Running rich I think parts help

I have a 1999 with a 5.7 engine in it and 150,000 miles. It starts right up on the first start of the day. Last week it got real hard to start when the engine was hot. You have to turn the engine over a long time before it cachets. When it dose cachet the RPM are about 400 and then slowly moves to 600. I replaced the plugs but that did not help. I noted that the tail pipe had a LOT of black soot in it. I also have 1996 5.7 and looked in that tail pipe and saw very little soot. Any ideas on how to fix the starting problem? Any help or ideas would be great. Thanks Dave

Did you note the colour of the spark plugs when you took them out?Black would mean a rich condition.Can you check your fuel pump pressure?I am also suspecting that there are no active codes since you did not mention them.Fuel pressure is where I would begin.
chuck's

Thanks Chuck, I did not get a active code. The plugs looked good with no sign of dark color. I am not shur where to tap into the fuel at or if there is a spot to test the fuel press. Some think it could be a fuel presser reg that it under the intake manifold that needs replacing. What do you think? Thanks again Dave

You should notice two silver coloured lines that rise up from the left rear of the engine and make their way to the centre of the intake.One of these lines has a schraeder valve on it to plug a pressure tester to it.For this type of application the pressure should be 60-66 psi.If you have 58 or 59,that is not enough for the engine.To check the regulator it involves a few more specialized tools.It involves creating a restriction in the fuel line to test the pump .If the pressure increases,the pump is not at fault,but the regulator is.To change the regulator it takes alot of work,so getting the pump and regulator tested properly is critical.I would test the fuel system first before doing anything else.I hope this can help you out.
chuck's

Thanks Chuck, I am going to do the testing first that is for sure. I was also thinking that one of my injector might be stuck a little open and flooding the engine. I did run some sea foam thru the gas just befor it started being hard to start when. warm. Dave

I guess I should have mentioned about changing the fuel filter.It could be possilbe the sea foam has plugged the filter.Sea foam-what is it?A type of fuel conditioner/cleaner?
chuck's

Chuck, Sea Foam is a gas and engine additive that I found on the Suburban site here. I was looking at some post and the guys were talking about it and how good it was. You can search the Suburban and Tahoe or Yukon site and find the thread I think. It is sold at NAPA and marine stores. You can got to seafoam.com to read more. I will change my fuel filter next week and let you know. Thanks Dave

Chuck – I tested the fuel pressure and it went to 62 psi and then after the pump was shut off it fell to 20 psi in 10 seconds and to 0 in 30 seconds. I also own a 1997 2 door and I put the fuel tester on it and it went to 62 psi and stayed at 55 psi for 3 minutes after I shut off the fuel pump. So something is allowing the fuel to bleed out of the lines and to the engine. My questions are, it the regulator or are the ejectors not closing and if not what are all the inputs to keep them open? The fuel is running into the engine after the switch is turned off so for some reason the stopping part of the fuel injector system is not working. That means to me it must be something mechanical, what do you think? I have
a Hanes manual but it’s not very good. I did change the fuel filter o by the way. Thanks much for you ideas. Dave

Chuck – I tested the fuel pressure and it went to 62 psi and then after the pump was shut off it fell to 20 psi in 10 seconds and to 0 in 30 seconds. I also own a 1997 2 door and I put the fuel tester on it and it went to 62 psi and stayed at 55 psi for 3 minutes after I shut off the fuel pump. So something is allowing the fuel to bleed out of the lines and to the engine. My questions are, it the regulator or are the ejectors not closing and if not what are all the inputs to keep them open? The fuel is running into the engine after the switch is turned off so for some reason the stopping part of the fuel injector system is not working. That means to me it must be something mechanical, what do you think? I have
a Hanes manual but it’s not very good. I did change the fuel filter o by the way. Thanks much for you ideas. Dave

My bet is on the fuel pressure regulator but it could be an injector. It is pretty common problem on the Vortec engines.

//2000CAYukon

Is it the fuel pressure regulator that shuts off the fuel to the ejectors or is each fuel ejectors that has a shut off? Thanks Dave

Is it the fuel pressure regulator that shuts off the fuel to the ejectors or is each fuel ejectors that has a shut off? Thanks Dave

The regulator's job is to maintain a given pressure. Each injector when not firing should not leak and maintain pressure.

The regulator uses manifold vacuum to adjust pressure. The diaphram leaks and gas leaks into the manifold thru the vacuum line.

If an injector leaks, it could be due to dirt in the injector or it has gone bad. As fast as yours dropped pressure, it is most likely the regulator.

//2000CAYukon

Before diving into the pressure regulator,I would find out if there is a check valve in the fuel pump.I believe that there is and this could be a problem with the pressure leak down.A leaky injector or regulator could also be the culprits.
chuck's

Thanks 2000CA – I am going to replace the regulator this week. Is there any thing else I should do when I have the upper manifold off? I am assuming that I can replace the regulator with only removing the upper manifold. Is this true? Is there any trick to make the job easier? Thanks for all your help and the explanation on the working of the regulator. I am an anal airline pilot that just wants to understand all. Dave

OK replaced the fuel pressure regulator today. It took 5 hours but I am slow. The fuel pressure now remains at 55 PSI with the pump off and it didn’t bleed down for 3 minutes. It now starts when hot right away. The only problem is it now has a 404 code (EGR) with the check engine light on that has never been on before. I checked all the parts and they looked ok with the wires hooked up. It also has a miss as well but it had been doing it for a sometime. I though the flooding of the engine was causing the miss but I guess not. Dose anyone know where the EGR valve is located? Hanes Manual has it on the passenger side just aft the injector body. Is it bolted onto the upper intake manifold with two bolts that also hold down the upper manifold? Thanks for all your help. It sure made my day easier. Dave

Your EGR valve looks like this: http://www.rockauto.com/ref/SMP/SMPDetail2.html?EGV542.jpg

It is an expensive parts so I would make sure if is hooked up correctly.

You can also try clearing the code to see if it comes back.

//2000CAYukon

Thanks 2000CAYukon, I took the EGR valve off and found a piece of loose carbon under the seat. It looked real clean and I don’t know were the chunk came from. I cleared the code and drove it all day with no codes or engine check light on. By the way with the fuel presser regular bad and dumping raw gas in to engine I took it down to be smog and it past two week ago. With CA in your name I am thinking you live in California as well. Dave

Thanks 2000CAYukon, I took the EGR valve off and found a piece of loose carbon under the seat. It looked real clean and I don’t know were the chunk came from. I cleared the code and drove it all day with no codes or engine check light on. By the way with the fuel presser regular bad and dumping raw gas in to engine I took it down to be smog and it past two week ago. With CA in your name I am thinking you live in California as well. Dave

Yep, I am in the San Jose area. I am glad that you did not need to replace the EGR since it is expensive. Sounds like you have it running right now. Your mileage should also come back to normal as well.

Take Care,
//2000CAYukon