Fuel Pump issue
Apr 3, 2009, 05:59 AM
#1
Fuel Pump issue
I took my car to get it custom tuned and both times they were unable to perform the tune because the car was running lean. Later it was discovered the the fuel pump did not change voltage under full load. The pump stays at 9 volts when it should kick up higher. Has anyone run into this problem at all or is just me? Also, I tried to locate the fuel pump relay but no luck, the relays under the hood aren't labeled. I would like to start out cheap and replace the relay if that is the issue. I just can't find the relay. I tried searching for the Mitsu tech manual but all the links are dead? 
this is killing me..I am back on my factory map..and I can't enjoy the mods on the car :-(
this is killing me..I am back on my factory map..and I can't enjoy the mods on the car :-(
Apr 3, 2009, 01:24 PM
#5
Well, I plan to upgrade the pump to the walbro kit that UR is selling...I talked with them today. So regardless that stock pump will be outta there. I am hoping it is as simple as a relay. I can't think of anything else that controls the fuel pump voltage. So I called up mitsu and the relay is 50 bucks. I will try changing that but it will take a week for it to come in. Yes, I agree..changing the pump won't solve the voltage issue..if it fails it fails right? I don't want to have to take off all that stuff I have on the car off just to take it to the dealer..it would suck ***** and let's face it, the dealer will just start replacing stuff left and right. So, I might as well start with the relay, if that doesn't work, then I will just take it back to AMS. I trust them more so than the dealer. I just think that I can save the techs there alot of work if I tell them what I've change and looked at, they have service manuals..I don't..lol. Feel free to keep the suggestions coming..
Apr 3, 2009, 01:31 PM
#7
maybe you can explain your diagnostics process, so you can be given better advice.
I only said to upgrade, because I assumed that the voltage you described as 9 volts is from the pump itself. I would assume that you're getting the full 12volts before the pump? Yes, it can be the relay and that should be changed if faulty. But also check the wiring and ground as these are also causes for problems. Honestly, since you've done everything else proper with your mods, changing out the pump and maybe the relay and checking the wiring, will only ensure you've covered everything possible and prevent future problems.
I only said to upgrade, because I assumed that the voltage you described as 9 volts is from the pump itself. I would assume that you're getting the full 12volts before the pump? Yes, it can be the relay and that should be changed if faulty. But also check the wiring and ground as these are also causes for problems. Honestly, since you've done everything else proper with your mods, changing out the pump and maybe the relay and checking the wiring, will only ensure you've covered everything possible and prevent future problems.
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Apr 3, 2009, 02:54 PM
#9
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I don't know how to post sections, but this will get you there.
http://lancer-club.ru/data/faq/2007/...erX_engine.pdf
In the lefthand column, click on the "+" next to the #3 section to bring down the submenus. The sixth (6th) submenu from the bottom is called "fuel pump relay control." Click on it and check it out. If that doesn't help, check other sections out.
http://lancer-club.ru/data/faq/2007/...erX_engine.pdf
In the lefthand column, click on the "+" next to the #3 section to bring down the submenus. The sixth (6th) submenu from the bottom is called "fuel pump relay control." Click on it and check it out. If that doesn't help, check other sections out.
Apr 3, 2009, 02:59 PM
#10
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you don't have any boost gauges or any aftermarket electronics in your car?I hope that doesn't happen to me.I was able to get a tune but what if my fuel pump goes out later and I don't know it.Thanks gonna suck.Maybe I should invest in a wideband or something like that.Let us know when you find the problem.
Apr 6, 2009, 10:44 AM
#11
I have a boost guage but that shouldn't effect why the car is running lean. I swapped out the fuel pump relay..and still I got nothing...so time to take it back to AMS to see what wrong. I hope they can find the problem before turns into a grand..lol.
Apr 6, 2009, 10:57 AM
#12
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Later, Ken
Apr 7, 2009, 06:01 AM
#14
Another option is to run a dedicated power line from the battery to the pump that is triggered by a 30 amp relay that activates when the original power lines are on. That should ensure maximum voltage to the fuel pump at all times and is what many have done on previous model DSM's. Tthe stock wiring was always cause for some voltage dip due to the undersized wiring.