Another fuel issue

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bzinsky

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So to make a long story short, I'm tired of mechanics replacing parts and failing to diagnose. I understand losing fuel pressure is a common problem and it could be a number of things. I bought a fuel pressure gauge, hooked it up, and sure enough, I am losing fuel pressure quickly. I've never hooked up a fuel pressure gauge before, so I don't know how bad it is.

From what I understand, it could be a stuck poppet or a leaking fuel pressure regulator. Can anybody hint at the problem judging by the video?

It starts pretty well when the engine is cold and has been sitting for awhile. Otherwise, long cranks. Fuel pump has been replaced.

Excuse the narration, I didn't think the engine would be that audible.

https://www.youtube.com/watch?v=Iv1NO3yRDLA&feature=youtu.be
 

2000tahoeZ71

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How many miles? Stuck poppet or fuel pressure regulator are in my mind the only things that can cause that. A leaking fuel pressure regulator is my guess as it will flood the intake plenum with fuel, essentially flooding the entire engine. A leaky poppet or two I wouldn't think would cause that. If you have never changed the intake gaskets, now may be a good time and while you are in there replace the poppet system with a new MPFI system.
 

willxfs

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My 98 Tahoe had the same symptoms many years ago. It was the fuel pressure regulator. Its an inexpensive part. As mentioned above, if your fuel injectors/poppet system has never been changed and you plan on keeping the rig for a while, now would be a good time to upgrade to the new style injectors. Only use Delco or Delphi. Its a pretty expensive part though. Probably $250-300. Check amazon and rock auto,
 
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bzinsky

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Thanks for your help guys, does the new mpfi kit include the fpr?

Also whats the difficulty of installation for both the kit and fpr? I'm more concern with labor than cost of parts. Wondering if I'm digging deep enough to do fpr I should get rid of poppets while I'm at it.

Any recommendations on conversion kits for a novice that doesnt want to be running around grabbing gaskets he didn't know he needed?
 
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bzinsky

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Read...read...read...youtube.

would have taken you about 5 seconds longer to answer my question, and save me a couple hours. I came to the forum to communicate with experts on my specific problem and take advantage of the power of on demand collectively shared knowledge.

---------- Post added at 03:07 PM ---------- Previous post was at 02:58 PM ----------

Also, I think I've came to the conclusion these mpfi conversion kits include the fuel pressure regulator, I even know which brands are best. What I cannot find is what other odds and ends I might need. I don't really want to get started and find out I'm missing something and kill an hour going to get it.

This is the kit I plan on buying, since I found it is the same as the delco. I can't find it cheaper since advanced auto will give me $50 off for a coupon code.
http://shop.advanceautoparts.com/p/bwd-fuel-injector-mfi-63886/20960205-P#fragment-4

This is what I found in the comments about extra parts


"With reference to your inquiry on the BWD Fuel Injector - MFI - Part No. 63886 you would need the following bracket and seal sets: BWD Fuel Injector Retaining Bracket - Part No. 28428 and BWD FI Seal Kit - Part No. 274789 for your 1996 GMC K1500 XC 5.7L truck. For any further assistance please feel free to call us at: 1-877-238-2623 or visit the nearest Advance Auto Parts store and one of our Parts Pros will gladly assist you with any questions or concerns you may have."

There's tons of other posts on amazon saying I might need to replace this gasket or that, but it's not clear

---------- Post added at 03:19 PM ---------- Previous post was at 03:07 PM ----------

Also there was a very thin, hard plastic vacuum hose coming over top of my intake manifold, i accidentally cracked and broke it. There's a vacuum pulling from the intake side. It connected to something in the fuel supply area in the plenum, back to a sensor bolted to the passenger side firewall, and then that sensor was wired to the MAF sensor. Not sure what it is, which means I don't know what to buy to replace it lol. Not a normal vacuum hose that I could use a plastic fitting to mend it, it's so thin it looked like a wire.

Didn't seem to effect how the engine ran oddly.
 

2000tahoeZ71

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Alrighty, first off, yes the MPFI system comes with a new fuel pressure regulator and the bracket. If you are going to replace the FPR, you are already there to just replace the whole thing. Next, if your truck has never had the intake gaskets changed, now is the time to do it. These engines were designed with a cheensy plastic supported intake gasket sandwiched between two dissimilar metals. Add a couple hundred thousand heat cycles and they crack and allow coolant to leak out of the engine if you're lucky, into the oil if you're not. Many people blame this problem on dex-cool coolant, which may exacerbate the problem, but I don't think was the sole problem.

However, Fel-Pro has an updated gasket set that includes every gasket to do the job, including the upper intake gaskets (which you will need to do the MPFI swap), and one valve cover gasket (you only need to remove one valve cover to get the lower intake off, but most people pull both of them).

Here's where youtube and the internet comes in handy. The gentleman above wasn't being a smart ass when he said this. Yeah everyone wants a quick answer here when often times that's not so. You usually will learn a hell of a lot more by researching yourself than having someone do it for you. Not nearly as convenient, but the truth. There are several videos of this job being performed on the 5.7 motors and several walkthroughs posted on the internet. It is a very tedious job as alot has to be removed from the top of the engine to get to the intake. It is a pain in the ass, but perfectly capable by someone who is decent with a wrench and is patient. While the job could definitely be done in a couple of hours, I would plan for about 6-8 depending on your skill level. As for what I would suggest as needed for the job.......

1) Felpro MS98000T Intake gasket set
2) Felpro VS50392R valve cover gasket
3) Delphi FJ10566 MPFI injection
4) Felpro ES72224 Intake manifold bolt set
5) A good INCH-pound torque wrench for the new lower intake bolts above
6)Crowfoot wrench set for the fuel lines on back of engine.
7)Cheap 4' fluorescent "shop" light- I used the included chains to hang the light across my hood, much better than wrestling with a work light.
8) Almost forgot, these trucks came with a no good, POS quick connect heater hose connection on the front passenger side of the motor. Now is a good time to replace it as it is likely corroded, or use a barbed fitting with a hose clamp in lieu of the original.
9) Coolant flush, new coolant and distilled water
10) Cheap oil filter, and cheap oil. When you do this job, some coolant and debris will inevitably find its way into the lifter valley and down into the oil. After you finish the job, drain the oil and change with the cheap filter and oil, crank it up, and run it for a little while then change back to what you normally use.
11) A good straight edge - the distributor must be removed to get the lower intake out. There are two straight lines on the distributor cap that I used in conjunction with a ruler to make two marks on the firewall so I knew the proper position of the distributor. This is imperative as these trucks have to be within +/- 2 degrees to keep the computer happy. If you have a tech II scan tool this isn't so important as you can use the tool to set timing. I didn't have this luxury so I made careful marks and have had no check engine light.

I would spend a lot of time researching this job before diving in. You may find yourself more comfortable paying someone to do it. Good luck!
 
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bzinsky

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Alrighty, first off, yes the MPFI system comes with a new fuel pressure regulator and the bracket. If you are going to replace the FPR, you are already there to just replace the whole thing. Next, if your truck has never had the intake gaskets changed, now is the time to do it. These engines were designed with a cheensy plastic supported intake gasket sandwiched between two dissimilar metals. Add a couple hundred thousand heat cycles and they crack and allow coolant to leak out of the engine if you're lucky, into the oil if you're not. Many people blame this problem on dex-cool coolant, which may exacerbate the problem, but I don't think was the sole problem.

However, Fel-Pro has an updated gasket set that includes every gasket to do the job, including the upper intake gaskets (which you will need to do the MPFI swap), and one valve cover gasket (you only need to remove one valve cover to get the lower intake off, but most people pull both of them).

Here's where youtube and the internet comes in handy. The gentleman above wasn't being a smart ass when he said this. Yeah everyone wants a quick answer here when often times that's not so. You usually will learn a hell of a lot more by researching yourself than having someone do it for you. Not nearly as convenient, but the truth. There are several videos of this job being performed on the 5.7 motors and several walkthroughs posted on the internet. It is a very tedious job as alot has to be removed from the top of the engine to get to the intake. It is a pain in the ass, but perfectly capable by someone who is decent with a wrench and is patient. While the job could definitely be done in a couple of hours, I would plan for about 6-8 depending on your skill level. As for what I would suggest as needed for the job.......

1) Felpro MS98000T Intake gasket set
2) Felpro VS50392R valve cover gasket
3) Delphi FJ10566 MPFI injection
4) Felpro ES72224 Intake manifold bolt set
5) A good INCH-pound torque wrench for the new lower intake bolts above
6)Crowfoot wrench set for the fuel lines on back of engine.
7)Cheap 4' fluorescent "shop" light- I used the included chains to hang the light across my hood, much better than wrestling with a work light.
8) Almost forgot, these trucks came with a no good, POS quick connect heater hose connection on the front passenger side of the motor. Now is a good time to replace it as it is likely corroded, or use a barbed fitting with a hose clamp in lieu of the original.
9) Coolant flush, new coolant and distilled water
10) Cheap oil filter, and cheap oil. When you do this job, some coolant and debris will inevitably find its way into the lifter valley and down into the oil. After you finish the job, drain the oil and change with the cheap filter and oil, crank it up, and run it for a little while then change back to what you normally use.
11) A good straight edge - the distributor must be removed to get the lower intake out. There are two straight lines on the distributor cap that I used in conjunction with a ruler to make two marks on the firewall so I knew the proper position of the distributor. This is imperative as these trucks have to be within +/- 2 degrees to keep the computer happy. If you have a tech II scan tool this isn't so important as you can use the tool to set timing. I didn't have this luxury so I made careful marks and have had no check engine light.

I would spend a lot of time researching this job before diving in. You may find yourself more comfortable paying someone to do it. Good luck!

Thanks, I just got finished today. I think I noticed a little oil in the intake mani. I couldn't tell if it was carbon build-up turned to slush from the gas leaking into the mani, or oil deposit from a slow but long term leak.

When I took the upper radiator hose off, I unfortunately noticed it had some of the dreaded milkshake. I couldn't tell if it was rust or oil. I wish I had read your post prior to starting. I figured if it was oil it was headgaskets, so I just let it be since I wasn't prepared to change the head gaskets.

I didn't have a chance to flush it yet, I don't think it's been flushed in a very very long time, maybe even the original coolant.

Took me about 8 hours, because of the not having correct tools, not wanting to force something, lighting, etc etc. The worst was trying to get those fuel lines disconnected. It would probably take 2 hours if I had to do it all over again.

I will say, was a pretty good feeling to have it start right up and purr. As you know, actual injector installation was the easiest part, relatively idiot proof too.
 

2000tahoeZ71

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Well, now that you've done that, you will be that much quicker in doing the intake gaskets. If you are already noticing choco milk, I would get to it. That water in the oil will wreck the bearings quickly.
 

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