1997 K2500 Suburban 454 Fuel System suggestions

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ZRoe

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Hey all,

Hoping to get some input on how deep to dive into my top end.

The fuel pressure regulator needs replacing because the truck doesn't like to start when it is hot and smells like it is flooded.

My concerns are how much else do I do while I'm in there.

I'm considering upgrading injectors to a newer 4 hole and possibly going up in size a bit to 24lb from the stock 19lb. I was looking at Accel 150824.

I have the gaskets to do the lower intake but I'm not sure what the signs for needing to replace the lower intake. No leaks on the front of the engine. Can't see the back of the engine yet. Anyone want to offer some advice here? What to look for, any tips?

I also have a slight tick in the driver side valvetrain that goes away once the oil pressure comes up. Wondering if checking the lash would fix this or if I should consider replacing that lifter?

Thanks for the help!

Pictures to come once I get it apart.





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454cid

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The fuel pressure relay needs replacing because the truck doesn't like to start when it is hot and smells like it is flooded.

Assuming you mean fuel PUMP relay, how did you determine it's bad?

I'm considering upgrading injectors to a newer 4 hole and possibly going up in size a bit to 24lb from the stock 19lb. I was looking at Accel 150824.

What problem are you trying to solve?

I have the gaskets to do the lower intake but I'm not sure what the signs for needing to replace the lower intake. No leaks on the front of the engine. Can't see the back of the engine yet. Anyone want to offer some advice here? What to look for, any tips?

Do you have coolant disappearing? If so, it's likely drying before you can see it.
 

ZRoe

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Assuming you mean fuel PUMP relay, how did you determine it's bad?



What problem are you trying to solve?



Do you have coolant disappearing? If so, it's likely drying before you can see it.
Thanks for the response!

Sorry I typoed, I meant fuel pressure regulator. I have read that the diaphragm goes bad and leaks into the intake tract when the engine is shut off.

I've heard that the factory injectors are not great and are a limiting factor when 6start to tune. I was hoping an improved 4 hole injector would provide better fuel atomization for better use of the fuel... Better mpgs when I'm not using the extra hp's

If I'm losing just a little coolant, hardly enough to notice. Nothing leaking enough to leave a green trail of liquid. I definitely have an oil leak somewhere on the back of the motor but I don't think there is any oil pressure held back by the intake? Just the top of the valley? More than likely it's my valve covers that are leaking.

Thanks again for the response.

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454cid

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Sorry I typoed, I meant fuel pressure regulator. I have read that the diaphragm goes bad and leaks into the intake tract when the engine is shut off.

What is your fuel pressure?

I've heard that the factory injectors are not great and are a limiting factor when 6start to tune. I was hoping an improved 4 hole injector would provide better fuel atomization for better use of the fuel... Better mpgs when I'm not using the extra hp's

MPG would be a nice gain.

If I'm losing just a little coolant, hardly enough to notice. Nothing leaking enough to leave a green trail of liquid. I definitely have an oil leak somewhere on the back of the motor but I don't think there is any oil pressure held back by the intake? Just the top of the valley? More than likely it's my valve covers that are leaking.

My truck has had an intake leak since it was new. I had the intake gasket replaced once, but the guy that did it, didn't use thread locker on the intake bolts like GM says to do. I'm probably going to have to do it again. It leaked visibly for quite some time, and now something is leaking a lot. If you're not hard on the engine, I probably wouln't bother replacing the intake gaskets yet... unless maybe it impacts tuning, or you're going to be in there already. I suppose if you're doing injectors, you are part way there.

Oil could be the pressure sender, too. It's back there.
 

Supercharged111

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Don't bother with bigger injectors, that'd require a tune. They're at least 21# stock anyway. But either way, a tune would wake it up.
 

ZRoe

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Thanks for the replies.

Fuel pressure was still at 55psi but it would fall to 45psi within a couple of minutes and was down to 30 in about 5 minutes. There was a noticable raw gas smell as well.

Replacing the FPR was not fun. The short little vacuum hose is a pain to get on. I ended up connecting the hose first and the pushing the FPR into position. The dizzy makes it hard to get a snap ring pliers in there but I eventually got it.

Scary part is the first couple times I cycled the fuel pump the pressure dropped even faster! Down to 20psi within seconds! I pulled the FPR back out to see if I had damaged the o-rings while installing but it looked okay, but I couldn't see the smallest one. Though I think if the o-rings were damaged it would be leaking into the return line and not the intake. I think it only leaks into the intake if the vacuum diaphragm is damaged.

I did notice a puddle (about a half of a cup?) of fuel in the back of the intake.

I'm guessing once the FPR wasn't leaking an injector or two started leaking. The pressure is dropping slower now like it used to but I can't see any injectors leaking. Is this something that I should be able to see?

At this point I'm strongly considering doing the 0411 swap while it is laid up and installing new injectors. I'm looking at the Five-0 replacement Bosch which are 4 hole 19lb, Trick Flow 4 hole 24lb, and Ford Performance 6 hole 24lb. All are made in the US. The Ford's are actually the cheapest but would require wiring adapters.

https://www.fiveomotorsport.com/bosch-454-j-code-024-blue-knight/

https://www.summitracing.com/parts/tfs-89024/

https://www.summitracing.com/parts/fms-m-9593-lu24a/

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Christian Steffen

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Thanks for the replies.

Fuel pressure was still at 55psi but it would fall to 45psi within a couple of minutes and was down to 30 in about 5 minutes. There was a noticable raw gas smell as well.

Replacing the FPR was not fun. The short little vacuum hose is a pain to get on. I ended up connecting the hose first and the pushing the FPR into position. The dizzy makes it hard to get a snap ring pliers in there but I eventually got it.

Scary part is the first couple times I cycled the fuel pump the pressure dropped even faster! Down to 20psi within seconds! I pulled the FPR back out to see if I had damaged the o-rings while installing but it looked okay, but I couldn't see the smallest one. Though I think if the o-rings were damaged it would be leaking into the return line and not the intake. I think it only leaks into the intake if the vacuum diaphragm is damaged.

I did notice a puddle (about a half of a cup?) of fuel in the back of the intake.

I'm guessing once the FPR wasn't leaking an injector or two started leaking. The pressure is dropping slower now like it used to but I can't see any injectors leaking. Is this something that I should be able to see?

At this point I'm strongly considering doing the 0411 swap while it is laid up and installing new injectors. I'm looking at the Five-0 replacement Bosch which are 4 hole 19lb, Trick Flow 4 hole 24lb, and Ford Performance 6 hole 24lb. All are made in the US. The Ford's are actually the cheapest but would require wiring adapters.

https://www.fiveomotorsport.com/bosch-454-j-code-024-blue-knight/

https://www.summitracing.com/parts/tfs-89024/

https://www.summitracing.com/parts/fms-m-9593-lu24a/

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Might not cause this issue, but did the old o-ring come out with the fpr? I had one get stuck once and i didn't notice until fuel was leaking outside of the FPR.
 

ZRoe

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Might not cause this issue, but did the old o-ring come out with the fpr? I had one get stuck once and i didn't notice until fuel was leaking outside of the FPR.
I got both of the old o-rings out. No fuel leaked by the FPR body itself, but it sure was going somewhere in a hurry. I actually caught it on video as I was starting to record my escapades in the barn for the entertainment\education of others.

I'll see if I can get a better look at it tonight. Ran out of gas (pun intended) last night.

Any other ideas of where to look for the fuel escaping? If it is indeed leaking into the return line I don't know how to quantify that? Is there any troubleshooting I can do other than replace the injectors or FPR again to see if it has an effect?

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Christian Steffen

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I got both of the old o-rings out. No fuel leaked by the FPR body itself, but it sure was going somewhere in a hurry. I actually caught it on video as I was starting to record my escapades in the barn for the entertainment\education of others.

I'll see if I can get a better look at it tonight. Ran out of gas (pun intended) last night.

Any other ideas of where to look for the fuel escaping? If it is indeed leaking into the return line I don't know how to quantify that? Is there any troubleshooting I can do other than replace the injectors or FPR again to see if it has an effect?

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If you pull the upper intake you can look to see if any of the injectors are whats leaking. If they aren't then replace the fpr again.
 

ZRoe

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Thanks for the tip Christian.

I wasn't sure I should be able to see the injectors actually leaking.

Could it also be the check valve in the tank draining back? Not sure how to test for that?

Reality is the stock injectors are 22 years old by now even if they only have 130k miles on them. I'm considering replacing them anyway and getting a tune\0411 swap.

The guys at 5-0 Motorsports suggested this injector as a nice step up if I was planning on doing some tuning. Any thoughts?

https://www.fiveomotorsport.com/0280155890-12456154-corvette-99-00/


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