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Chevy 454 not getting gas
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Gardner
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May 20, 2015, 8:59 PM
Post #1 of 21
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Chevy 454 not getting gas
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My 87 motor home wont start
unless gas is poured into carburetor.
I replaced the weak fuel pump
and the in-carburetor filter.
It made no difference.
What do I try next ?
P.S. -
I could not blow through old Filter, assumed it was plugged.
New one is similar. Seems like there is a pressure valve in it.
Is that normal ?
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Hammer Time
Ultimate Carjunky
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May 21, 2015, 1:59 AM
Post #2 of 21
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Re: Chevy 454 not getting gas
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Mechanical fuel pumps are designed to pull, not push. When the rubber hoses in the supply line get old and start to dry rot, they get porous and the pump will pull air instead of fuel. You can test this theory by running the truck on a 5 gallon gas can connected directly to the fuel pump. If it runs OK that way, replace all the rubber hose in the fuel line.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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May 21, 2015, 3:41 AM
Post #3 of 21
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Re: Chevy 454 not getting gas
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All of what HT just said. Fuel filter in carb (new and dry) you should be able to blow thru but could have a check valve such that fuel doesn't want to run backwards.
Some RV things may not put a real filter there but rather under the fuel pump like a screw on oil filter, water separator. If never touched and has one it should be replaced - both checked for debris or rust mud perhaps?
T
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Gardner
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May 21, 2015, 9:49 AM
Post #4 of 21
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Re: Chevy 454 not getting gas
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1 - The Fuel Pump is brand new.
2 - Gas comes out of the gas line
at the Carburetor Full-bore.
3 - The Carburetor Gas Filter is new.
4) - The engine starts only when gas is poured into the Carburetor,
but only for a few seconds.
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Tom Greenleaf
Ultimate Carjunky
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May 21, 2015, 10:34 AM
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Re: Chevy 454 not getting gas
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I asked you what kind of debris came out of old filters - need to know. RV things sit around. If you have fuel at the 5/8th line full blast it has fuel. If it somehow can't get thru that filter and use at least a fine screen filter there if two on this then floats inside carb have probably nailed themselves up. Either just stuck or raised in an insane mud puddle of usually rust mud from tanks/lines, whatever.
Other trick that's dangerous it to whack the sucker but TOTALLY AYOR AND GENTLY WITH BETTER A MEDIUM PLASTIC HAMMER RIGHT WHERE 1" HOUSING GOES INTO TOP OF A QUADRAJET WHICH THIS MUST BE?
That's common for road RV stuff with lots of off time and cars did that too. DANGEROUS AS SAID AS THAT CAN BE WET WITH FUEL AND POOOOOF! Got it? Be ready but that's now likely IMO and actually fixes it if nothing else wrong. Otherwise if you are careful and watch tons of screws and adjustments you can take just the top of a Quadrajet off for a look-see. Magnets work to take rust out! Then clean. If clever you can hold float to jet shut off at pivot, down and run engine with the top off but don't if not well used to that - losing parts is much worse!
Quadrajets freak mechanics out even. If it needs work find the right OLD MAN now who knows how to deal with them -- not many around
T
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Gardner
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May 21, 2015, 10:48 AM
Post #6 of 21
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Re: Chevy 454 not getting gas
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I have not seen the smallest speck of anything in gas line or old pump.
Finger-sized pleated-paper filter in carb looked new.
I replaced it because I could not blow through it.
New one is similar.
I ran it every week during Winter
until coolant warmed up.
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Tom Greenleaf
Ultimate Carjunky
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May 21, 2015, 11:31 AM
Post #7 of 21
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NO! These only used smaller or larger inside the filter housing at carb not either! Now it can let anything thru with the smaller as spring now missing no doubt doesn't have a chance to hold it tight.
It doesn't make a rat's butt if it ran before or all Winter it's what's happening right now and it's locked up the needle valve this way or that way.
Don't touch this until you fix that filter! Look at the larger housing the screws into housing of carb too. There's a minute usually clear plastic gasket on the end with the threads into carb that IS THE SEAL and if missing leaks. Idiots put Teflon plumbler's tape to stop it and you are screwed if anyone did that to take whole carb apart to get shards of that out,
T
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Gardner
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May 21, 2015, 12:32 PM
Post #8 of 21
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Re: Chevy 454 not getting gas
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The Filter is A-OK.
I bought them both.
to be sure I had the right one
before I took it apart.
Turns out it took the long one.
The plastic washer is intact
and no Teflon Tape.
Sticking Needle Valve;
how common is that
on an old beast ?
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Hammer Time
Ultimate Carjunky
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May 21, 2015, 1:19 PM
Post #9 of 21
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Re: Chevy 454 not getting gas
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Did you install the filter facing the right direction?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Gardner
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May 21, 2015, 1:55 PM
Post #10 of 21
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Re: Chevy 454 not getting gas
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Filter will only go in one way.
end with opening is bigger than other end.
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Tom Greenleaf
Ultimate Carjunky
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May 21, 2015, 6:53 PM
Post #11 of 21
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From post #9"
Sticking Needle Valve;
how common is that
on an old beast ? "
That could happen to any "needle valve" on any make or model. Not sure why as most would self correct or that "love tap" I mentioned and either never do it again or replaced the valve just because it did it once. They could fail the other way and flood fuel all over the place.
Did you ever check if this has a filter on the fuel pump? This is an RV engine - not the same stuff everywhere just a size you've heard of for a workhorse.
The little (either longer or shorter fuel filter at carbs) was kinda little for wild fuel hogs like RV and Marine use so didn't put one there at all but rather a screen (nylon) on most and a huge on under fuel pump - maybe, maybe not? Maybe changed when someone found out how much it cost or when failed along the way?
By rights, parts for this should be coming from RV/Marine places but automotive stuff can fit so by now you have to figure out what might have been messed with.
One clue it's been altered is if the fuel line from pump to carb is rubber not steel. Pump to tank could be as said earlier for this but not showing those symptoms,
T
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Gardner
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May 21, 2015, 7:10 PM
Post #12 of 21
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Re: Chevy 454 not getting gas
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The new Fuel Pump I put on last week
was an exact replacement
for the number stamped in the old one.
It has no bowl or filtering.
The line going to the Carb is metal.
Does gas to the Carb go from the Filter
directly to the Needle Valve ?
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Tom Greenleaf
Ultimate Carjunky
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May 21, 2015, 7:43 PM
Post #13 of 21
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Re: Chevy 454 not getting gas
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Matching parts may be right for the wrong stuff but not why it isn't running right now.
Yes fuel goes thru filter or screen right to needle valve. Google out pics of how a needle valve and floats work. Lots like water level in a toilet tank type thing for carbs. Ball or floats, float and water/fuel in this case shuts off - same basics.
I have mega hours of work on Marine and only some on RV monster engines. None used fuel filters at carbs expecting to use obscene amounts of fuel so used a screw on oil filter looking one under the fuel pumps. Either could work and run just too much fuel to filter thru the dinky ones and always replacing them.
Right tools to do those for any reason. Fine threads of the housing send in shards. All are a bit fussy and must thread in properly by hand, both the larger housing then the 5/8th metal line with flare nut. Crossing those up just makes real troubles.
You use flare nut wrenches for both the ONE inch housing and 5/8th flare nut.
Filter will only go in one way but smaller will fit. Spring hold those tight to seal. A flap is there to make it one way flow only and you can blow thru most easily? Ones without that flap available just extend crank times a lot to get fuel up there after warm/hot shut downs.
Job 1 for now is get it to run properly for test runs. Long haul running you'll want a lot more checked or maybe alter some things yourself and carry spares.
Of all things right now messing with this be careful of fuel and fires. Things are tight for working and leaks happen so just be ready,
T
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Discretesignals
Ultimate Carjunky
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May 22, 2015, 4:36 AM
Post #14 of 21
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Re: Chevy 454 not getting gas
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You would think if it was a fuel filter or pump issue, it wouldn't run very well after he primed the engine and got it running. Does the choke plate close when the engine is cold after you press the accelerator pedal down once?
After it has sat and is cold if someone presses down on the accelerator pedal do you see a stream of fuel squirt out the accelerator pump shooter?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Gardner
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May 22, 2015, 4:33 PM
Post #15 of 21
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Re: Chevy 454 not getting gas
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Since this problem began a week ago,
the engine has only run for seconds
after being primed.
Where do I see this
"accelerator pump shooter" ?
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Tom Greenleaf
Ultimate Carjunky
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May 23, 2015, 1:31 AM
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Re: Chevy 454 not getting gas
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You won't see any because the fuel bowl is empty.
YOU HAVE A STUCK NEEDLE VALVE! THIS IS COMMON AS SAID. TIP OF VALVE STICKS IN ITS BORE EVEN WHEN FUEL LEVEL DROPS AND NO MORE FUEL CAN PASS THRU. YOU CAN EITHER REPLACE IT FROM TAKING TOP OFF THE CARB OR TAP ON THE TOP WHERE FUEL GOES IN WHICH IS DANGEROUS IF YOU CAUSE SPARK OR DAMAGE THE CARB.
Barely matters what type of carb or a damn toilet tank. They fail either way, no flow or flow won't stop.
You ran this all Winter till warm. Shut down so engine heat rises (all normal any time of year) and floats rise up to shut needle valve harder and it sticks there!
Any needle valve can do this - video.........
https://www.youtube.com/watch?v=vzunVSU9rfk
That one is being taken apart to fix.
This is what can happen to tip of the valve to make it stick............
Some would come with a tiny wire to pull it back out automatically every time some were lost or not used at all.
It's scaring me because you already put a wrong fuel filter in this and blowing thru the dang things if you should mess with it at all.
This is common and be done with it in a few seconds.
Said, Best would be new valve. To get it running usually tapping on it frees it but not for sure. Plastic something not metal and no sparks.
Bowl is empty so you wont know till cranked up or primed and after that try it should stay running about like you had just run out of fuel totally.
It still means carb in general has to be working along with choke.
Have a helper crank engine to be able to shut down. If fuel sprays around for any reason from messing with this be ready to shut it off and fire extinguisher is always suggested working around fuels,
T
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Gardner
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May 23, 2015, 4:37 AM
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Re: Chevy 454 not getting gas
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I DID NOT "already put a wrong fuel filter in this".
I put the identical Filter (with valve) in,
which looked and functioned identical to the old one,
which worked fine all Winter,
until last week, when something went amiss.
It seems that the Needle Valve may be the culprit.
Does it have a rubber tip ? - yikes !
It seems the Needle Valve allows the bowl to fill,
and prevents overfilling.
A SECOND cause could be
whatever path the gas takes
going from the Bowl to the Cylinders.
1) - What is in this path ?
I remember simpler carbs having an Accelerator Pump.
2) - Does this 4-barrel have one ?
3) - Will repeated pumping of the Gas Pedal
empty the Float Bowl ?
OR is it a 1-squirt deal ?
I'm going to the Plastic Mallet Store today.
But if the Needle Valve is sticking,
replacement is probably the only cure.
I hope I can get a top Gasket,
without buying a Rebuild Kit.
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Tom Greenleaf
Ultimate Carjunky
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May 23, 2015, 5:45 AM
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Can't be sure of anything from here but this one is too easy so far.
Stuck needle valve - that's it.
No joke, a LOT like a plain old toilets w tank on back has a float and valve to shut off water when full enough. You can adjust where that level will be same as carbs and need to have that right in carbs for proper fuel mixture.
It's just a pencil in a hole type thing. Allows more or less flow as fuel gets used and stop all flow when full like fuel expands and it doesn't allow more in after you shut the thing off.
Rubber tipped or perhaps nylon of some sort? Carbs would be so called "rebuilt" almost on a schedule which is/was a kit of gaskets, new needle valve and its seat, some assorted clips, check balls and a NEW accelerator pump. Rochester carbs like this use a plunger type and would squirt till you flooded it but not totally empty the bowl.
Note: If dry and you keep pumping it you'll wreck the plunger and find junk in the bowl or might anyway from time. Redos were just about a 40,000 mile service and folks don't like that. Quadrajets were the best fuel mixing machine ever made but so fussy they couldn't make two NEW run the same never mind ongoing service of them so quit carbs for injection you can't fool with.
Right now you just want this thing to so much as fart and run and might run well all year for you. At some point you should consider a total redo as said. It takes HOURS to set one right. It's NOT labor time friendly. What you should (I would hope) is get a kit that is now also Ethanol friendly - a carb killer as even some plastics don't tolerate it.
You should have front and rear choke pull-offs too. For this I'd say you only need the front one. The diaphragms in those fail from even fuel fumes in time and the adjustment of those is critical to instant starts, fast idle, no black smoke, ready to drive stone cold if perfect which is hard to achieve. It would save a LOT of fuel to get this whole carb right if you can find the right person or really do some serious homework on them. Old kits came with excellent diagrams and specs - can't speak for what you might find.
I'm just being real cautious with you about tapping on the inlet with a hammer thing. Said it was common on any not just this exact one with those symptoms. Also could stick and blow fuel all over a hot engine if failed open too - not good of course.
Just a typical view, there were 100s of small differences in these carbs.........
See fuel filter housing - yours could be to the side. Tap on metal of top of carb there is what I meant. If not that try spraying carb cleaner down the tallest pipe showing in that pic. That should put carb cleaner or if you can get fuel just into that into bowl. If it runs for a while it might shake needle valve to work indefinitely?
To replace it you seriously need to pay attention to where all rods and clips were in order. You can take just the top off with it in the vehicle most of the time as room allows.
By '87 expect some or many adjustments to be riveted or sealed off if you do a redo on it. Kit should explain where to drill out and knock out what to do what. Was just a means to stop folks from messing with them easily but can't clean one out with the tamper proof plugs and things in place,
T
(This post was edited by Tom Greenleaf on May 23, 2015, 11:27 AM)
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Tom Greenleaf
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May 23, 2015, 5:54 AM
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Quick addition - sorry. You said you hoped you could get a top gasket only. I never have. The one there will probably be fine for re-use if very careful - otherwise need the kit.........which would also have a new needle valve while there it's nothing,
T
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Gardner
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May 23, 2015, 7:08 AM
Post #20 of 21
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Re: Chevy 454 not getting gas
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Thanks a lot Tom !
you're a wealth of information !
I can tell you've "been there and done that"
I wish I had you under my Bonnet,
and my Motor Home Bonnet : )
I'm familiar with Needle Valves and commode Tanks.
But I draw the line at Computers and 4-barrels.
I have a shop full of tools,
from Power Hacksaw to Welder to Metal Lathe.
I'm not only a Frugal Pennsylvania Dutchman,
but enjoy the satisfaction of fixing things myself.
I built my own house with hammer and saw at 23.
And I retired from Business at 48.
Now I write for Homesteading Magazines, and Poems for fun.
Here's one for you:
- - - - - - - - - - -
"I Thank You"
© Nevin
This little note I send to you,
seems such a little pay.
To thank you for the thoughtfulness,
you chose to send my way.
Such little time and ink I used,
inadequate it seems.
To show that I appreciate,
how much your kindness means.
But be assured this sentiment,
is genuine and true.
And so I sit with pen in hand,
to write these words to you.
Thanks again for thoughtfulness.
and thanks for kindness shown.
May you and yours be blessed like me,
with blessings of your own.
- - - - -
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Tom Greenleaf
Ultimate Carjunky
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May 23, 2015, 7:37 AM
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Appreciate that.
Hurry sport - I'm getting old and the bod shows it. Where are my keys anyway? Screw the keys, where did I leave the car? Do I even have a car? You know or do you?
You can do this if you put your mind to it. Ask and find out like anything. Impossible to be a machine or homeowner and not be at least somewhat handy and still spend too much time working on them then using them
*****************
Tis that weekend so have some runs to do but will be around,
Tom
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