Fuel pump always running koeo

[eighty6gt]

I have a KB BAP wired pre fpdm. White wire that used to power fpdm in factory configuration triggers a relay that puts power from my wiring upgrade to the BAP input. BAP output of 17v goes to white fpdm input.

I put a multimeter at the fuel pump hat connection on the wiring harness. I see 17v as long as I have ignition on engine off. I know that the ecm should be shutting off the pump after a few seconds even if the rail sensor doesn't see pressure... Otherwise why would we need a tune to drain the tank.

Car says it has no fuel, 0 miles to empty on dash display. Could be related, am pulling hat to look at wiring.

 

[eighty6gt]

Fuel gauge works now.

I took the BAP out of the equation while I troubleshoot. Back to constant 12v between the hot and ground leads that connect to the fuel pump whenever the key is on.

P0191 (fuel pressure out of range)
P2163 (unrelated I'm sure, TPS.)
P1233 (probably because I was cranking the engine with the relay out to depressurize.)
P12FF (I cannot get any info on this one.)
P1237 (Fuel pump secondary circuit fault.)

So - no short to ground on FPDM to pump ground wire. No short to ground between pump housing and pump negative terminal on hat.

I replaced the FPDM with a junkyard unit - performs identically.

Next up, going to check for a short to ground or voltage present in the secondary driver wires, blue with red and white with red.

I'd love to find a stock pump and hat to try. I have a 405. . If anyone has one they can sell me, send me a PM.

 

[RocketcarX]

The pump could be grounded through the hat, shorted out there. That white wire is hot KOEO, it's the ground that runs the pulse width modulation for the returnless system and actually turns the pump on and off.

 

[eighty6gt]

And it's done. I kept testing things. Got a new FPDM from the wreckers (same
symptoms.) I finally found that only with the pump plugged in I had
ground at the driver end of my fuel pump harness. That's not right,
should be isolated. The only source it could be: the level
sensor. Took the pump out again, probed the leads. Ground all over!
Stuff crossing over like crazy. How did I miss that?

Examined and examined the pump and hanger.. finally it dawned on me -
a tiny screw that fastened and connected the level sensor ground
leads... went through the plastic base on the hanger... and TOUCHED
THE METAL PUMP HOUSING! By angstroms! Unbelievable.

So.. put it back together, fired the car up, tested trans thru the
gears on the stands (works great..) tomorrow fix my newly hacked up
and dismantled wiring and get to work on the brakes.

Sheesh.

 

[Pentalab]

You got chains to go with the snow tires for this winter ? Glad you got the issue resolved.

 

[eighty6gt]

I don't have a daily driver any more - has been a great decision

- no fines
- no insurance
- no gas
- no repairs
- no worrying about winter tires

Needless to say the car will be stored in a few weeks, I can work on the paint and get the exhaust quieted down some.


I just take transit, walk, ride my bike. I live 9 km from work so it's not an issue. If I need a car, I can borrow my wife's for a few, I use it maybe 1-2x a week. Last night used it to go get the test leads I should have replaced years ago on my multimeter so that I could use it to ohm out grounds. Would have solved my problem a lot earlier if I wasn't negligent!

 

[06monera96]

Sounds like you got one of those famous Walbro that wired it incorrectly.
On these high-performance pumps, the smart arse ran a ground wire to the hanger on the side(spring) and up to the hat.
Just cut off the ground going to the hang and you be good.

 

[eighty6gt]

well... no... but thanks for thinking about this, anyway!