my eec is acting up... ran codes...

[MrShorty]

As an ex-coworker of mine used to say, "no wonder the cow died."

If that is the fuel pressure, that's way too high, and no wonder it's running rich. Off the top of my head, only two possible causes for that high of fuel pressure: 1) FPR stuck closed or 2) plugged/kinked/restricted return line.

 

[91ROKKRAWLER]

how would i find out if the line is kinked? it doesn't look like it is. i am gonna buy a new fpr and see if that does it.

 

[MrShorty]

Visual inspection. I would think a kink bad enough to restrict the return flow would be obvious. Less obvious would be an internal plug inside the line. I expect something like blowing low pressure compressed air through the line (take off gas cap so the pressure has somewhere to go) would be able to tell if the line is plugged. A bad FPR seems more likely.

 

[91ROKKRAWLER]

so i got the fpr with the screw on top for the fuel line. i'll be replacing it tomorrow as well as doing my oil change thats overdue... i'll let you know if that does it

 

[91ROKKRAWLER]

i got the fpr in today while i was waiting for my girl to get out of the MRI for her back. literally a 10 minute-20 minute install. i think the hardest part was puttin the bolts in and takin them out...

I also ran codes again...

KOEO-79
CM-96
KOER-111

 

[91ROKKRAWLER]

the CM 96... thats fuel pump circuit open battery to pcm. does that mean the fuel pump circuit isn't grounded? or a positive wire is not connected to the pcm?

 

[MrShorty]

CM 96, without an accompanying KOEO 96 (or similar) means that at some point in the past, the computer saw a break in the fuel pump circuit. So it could mean either of those things or any number of other things, and it probably means the fault is intermittent. On my '92, I used to occasionally an equivalent CM code, but I could never figure out why until one morning when it wouldn't start. Then, the fault was permanent enough that I was able to track it down to a loose connection between the fuse and the relay.

If you unplugged the fuse or relay or inertia switch or ?? to depressurize the fuel system when changing the FPR, the CM 96 could be left over from that operation.

Where the truck seems to be running, this suggests that the fault is intermittent enough that it isn't effecting how it runs. I would probably clear CM, and then periodically check codes to see if/when it is coming back. I might try some kind of wiggle test in the fuel pump circuit to see if I can locate the fault, but I wouldn't go to great lengths until the fault becomes consistent enough to diagnose.

 

[91ROKKRAWLER]

so it still has the a/c on for the EO and i did pull the fuse to drain the rail for the fpr. i reset the pcm by takin the ground off. it got rid of the 96 code. i'll run codes and check psi tomorrow for more details.

 

[91ROKKRAWLER]

well truck is running great, starting better, and gettin ALOT better mileage... i was movin the needle anytime i moved the truck, now it doesn't move unless i drive it for a while. to put that in better words... i was goin through 10 gallons every 2-3 days. now i've been drivin on it for a week almost...

anything else to gain mileage?

current mods

K&N Conical filter
new FPR
cleaned TB
cleaned MAF
New plugs
tires are ran at 40-45psi
Hubs unlocked
moderate driving conditions...
Flowmaster exhaust
3.55 gears
31x10.50s