Rom

Hi all,

I found an issue where there was some fuel leaking from the top of the fuel pump carrier where I had passed the wires for my 416lph pump out the top. So I took it all apart, fixed the leak, put it all back together again, but now I have a major issue that's driving me crazy!

Basically the car feels like it is being starved for fuel. I can barely get it to idle. I have gasoline in the tank right now, but for me to even keep it running I have to have the map in E85 mode (so it flows more fuel). In gasoline mode it sputters then dies almost immediately (it catches, but then dies about 3 seconds later). In E85 mode (with gasoline), as long as I'm revving it, it stays running, but I can't drive it of course.

I can hear the pump running at start, and I can hear it speed up when I rev. It all worked perfectly before I took it apart. I've since taken it apart and put it back together THREE times - I even added extra O-ring seals where the pump meets the carrier (thinking maybe the high pressure was leaking on the inside).

If I run a pipe off the supply port on the carrier and try to start the car, plenty of fuel comes out so it's definitely flowing something.

My only working theory right now is that, for some reason, it's not pressurizing the rail enough (although a 416lph pump that I can *hear* running, should be working). My AFR meter definitely appears more on the lean side. I'm running the stock rail (with 1200cc injectors) so I don't have a point for a fuel pressure gauge, so I haven't tested that.

Also, I pulled off the return lines on the carrier, and no fuel comes out - so it's not overpowering the FPR.

Anyone have any ideas? Is there any way for me to test fuel pressure easily without an aftermarket rail? Ideally I guess it would be good to test the pump, but I don't really want to buy another 416lph pump just to test that theory until I've exhausted everything else (unless there is some way to bench test it?)

Thanks in advance for any help!

S.

Rom

Hi all,

So I tried running the pump without the filter at the bottom in case there was a blockage there (only for a couple minutes) and it made no difference whatsoever.

I wonder if the pump is having issues, but it was working perfectly before I took it out!

Anything else to check? Anyone?

Thanks!

S.

timmeqn

I hate to tell you this but your fuel pump might be shot. I was having issues with mine and my evo was getting harder and harder to start and finally my pump just died and I had to get another one. My first one was a wally 255 put in by the previous owner and I just bought another to replace it

WikdEvo

iTrader: (8)

Do you have an actual wideband afr gauge? It's kind of hard to diagnose a fuel problem and know that it is either lean/rich without one...

Rom

Hi Tom,

Yes - I have a wideband afr - and it's staying on the lean side - especially if I put any kind of load (ie try to move the car). The issue isn't subtle though - the car literally will not stay running in gasoline mode and in e85 mode (with gasoline in the tank) it won't idle (but will run a bit if I keep the revs up). I'm guessing that since in e85 mode the duty cycle on the injectors increases to flow more fuel, it's compensating a bit for the lack of pressure. I can't move the car at all as any load the car quickly bogs down, mixture goes very lean and then it shuts off.

Also, as I understand it, I should see some fuel flow out out of the return line but I'm not seeing anything there at any rpm - which makes me think the pressure is never even coming close to the stock fpr max pressure..

Thanks again for your help guys!

S.

DSMolition

iTrader: (17)

I'm having fuel issues also. Do a re wire on your fuel pump so its getting more voltage. And you need to test the fuel pressure to make sure it is raising at a 1:1 ratio per psi of boost.

Rom

Hi DSMotion,

Thanks for your reply! I did rewire it three times, but I will check the voltage too.

As for the pressure, I will check that - but I can't even get it to idle, let alone boost, so I have some fundamental issues there!

I just bought a fuel pressure gauge so I plan to splice in to the flow side to measure the pressure some how.

Any one have any tips for doing that on a stock fuel rail?? I can get in to the return line easily, but I don't think I'll see anything there.

Thanks!

S.

IzzyRS

iTrader: (8)

Someone sells a fitting that mounts on the stock rail, maybe between the rail and regulator. I can't think of who it is.

DSMolition

iTrader: (17)

when I say rewire I mean with a relay and 12v right to the relay with at least 10G wire. So its getting max voltage.
https://www.evolutionm.net/forums/ev...mp-rewire.html and yeah you need to measure pressure pre regulator.

andrewzaragoza

iTrader: (6)

another thing that may be causing the issue your fuel filter inside the pump carrier. Also make sure the polarity of the wires connected to the pump are correct.

Rom

Hi all,

Thanks for all the suggestions.

Today I hooked up the pump output (off the top of the carrier) to a pipe with a fuel pressure gauge and a 45psi fuel pressure regulator on the end. I then fired up the pump directly to a battery with fairly short wires. I ran the pump for 10-15 secs and fuel pressure only rose to 10psi!

So the issue has been located to the pump carrier. Now I don't know if fuel is spilling past the grommet on the inside, if there is a blockage in the carrier, or if the pump is screwed. I know it's NOT the filter because i tried running it temporarily without a filter at all and the results were the same.

I'd love to be able to run the pump outside the fuel tank. Is there a good substitute for gasoline (not sure about purified/distilled water).. I'd rather not be testing in a bucket of gasoline, but maybe there is no other way?

I want to basically eliminate the grommet/carrier as issues before buying a new $300 pump! The issue is tho that I can't see inside the fuel tank while it's running...

Thanks again all!

S.

IzzyRS

iTrader: (8)

Snap a picture of how the pump is installed, maybe you are missing a very simple detail that is making it not operate properly.

Rom

Hi Izzy,

I can do that tomorrow, however it's been functioning perfectly for two years so I don't think it will be a visual issue. The carrier itself installation itself is pretty straightforward - it's the bits you can't see that worries me (like the grommet seal or the internal piping inside the carrier).

I do plan to run a pressured liquid through the assembly without the pump to ensure there are no blockages there, and I guess I can replace the black grommet with a new one (if it's sold separately - I used the old one when I originally put it together a couple years ago).

If none of that works, I guess I'll replace the pump...

Thanks!

S.

IzzyRS

iTrader: (8)

I've replaced my pump before because of a Speed Density issue. My MAP sensor went bad and was making my car super lean. Sometimes I would start it and it would run lean and misfired, only staying on if I tapped the gas repeatedly. I thought for sure the pump was going out. After lots of troubleshooting I changed the MAP sensor and everything was good. Just buy a new pump, install it, and hopefully it fixes the issue. If it does not, you will know for sure its not the pump. Also, triple check that wiring and install, just in case.

Rom

Okay, now I'm lost... I replaced the fuel pump with a brand new 450lph from walbro.. Put in all new wiring on the inside of the tank with as few connections as possible... And I still have the same issue?!?!

I'm wondering now... Could the fuel be bad?? I've been working on it for 3 weeks and the tank wasn't sealed for a lot of that time. A lot evaporated off, so it could be bad. The ethanol content (10%) could also have sucked in some water..

Still doesn't explain why I can only get 10psi of pressure when connected directly to it, but maybe that's an issue with the test procedure. Since I can get the car to run if I gas it, it MUST be higher than 10psi (I'd assume).

The tank is only half full right now so I'm going to try to empty it and put fresh gas in..

Thanks!

S.