code 55

[aafc]

I have been trouble shooting a code 55 for the last few weeks. First pulled the fuel pump assy and one of the pumps strainer had come off reinstall removed fuel filter had some dirt , so sent the injectors out for cleaning and flow testing. Came back two inj were dirty, flow was good. reinstall in car ran fine. a week later code 55 again.
Went to section 6E3-A-pg 78 Step 1. ing off remove primary (fp1)fuel pump fuse, ing on. secondary pump runs for 2 seconds. Step 4. attach fuel pressure gauge, showing about 48 lbs pressure. Next step replace O2 sensors . Clear code went for test ride code 55 again. So i need some guidance, one other thing my insta/mileage only shows 5 to 6 miles at any time. avg mileage is working ok. also car has secondary delete option. And i have access to a tech 1a if needed.
Thanks
John
1990 white/black #2546
one of a few auto eq. 4l8OE ZR-1's

[aafc]

I have a question for those who have secondary delete option (1990). When
you use a tech 1 or 1A to look at your engine data list , rpm,coolant temp and other readings, what do you show for power switch while car is running and secondary system. If you do snapshot at WOT what readings do you see for
power switch and secondary system.
When i go WOT i have a light connected to secondary fuel pump to see if pump comes on, it comes on but it dose not go out until i turn off car. When looking at snapshot data i see O2 sensors readings of 27 left and right. the power switch shows full and secondary system is off. I get code 55.
Normal driving is see fuel pressure of 48-50 lbs

John
1990 auto 4l8OE eq.

[aafc]

Update code 55 cleared.
I went through the fuel system and have determined that the primary pump was going bad.It worked fine until you asked for WOT then it would fail.
What i also founded out is that the hose clamps were not tight enough to hold
fuel as it was leaking when WOT was applied. So with the primary pump going
bad and fuel leaking at WOT i would get code 55.
So i replaced both fuel pumps and screens, fuel filter, installed carters "y"
block, new hoses and correct size clamps for 5/16 hose and 3/8 hose.
Checked static fuel pressure, key on,motor off 50 bs. removed FPR hose and blocked plenum vacuum fitting, started car fuel pressure showed 56 lbs.
Reconnect everything and made a test run from about 40 mph in 3rd gear (auto 4l8OE). I run a fully automatic trans and gear changes are handled by
the compushift (it was new in 2004) controller which is set to shift at 6500 rpm for each gear change. Low shift point as i run 1/8 mile drag race no use in running up to 7000 rpm for 1/8 mile.
I hope this helps anyone with a fuel problem, just check everything, take
nothing for granted.
John
1990 white/black #2546
one of a few 4l8OE EQ ZR-1's

[Hib Halverson]

(snip) no use in running up to 7000 rpm for 1/8 mile.(snip)

You're no fun at all!:(

[Ccmano]

:thumbsup:
Persistence pays off... too late now but I’d love to know what the amp draw on the failing pump was.
H
:cheers:

[aafc]

Hib,
I run 1/8 mile drag racing and for qualifying you make two runs, but they only show 1/8 mile times. So running it out serves no purpose. Now on open track days when i'am testing i'll run the full 1/4 mile and shift at 7000 rpm. Then i can check my 1/8 times also.
Hey Hib Roger Vinci says to say hello, i worked with him for about 6 years after i retired from AT&T in 2004.

Ccmano,
If i remember i was reading about 3.8 amp draw on primary pump only.
Plus my clamps on the main feed were leaking at the same time. Replaced the clamps when i replaced the pumps (2) and all is good.

John
1990 white/black #2546
one of a few auto (4l8OE) eq. ZR-1's

[Ccmano]

Ccmano,
If i remember i was reading about 3.8 amp draw on primary pump only.
Plus my clamps on the main feed were leaking at the same time. Replaced the clamps when i replaced the pumps (2) and all is good.

Perfect...I suspected that, under 4amps is a dead give away that the pump is failing.
H
:cheers:

[jss06c6]

Perfect...I suspected that, under 4amps is a dead give away that the pump is failing.
H
:cheers:That's good Intel Hans! Thanks!!

Sent from my SM-G950U using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[-=Jeff=-]

where/how are you reading the pump current? I assume AMMETER in line, but?

[Paul Workman]

where/how are you reading the pump current? I assume AMMETER in line, but?

Set up the VOM to read Amperes. With the ignition switch OFF, connect the meter in series with the POS battery post and the pump diagnostic wire jutting out of the big wire loom, next to the windshield wiper motor.

Each pump should draw 4-5 amperes for a total of 8-10. However, it is recommended that you then pull one of the fuses for one of the pumps and read the draw again. That, and the help of a little arithmetic, you can know exactly what each individual pump current draw is.

[-=Jeff=-]

Is that the single terminal in the loom?

[Ccmano]

Is that the single terminal in the loom?

Yes, the one that sticks out near the brake vacuum booster. Paul did a nice write up of the entire process a few years ago.
H
:cheers: