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> power to fuel pump, intermitent
jimkelly
post Jul 5 2009, 09:34 AM
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yesterday i wasn't sure if my fuel pump was getting power - or if my injestors were getting fuel - so i removed my injectors and my spark plugs - put my injectors into yogurt cups and turn the engine but no fuel.

i pulled my stock front mounted fuel pump and it did not make any noises when i turned the key. so i hooked up a volt meter to the fuel pump power wire - i was getting power - so i assumed my pump was bad.

this morning i go out to the car and turn the key and the pump runs - so i turn over the engine some to see how fuel is going thru my injectors into the cups - they all spurt fuel - so i put the injectors back in and the plgs back in - and then - bam - the fuel pump is not getting power again??

i swapped out several reays - no success?

http://www.youtube.com/watch?v=PrLcva9o8LA
http://www.youtube.com/watch?v=8pipbKl_ZQU
http://www.youtube.com/watch?v=bOAhJ9OZpm4
http://www.youtube.com/watch?v=9gMp0eoXvYc


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anderssj
post Jul 5 2009, 09:45 AM
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Jim,

I had a similar problem some time back--turned out to be an "old" fuse on the relay board. The fuse's ends had gotten kind of crappy, and it only made an intermittent connection. Just a thought . . . .

Best,
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jimkelly
post Jul 5 2009, 10:04 AM
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i scuffed up the fuse ends a little biyt - no change.

i jumped the fuse with a piece of wire and some aligator clips - no change.

jim : (


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ejm
post Jul 5 2009, 10:50 AM
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QUOTE
so i hooked up a volt meter to the fuel pump power wire - i was getting power - so i assumed my pump was bad.


How did you ground the meter? Checking across the pump terminals would verify power and ground is at the pump. The factory ground terminal can be reached thru the pump opening. They are often corroded and can cause intermittant pump operation.
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jimkelly
post Jul 5 2009, 11:07 AM
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here is how i got my crappy meter hooked up - just plugged into the two wires that run the pump. i do not think this style pump has a ground?


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70Sixter
post Jul 6 2009, 03:30 PM
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Delete please.
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70Sixter
post Jul 6 2009, 03:31 PM
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I do not know anything about high pressure FI pumps. But my carb'd 70 911 had an intermittent fuel pump problem I went crazy diagnosing.

Finally through money at the problem and tore old pump apart after replacement with new one.

The rubber gasket between the electric side and the pumping side had deteriorated and gas would eventually flood out the electrical side killing the power.
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yellow914
post Jul 7 2009, 06:42 PM
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what is it with the friggin fuel pumps lately!!! (IMG:style_emoticons/default/mad.gif) I still have the same issue. It runs then it won't...Ghost in the machine or one of those martian thingy-ies from war of the worlds keeps passing by my house...
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buhs914
post Jul 7 2009, 10:11 PM
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well my fuel pump had issues like that before and all it needed was a new connection at the ignition coil. the wire was barely sitting in it causing it to lose power ALOT lol. i just cut the wire and put in a new connector.. my fuel pump is different from the ones in the pics though.
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swl
post Jul 7 2009, 10:22 PM
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jim if you are getting reliable 12v at the pump then the pump has to be having issues. Do a search for fuel pump brushes. There was a thread maybe a year ago where the intermittent had to do with the brushes sticking. Try giving the pump a bit of a whack with a hammer. That can help the springs push the brushes back into contact with the armature.
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buhs914
post Jul 8 2009, 12:58 AM
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Hey if your pump is screwed then i have a 12v fuel pump that used to be on my car. It's not stock but It works well, i just recently tested it. Here are some pics:

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if you want it just let me know, i'll probably just give it to you or whatever.
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underthetire
post Jul 8 2009, 10:20 AM
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The above pump won't work. Low pressure pump for carbs.

I have had multiple problems just like yours. First one, cracked fuse on the relay board and tarnished terminals that hold the fuse. A quick shot of WD40 and scotch bright with a new fuse fixed that.

Relay pins were causing an intermittent problem in the socket. They have a little slot cut in the pins you can spread them with a small minus driver ( slotted screwdriver).

Third was the cable to the pump, being under the car it turned green after so many years it would not carry enough current.
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buhs914
post Jul 8 2009, 07:26 PM
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ah my bad i forgot i had a carb lol
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