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edsfine
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Post subject: 84 cabby not running, vacuum?  Posted: Sat Feb 06, 2010 4:08 pm |
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Joined: Mon Jan 25, 2010 1:34 am
Posts: 4
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Just picked up 84 cabby, starts, runs for 5 seconds or so and stalls. If I give it gas it stalls even faster {New fuel pump and filter} If i prop open the air flow sensor plate just a half a mm or so it stays running. Plate in proper position and moves smoothly no binding. Thinking that I have low pressure or vacuum issue that is not enough to draw the plate up and uncover any or more metering ports. No fuel comes out my injectors while cranking or running unless the plate is propped open, for the 5 seconds that it does run it is only running off the cold start valve injector fuel. Any known vacuum leak locations ? Can there be any vacuum leaks internally ie inside the intake manifold? can not find any leaks yet, am I on the right track, or way off? seems to idle well with plate propped open. Help if you can please? Thank You!
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Briano1234
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Post subject: Re: 84 cabby not running, vacuum? Posted: Sat Feb 06, 2010 8:30 pm |
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| Whats that smell? |
Joined: Mon Mar 21, 2005 6:45 am
Posts: 2314
Location: Duluth, Ga
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edsfine wrote: Just picked up 84 cabby, starts, runs for 5 seconds or so and stalls. If I give it gas it stalls even faster {New fuel pump and filter} If i prop open the air flow sensor plate just a half a mm or so it stays running. Plate in proper position and moves smoothly no binding. Thinking that I have low pressure or vacuum issue that is not enough to draw the plate up and uncover any or more metering ports. No fuel comes out my injectors while cranking or running unless the plate is propped open, for the 5 seconds that it does run it is only running off the cold start valve injector fuel. Any known vacuum leak locations ? Can there be any vacuum leaks internally ie inside the intake manifold? can not find any leaks yet, am I on the right track, or way off? seems to idle well with plate propped open. Help if you can please? Thank You! Don't over look that your main crank timing gear may have sheared....
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Briano
Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
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gull
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Feb 09, 2010 2:21 am |
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Joined: Sun Feb 19, 2006 7:30 pm
Posts: 604
Location: Auburn, WA
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edsfine wrote: Any known vacuum leak locations ? Can there be any vacuum leaks internally ie inside the intake manifold? can not find any leaks yet, am I on the right track, or way off? seems to idle well with plate propped open. Help if you can please? Thank You! You're obviously running very lean. A massive vacuum leak could certainly cause that. Look for a hose knocked off somewhere (brake booster?) Sometimes I'll disconnect and plug or pinch off whole sections of the vacuum system when I'm testing for leaks, just as a process of elimination thing. Don't overlook the accordion boot, sometimes cracks and splits happen in the grooves. How about the frequency valve in the fuel distributor? Is it buzzing? If it's stuck or otherwise not operating your mixture will be way off. Wouldn't hurt to check the control pressure, either, maybe it's wrong and that's throwing off the mixture. _________________ 
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sixsracing
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Post subject: Re: 84 cabby not running, vacuum? Posted: Mon Mar 01, 2010 7:42 am |
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| Forum Niceguy |
Joined: Mon Jan 19, 2004 4:14 pm
Posts: 1080
Location: Bangor, Maine
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I'm with Gull here. Frequency valve inop. will give you exactly these symptoms. Located on the backside of the airbox. Small Bosch style plug. Check with key on for vibrations/buzzing from the valve. If it is, move on. If it isn't then pull the plug and check for power, should be at least battery voltage give or take .02 volts or so. If you have battery voltage you have a bad valve. If you don't have battery voltage you most likely have a bad relay. Let us know and good luck.
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90 Cabriolet, red w/white
97 Jetta, dark green (oldest daughter)
97 Golf, black (youngest daughter)
98 Beetle, red
94 Cabrio, dark green
New Beetle convertible very soon
Cogito Ergo Zoom
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edsfine
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Post subject: Re: 84 cabby not running, vacuum? Posted: Mon Mar 01, 2010 11:53 pm |
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Joined: Mon Jan 25, 2010 1:34 am
Posts: 4
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OK Guys, I appear to have 0 voltage going to the frequency valve, does anyone know which relay operates it. I think you guys may have nailed this one Thank you so much, I will keep trying to find a diagram for the relay location and cross my fingers that this is it! Thank You!
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gull
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 12:15 am |
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Joined: Sun Feb 19, 2006 7:30 pm
Posts: 604
Location: Auburn, WA
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sixsracing
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 12:22 am |
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| Forum Niceguy |
Joined: Mon Jan 19, 2004 4:14 pm
Posts: 1080
Location: Bangor, Maine
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Fuel supply relay, not to be confused with the Fuel pump relay. Different altogether.
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90 Cabriolet, red w/white
97 Jetta, dark green (oldest daughter)
97 Golf, black (youngest daughter)
98 Beetle, red
94 Cabrio, dark green
New Beetle convertible very soon
Cogito Ergo Zoom
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gull
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 12:26 am |
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Joined: Sun Feb 19, 2006 7:30 pm
Posts: 604
Location: Auburn, WA
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EDIT: Just remembered...this relay won't turn on with the engine not running, because the fuel pump relay turns off for safety reasons if it doesn't see any ignition pulses, and this relay is powered off the fuel pump relay. So seeing zero volts may be normal, depending on how you did the test.
You can either remove the fuel pump relay and replace it with a jumper; or you can listen under the hood while someone cranks the engine. You should hear the frequency valve buzz for a second or two after they let go of the key, before the fuel pump relay shuts off again. It's fairly loud with the hood open.
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edsfine
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 1:44 am |
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Joined: Mon Jan 25, 2010 1:34 am
Posts: 4
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I hear no buzzing well cranking and have 0 volts well cranking, thank you very much for the diagram, I pulled the relay and will replace and see. Ed
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Briano1234
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 7:30 am |
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Joined: Mon Mar 21, 2005 6:45 am
Posts: 2314
Location: Duluth, Ga
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gull wrote: EDIT: Just remembered...this relay won't turn on with the engine not running, because the fuel pump relay turns off for safety reasons if it doesn't see any ignition pulses, and this relay is powered off the fuel pump relay. So seeing zero volts may be normal, depending on how you did the test.
You can either remove the fuel pump relay and replace it with a jumper; or you can listen under the hood while someone cranks the engine. You should hear the frequency valve buzz for a second or two after they let go of the key, before the fuel pump relay shuts off again. It's fairly loud with the hood open. The fuel pump relay actually pulses on and off via a signal off the hall generator.
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Briano
Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
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gull
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 1:46 pm |
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Joined: Sun Feb 19, 2006 7:30 pm
Posts: 604
Location: Auburn, WA
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edsfine wrote: I hear no buzzing well cranking and have 0 volts well cranking, thank you very much for the diagram, I pulled the relay and will replace and see. Ed OK, Ed, let us know how it goes. _________________
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edsfine
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 9:39 pm |
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Joined: Mon Jan 25, 2010 1:34 am
Posts: 4
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Well, Gentlemen it was not the relay, but it was the frequency valve wiring connector! It seems that the PO pulled on the wires and not the plug, and pulled the the contacts into the plug boot so they would would not make contact with the valve blade connectors. You have all been a great help, Thank you, Cheers! ED
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gull
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Post subject: Re: 84 cabby not running, vacuum? Posted: Tue Mar 02, 2010 9:42 pm |
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Joined: Sun Feb 19, 2006 7:30 pm
Posts: 604
Location: Auburn, WA
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Glad to hear you figured it out!
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