99 Burb start great then pukes in Minutes

[pflyman]

99 k2500 burb 454
I have a unique problem, from all I've read in the AF. My burb will start every single time by reaching through the window and turning the key. Bam! she is running. Alittle rough at first but in a few seconds it smooth right out. After 4 to 5 minutes gags and pukes exactly like it's running out of gas. Wait ten minutes, reach through the window and she will fire right back up and die again in 4 to 5 minutes, time after time , all day long. I went through the usual start of replacing the in line filter, no such luck. While I had the fuel line off of the filter I put a hose on the line from the pump and turned the key to on. I had a nice 2 second flow of gas and the pump sounded good. I also had a good flow when the key was turned to off for about the same 2 seconds. Fuel pump, crank sensor, agnition sensor, fuel reg,o2 sensor or what? I do have a Check Engine Light on . How do I even begin to eliminate them. I've read the nightmare stories about burb fuel pump problems. You guys have already been through this, ANY HELP would more than appreciated, Thanks So Much In Advance!!
Dan

[777stickman]

1st thing is to pull the codes (DTC'S) that are turning on the CEL and post back the numbers, not the descriptions.

As far as "pukes" goes. How long does it take you to clean the mess up? (just kidding)

So, when it dies, is it like the key is turned off or does it start to shutter and miss like it's starving for fuel?

[pflyman]

Thanks for writing back and ya I sure need to pull the codes and I will as soon as I can and I will sure post them. I live in a cabin in the woods in northern Michigan and the snow is a problem since I don't have a garage or any place to really work. I may find someone around here to help me find a place to get a reader. To answer your question, it definately shutters and shakes like Elvis on drugs, fuel pump runs when fuel line is disconnected from the in line filter and sounds good, but when I connect it back up and turn on the key, I can't here it run at all. Maybe there just isn't enough pump pressure to overcome the injectors. What do you think about that. I'll get a ride to town to the NAPA store and buy a fuel pressure gage. I found the scrader valve so I can hook on and see the pressure readings and post them. I have Hughes net and the snow storms keep me from getting on my computer sometimes except in decent weather. I'll post back as soon as I can. Thank You again!!

[pflyman]

I have spent a few days doing research on "" The Suburban Fuel Problem NIGHTMARE"". Fuel pump,ignition Mod, oil pressure switch, crank position sensor, worn distributor gear, cam sensor, dancing fuel guage, fuel pump pigtail,fuel pressure regulator, leaking injectors, CRAPPY aftermarket fuel pumps, even gas cap sensors " FOR GOSH SAKES". It appears like ONE or all of these can cause the problems, we all know and LOVE, and fondly refer to as a Freekin NIGHTMARE!!!!!!!!! One of you guys who have been through this comedy of crap, should make up a flow chart, and make a \MILLION BUCKS. I would buy it in a minute. And send you a Christmas card EVERY YEAR----------------FOREVER!!! Just a thought from a frustrated burb owner!! I'm not broke yet, But I'm badly bent.

[777stickman]

Hey, I feel your frustration. Todays cars are all computerized. The days of being able to "shade tree" a problem are over! You listed a lot of stuff that could cause your troubles, but the most likely thing is fuel pressure.

So get the codes and fuel pressures posted back to us.

Do a search on fuel pressures by "MT_2500" to get some parameters.

Another thing to look at are the connectors and ground connections for the fuel pump since you live in a road salted area.

In the meantime put your snow shoes on and take the dog for a hike to clear your mind.

Do the tests and post back and hopefully we can make your "New Year" a good one.

[pflyman]

Stickman Hang with me on this! A new twist! Since my engine fails after 4 to 5 minutes, then after 10 minutes starts right back up, I tried something that worked. Weird but worked. I opened the hood and removed the relay cover. I let my truck run for the 4 to 5 minutes until it puked. I did this 5 times. 4 to 5 minutes then die, time after time. So I watched the clock. After 3 minutes of running, I would quickly pull the pump relay out off its socket. The engine would begin to puke,but before it died , I would quickly shove the relay back in. The engine would pick up and run again. I would let it run again for 3 minutes and repeat the process. I could keep it running this way indefinately. So after doing this for a half hour, I decided to see how long it would run if I just left the relay in this time. Well it never stalled again and I finally got my road plowed. It seems that by giving the engine short 2 second bursts of fuel using the relay and never allowing the engine to die, I have forced something ( I don't know what) to be overcome. I guess I could have had a dirty fuel tank screen or something else. In any case I'm sure this is no fix, just another piece of the puzzle. Going now to get Auto X-ray scout 1500 hundred to pull code and a fuel pump pressure guage. Isn't this a wierd one? Any thoughts? I'm almost enjoying this crap. I love a good challenge! But a flow chart would be nice. wish someone would " GET ER DONE"

[777stickman]

I'm probably too late with this, but why don't you pick up a new relay while your getting the other stuff. A relay that's failing after 4-5 minutes is not out of the question.

I applaud your thought process. Well done.

[pflyman]

I have my reader and fuel pressure test equippment. Priced the delco fuel pump. Guys at NAPA very very helpful. On my way back to get the relay along with the fuel tank hose removal tool. Thanks for the suggestion, I should have thought of that. I guess there is a possibility that it could be that simple. WE went to the Eagles last night and I met a guy up here who races stock cars and offered me his fully equipped garage for as long as I need it. He had his own ideas and is curious to see how this turns out, and even offered to spin wrenchs with me. He says he will work for beer and thats something I have on hand ALL the time. Great people here. My burb is running now, but I need to be able to trust it, so I will press on with diagnostics until me and my ole burb are both happy. Thanks Stickman. I'll report back!

[Elbert]

not to throw too much gas on the fire....but consider you may have some bad gas. I would replace the fuel filter right off the bat since its not expensive and not to hard to do. Do that and see what happens.

[pflyman]

Thanks for your suggestions , I do appreciate it. The first thing I did was to change the filter and to be honest, The one I took out was wide open, but I replaced it anyway. I now have a reader and got . Bank 2 sensor 2 Is running rich. Also, "Idle Higher than expected" code. I'm on my way outside to do the fuel pressure test on the fuel system. I have a new fuel pump relay as suggested by 777 stickman, but I'm reluctant to put it in right now because my truck is now running and I don't need anything to confuse me further. I cleared all codes and have decided to put my plow back on and use it here close to home until the codes return. I ran out the gas that was in the tank and I went to town and brought back 15 gallons of shell gas. The one thing I'm sure of is that it does idle at a higher RPM than it did. Around 900 RPM's , whereas it used to run very smoothly at 600-700. It also idles rough now and it used to run smooth as a baby's butt. I'm doing the dist., rotor and wires along with a good set of plugs, just to eliminate the obvious. FUEL PUMP TEST is a must so I'll take my time and get the proper data before I get to geeked up. Its running and the snow has let up here so I'm sleeping alittle better. I live in the woods off a two track so I was strarting to panick alittle but all is well now. If it PUKES again I'll clean up the mess like stickman said and get back on the problem till I cure this virus that my old burb has contracted-- I hope its just a bad cold, and not The Flu. I'm not ready to put ER OUT OF HER MISERY YET!!!

[pflyman]

Just In Case anybody may be following this "Burb Fuel Problem Saga". You may at this time proclaim A very loud ______"I freekin Told you so!! Ya I did a quick check with my handy dandy Actron CP 7818 fuel pressure tester and guess what, Key on, engine not started 48 Lbs. and falls to 0lbs in a couple of seconds------Key To "OFF" 48lbs falls to 0 in the same couple of seconds. Engine started, a constant 45 lbs. all checked at scrader valve. No 62-65 lb pulse and no constant 55- 58 when running. Just for a grin I will go ahead and pinch off the return line briefly and see what I get. I'm not expecting to see anything near 80lbs that I should see. Bummer , I'm feeling a drop the tank situation comin' on. I ain't likin' this bull crap. But I suppose I was grasping at straws. Turns out its the straw that broke the camels back. Delphi/Delco/AC here I come. Floor jack and a cold hind-end--I'm really getting to old for this S__T.

[777stickman]

Originally Posted by 777stickman

1st thing is to pull the codes (DTC'S) that are turning on the CEL and post back the numbers, not the descriptions.

Also, do the pinch off test as you may be looking at a faulty fuel pressure regulator.

PS: I looked at your age and you're just a pup!!

[Elbert]

does the suburban have an access panel to get to the tank (fuel pump) or do you have to drop the tank to get to the fuel pump? I'm guessing you have to drop it, but would be worth finding out first. I loved replacing the pump on my pickup.

[pflyman]

Ya Elbert, drop tank for sure. I'm not spooked by that though. I'll get it done. Hey, Stickman, can you tell me why you think it could be the Regulater. Is it because the pressure drops to zero so quickly? That would be OK with me because I have to remove all the air con. hoses anyway to get to the distributor along with removing the intake cover. Regulator has to be in there too. When I pinch off the return hose should it hold that pressure and not bleed down? Sounds like when return hose is pinched off it should hold whatever pressure I see. Is that right? As you may have noticed, I take things pretty slowly and try not to get in a hurry until I'm armed with the correct Info. It took me 10 years to build my cabin for God sake. I enjoyed that and am beginning to sink my teeth(the 2 I have left) into this. This young PUP sure appreciates the info. from all you guys from AF. You make this job alot more enjoyable and I love learning new things.You know "Give a man a fish!" Thanks Again!
Dan

[777stickman]

Dan: There are 30 items in the my '98 7.4 flow chart for diagnosing the fuel system. After reading most of those 30 items I would say that if you can close off the return line and the pressure stays constant, the press reg is faulty.

I am by no means an expert on this as I have not done it.

Hopefully someone with fuel related problems with the 7.4 will step in and provide some detailed info.

For sure, the pressures you listed are too low and the pressure drop off is not good.

One other thing. You do not need to pull the dist to change the press reg under the upper plenum. If you do pull the dist you will be opening a whole 'nother can of worms.