96 Tahoe running rich

[edwcdc]

Hey Guys,
My 96 Tahoe is having some problems. It started when my fuel pump went up. I replaced it and I started having problems with it being rich. I discovered that during the replacement I kinked the fuel lines to the point where they were restricted. I dropped the tank again and replaced the plastic lines with rubber fuel line. In the mean time I also did a tune up replacing plugs, wires, air filter, pcv valve, and cap/rotor. The problem is that it runs rich, I get bad gas mileage and it idles rough. My SES light comes on and I get codes saying that the left and right banks are rich and I have multiple cylinder misfire. I even took the plugs out and made sure the gaps were right.
Also when I first start my truck in the morning it fires right up but after I drive it for a bit and shut it off it doesn't start right up. I have to keep the key turned for a few seconds.
I appreciate any help.

Ed

[maxwedge]

Check fuel pressure first, make sure you did not kink the return line somewhere this would boost pressure and cause the rich condition.

[edwcdc]

Well thats the thing, I have had the tank down 3 times and replaced kinked lines. Last weekend while putting the tank back up I made sure the lines were free and clear with no pinches or kinks. I was sure the problem would go away but here it is still.

[2000CAYukon]

Fuel pressure regulator is probably worn and leaking fuel into the intake causing rich condition and hard starting after the truck has been driven.

Do a search and you will see how common this is.

//2000CAYukon

[edwcdc]

Originally Posted by 2000CAYukon

Fuel pressure regulator is probably worn and leaking fuel into the intake causing rich condition and hard starting after the truck has been driven.

Do a search and you will see how common this is.

//2000CAYukon

Thanks 2000CAYukon,

I did a search but my findings lead me to believe that if my fuel pressure reg was bad I would lose fuel pressure but I don't have any trouble starting it in the morning. There seems to be enough pressure and it starts right up.

[maxwedge]

Get a gage on it and settle the question!

[2000CAYukon]

Originally Posted by edwcdc

Thanks 2000CAYukon,

I did a search but my findings lead me to believe that if my fuel pressure reg was bad I would lose fuel pressure but I don't have any trouble starting it in the morning. There seems to be enough pressure and it starts right up.

The regulators job is to control the fuel pressure based on engine load (using engine vacuum). The regulator can leak when there is pressure. Yes you can still start the truck in the morning but it can be hard to start when the engine is off for 15 minutes or more depending on how much it is leaking. Basically the bad regulator floods the engine while the engine is off and makes it hard to start. Overnight, the fuel evaporates and everything is fine. It can also cause a rich condition since the computer can not compensate for the extra fuel.

Like Maxwedge said, get a gauge on it and watch the pressure AFTER you turn the engine off. It should hold pressure. If it drops to zero, the regulator, or fuel injector(s) or check valve in the fuel pump is bad.

My money is on the regulator but it could also be an injector.

//2000CAYukon

[edwcdc]

Thanks guys! I will get the pressure checked and go from there. I don't look forward to replacing my regulator but if it turns out to be that I guess it will be worth it.
Thanks again, I will post a follow up when I get my pressure tested.

[Blue Bowtie]

The regulator si fairly easy to replace, and it's a good excuse to clean the intake tract and poppet injectors. It's also a good idea to check/adjust the regulator set point BEFORE reassembling the upper intake. I've had some out of the bag that were set a little low, and we're all painfully aware of what a little lower pressure will do on the CPFI systems:

[rhandwor]

Normally the pump has a check valve to prevent bleedback thru the pump. This maintains pressure for quick starts in the morning.
As bowtie says the pressure regulator controls pressure.

[edwcdc]

Thanks again guys and thanks Blue Bowtie for the pic. Being a newb I wasn't sure where to hook up a pressure gauge. Now I just need to find somebody with one.

[edwcdc]

Hey Guys,
I bought myself a fuel gauge and I will check my pressure after work today however I have some questions.
If it turns out to be the FPR how difficult is it to take the upper manifold off? Will I need to remove the distributor? What parts should I order to complete the job? I imagine there will be a gasket or two involved but I'm not sure.
I did a search and read the intake diy sticky but it wasn't too clear about just the upper manifold.
I appreciate any information.

Thanks,
Ed

[edwcdc]

Update:
I hooked the gauge up and turned the key on. The needle shot up to 60 and quickly dropped like a stone. I guess its time to get my hands dirty.

Could someone tell me what parts I should order so I don't get half way into the job and need a gasket or something. You guys and this forum have been a great help. It sure would be nice to get this thing behind me after putting up with it all summer.

[rhandwor]

Are you going to just install a fuel pressure regulator or are you also going to clean the fuel meter body assembly? Your not supposed to soak it but use carb cleaner to remove deposits.
Disconnect bat.neg.
relieve fuel pressure.
remove coil.
remove intake manifold plenium
Disconnect vacuum line
Remove snap ring from reg housing
place towell under
remove reg twist back &forth
remove o-rings
lube new o-rings with oil
install with new parts vac line pointed same dir.

[edwcdc]

Originally Posted by rhandwor

Are you going to just install a fuel pressure regulator or are you also going to clean the fuel meter body assembly? Your not supposed to soak it but use carb cleaner to remove deposits.
Disconnect bat.neg.
relieve fuel pressure.
remove coil.
remove intake manifold plenium
Disconnect vacuum line
Remove snap ring from reg housing
place towell under
remove reg twist back &forth
remove o-rings
lube new o-rings with oil
install with new parts vac line pointed same dir.

Thanks,
I'm going to replace the FPR so I know I will need that. Will I need an intake gasket?