It does sound like a loose connection or a short thats periodically making contact.. If it happens every time you are cruising, then its the low speed circuit when the pump operates at a lower rate which makes it quieter for idle and cruising... my guess is when the car is idling, its not bouncing around shorting out anywhere, but when the car is at highway speed, the bumps may be causing it to ground out and blow the fuse.. Check to make sure the relay isn't damaged, wires exposed, or its metal housing isn't "hot" when the car is idling (measure against the ground to see if its hot)

Since all that was handled was the wiring for the Pump, check under the seat where the pump/float access panel is, make sure the wires are in good condition, and didn't become crimped and chafed..

 

Man, I really don't know.

After you had the pump installed, did Al re-flash you?

After posting my reply earlier, I went over to the DynoFlash board and read through some of the "fireball 3" posts.

Supposedly, the fireball 3 tune is specific for those with the upgraded Walbro pumps. Al isn't saying what his changes are, but now I wonder if he is altering the ECU signal to whatever is driving the fuel pump. I remember that before, all he did was scale the injectors accordingly, but until he specifically addresses his changes for the Walbro, who knows?

It could be the flash that's causing this guy's problems.

 

Probably not the reflash.. the better fuel pump increases the fuel volume and pressure, so the stock injectors are getting a "Bit more fuel" than necessary, which requires a bit of scaling otherwise it'll run a bit rich. From what I know, the High-load/low-load transition that controls the pump is not in a region of the flash that would be manipulated If it were even a flashable parameter (I dont see why I couldn't be though)..

before you go too crazy, look for the obvious things, since the pump was replaced, look at the components attached to it, look at the area that the pump sits in, and the wiring around it.. make sure nothing's stretched, shorted, frayed, etc..

Since your saying its happening with the stock pump back in the car, its definitely not transition load, startup load, or sustained load. A leak or a blockage would hurt performance in addition to overheating (and possibly overloading) the pump and you'd know it.. If your getting very poor gas mileage, it could be gas leaking and shorting out the wiring, so look for moisture, and a strong gasoline odor.. also make sure the actual lines are connected correctly.. Obviously the pickup is, but its possible the vent line and the return line got switched or the return line is blocked, that can also cause the pump to overheat as if it were a blockage..

Again, since the stock pump has the same symptoms, and the odds the flash caused the problem are extremely low.. focus on the connectors and stuff in the immediate site of where the pump is located.

 

First off, thanks for the replys. I had the Walbro installed 2 hours prior to the dynoflash. I watched the installation, and he used extreme caution. Al told me that my problem is because of the pump being incorrectly installed. The thing that puzzles me is that the car was ran for 2 hours on Friday and 1.5 hours on Saturday then all hell started breaking loose. My car was running awesome for that period of time. I do not smell any fuel and the pump is very quiet. I still don't understand why it's blowing the engine control fuse, and not the fuel pump fuse. I am going to talk to Al today, so I'll see what his exact diagnosis is.

 

If it is not blowing the fuel pump fuse then it is probably not any issue with the fuel pump or it's related circuit. You say it blows the "engine control" fuse?

 

Yes, its blowing the engine control fuse(20 amp).

 

Double check the connections to the ECU behind the glove box.

 

yeah, that changes the nature of the problem.. I didn't realise it wasn't the pump fuse you were referring to.. Hmm.. let me ponder this for a bit and I'll try to post some insight.

 

i am moving this to the dynoflash forum so Al can also try to help you out and give you some feedback.

thanks

Snir

 

My diagnosis is that when the loose plug was making poor contact some damage was done to either a wire or a component of the electrical system

Having the main plaug that carries the voltage and ground to the fuel pump half way in and half way out is a sure fire way to raise resisitance and spikes in voltage which can blow transistors and sesitive electrical parts

I am not trying to shift blame here - however - think about this - I have done over 560 reflashed Evo 8 ecus and NOT ONE other customer is having these problems with the dyno flash

Its aparent to me that the loose plug is the likely culprit of your problem - its too much of a co-incidence

in the mean time as a diagnostic step - i have your calibration from your custom tune saved on file - send in your ecu and I will flash it back to stock and you can drive it that way to see if the problem persists

I am very sorry you are having these problems and I am willing to help in any way I can

I am going to review the wiring scematics tonight and see if I find any suspect components which I feel should be tested - i can help you find some spares to try and test with

From what I recall from our telephone conversation, you already tested it with the stock pump - correct?

 

Do this test also

STEP 6. Check the fuel pump resistor.
(1) Disconnect the fuel pump resistor connector B-121.
(2) Measure the resistance between fuel pump resistor side
connector terminal No.1 and No.2.
Standard value: 0.45 − 0.65 ohm
Q: Is the resistance between 0.45 and 0.65 ohm [at 20°C
(68°F)] ?
YES : Go to Step 7.
NO : Replace the fuel pump resistor. Then confirm that the
malfunction symptom is eliminate
1 2
CONNECTOR: B-121
B-121 (B)
HARNESS CONNECTOR:

 

I have to agree with Al.. The controller module (resistor/relay) that controls the pump speed is likely damaged.. If its transistorized its possible that the signal (and/or voltage) is going where it shouldn't, causing the fuse to blow..

I don't recall specifically, but I think you can replace the speed control module as a unit.

And its almost certainly (as Al said earlier) due to a poorly connected component since arcing and intermittant connections can cause noise and spiking, and can definitely damage solid state components. If the resistor is bad you'll have trouble too, therefore its good to check that too.

I would have posted this last night, but I couldn't find the thread, I've spoken to Al and several other people and it seems like we've all come to the same conclusion about it.

This probably happens frequently, which is probably the reason why Mitsubishi doesn't consider the pump assembly (and its filter) a servicable part. (They outright refused to change the filter for me when I thought it was plugged with gunk and said the filter was good for umpteen thousand miles before a change)

 

Where is the fuel pump resistor located? Anyone have visual aides or additional info to locate it? Thanks.

 

Bringing this one back to the top.....

I had my stock 05 do the samething. I blew two 20A fuses #8 under the hood on the FWY, and one while taking off from a light slowly. It hasn't happened in a couple of days, but I fear it will happen when I am in the throttle=boom. Stock fuel pump.

 

In the end - the above gentleman's issues were attributed to a faulty turbo timer harness. Do you have a turbo timer of any after market eletrical parts, alarms, stereo etc. And do you have a Dyno Flash? Thanks