power this. I have made a wire with an alligator clip on one end, and a male spade connector on the other end for just this purpose. If you pressure is so low, (a) the voltage to the pump may be low, especially if you don't have a 'hot wire" connected (b) the filter may be clogged (c) your gauge may not be accurate, or (d) the pump may be failing. And (d) is fairly likely. Each must be checked to determine the issue.
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Scott Keller - GNTTYPE Founder & Moderator
Last edited by Keller; 12-16-2012 at 05:54 AM. |
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Re: Fuel pump won't prime
Thank you Mr. Keller for your response. I'm pretty confident the fuel fuse is ok and the fuel pump relay is okay as well. I've owned my car for 2 years now and have never changed my fuel filter so that is the next thing I'm going to check before buying a new pump. Thank you for the advice concerning the wire trick. I will have to make that wire and will see if I can manually power up the pump from the 12volts from the alternator. I appreciate your feedback very much!
Jamie C. |
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Re: Fuel pump won't prime
Scott,
When I applied the alligator clip to the alternator and the male spade to the factory plug I do hear the pump making a continuous sound all most a constant humming sound and not the typical 2 second prime when I turn the key to the on position. I tried to start the car while the pump was making the constant sound but car still did not start. Fuel gauge at the rail was displaying 40. What are your thoughts on this????? I'm in the process of changing the fuel filter because I know that needs to be done regardless of the problem. |
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Re: Fuel pump won't prime
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There are three things to make an engine run: fuel, air, and spark. You have fuel pressure, but are the injectors being activated to spray into the cylinders? This can be checked with a "noid" light to see if the injectors are getting a firing signal. Do you have spark? You can use a test light or a spare plug in one of your plug wires to see if the plugs are firing, and you can see if you have a cam or crank signal as well. Do you have a scan tool? You can check for any errors, such as if your MAF sensor has failed. You can also unplug the MAF and try to run without it. The car will run very poorly, and the check engine light will be on. But this allows the car to go into a "limp home" mode since the MAF is presumed failed when the signal is not present. There is no clear singular answer. It is going to take some work and investigation.
__________________
Scott Keller - GNTTYPE Founder & Moderator
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Re: Fuel pump won't prime
I have a scan master but every time I turn the key on it will display "2.1" then the screen goes black so I can't check to see any numbers. Does the engine have to be running continously to see any data????? I guess I never really paid any attention so I'm not sure if that is a normal thing or not.
I changed my fuel filter and fuel pump relay switch now. I pulled spark plug from cylinder wall #1 and it is completely fouled due to me trying to give it a little boost of the pedal when trying to start the darn thing. However, even if the spark plug was fouled I should still hear the fuel pump prime the system for 2 seconds. At least that is what my common sense tells me but maybe I'm wrong. I will change the plug wires tonight and will test to see if there is a spark and I will try the MAF trick as well and let you know. At least I don't have to order a $100 pump right......lol |
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Re: Fuel pump won't prime
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Yes, the pump should prime at key on. Why are you changing the wires if you have fouled plugs?
__________________
Scott Keller - GNTTYPE Founder & Moderator
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Re: Fuel pump won't prime
It sounds like you have another issue and the fuel system is possibly a red herring. It sounds almost like the ECM is NOT powered or something. Do you see the Service Engine Soon light lit up with KEY ON / ENGINE OFF? It should be lit. If not, the ECM is dead/not powered.
Is there a kill switch somewhere in the orange wire to the ECM (up by the battery). Or is the orange wire disconnected or the goofy twist connector up by the battery bunged up or corroded?
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Ken Mosher 1987 GN original owner 650+ HP Black 2015 BMW 328xi XDrive wagon 2012 Volkswagen Tiguan (the Tig!) Night Blue Met (sold) 2006 Trailblazer SS Red Jewel Tint 395 HP AWD (sold) 2014 Silverado LTZ Crew 4WD 2012 Honda VFR 1200F Tahitian Blue (sold) 2015 BMW S1000R Racing Red 2013 Honda CBR500R Red (wife's bike) 2014 Triumph Bonneville T100 2003 Harley Davidson V Rod Anniversary Edition |
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Re: Fuel pump won't prime
Scott,
I originally stated I was changing the spark plug wires and what I meant to say is that I'm changing all the spark plugs........not the wires.....lol (Sorry 4 the error). Since the scan master should display data with the key on, I'm wondering if the ECM wires are all intact. Since I recently replaced my carpet I'm wondering if a wire got cut or is pinched perhaps. Tonight after changing the spark plugs, I will inspect all the wires going to the ECM to see if one got cut, pinched, or is loose. I'm now thinking this an electrical issue which would explain why the fuel pump is not priming as well as the scan master not working properly. Thanks for steering me in the right direction. Jamie |
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