I have a 1969 dart with a 408 stroker.My fuel pressure goes to 7lbswhen i first start car then after driving it it goes down to .5lbs I changed fuel pump can i be the carb or did i just get a dud fuel pump the last fuel did the same thing can your carb hold your pressure up
Fuel pressure
- Thread starter klingon
- Start date
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Is this an electric fuel pump or mechanical? I have an electrical pump with relay wired to the ignition switch that dropped pressure. I had to wire it directly to the battery with a toggle switch and that cured it.
Mad Dart
Nothing to see Here!
If you have a Liquid Filled Gauge.... Get rid of it. They read messed up when they warm up. PSI Drops. Get a non liquid filled gauge. I just went through the same thing.
67Dart273
Well-Known Member
We need more details!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Mechanical or electric?
Where is it mounted?
What filters are "in between?"
What have you done to troubleshoot?
Where is the gauge plumbed?
"I'm guessing" you don't run either a return line or regulator
Mechanical or electric?
Where is it mounted?
What filters are "in between?"
What have you done to troubleshoot?
Where is the gauge plumbed?
"I'm guessing" you don't run either a return line or regulator
It's an Mechanical pump. filter is just after the fuel pressure guage elebrock line is the filter is ran good for a long time now may guage goes up and down slowly sometimes right to zero when engine under load put new Mechanical fuel in and the same thing let car sit then good but same thing will happen
Mad Dart
Nothing to see Here!
twayne24365
Well-Known Member
maybe the regulator? i once had a cheap holley regulator that came with the electric pump and the pressure would be different every time i looked at it. got an aeromotive regulator and no problem since
pntastar69
Well-Known Member
He never said he had a regulator. If I were you, I'd install one.
moe7404
moe7404
elec pump ONLY.
67Dart273
Well-Known Member
READ the service manual. There's a procedure in there to check inlet vacuum, outlet pressure, and estimate flow rate
SUSPECT, INSPECT, and CHECK everything from the tank sock, the pickup tube and the hose back by the tank, the line coming up front--------could have pinholes or be plugged with rust-----or either hose at the tank or at the pump could be collapsing.
You could have a damaged pump, or something wrong with the pump cam
You have to CHECK this stuff. You cannot just stand there and look at it, with your something-pad in one hand and scratching your *** with the other.
Service manuals...........free:
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
http://www.mymopar.com/index.php?pid=31
Chapter 14, the "Fuel" section, see "fuel pumps"
So what's the issue? 5 psi is plenty. Are you having running problems or do you just like watchin the gauge move?
67Dart273
Well-Known Member
Unless I misread this, he stated POINT 5 psi, in other words 1/2 psi. Maybe we are chasing our tails? It would not be the first time. This is what happens when you have something-pads instead of real computers.
pntastar69
Well-Known Member
I saw that too, .5psi. Wonder if it was a typo.
moparlover
Well-Known Member
sounds like the pump is fine but the line feeding it is clogged or the tank has gump in it or both
fuel starvation
fuel starvation
67Dart273
Well-Known Member
Do you have some sort of mental block?
Are your fingers broke?
Why can't you give us some details?
What have you DONE? What have you CHECKED? What do you PLAN to check?
Ya know there's people here happy to help
THIS IS A TWO WAY STREET
Mad Dart
Nothing to see Here!
That's why I posted the beating of the dead horse! Lol
67Dart273
Well-Known Member
pntastar69
Well-Known Member
Klingon - any updates?
nm9stheham
Well-Known Member
I would suspect heat in the fuel the pump causing the fuel to boil and the pump gets into a partially air-locked state; it is a sort of vapor lock state inside the pump. OP, does this pressure drop when hot or does it do this when cold? (Not expecting an answer after all this time, but what the hey...)
I have experienced this good-pressure-then-low-pressure symptom happen on certain small aricraft when the old AC style mechanical fuel pump is exposed to too much heat; the cure is to put a cooling shroud around the pump and route cool air to it in those applications.
I have experienced this good-pressure-then-low-pressure symptom happen on certain small aricraft when the old AC style mechanical fuel pump is exposed to too much heat; the cure is to put a cooling shroud around the pump and route cool air to it in those applications.
I have the same issue with mine. I have a mechanical fuel pump and a liquid filled gauge and when I broke the motor in I was getting good pressure, and at about the half way mark it was reading 0, well I figured it was the gauge because the motor continued to run like a champ during the rest of the cam break in. Bad gauge I guess.
Mad Dart
Nothing to see Here!
You can't beat a dead horse LOL
Haaaaa, Lol...... Just seen these ones. I MUST save them! Thx.
it would not work with a .5 lb my car would just barley move with 3 lbs .
67Dart273
Well-Known Member
Look, this stuff is a two way street. We cannot see or hear what the OP sees or hears. We can't "imagine" what he's checked, done, replaced, 'effed up' and so on.
If the OP cannot "man up" get on here and type in good clear details "what the deal is" then "we" can't help him.
About one more round of this, and yet one more will be on my less-than-a-dozen ignore list. The most recent Alpha Hotel that made it will never get off. He can't even type decent thread titles, and loves to start new threads about what amounts to the same problem.
If the OP cannot "man up" get on here and type in good clear details "what the deal is" then "we" can't help him.
About one more round of this, and yet one more will be on my less-than-a-dozen ignore list. The most recent Alpha Hotel that made it will never get off. He can't even type decent thread titles, and loves to start new threads about what amounts to the same problem.
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