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Old 11-03-2009, 09:35 PM
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Warm stall re-visited and solved

Hey y'all. It appears that my warm stall issue is resolved. After the close of the nightmare thread, I went in and continued some diagnostic work trying to keep my focus on things that would have logically been affected by recent work done to the engine.

First I confirmed proper operation of both spark and MAF during the stall. They both checked out.

Next considering fuel delivery issues, I checked injector voltages at the ECU terminals, but didn't quite do it right. The FSM shows that the injector wires lead into 2 connectors...I checked the numbered terminals, but all on one connector. Anyway, the ones I had checked correctly were within spec, so I left it at that.

Still thinking it was fuel, I tried a new test to verify that. When the stall began to occur, I sprayed starter fluid into the intake via a vacuum tube hole. It prevented the stall for a few seconds. It would keep "not stalling" as long as I sprayed starter fluid. So, that was enough for me to focus on fuel.

At that point I really started to think about the issue I had about 6 months ago when it would crank but not start due to no fuel. What ended up "fixing" that issue was a new battery, but I didn't get to that point until I had checked basically every component in the fuel system circuit...relay, pump, fuses, modulator, resistor, etc.

Here's that thread...

Well, I decided to revisit all those components.

I immediately found that the resistor for the fuel pump modulator was unplugged. I have had no issues since re-connecting the resistor.

So, with that the issue is put to sleep. I apologize for wasting y'all's time with such a simple issue. I guess it goes to support the idea that diagnostics should focus on what has changed most recently. Thanks for all of your support throughout. This is the best forum on the net.
Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's will always be STi to me
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Old 11-03-2009, 10:49 PM
oab_au oab_au is offline
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Re: Warm stall re-visited and solved

Thanks for the results. That makes sense, when the ECU wants to cut back the fuel flow, it runs the pump through this resistor. As it is open the pump stops, you hit the throttle to stop it from stopping, .and the ECU turns the pump back to full, and it pumps again.
Good one to remember, thanks.

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Old 11-04-2009, 10:03 AM
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Re: Warm stall re-visited and solved

Excellent! Im glad you got it figured out, as I thought of every reason under the sun but couldnt help you nail it. Good work!

"A person convinced against their will, is of the same opinion still"

New?? Find the downloadable SVX Online Service Manual Here
RECOMMENDED READING for newer SVX owners Here some cool info if not fully accurate.
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Old 07-20-2018, 10:49 PM
SacSVX SacSVX is offline
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Re: Warm stall re-visited and solved


Almost a decade later I'm resurrecting this thread.

After reading all of SVX10's threads, I'm confident my stock 92 is experiencing the exact same stalling when warm issue.

I've ruled out the following components. MAF, cam sensor, and TPS. I have not checked the crank sensors but I'm not getting any codes.

Can anyone elaborate on where and how to access the Fuel Pump Moderator? My car is stock and I've never disassembled anything in the trunk so I doubt it can be unplugged like OP's scenario.

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