420A Cranks but not starting

[PupMaestro02]

Hi! I’m new to this site and I’ve been recommended to this site a lot for whenever I have problems with my eclipse (and I still do..) and so I was wondering if you guys could help me?

About 2 or so years ago I had bought this car from someone in Florida and it drove good and lean because it was tuned for it to be a daily car due to the previous owners choice (I suppose?). Well as the years gone by I came across this ONE problem that has been bothering me and made me dump so much money into this car that it’s not even funny…

And that one problem is when I turn over the car, the fuel pump won’t go on at all. I’ve changed the fuel pump at least 2 or 3 times. I have changed the fuel pump relays, the relay that sits behind the radio in the center. I’ve changed the battery (due to the previous ones being bad and not giving it some juice). I’ve also changed the cam shaft position sensor, the crank shaft position sensor, the ignition switch. I’ve checked EVRY fuse possible in the car and it’s all good. And yet I still have this problem…

Could anyone possibly have some sort of knowledge I don’t know about that could possibly help me fix this one problem I’ve been having?

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[Sirius1995]

Do you run an aftermarket ECU?

Also since it has a turbo upgrade I assume fuel pump is also changed, at least to Walbro 255. They have some issues with stock relays, try to feed 12V for it by bypassing the relay and that should fix it. You should run a deadswitch for the fuel pump, they sell wiring kits for fuel pump upgrades

 

[PupMaestro02]

do you run aftermarket ecu?

That part I’m not quite sure about.

also since it has a turbo upgrade I assume fuel pump is also changed, at least on walbro 255 they have some issues with stock relays, try to feed 12V for it by bypassing the relay and that should fix it, you should run a deadswitch for the fuel pump, they sell wiring kits for fuel pump upgrades

I’ll try and give it a shot. I’m not too good with wiring anything but I’m sure I’ll have some friends who could

 

[Sirius1995]

I’ll try and give it a shot. I’m not too good with wiring anything but I’m sure I’ll have some friends who could

I mean trick for this is you just feed 12V straight from the battery to the fuel pump because walbro pumps need constant 12V feed, with factory relays pump only gets ~6V and when accelerating ~12V, and for some reason those pumps stop receiving power, I don't know why exactly but once you feed 12V to the pump, it will work again

 

[Sirius1995]

That part I’m not quite sure about.

Do you have this part somewhere in your car? Originally it's located in the engine bay on driver's side and is bolted on the fuseblock and strut tower

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[PupMaestro02]

Do you have this part somewhere in your car? Originally it's located in the engine bay on driver's side and is bolted on the fuseblock and strut tower

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I have that for sure. Just not too sure if it’s after market or not

I mean trick for this is you just feed 12V straight from the battery to the fuel pump because walbro pumps need constant 12V feed, with factory relays pump only gets ~6V and when accelerating ~12V, and for some reason those pumps stop receiving power, I don't know why exactly but once you feed 12V to the pump, it will work again

I gotcha. I’m gonna go grab some supplies for me to try and attempt to run these wires and pray I did a good job

 

[99dsmer4g63]

I’m doubting it’s an aftermarket ecu. There is an fmu bolted in the engine bay above the cruise control stuff. If I remember correctly your fuel pump should not turn on and run with just the key in the on position. It may prime for a slight second but will not activate again until it receives a signal that says the engine is rotating and will then fire the plugs, injectors and fuel pump will be on at that point.

You don’t have a profile so idk what year your car is but the fuel rail/ fuel pressure regulator varies on different years for 420’s. The regulator may be near the fuel tank or could be on the fuel rail like the 4gs are.

Reason I say about the fuel pressure regulator because of the fmu and you saying it runs lean. I don’t believe there is an actual “tune” on your car. The fmu has a ratio spring in it to bump the fuel pressure up per pound of boost it sees. So for example a 10:1 fmu raisies the fuel pressure by 10 pounds for every 1 pound of boost it sees.

My dad ran an fmu for years and the a/f ratios were actually pretty good. We didn’t have logging capabilities but by watching the wideband it was usually pretty happy. His is either a 10:1 or a 12:1 I can’t recall right now.

We also have a 255 walbro for a fuel pump and have no rewire kit for it and it does fine, just does the traditional turn signal whine.

I also see a pile of tees in the signal vacuum hose for the fmu. I would recommend changing that to just a dedicated line from intake manifold to fmu. We tapped the intake while it was off the car and added a dedicated intake source.

Also does the car not start or something? You say the pump doesn’t turn on but nothing about the problems your experiencing when you think said pump is off.

Also your timing belt looks kinda suspect. Are there grooves on the inside of the belt? Looks like it rides pretty tight to the inside of the motor. Does the car have the inner and outer timing covers on the bottom end?

-Daniel

 

[Sirius1995]

I’m doubting it’s an aftermarket ecu. There is an fmu bolted in the engine bay above the cruise control stuff. If I remember correctly your fuel pump should not turn on and run with just the key in the on position. It may prime for a slight second but will not activate again until it receives a signal that says the engine is rotating and will then fire the plugs, injectors and fuel pump will be on at that point.

You don’t have a profile so idk what year your car is but the fuel rail/ fuel pressure regulator varies on different years for 420’s. The regulator may be near the fuel tank or could be on the fuel rail like the 4gs are.

Reason I say about the fuel pressure regulator because of the fmu and you saying it runs lean. I don’t believe there is an actual “tune” on your car. The fmu has a ratio spring in it to bump the fuel pressure up per pound of boost it sees. So for example a 10:1 fmu raisies the fuel pressure by 10 pounds for every 1 pound of boost it sees.

My dad ran an fmu for years and the a/f ratios were actually pretty good. We didn’t have logging capabilities but by watching the wideband it was usually pretty happy. His is either a 10:1 or a 12:1 I can’t recall right now.

We also have a 255 walbro for a fuel pump and have no rewire kit for it and it does fine, just does the traditional turn signal whine.

I also see a pile of tees in the signal vacuum hose for the fmu. I would recommend changing that to just a dedicated line from intake manifold to fmu. We tapped the intake while it was off the car and added a dedicated intake source.

Also does the car not start or something? You say the pump doesn’t turn on but nothing about the problems your experiencing when you think said pump is off.

Also your timing belt looks kinda suspect. Are there grooves on the inside of the belt? Looks like it rides pretty tight to the inside of the motor. Does the car have the inner and outer timing covers on the bottom end?

-Daniel

Why I'd first check the pump, is that it's really common problem, and if that won't work, then go more deep into it

 

[PupMaestro02]

Also does the car not start or something? You say the pump doesn’t turn on but nothing about the problems your experiencing when you think said pump is off.

Well the car will try to start but like I said, the fuel pump won’t prime.

Do you have this part somewhere in your car? Originally it's located in the engine bay on driver's side and is bolted on the fuse block and strut tower

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Yes I do

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[Sirius1995]

Yes I do

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Could also be bad ecu then, I would switch to aftermarket ecu so you can get a proper tune

 

[PupMaestro02]

Could also be bad ecu then, I would switch to aftermarket ecu so you can get a proper tune

What after market ecu would you recommend?

 

[Sirius1995]

What after market ecu would you recommend?

MegaSqruit V2 or V3 is probably the best and most affordable option, it should cover everything you need and you can save more money for dyno tuning time

 

[PupMaestro02]

MegaSqruit V2 or V3 is probably the best and most affordable option, it should cover everything you need and you can save more money for dyno tuning time

Oh alright, I’ll look into it.

So far all I’ve done to the car in the mean time was run a 10awg wire from the battery into the interior of the car and my plan was to connect that with a different 30 amp relay and a toggle switch as well and hook all that up to the fuel pump

And which megasquirt would be the right one for my car? It is a 99 Mitsubishi Eclipse RS with a 420a motor and has an EMUSA turbo kit attached to it.

 

[Sirius1995]

And which megasquirt would be the right one for my car? It is a 99 Mitsubishi eclipse RS with a 420a motor and has an EMUSA turbo kit attached to it

well personally I'd choose MS V3 but you need to choose which one fits best for your needs, but did you try out that fuel pump yet? you should figure that out first, also megasqruit is not plug and play, it will include soldering and a lot of wire configurations

 

[PupMaestro02]

well personally I'd choose MS V3 but you need to choose which one fits best for your needs, but did you try out that fuel pump yet? you should figure that out first, also megasqruit is not plug and play, it will include soldering and a lot of wire configurations

No I haven’t yet, it was getting late . I’ll figure it out tomorrow after work

 

[PupMaestro02]

Does anyone have a wiring diagram of the fuel pump for my car? It’s a 420a 99 Mitsubishi Eclipse RS

This is the ECU that I am currently running.

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