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I suspect the fuel pump

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Old Apr 23, 2011 | 02:10 AM
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I suspect the fuel pump

My 82 has a 91 NA with a mild street port. I'm running a Haltech. Makes about 175-180hp at the wheels (dyno'd 167 at 5000 feet, now I'm at sea level). I had the 460 injectors on primaries and secondaries and was getting leaning at full throttle at about 6000 RPM (wideband confirmed). The injector duty cycle was about 80% at that point, so I thought I might be pegging the injectors. I replaced the secondaries with 550s. Made MAP corrections and I'm still having the same lean AFR problem at the same engine speed and full throttle. I assume now that it's the fuel pump. I'm using an Aeromotive 11109, which is supposed to be good for my meager hp levels, but I'm thinking that it must be the problem.

So my question, any suggestions for a good, reliable, quiet in-line fuel pump that will fit relatively well in the stock position? Something that won't have any problems with my HP level?
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Old Apr 23, 2011 | 12:01 PM
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From: https://www2.mazda.com/en/100th/
fuel filter ok?
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Old Apr 23, 2011 | 03:27 PM
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what pressures are you running and where is it compared to the maximum flow rating of that pump?
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Old Apr 23, 2011 | 06:30 PM
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Originally Posted by j9fd3s
fuel filter ok?
I'm pretty sure it is. Newly finished tank and the filter's less than 8k miles old.
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Old Apr 23, 2011 | 06:31 PM
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Originally Posted by diabolical1
what pressures are you running and where is it compared to the maximum flow rating of that pump?
Good questions. My fuel system is stock. I don't have an easy way to measure it.
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Old Apr 23, 2011 | 06:38 PM
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It turns out that both of the pumps that I tried are low on fuel delivery rate. Like 25-30% less than a GSL-SE pump and the same at pressure delivery. I'm going to try a new SE pump and see how it goes.
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Old Apr 24, 2011 | 03:34 PM
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How old is the pump?

Some of the big name pumps are really crappy in construction, like the pump vanes ride directly on aluminum and wear out quickly and fill your fuel system with aluminum particles. (Why do people think "billet aluminum" is a good idea? It's cheap and that's it)
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Old Apr 24, 2011 | 05:52 PM
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Any suggestions on the easiest way to prime the new pump? I may just use my little hand suction pump to try and pull gas through it.

http://www.druck-temperatur.de/bilder/hap02_75.jpg
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Old Apr 25, 2011 | 05:17 PM
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Originally Posted by purple82
It turns out that both of the pumps that I tried are low on fuel delivery rate. Like 25-30% less than a GSL-SE pump and the same at pressure delivery. I'm going to try a new SE pump and see how it goes.
sounds like a plan. when i was researching pumps for my brother's car, i actually concluded that for an N/A fuel injection project like this, the SE pump is one of the best choices. it's what i went with.
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Old May 1, 2011 | 12:22 PM
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The SE has a screwy banjo fitting at the inlet. Had to order one with the pulsation damper from Sam at Atlanta Rx-7. Should be here on Tuesday.
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Old May 10, 2011 | 12:03 AM
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-Unexpected project-

The fuel pump from an SE has a 1/2 to 3/4 inch long threaded end on high pressure side with a hole in the end. It takes a banjo fitting with a pulsation damper at the end pressing the fitting down onto the pump body. Fuel comes out of the pump, into the pulsation damper and then makes a 180 into the banjo fitting and then out.

The tubing makes (2) 90 degree turns as it comes out of the banjo fitting. First it turns towards the inlet side of the pump and then it turns outward away from the pump body.

In my set up, I only needed the fuel line to turn towards the inlet side to meet my fuel filter. Cutting the second bend was easy with a pipe cutter. Double-flaring this extra thick piece of tubing was not. The flaring tools that you can get from auto parts stores suck. I had to take it to a hot-rod shop to use their tool with heat.

After all the waiting for parts, backsteps and driving around to get all the parts together, it finally all went into the car. I primed the pump by pulling fuel through it with my hand pump.

Unfortunately, the problem persists. I'm going to start playing with my full throttle map now that I know I have pleny of fuel.
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Old May 14, 2011 | 09:10 PM
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Well, the full throttle map seemed to do the trick. No more bucking, just 200hp of growling acceleration! Love it when things work out!
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Old May 15, 2011 | 09:23 AM
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great news! it kinda sucks that you had to go through all of that, but in the end, you learned and that's never a bad thing.
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