question about fuel pressure reading - Hemi Truck Club
 
Go Back   Hemi Truck Club > HEMI | Performance Zone > Engine | Modifications, Repairs and Performance

Like Tree7Likes
Reply
 
Thread Tools Display Modes
 
Old 11-28-2018, 03:40 PM   #1
Member
 
Join Date: Oct 2017
Location: Ashland City
Posts: 32
question about fuel pressure reading

Hello all.....

2004 Dodge ram 1500 5.7 HEMI 83k

diagnosing a p300 error.

the truck started running really rough, missing,would barely pull itself, and shacking to the point that it would die while running down the road. the only way to get it to start back up was to hold the gas peddle to the floor (i know it shouldn't make any difference it's fuel injected) There is also a strong fuel smell (flooding condition i assume, my LTFT are at -25 +/- 1 across B1 and B2) and that's not even with the motor running. Pulled injectors looking for leaks and they are all dry when i turn on the truck, checked with a paper towel(with key on), also put a pressure gauge on the fuel rail and when i turn on the truck it will get to 59PSI but as it sits there (with key on) it will start to drop down over time. no leaks from the injectors and can smell gas fumes.

I hit the pressure release button on the fuel gauge by accident and the pressure dropped (of course) but it didn't build back up. will it rebuild that pressure or does that only happen when the engine is running.

sorry, lots of info (it could even be considered ramblings). I know i missed something as im posting this in a hurried manner.

do i need to look at a new fuel pump?? p0300 is the only code i have right now. have also gotten p0430 (i think) catalytic converter efficiency bank 2 in the past

Ram50 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-28-2018, 04:29 PM   #2
John
 
SUPER BEE's Avatar
 
Join Date: Feb 2014
Location: Meridian, MS
Posts: 3,646
Garage
__________________

SUPER BEE is offline   Reply With Quote
Old 11-28-2018, 05:08 PM   #3
Member
 
Join Date: Oct 2017
Location: Ashland City
Posts: 32
thanks for the welcome.

update.,

got everything put back together and started the truck. running rough of course but the fuel pressure gauge bounces wildly when running, between 60 psi and 50 ish psi was really bouncing fast. does that point to a fuel pump or possible vacuum leak.
Ram50 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-28-2018, 06:52 PM   #4
2012 Truck of the Year
Engine Specialist
 
charged392's Avatar
 
Join Date: May 2011
Location: Fort pierce, FL
Posts: 17,234
Garage
Bouncing fuel pressure is most times a failing regulator in the pump at the tank it should stay pretty steady.

-25 is not a fuel starve issue thatís for sure. If both banks are reading -25 then you likely have a bad MAP sensor as thatís really the only sensor that can make the fuel go crazy rich. A shorted intake temp sensor can also do it but not likely. Do you access to a scanner of some sort to get some data of the idling engine and at 2,000 rpm
__________________
"CMR TUNER" [email protected] 1/4 with a 7.32 1/8 custom long/short bars by "Me" Turbocharged 392 on 9psi S475/96/1.32 . Running thru an A518! [email protected]
charged392 is offline   Reply With Quote
Old 11-28-2018, 07:35 PM   #5
Member
 
Join Date: Oct 2017
Location: Ashland City
Posts: 32
yes i can pull some live data. but the motor is running so rough right now that i don't think i can get it to stay at a constant 2k rpm, I'll try in the morning.

The fuel regulator appears to be on the top of the fuel tank made as part of the fuel pump assembly. replacement one is 107.00 new fuel pump with regulator is 169.00 both will have to be ordered. may just get a whole new assembly just so that i know everything is new.
SUPER BEE likes this.
Ram50 is offline   Reply With Quote
Old 11-29-2018, 03:06 AM   #6
Stu
 
Join Date: Oct 2009
Location: FL
Posts: 20,359
Garage
Welcome back.

Keith will help you to get your truck straightened out.
Ghost03hemi is offline   Reply With Quote
Old 11-29-2018, 06:28 AM   #7
2012 Truck of the Year
Engine Specialist
 
charged392's Avatar
 
Join Date: May 2011
Location: Fort pierce, FL
Posts: 17,234
Garage
start out by getting some sensor readings or pictures of the scanner while truck is running and lets go from there.
__________________
"CMR TUNER" [email protected] 1/4 with a 7.32 1/8 custom long/short bars by "Me" Turbocharged 392 on 9psi S475/96/1.32 . Running thru an A518! [email protected]
charged392 is offline   Reply With Quote
Old 11-29-2018, 12:54 PM   #8
Member
 
Join Date: Oct 2017
Location: Ashland City
Posts: 32
I had another MAP sensor so i put that in last night, so i imagine that the reading will have changed. I have another to try if need be. the way the truck is running has changed. Not as rough but there is still a miss or something. the wrong fuel pump came in this morning so i have to wait until 5 pm today for the replacement. Had was able to get some pictures of the scanner tool Live data, Ill post below. I also had the battery disconnected for a time lastnight. That may skew the reading some also









http://i1339.photobucket.com/albums/...psscegf0oz.jpg
Ram50 is offline   Reply With Quote
Old 11-29-2018, 04:55 PM   #9
Member
 
Join Date: Oct 2017
Location: Ashland City
Posts: 32
update:

The new fuel pump is in. The fluctuating fuel pressure is fixed. It sits at 64 PSI. (running at idle) now that that is done I can concentrate on the the rough running / miss in the truck. Looks like im (with this sites help) chipping away at it one issue at a time

While I'm waiting for the help/replies (thank you so much by the way) I going to do a compression test just to make sure that is all good. plus my oldest son is helping so Ill make him get the plugs in the back
Ram50 is offline   Reply With Quote
Old 11-29-2018, 06:01 PM   #10
Greg
 
Redtruck-VA's Avatar
 
Join Date: Jan 2011
Location: Virginia
Posts: 19,007
Garage
The rail pressure for a 05 is 58psi, 64psi is high but most likely can be compensated for by the pcm. I had a 03 which should be 48psi that compensated for 58psi for a few months but then couldn't and caused tuning issues. Keep a eye on the trims.
__________________
2003 RCSB, 2wd, "Pro-Street"
6.4L/cog driven V7-Ysi/46rh trans/HTH Truckarm coilover suspension. HP Tuning...

1# 2017 HTC FASTEST HEMI List....
Current 1/4 mile [email protected] (2018)
Current 60' PB 1.351 (2019) mechanical issue for 1/4m

HTC 2018 TOTY

Support vehicle- 2007 QC G56 4x4 diesel
Redtruck-VA is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Premium Vendor Showcase
n2 Speed Edge InTune Edge OCPerformance Parts

All times are GMT -6. The time now is 04:19 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.