1999 Suburban idleing and starting issues

[cwh13]

I bought a 1999 K2500 suburban with a 7.4L used and I'm having a few issues. The suburban idles a little rough. I've had and driven many big block Chevrolet trucks and have never had one idle other than smooth. Also the suburban is tough to start at times. Seems like if it sits for a short time it will crank for an extended time, run rough and then smooth out. I've read many of the treads in this forum and still have some questions. My fuel pump is a new delco unit so I feel that it is not a problem. I also changed the fuel filter ver recently. When I turn on the ignition I see 62 - 64 psi at the rail. When I start it I see only 54 at the rail. When you give it some rpms it will gain about a psi. Power on the highway doesn't seem to lack. Our local library has an awesome reference section and I made some photo copies. It says to pinch the return line and check for an increase of fuel pressure. Where is there a flexible return line to grab on to? If it is the regulator, would it be wise to purchase a delco unit or is a like NAPA or carquest sufficient on an item such as this. If I do replace the regulator I'll need to take the upper manifold off. What is a telltale sign of a bad injector?

Thanks,

Chris

[010175]

I had the same problem with my 1999 5.7 engine. The folks here said it was the fuel controller. They were 100% right. You can the search this forum in the upper right side to find most the answers out for any problem you have. It works well to start out. If you do that you will find out the answers faster than posting and waiting for the reply. I hope this helps you. Dave

[cwh13]

Thanks. I've read a bunch on this forum. Its layed out much better than some of the others. Makes it much easier to find a similar issue and responces. I havn't had a chance to dig in deep and read a bunch of the posts but I will.

Chris

[grumpy5]

My 99 has idled rough since I bought it. I tried a tune up. No help. Bosch plugs actually made it worse. I think GM had to lean the fuel mixture at idle to apoint wereit runs rough just to get some kind of decent mileage out of it. I also have a starting problem with mine. About every tenth start, it sputters and doesn't want to fire off. I replaced the fuel pump with a non GM pump a couple of years ago, so i don't know if it is the pump or possibly the starter. I did the starter about a year ago, which is when the problem popped up. So, to make a short story long, the rough idle seems to be inherent in the 99 7.4. The starting problem, I'm leaning towards a fuel delivery problem.

[cwh13]

I had to have the engine replaced shortly after I bought it and I couldn't afford a new 7.4 so I had a used one installed. I have the original engine in my garage so I may try the fuel regulator from it. I havn't priced the regulator yet but I'm sure its spendy. I believe that its integrated with the fuel rail. We'll see. Thanks for the input, glad I'm not the only one pulling my hair out.