Bloomie

iTrader: (4)

I am attempting to fix an apparent fuel pump power supply problem (history follows). I have tested fuel pump relays 1 & 2 on the inside fuse panel according to the shop manual, using a meter & 12V procedure and they are ok (proper continuity through the correct contacts with and without 12V power).

The shop manual I have does not detail a "meter" check for fuel pump relay 3 (the one under the hood on the firewall). It only describes a test with a special dealer instrument through the vehicle electrical system.

Can anyone tell me how to check the function of relay 3 with a meter? Right now, all I know is that it has continuity through the two large contacts with no voltage applied. If I can find out to which contacts 12V should be applied, and which contacts should be checked for continuity once the relay operates, I will be able to diagnosis that item.

Thanks, everybody!


2003 Evo VIII

The pump (Walbro 255) and associated components worked before I started this job. However, since a tank of contaminated gas, the engine has been missing at stable 5th gear speeds 50-70mph and cutting out badly on the track at high rpm.

I replaced the fuel pump module (the big white plastic tank insert, which contains the filter). This involves moving the pump, fuel gauge float, in-tank wiring harness, etc. to the new module.

After assembly and installation into the fuel tank, I turned the key and the fuel pump did not operate (the pump is audible when running). The engine would not start (many attempts). The fuel gauge (wiring through the same harness and D-12 fuel pump module connector as the fuel pump) does work.

With a meter, I checked connector 4 (ground) of the fuel pump module harness side D-12 connector to ground and found an open circuit. Connector 5 (power) on the harness side is also open.

I tested the pump with a test lead direct from the + battery post to the module side connector 5 and a test lead from the module connector 4 to ground, and the pump operates.

I have touched nothing other than the components accessible through the fuel pump access port under the driver-side rear seat. Since power is not getting to the pump through the wiring harness, it appears that the problem is somwhere upstream, which would be amazingly coincidental.

I am baffled because my experience tells me it is very unlikely that the problem is anywhere other than where I have messed with the components.

Any ideas?!

Thanks,

Steve Moe

SLO-EVO

iTrader: (52)

make sure that the power to the housing units on snug... try taking the power sending unit (in the middle of housing on top) and reconnecting it... either that, or take the housing back out and check to see if you accidently unplugged one of the in tank wires... ive done that before on accident...

Bloomie

iTrader: (4)

I have had the power plug (D-12 in the shop manual) that goes to the middle of the housing unit on and off a bunch of times. The pump runs if I put direct power via a test lead from the battery positive terminal to the housing side plug-in terminal #5 (and #4 grounded with another test lead). From that, I have been presuming that things are connected inside the tank.

I am puzzled about why, when I test the terminals in the power plug with the key on, there is no power through #5 and no continuity to ground from #4. I am hesitating tracing back through the wiring harness (it is really complicated) because I haven't messed with anything except the power plug at the housing. The only possibility that makes sense to me is that I broke some wires inside the harness near the plug from bending it around getting the pump assembly in and out of the tank.

The other end of the power plug harness is connector D-34. Do you know where that connector is located? If I can find it, I can test the continuity in that segment of the wiring to determine if any of the wires inside the harness are broken.

Thanks,

Steve

Bloomie

iTrader: (4)

The fuel gauge sender, serviced through the same plug as the fuel pump, works. When I connected a direct lead from the battery to the #5 contact on the pump housing, the fuel pump operated.

Just to be sure there is no secondary problem, I removed the pump housing and inspected the electrical plugs. All of them are seated.

I have discovered another dynamic. Previously, I thought I heard the pump operating briefly upon releasing the key when trying to start the car.

Today, I attached a lead to the fuel pump power contact (#5), in the fuel pump harness plug and led it to the drivers seat and connected it to a grounded meter. There is no power through that contact when the key is turned to “On”. However, as I thought, when releasing the key after operating the starter, there is a 2-second connection to power (12-13v).

It appears that the work I have done has resulted in a problem somewhere upstream (electrically speaking) from the wiring harness.

If anyone has any ideas I would appreciate the benefit of your expertise!

Thanks,

Steve Moe

SmurfZilla

iTrader: (33)

Did you ever find a resolution to your issue?

tony gibson

iTrader: (1)

I too am having a fuel pump issue. I have a home made double pumper (two in tank walbros) and the car has been running fine til the other day...I turned the key to on and noticed the pump only primed for about half a second (Im running AEM EMS) where normaly it primes between two and three seconds. Turn the key back to off and then to on again and the primary pump primed as usual and the car fired right up. Drove down the road and stopped at a gas station and right as i came to a stop in my parking spot the car died! Turned the key off and back to on and no prime....the car turns over fine but will not crank even using a hard wire connection to my secondary pump. I rewired the in tank connections and swapped pumps around to no avail. Car still sits...if i cant find a solution by tomorrow I will have to have it towed home...for the first time ever with 93,000 of abuse and a built motor running e85...starting to think she was invinsible besides the clutch Any ideas would be much appreciated.

tony gibson

iTrader: (1)

Nobody huh? Well I am thinking its a factory relay...going to do some testing with a test light today...the primary pump simply isn't recieving power and that factory harness has not be fooled with.

Bloomie

iTrader: (4)

Tony,

I eventually did get it resolved but I don't remember, at the moment, what the solution was. If it comes to me, I'll be back.

Steve

tony gibson

iTrader: (1)

Oddly enough I got the car running....right after it was towed home...i do not know what fixed it because i rewired the sec pump to include the grounds and drove it around with no issues...today it did it again headed back from the mall...put it into neutral and it died so i put it back in hgear to steer it off the word....after a few attempts the pump primed and it cranked and i drove home...scared to drive it again Maybe a crank angle sensor???

tony gibson

iTrader: (1)

Drove the car 120 miles in the rain today...can't get the car to repeat...I did redo some grounds and connections throughout the car that weren't looking too reliable...maybe its fixed

hrvat-9

I’m having the exact same problem right now , but I have ground but no power. I will check the key turning like you did.