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84 3.2 DME / Fuel Pump On With Ignition On
Initial problem is no ignition from high tension side of coil.
- Yes, new DME relay - 12V+ and ground pins on harness all check OK - What is really odd is that fuel pump runs with ignition on and engine not turning (old fuel pump was bad too). Wiring for pump all looks stock. Car has sat for a few years and there is evidence of water in the interior. I have the DME apart, and it smells like something burned. The bottom of the pan underneath the DME also took a hit. I had to knock the pan back in place (yes DME was removed for that!). Why would the fuel pump run without the engine turning? This is sounding like a bad DME - that the DME is sending a false signal to run the fuel pump while the engine is not turning. Yes, I've read all I can on this here at Pelican. What I really want to do is ditch the entire thing! And go back the old way with carbs or run the Triumph ITB's and Megasquirt.
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Current: 914/6 GT Conversion, Cayman Old: Many PCars + Formula Racecars |
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12-05-2012, 05:23 PM
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The DME turns the fuel pump on thru the DME relay, and this relay output also powers the O2 sensor. On the DME, it's pin 20 IIRC - you can open up the DME and probe this pin to verify. Sounds like you may have a bad DME, either from trauma or water damage.
Chuck.H '89 TurboLookTarga, 342k miles |
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12-06-2012, 05:23 AM
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Thanks Chuck... I opened up the DME last night and a piece fell out - about a 1/4" thick piece of what looks like aluminum - 3/4" wide X ~1" tall with a small hole in the top. No idea...
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Current: 914/6 GT Conversion, Cayman Old: Many PCars + Formula Racecars |
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12-06-2012, 05:35 AM
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That's just a spacer to hold the PCB (printed circuit board) off the bottom aluminum plate. Do you see any components that have let their 'smoke' out?
You can separate the two boards by prying up gently at the back (near the ribbon cable) and then there are two tabs near the connector that will let the top board slide back. Keep yourself grounded (touch metal) so you don't build up any static electricity when working on the DME. Where in Connecticut? I used to live in Rye, near Greenwich... Chuck.H '89 TurboLookTarga, 342k miles |
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12-06-2012, 05:42 AM
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Diss Member
Join Date: Jul 2002
Location: SC - (Aiken in the 'other' SC)
Posts: 5,020
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A chunk of aluminum bouncing around the inside of a DME can't be good. I'd be surprised if it didn't short something out. Time to have the DME tested.
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- "Speed kills! How fast do you want to go?" - anon. - "If More is better then Too Much is just right!!!" - Mad Mac Durgeloh -- Wayne - 87 Carrera coupe -> The pooch. |
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12-06-2012, 06:19 AM
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Quote:
Chuck.H '89 TurboLookTarga, 342k miles |
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12-06-2012, 06:25 AM
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Ahh! I found where that piece goes. Thank you much. I did remove those screws to look at the bottom side, so that piece was NOT bouncing around inside.
No evidence of anything losing "smoke". Seems to be quite a bit of crud/dust/dirt though. I'm in northeast corner of CT - Scotland.
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Current: 914/6 GT Conversion, Cayman Old: Many PCars + Formula Racecars |
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12-06-2012, 07:42 AM
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2014 
