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Drinks Gasoline
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Discussion Starter #1
Hey everyone,

'95 Impala SS. 13K miles. Over the last several weeks I've had to hit the key two or three times in the morning when the car has sat overnight to get it to start. It'll start and immediately die on the first couple attempts. Once warmed up for the day it starts no issue.

Over the weekend it has gotten worse, now it requires several start attempts before it'll run even when it's warmed up. I am concerned about being left stranded.

I've done a little looking and it appears that others have had to replace a fuel pump to get this resolved. Figured I'd ask if there were any other known issues that could cause this before I sought out a fuel pump. Also, I wasn't clear if others are replacing the entire fuel sender assembly, or just the pump and sock. I was also curious as to the brand of fuel pump people like, AZ lists an available but special AC Delco unit, is that a better choice?
 

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They do make an aftermarket check valve that you can install on the fuel line coming from the pump. It keeps the fuel from draining back into the tank by maintaining pressure in the fuel line. What is your fuel pressure right now?
 

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Have you tried cycling the key a few times without actually cranking the engine? When you turn the key on the fuel pump is supposed to prime for a couple seconds if doing this a few times before cranking and it then starts on the first cranking attempt I think that would be a pretty good confirmation of a fuel prime issue like pressure bleeding down too soon.

I would check the ground on the trunk lid support and put a new fuel filter in it first thing.

Is the car going to stay near stock or do you plan to modify it? I ask because it affects the choice of which pump to buy should it come to that.
 

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What Dwayne said...mine did this for about a year before the pump shit-the-bed.
 

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Drinks Gasoline
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Discussion Starter #7
Okay, just had time to check the car out.

Key on, engine not running, 38psi
Key on, engine start, jumps up and down and settles at 38psi
Engine running, revving up, drops to about 35 psi
Engine shut off, jumps up to 48psi and then back down to 38psi

From what I've read around various sources, 38psi is a tad on the low side.

I did not do a "leak down" type test, ie, pressurizing and letting it sit for awhile. Figured I'd button up the garage for the moment.

Oh, dumb question...

I pulled the sound baffle "home plate" thing and sat it aside and tried to start it probably half-a-dozen times with symptoms similar to, but not quite the same as what I was having before I started this- it would start and peter off, but a little more slowly than before. In desperation I stuck the baffle back on at an angle so that the hole in the intake pipe was closed off. I had figured that the throttle body, being right on the front of the engine was behind this opening and wouldn't matter, but it appears that this was an incorrect assumption and that the the pipe has to be intact all of the way to the air cleaner housing... I'm much more familiar with carbureted vehicles, what am I missing?

Drivetrain is probably going to remain stock. I have a couple of restoration projects that are the true toys, this is my daily driver. I plan to do some suspension improvements as I had to do a panic avoidance maneuver and almost lost control of the car it wallowed so much, and I put a hitch on it and have dragged it a couple times, so some helper airbags in the coils to add just a little pressure will probably also happen.
 

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I think that the mass air sensor has to see air flow for the engine to keep running after the start.
With the sound baffle pulled i take it that unfilter air would be by passing the mass air flow sensor causing the computer to become confused , leading to a stall or shut down of the engine.
The home plate deleat is when the resonator is removed and a round plug is placed in the hole in the piping(a hockey puck is what is normaly used).
You might want to look for carbon build up on the throttle body and plates as this may be adding to the peter out after the start.:idea:
 

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Drinks Gasoline
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Discussion Starter #9
I'll take a look. The car has less than 13,000 miles on it, so I'd really hope that it wouldn't be all carboned up yet, but I'll look.

While I was in there today, it looks like the front seal on the AC compressor is going, standard splatter pattern along the belt path, some on the hood insulation, most down low. Always something to fix...
 

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Drinks Gasoline
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Discussion Starter #11
Yeah, I'm keeping an eye on things. The car was in a climate-controlled garage for the 6,400 miles that it was driven until mid-2012, and when I pulled the belt off it was original and uncracked, so I put it back on. The hoses were also firm but pliable. I keep a set of radiator hoses and a belt in the trunk in case there's a problem on the road, and at least the tool for the belt in the center console. The A/C wasn't fully pressurized when I bought it, but had some pressure, so I added a couple of cans of refrigerant and brought it up to pressure and it worked for the summer. I used the stuff with the dye, but it's pretty clear where it's leaking.

And yes, I did the differential service with the gasket with the added holes.

I've got a couple sets of factory service manuals, a rougher set out in the workshop and a clean reference set at my desk so I can look stuff up as I need. So far I haven't really needed them yet, but I'm sure I will.
 

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Drinks Gasoline
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Discussion Starter #12
Okay, did a leakdown test for an hour and fifteen minutes, ended up turning on ignition to check mileage and forgot that would reset the pressure...

Initial read - 38psi
15 minutes - 34psi
30 minutes - 33psi
45 minutes - 32psi
75 minutes - 31psi

I'm going to check it again in a few hours after it's sat.

I also checked the air filter and found it FILTY. It's original. 12,821 miles but eighteen years... Put a new high pleat count WIX in. Thought about K&N, but I don't feel like messing with cleaning and oiling a filter on a regular basis.
 

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Drinks Gasoline
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Discussion Starter #13
Oddly, the problem hasn't manifested in a few days.

I'm starting to suspect that either fuel temperature is playing a role, or that the fuel blend is an issue. The problem started back in either October or November, and has subsided in late February or early March.
 

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The pressure is holding fine. Though it starts a little low. With the engine off or with the vacuum line disconnected pressure should be 43-45psi.
 

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Drinks Gasoline
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Discussion Starter #15
When it cooled off the problem resumed. I'm fairly sure that it's triggered by temperature. I've ruled out winter fuel issues because we're still on winter blend until the end of February. Temps are expected to climb this week, I'll see if the problem goes away. If it does, then I'll need to figure out why 40-60° temps cause this, and why it goes away above sixty degrees...
 
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