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View Full Version : Fuel pressure and general questions(UUGG NOT FIXED YET!!!!!)



XxSlowpokexX
06-23-2008, 01:03 AM
WHat should fuel pressure be at idle with car running and vacuum on,,

I'm getting 32 at 14" of vacuum and 40 at 0(autometer gague)

Now what would cause this problem

I am getting a bucking every so often and sometimes worse then others. It seems to have gottten worse. Usually if I rev teh engine the bucking will clear up

Along with the bucking teh car goes ultra lean....

Thsu why I installed the fuel pressure gague. When teh car starts to buck however fuel presure remains unchanged

Can this be a TPS issue?....I need to pull codes as I have a permamnant CEL due to my EGR not being connected

Thansk all

Damont

ndiiorio
06-23-2008, 03:27 AM
your fuel psi should increase with boost/ less vacuum. you should be about 37 at idle and around 43 with 0 vac. this sounds like my vac leak problem. u might have one that's very small and doesn't effect your vac gauge but depending on climate and driving conditions makes the car buck, sometimes worse than others. if your fuel pressure goes down with less vac/ boost than its a fuel related problem either regulator or pump. if you 100 positive of no vac leaks (vac. leak test) then I would look at your sensors.

XxSlowpokexX
06-23-2008, 07:51 AM
I had put in a new 255 pump a few weeks ago....WHich is why I'm thinking it may be the pump..Howeve rteh fact that it just start randomly bucking with no sway in pressure leads me to believe that may not be the issueveer..But 32-34psi seemed low to me..I just dont know!

Mike8675309
06-23-2008, 11:10 AM
did you put in a new fuel filter?

XxSlowpokexX
06-23-2008, 03:14 PM
Not since about months ago..SO I didnt directly after the install. DO you think that can be it even though fuel pressure stays consistant? I need to check codes still s well. I'll updat eif I find anything out..Busy work week

XxSlowpokexX
06-23-2008, 06:30 PM
Mike well you are 100% correct. Seems teh problem with owning to many cars is you forget what you did to what when..Apparently my fuel filter was clogged. I pulled it out and could barely blow into it at either end..Changed it and wallaaa.....EVen looked to be factory ford...Scary...Anyways Imma happy

Thanks dude..Wasnt expecting this!

Mike8675309
06-23-2008, 09:20 PM
My guess is that there was some crud in the fuel pump you swapped out. moving the stuff around to change out the pump dislodged and/or the new pump's fresh pressure cleaned out stuff just sitting in the line. I'll throw one more suggestion at you.

Search and find how to jumper the fuel pump on. Then disconnect the feed line into your filter and run the fuel into the bucket, just in case there is little more stuff in there.

No smoking while working on that stuff.

Miller
06-23-2008, 09:31 PM
hey I should read befor i post! MIKE FTW

XxSlowpokexX
06-23-2008, 10:21 PM
SO isnt this how it always goes.....Runs great then all of a sudden.SAME CRUD!!!

Stilll doing it just as bad.....I dont know,,

THis will be a wekeend project. Apparently I need to start checking sensors or hook it up to a scanner as th eblinking check engine light method isnt working well for me

Definitely thinking of flushing the fuel out ..perhaps filter has reclogged...Dont know

fturner
06-23-2008, 10:55 PM
At idle my rail pressure is around 32psi if that helps you any, and I don't have any issues.

Frit

David Neibert
06-23-2008, 11:37 PM
WHat should fuel pressure be at idle with car running and vacuum on,,

I'm getting 32 at 14" of vacuum and 40 at 0(autometer gague)

Now what would cause this problem

I am getting a bucking every so often and sometimes worse then others. It seems to have gottten worse. Usually if I rev teh engine the bucking will clear up

Along with the bucking teh car goes ultra lean....

Thsu why I installed the fuel pressure gague. When teh car starts to buck however fuel presure remains unchanged

Can this be a TPS issue?....I need to pull codes as I have a permamnant CEL due to my EGR not being connected

Thansk all

Damont

Damon,

Sounds more like an ignition problem than fuel starvation.

David

Miller
06-24-2008, 02:04 AM
Maybe its that broke-~~~ coil pack that I totaled out. that one plug broke ?

XxSlowpokexX
06-24-2008, 05:03 PM
Miller..I actually ordered a new coil pack. I tested it and it doesnt seem to be the issue but who knows
Yah fuel pressure is between 32-34 so I guess thats about right..

Well new flywheel and clutch going is soon as well....ITS BECOMING A MONEY PIT! haha!

David Neibert
06-24-2008, 05:15 PM
Miller..I actually ordered a new coil pack. I tested it and it doesnt seem to be the issue but who knows
Yah fuel pressure is between 32-34 so I guess thats about right..

Well new flywheel and clutch going is soon as well....ITS BECOMING A MONEY PIT! haha!

Damon,

Is it one of the Screamin Demon coil packs ?

David

lube70
06-24-2008, 06:01 PM
The problem you are having is with the wires....I had the same problem on my wifes 94 SC. Changed the wires and whamm....No more issue. Could also be a broken plug, definitelty ignition related.

Don

XxSlowpokexX
06-24-2008, 06:12 PM
Yes I have one dave..We had a lil issue where we broke a wire mount off the coil pack and I epoxied it back on...That was a few months back but it could potentially be an issue..I checked and all looked well.

Now I wonder if there can be a wire issue I did pull them off and put them back on and it didnt make a difference. I'll go do a resistence test and see whast crackin,,,Its intermittent so I dont think its a plug..I justneed a day to start testing and time has been short..Thansk for ll the ideas guys

David Neibert
06-25-2008, 01:00 AM
Yes I have one dave..We had a lil issue where we broke a wire mount off the coil pack and I epoxied it back on...That was a few months back but it could potentially be an issue..I checked and all looked well.

Now I wonder if there can be a wire issue I did pull them off and put them back on and it didnt make a difference. I'll go do a resistence test and see whast crackin,,,Its intermittent so I dont think its a plug..I justneed a day to start testing and time has been short..Thansk for ll the ideas guys

I'd try swapping coil packs with one you know is good.

David

Ira R.
06-25-2008, 01:23 PM
I'd try swapping coil packs with one you know is good.

David

That's the ticket! Hey Miller, start selling him back the extra parts off your car now ;) :D


Ira

XxSlowpokexX
06-25-2008, 08:55 PM
I have a shelf of coil packs:O)

Miller
06-25-2008, 09:00 PM
well then put one in , sancho

XxSlowpokexX
06-26-2008, 12:57 AM
coil pack is not the problem..

XxSlowpokexX
06-29-2008, 08:37 AM
It was.....the TPS!

CMac89
06-29-2008, 10:22 AM
Glad you found the problem. It's weird how much the TPS affects the 94/95 cars. I have forgotten to plug my TPS and IAC in, once, and drove around all day with the only problem being the cruise control wouldn't function properly.

My friend's '95 went bad and the car wouldn't even start.

XxSlowpokexX
06-29-2008, 03:03 PM
I had a feeling thats what it was but last I checked it it was fine. Lately with the problem being more persistent It was easy to diagnose..Just needed the time to do it.

I did however replace teh coil pack because that was bothering me...Rge crack that is..But I replaced it after I solved teh problem..Coil pack tested fine last week...Now for the clutch..Then a lil juice