2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Rebuild question

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Old Jul 8, 2009 | 06:32 PM
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CA Rebuild question

REbuild a s4 engine.Stock ecu i have upgraded the injectors to 550 cc and also the fuel pump is a Walbro 550HP 255LPH In-tank EFI HP fuel pump - Mazda RX7 86-88 Direct Fit. So could the reason it is not starting due to way too much fuel or does that not matter?
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Old Jul 8, 2009 | 06:43 PM
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Originally Posted by knivesm
REbuild a s4 engine.Stock ecu i have upgraded the injectors to 550 cc and also the fuel pump is a Walbro 550HP 255LPH In-tank EFI HP fuel pump - Mazda RX7 86-88 Direct Fit. So could the reason it is not starting due to way too much fuel or does that not matter?
I don't think it would cause it to not start, but it will probably run like ****. Maybe it did end up flooding itself out?
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Old Jul 8, 2009 | 07:00 PM
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is this on an NA or TII?
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Old Jul 8, 2009 | 07:03 PM
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CA

Sorry it is a Na and the stock ecu is a na s4 which the ecu is for 460 cc fuel injectors.
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Old Jul 8, 2009 | 07:07 PM
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Is this rebuild on used housings? If so I would venture to guess a lot of extra fuel and low compression are the culprits. Have you tried deflooding and possibly a pull start? May need to at least temp. wire in a fuel pump kill switch until the engine build compression.

Already verified the standard issue items like CAS timing and TPS settings?
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Old Jul 8, 2009 | 07:11 PM
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Dude, you cant run a walboro fuel pump and 550 cc injectors without running stupid rich and flooding. The na run rich to being with
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Old Jul 8, 2009 | 07:16 PM
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yes did the cas. How do i set up tps? May need to at least temp. Wat u mean by that?
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Old Jul 8, 2009 | 07:21 PM
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Originally Posted by knivesm
yes did the cas. How do i set up tps? May need to at least temp. Wat u mean by that?
i thought in order to setup tps the car has to be running?
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Old Jul 8, 2009 | 07:55 PM
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take the 550cc out and put back the stock injectors(NAs dont need that much fuel)and wire a fuel pump kill switch,turn the fuel off while cranking as soon as it start turn the pump on.
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Old Jul 8, 2009 | 07:59 PM
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From: CALIFORNIA
k i am going to put back the stock injectors and stock fuel pump and see if it turns on thxs all for help
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Old Jul 8, 2009 | 08:00 PM
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Originally Posted by knivesm
yes did the cas. How do i set up tps? May need to at least temp. Wat u mean by that?
Sry I was being lazy temp. = temporarily

Is this rebuild with used housings?
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Old Jul 8, 2009 | 09:50 PM
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yea you basically screwed yourself. you don't need 550 injectors or an upgraded pump. and joeyrylech is right add a fuel pump cut off switch, that helps a lot with rebuilds.
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Old Jul 8, 2009 | 11:55 PM
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From: cold
walbro 255 on an n/a is just overkill. it will have a rich idle and not result in any performance increase.
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