 when relay boards go bad.... |
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| type47 |
 Nov 21 2007, 04:06 PM
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#1
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Viermeister  Group: Members Posts: 4,254 Joined: 7-August 03 From: Vienna, VA Member No.: 994 Region Association: MidAtlantic Region  |
got a chance to do some work on the teener today. plans were to weld (IMG:style_emoticons/default/welder.gif) in a bung for an O2 sensor for LM-1. rod (root) was going to do some tig work on the bung. problems with car on the way to his shop. car quit twice. i carry a pressure gauge so i connected it on the cold start valve port and got zero pressure. simple i thought, bad fuel pump. even connected a voltmeter to the fuel pump power plug to verify voltage to the pump. however, didn't see that voltage was 12 mV not 12 V (where are my glasses...). long story short, i was able to get to rods shop and, third times a charm, bung got welded in (by the way, this may be a "DUH" to many but don't try to weld in the bung with the plug screwed into the bung, it'll just seize the plug. i/we didn't know any better). attempt to start the car to go home, no start. no pressure then we observe 12milliVolts at the pump connector. rod says all signs are pointing to a bad relay board and graciously lends me his relay board to get me home (IMG:style_emoticons/default/smilie_pokal.gif) so now my question is: how often/frequent do these fail and would like to hear some experiences about how the faulty board was discovered. it's hard for me to believe the board failed and i'm going to do some continuity tests on it. to me, all signs led to a bad fuel pump.
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| brp986s |
Nov 21 2007, 04:31 PM
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Member Group: Members Posts: 434 Joined: 27-September 07 From: los angeles Member No.: 8,167 |
I've heard of the boards going bad due to corrosion of the riveted electrical connections on the underside. But first I would pop out the pump fuse and clean the contacts, as well as swapping in a pump relay.
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| JeffBowlsby |
Nov 21 2007, 08:31 PM
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#3
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914 Wiring Harnesses & Beekeeper Group: Members Posts: 8,963 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None 
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QUOTE(brp986s @ Nov 21 2007, 02:31 PM)  But first I would pop out the pump fuse and clean the contacts, as well as swapping in a pump relay. There is no dedicated fuel pump fuse, only the 25A main fuse which is located at the aft fuseholder on the 914/4 regulator plate. Another thing to check is the AAR circuit, it is shared with the fuel pump. If the AAR wiring shorts out (especially check where the wire enters the AAR housing) , it can take the fuel pump circuit down too. |
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Posts in this topic
type47 when relay boards go bad.... Nov 21 2007, 04:06 PM
bperry The relay board is braindead simple that is why it... Nov 21 2007, 04:48 PM type47 i did the swapping of the fuel pump relay for a go... Nov 21 2007, 05:16 PM
Tom An ohmmeter is a good troubleshooting tool, but it... Nov 21 2007, 06:49 PM |
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