Problems starting lately
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
Likes: 2
From: Minneapolis MN
Originally Posted by RRT vette
You had pressure in the system the second time.
As far as ohming them I need to wait till my buddy comes out with his ohm meter, I can't find mine.
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
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From: Minneapolis MN
Originally Posted by rick lambert
Sounds to me like he just proved his check valve on the fuel pump is leaking.
Whats crazy is it fired right up again this morning, I will see what happens when I try to start it at lunch.
Le Mans Master
Joined: Oct 2003
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From: seattle WA
Yeah, bad check valve=new pump. Could be your fuel pump is just getting tired, your fuel pressure sounds fine, but it seems like at some points it's flowing back into the tank thru the pump, which indicates the check valve.I only come to this conclusion because it sounds like pressure holds everywhere while the feed line is clamped...but loses pressure when you unclamp it.
Actually, now that I remember back, I had the same symtoms you have when my fuel pump finally died.
Sometimes it would fire right up, sometimes I had to play with it...finally just went poop, and I knew I wasn't getting any fuel.
Actually, now that I remember back, I had the same symtoms you have when my fuel pump finally died.
Sometimes it would fire right up, sometimes I had to play with it...finally just went poop, and I knew I wasn't getting any fuel.
Last edited by rick lambert; Jun 30, 2006 at 09:59 AM.
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
Likes: 2
From: Minneapolis MN
Got it in but I am almost wondering if this isn't it since it starts the same after 24 hours of sitting as 3. The pressure after 24 hours is going to be low as well. After installing everything the pressure is still on at 40 when I click the key foward. This is what it was at when I had the bad gas and I wasn't having this problem.
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
Likes: 2
From: Minneapolis MN
Originally Posted by RRT vette
Not sure I understand you n1kki6, when you turn the key the pressure reads 40 psi? Thats o.k. ... other than that is it starting like it should or is it not?
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Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Originally Posted by n1kki6
The first start after sitting even overnight it will read 40 psi but still turn for about 5 seconds before starting. Then if I shut her down for a few minutes it start fine. So it only hard starts after sitting for more than a few hours but even then the pressure will still read 40 psi when I click the key foward.
It could either be spark or injector pulse. You can use a test light on the injector pigtail and have someone attempt to crank the engine and the test light should light up at that time. For spark use a spare plug and put it in one of the spark plug wires and hold it about 1/2" or so, from the exhaust manifold and have some one crank the engine and you should see a blue spark. Try both of these when you suspect it will take the 5 sec to start the engine. BTW, have you ohmed the injectors yet, this could show you something as well.
You can also try the fuel pressure test as you did earlier and see what happens.
Le Mans Master
Joined: Oct 2003
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From: seattle WA
Can you hear the FP relay energizing the system? If the FPrelay is shot, it will take longer to fire, at least until the oil pressure reaches 4 lbs. BTW, check the wires going into the FP relay, the insulation shrinks and they can be bare and shorting.
Le Mans Master
Joined: Feb 2006
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From: Louisiana
Originally Posted by rick lambert
Can you hear the FP relay energizing the system? If the FPrelay is shot, it will take longer to fire, at least until the oil pressure reaches 4 lbs. BTW, check the wires going into the FP relay, the insulation shrinks and they can be bare and shorting.
Thread Starter
Le Mans Master
Joined: Dec 2000
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From: Minneapolis MN
Originally Posted by RRT vette
It could either be spark or injector pulse.
By the way thanks a ton for the help so far.
Le Mans Master
Joined: Feb 2006
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From: Louisiana
Originally Posted by n1kki6
Wouldnt the car be running funny? The pressure still seems to drop so I still dont have that fixed either.
By the way thanks a ton for the help so far.
By the way thanks a ton for the help so far.
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
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From: Minneapolis MN
Originally Posted by RRT vette
Yes, it would. But these are two essential things needed to start an engine along with air flow. So, the pressure is doing the same as before? I would still like to see what the injectors ohm at , but I understand, that you don't have a ohm meter as of yet. Are you sure the only code you have is a current 72? If the spark and pigtail test work we will look elsewhere.
New test. Last night I clamped the feed line at the rail, unclamped and pressure dropped. Tongight I clamped it at the tank, removed it pressure dropped again, could the problem be somewhere in the feed line not nessecarily something in the tank. Couldnt be something like a mas airflow sensor not getting a good reading when cold could it?
The only code I am getting is a c72 on module 1.
Last edited by n1kki6; Jun 30, 2006 at 10:54 PM.
Le Mans Master
Joined: Feb 2006
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From: Louisiana
If you are getting spark and you know the injectors are getting signal for the PCM, I would check the ohms on the injectors to see if they are working properly. Even though they don't leak and there is pressure, doesn't mean the coils are good. Make sure that when you turn the key to the on position (not cranking), the fuel rail is primed with at least 40 psi. If not, then I would suspect the fuel pump relay. Come to think of it, on a LT1 the fuel pressure reads mid 40's with the vacuum on and low 50's with the vaccum removed, when engine running. The FPR controls the pressure delivered and would be at fault with a diaphram rupture which you would see with gas in the vacuum line.
Le Mans Master
Joined: Oct 2003
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From: seattle WA
BUT...what I think I'm hearing is when he turns the key on pressure is 40#, he clamps off the feed line and pressure holds. That in my mind eliminates leaky injectors (not say the coils couldn't be bad) and also eliminates the regulator. But, when he unclamps the feed line pressure drops..how much? because that to me indicates a leaky check valve or pulsator.
Thread Starter
Le Mans Master
Joined: Dec 2000
Posts: 8,740
Likes: 2
From: Minneapolis MN
Car fired right up this morning. I think it might be fixed I think the pressure gauge was leaking because when I came out this morning the pressure gauge hose was cracked open where it has to bend a bit for the egr valve.
need to replace the hose.
Le Mans Master
Joined: Feb 2006
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From: Louisiana
Originally Posted by rick lambert
BUT...what I think I'm hearing is when he turns the key on pressure is 40#, he clamps off the feed line and pressure holds. That in my mind eliminates leaky injectors (not say the coils couldn't be bad) and also eliminates the regulator. But, when he unclamps the feed line pressure drops..how much? because that to me indicates a leaky check valve or pulsator.