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

Fuel pump question

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Old Aug 8, 2011 | 02:57 PM
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Fuel pump question

Well I have a stock s4tII with a stock jdm tII motor. I installed a walboro 255 but it continues flooding (stock ecu ) do I need to install a fuel regulator?

Thank you guys once again
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Old Aug 8, 2011 | 03:04 PM
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Well you probAbly made your flooding issue worse by installing the pump, as it allows for more flow to the engine. Go back to stock, reduce your fuel ratio, and you should be fine. Theres a little black box by the stock airbox with an empty cylinder next to it that you can fit a small flat head into and itll have markings on the rearward side that have a double sided arrow and an L and an R (lean and rich). Just turn it a little more towards to the lean and it'll "aid" in preventing flooding.
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Old Aug 8, 2011 | 05:00 PM
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Ok thanks... I will need to look for a stock pump.

But a fuel regulator wouldn't fix that issue either?
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Old Aug 8, 2011 | 05:17 PM
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The variable resistor has no effect on start up fuel. It only affects idle mixture. To reduce the amount of fuel delivered during cranking you need a programmable ECU or standalone EMS.

An FPR would allow you to bring fuel pressure back down to stock levels (~38-40 psi with no pressure/vacuum applied), but it won't prevent flooding if you had it before upgrading the pump.

Another possibility is leaky injectors, which could be fixed by getting them serviced.
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Old Aug 8, 2011 | 05:36 PM
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Ok kewl... Well I will look for a stock fuel pump then.
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Old Aug 8, 2011 | 09:40 PM
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+1 on leaky injectors. if you dont need your car for about a week. Send them to witchhunter and have them cleaned. I have a walbro and it hasnt caused flooding. (usdm). probably leaky injectors though
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Old Aug 8, 2011 | 11:48 PM
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get the injectors serviced, going back to a stock fuel pump will lower fuel pressure at idle (on the stock regulator) but it probably won't solve a flooding problem
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Old Aug 9, 2011 | 01:41 AM
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Originally Posted by RotaryRocket88
The variable resistor has no effect on start up fuel. It only affects idle mixture. To reduce the amount of fuel delivered during cranking you need a programmable ECU or standalone EMS.
Ah thanks for the heads up! We learn something new every day... also, i noticed it had an effect on my emissions output (I have to pass in my county ), i turned it to near enough full lean just to try and get the damn thing to pass and it did lower my hydrocarbons down about ten points... not meaning to thread jack, but why would that be if it only affects idle mixture? Remember that my car has to be dyno tested for its age group.
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Old Aug 9, 2011 | 07:28 AM
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Ok thanks guys I will look into the injectors of the rx7 as always I greatly appreciate the info and the help. I'd it wasn't for you guys I don't think my car would be running at all...
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Old Aug 9, 2011 | 12:34 PM
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Here's a thread that goes into detail about the amount of cranking fuel relative to water temperature: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/looking-car-has-hot-start-problems-499744/.

Originally Posted by REAmemiya_fan
Ah thanks for the heads up! We learn something new every day... also, i noticed it had an effect on my emissions output (I have to pass in my county ), i turned it to near enough full lean just to try and get the damn thing to pass and it did lower my hydrocarbons down about ten points... not meaning to thread jack, but why would that be if it only affects idle mixture? Remember that my car has to be dyno tested for its age group.
Probably just differences between runs. In the past, I've had my car fail a 15/25 mph test, but then pass on a 2nd try. Nothing changed between the runs.
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Old Aug 9, 2011 | 02:34 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by RotaryRocket88
Here's a thread that goes into detail about the amount of cranking fuel relative to water temperature: https://www.rx7club.com/showthread.php?t=499744.



Probably just differences between runs. In the past, I've had my car fail a 15/25 mph test, but then pass on a 2nd try. Nothing changed between the runs.
yes, cat temp has a HUGE impact. driver technique does too, sudden changes in throttle position = higher emissions, a GOOD smog guy can actually drive the car better to pass.

its been forever since i messed with the idle mixture, it does matter, but we don't test @idle in CA
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Old Aug 9, 2011 | 02:45 PM
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^ That would be my guess. The guy I go to for smog tests will do a quick trial run on my car before doing the official test. He also does a good job of letting the car run for awhile to heat the cat up.
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Old Aug 9, 2011 | 03:40 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by RotaryRocket88
^ That would be my guess. The guy I go to for smog tests will do a quick trial run on my car before doing the official test. He also does a good job of letting the car run for awhile to heat the cat up.
we don't turn it off!

funny story. i bought a 79 Rx7, with a THERMAL reactor. i have a foggy notion of how this thing works, but i just set the idle mixture with my nose, and it seemed ok. i drove it over to the smog place on the freeway, i got it HOT, we pretested it, and it passed with flying colors. he shut it off for 30 seconds while the somg machine dialed up the DMV (yes, dial up), and then restarted it to do the test and it almost failed....

the THERMAL reactor needs to be HOT! it is appropriately named
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