 BK3
join:2001-04-10
Geneva, IL | [Help] Hard starting when warm / hot 1999 Bonneville 3.8L NA 163,000 miles
When the car is cold, there is little problem starting. After the engine warms to operating temp, it is very often difficult to start. It turns over fine, but cranks unusually long, fires a few times, then fires and runs OK.
CEL light is on, P0171, lean condition.
I have replaced the FPR, some bad vacuum lines, spark plugs and the upstream O2 sensor.
I have cleaned the MAF (but have not ruled this out as the problem yet) If I disconnect the MAF while idling there is no change idle quality.
Fuel economy is poor (about 16 MPG) combined driving.
Coolant level remains constant (full)
No drivability issues noticed.
I do know that the plug wires are not in the best of condition, and will replace them at next opportunity.
Can anyone help me pinpoint where the problem lies?
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Gun control is being able to hit your target. |
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 GemstonePremium
join:2000-12-20
Long Island | How old is the fuel pump?
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BK3
join:2001-04-10
Geneva, IL | said by Gemstone:How old is the fuel pump?
As far as I know (only got the car this past January) the fuel pump is still the original.
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Gun control is being able to hit your target. |
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 mattmagPremium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3 |
Age is not a diagnostic factor, but pressure is. Do you have a fuel pressure gauge?
There is a significant amount of diagnostics that must be performed with this type of issue. The P0171 Lean code may be indicative of a failing O2 sensor and the ECM's response is to increase fuel flow to compensate. This of course uses more fuel than needed, and kills mileage.
The sensors need to be observed while in operation, and that requires a good scantool, which most DIY folks don't have. Other potential issues include leaky intake manifold gaskets, the MAF sensor and a coolant temp sensor giving false readings.
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GemstonePremium
join:2000-12-20
Long Island | reply to BK3
I have a 2001 Impala LS with the same 3.8L motor as the OP... A few years back I was having hot re-starting problems same as the OP is describing... It turned out to be a failing fuel pump which finally died completely and left me stranded on the road... I had the pump replaced and no more hot re-start problems... I agree other issues can cause this also, and I did not have a CEL or any codes...
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Go Mark Martin! |
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mattmagPremium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3 | said by Gemstone:It turned out to be a failing fuel pump which finally died completely and left me stranded on the road...
I'm not saying you're wrong at all, and it is very likely a pump problem. However one can't just say "Your pump is too old, that's the cause". I've seen pumps only a few weeks old fail, and other go for decades without a burp.
My only point as an automotive professional is to NEVER guess, and ALWAYS test. It just wastes money to throw parts at a car because of what "may" be wrong.
See what I mean? |
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 shdesignsPowered By Infinite Improbabilty DrivePremium
join:2000-12-01
Stone Mountain, GA | reply to BK3
It does sound like a fuel pressure issue. Could be fuel pump or regulator.
It would probably be worthwhile in investing or borrowing fuel pressure gauge. There are procedures to test if it is the pump or the regulator. |
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BK3
join:2001-04-10
Geneva, IL | I do not own a fuel pressure gauge (yet). Advance Auto Parts near me has loaner tools. Do you think that a fuel pressure gauge/tester may be among these tools?
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Gun control is being able to hit your target. |
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mattmagPremium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3 | reply to BK3
Re: [Help] Hard starting when warm / hot
I'd say there's a real good chance of that. They can cover many models with just a few adapters, so it would be worth asking about. |
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BK3
join:2001-04-10
Geneva, IL | said by mattmag:I'd say there's a real good chance of that. They can cover many models with just a few adapters, so it would be worth asking about.
I stopped by, and asked. They do not have a fuel pressure gauge / tester. So, the hunt begins. Do I go cheap with one from Harbor Freight, mid-range from a local auto parts store, Jeg's or Summit, or full blown from MAC or Snap-on? (MAC and Snap-on are probably too expensive for my once or twice a year usage. But it would be nice, though).
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Gun control is being able to hit your target. |
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shdesignsPowered By Infinite Improbabilty DrivePremium
join:2000-12-01
Stone Mountain, GA | reply to BK3
AutoZone shows a fuel pump diagnostic kit on their load-A-tool list (pressure gauge and adapters.)
I picked up an Actron pressure gauge. It works well on my 2 cars. Note: there is another version for GM TBI engines (or an adapter.) Was $45 and well made. |
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mattmagPremium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3 | reply to BK3
Definitely no reason to go high-end unless you're planning on using it multiple times a day. 
Don't even bother with the junk low-end stuff either though, so the parts store version is likely the best. They are a truly invaluable tool when it comes to automotive diagnostics. |
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BK3
join:2001-04-10
Geneva, IL | I was was looking at these:
»www.jegs.com/i/Equus/390/3640/10···essories
(I can use the extra parts on my mini-van, which doesn't have a schrader valve).
or
»www.summitracing.com/parts/anm-c···a/images
or for cheap:
»www.harborfreight.com/fuel-injec···699.html
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Gun control is being able to hit your target. |
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mattmagPremium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3 | Definitely the Actron from Summit.
The first one has easily-breakable plastic tee's and such, the Actron components are brass.
I didn't even click on the last one...  |
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 Doctor OldsI Need A Remedy For What's Ailing Me.Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18 | reply to BK3
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 cdruGo ColtsPremium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7 | reply to shdesigns
said by shdesigns:AutoZone shows a fuel pump diagnostic kit on their load-A-tool list (pressure gauge and adapters.)
I've used the AutoZone kit before. It's $150 but comes with a ton of stuff for testing just about any type of car. Online it say's Great Neck which is their store brand, but the kit I got was either orange or blue and was Actron branded.
I also had a basic Harbor Freight pressure gauge that must have cost all of $10. Worked fine for what I needed it for until I lost the little adapter to go from the schrader valve to the larger size on the gauge's hose. Oh well. |
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