Hello All...

2000 4dr 4wd LS 4.3l V6

I've had the truck leave me stranded a couple of times recently. When it's cold and he vehicle has had a chance to sit for more than just a couple of hours, it'll turn over (and turn over and turn over)...but not start. After a couple of tries starting, this seems to result in a flooded condition. I say this because the oil smells strongly of gas...and...because it just acts flooded. When it's warmer out, the truck starts better...but, still turns over more times than "normal" before it starts. It does this whether I "prime" the fuel system or not. By "prime", I meanturning the key part way first (for a few seconds) and then turning it the rest of the way to start to allow the fuel system to pressurize prior to starting.

I've done some online reading (a significant portion of it here), and found that these are common symptoms of a bad fuel pump check valve (leaking), fuel pressure regulator (leaking), or bad fuel injectors (leaking).

I tested fuel pressure at the fuel rail and found that I have about 60psi fuel pressure immediately after I turn the key...just letting the fuel pump cycle (no start). Within less than one minute, fuel pressure falls to zero (yes, that fast). If I start the vehicle, fuel pressure stabilizes around 55psi at the fuel rail (running). All this really tells me is that I cannot maintain standing fuel pressure...because of a leak somewhere.

I have looked inside the TB past the throttle plate, and do not see raw fuel (before and after fuel pump cycle). I do, however, smell it inside the TB after fuel pump cycle. While I cannot eliminate the possibility of leaking fuel injectors...this set of cirsumstancesleads me to lean strongly toward a leasking FPR.

I had the fuel pump replaced about 6 months ago. So, while POSSIBLE...I'm thinking that a fuel pump problem is unlikely.

So, here are my questions...

1) Am I on the right track to be targeting the FPR and fuel injectors?

2) If so, how do I identify the single problem component without removing the upper intake plenum for individual component inspection?

3) If not, where should I be looking?

Also, I see information on how to go about changing the FPR for "CPI" systems all over. I think that means "central port injection". I've been told that my injection system is a "multi-port" fuel injection system.

Is this true? Is FPR replacement the same for each? If they are different...what is the correct procedure for replacing the FPR...assuming that is the problem.

Thanks in advance for the direction!!

Icarus76

 

Yes your truck has the multi port not the cpi FI. The only way you will see what is leaking is to take the upper intake off. Then put the fuel lines back on, and prime the system. The FPR is of the same design as the old CPI units. I have not replaced one yet, but it should be really easy once you are under the upper intake. Pulling the upper intake is pretty easy, and the gaskets are even reusable, but I would replace them since they are pretty cheap. Korey

 

OK...

Sinceabout15 people have looked at this thread...and no one's piped up to tell me what a fool I am [&:]...I assume I must be on the right track to be looking at the FPR and injectors for leaks.

With that assumption, my primary concern is that I'll get everything opened up and not have the right part(s). So, I'm considering buying everything I think I could need...and just returning whatever I don't use.

What I'm awareI could need is:

FPR: GM PN89017453 $74.99
FI: GM PN 17091432 $107.44 (6 of these)
FI Seals and Retaineer Kit: GM PN17113205 $37.81
Plenum Gasket Kit: GM PN17113215 $42.11

$645 ($107 x 6)is alot of moeny to spend on something I may need for injectors. Which begs the questions:

How likely is it that a leak in the plenum area is due to faulty fuel injectors...say, as opposed to the FPR?

What is the reasonable lifetime of a fuel injector...shouldI be changing them while I've got things opened up, even if they aren't causing trouble now?

If a FI's lifetime exceeds the life of the vehicle, and I only need to replace the one(s) that are leaking...what would be a good number to have on hand for the job? (ie: 1, 2...all 6...?)

Thanks again!

Icarus76

 

Like Kordog stated, you really need to open it up, reinstall the fuel lines and repressurize the system to find the leak. It is quite possible that it is simply an o-ring on an injector.

The stock SCFI system has an injector and a poppet nozzle. If the injector is leaking, then so will the poppet nozzle until the pressure drops to below ~45psi after which it may still weep (due to their notorious tendancy for tarnish buildup on the seat), but not at the same rate. If the pressure bleeds off from 60psi at a steady rate, I'm thinking you have either an injector oring problem, a leaking FPR or the check valve in the fuel tank is spent.

As far as buying new injectors... Well, it is MUCH more economical to purchase just the FPR if that is the only problem. But instead of buying new injectors/poppet nozzles, the updated MFI spider that is a direct replacement for the original setup is a much better option If you have to replace the FPR and 2 injectors, you just paid for a new MFI setup from the dealership, but if you only have to replace some o-rings, well... The entire MFI spider sells for $160 +s&h at GMPartsDirect.com and is available under PN 12568332, but the s&h is steep and shipping is slow in my experience with them. It should be available from the dealership for around $200-250, but could be as high as the $300 list noted on GMPD.com.

And I wasn't ignoring this post. I thought that Kordog had given the necessary suggestions and was waiting for a followup as to your findings.

 

Kyle...

I didn't feel ignored at all. Ithought that no one had responded with contradictory information because I was on the right track...that's all. No sarcasm there.

I realize that I have to open it up to see what's going on. I'm just trying to be prepared for most anything once I get in there...and to make smart use of my time there.

I'll investigate the MFI spider assembly...and follow-up with findings.

Thanks,

Icarus

 

I didn't see it as sarcasm either. No worries!

Where in CNY are you located?

*EDIT* - Now with the removal of the plenum, you will need to remove the fuel lines. This can be a pain in the *** with the distributor in. I was able to flex mine out of the way enough to get the upper plenum off, but I will NOT do that again nor would I recommend it. I had a really fun time attempting to get the lines back into the SCFI body.

Best advice that I can give is to use a stubby wrench to disconnect the fuel lines. If you don't have enough room, then you may have to mark and remove the distributor and make darn sure that you don't bump the starter at any point before you drop it back in.

 

Hmm...

According to the chevy dealership...I cannot get a "spider" for my vehicle. GMPD verifies this. PN 12568332 is not listed under my vehicle in GMPD's catalogue...only the sigle FIs (PN 17091432). I guess I'll just grab a couple injectors...and hope that I don't need them.

Icarus

 

This is wrong and is because they do not show it for your application is even more wrong. It is a direct fitment and what is used on the 2001 or 2002+ engines. The PN is correct. It won't show up under GMPD.com's catalogue, but I assure you it is correct. I have a TSB referencing this replacement spider for the fix for varnished poppet nozzles that resist cleaning.

 

Maybe I'm confused...

Does this PN 12568332 include fuel injectors, or is it just the spider body?

If it all inclusive, I may still be interested. I understand it requires the use of an additional bracket (PN 88894355).

Does it come with seals and retainers for the FIs? If not, are the seals and retainers the same as in kit PN 17113205?

Icarus

 

PN 12568332 is an entire injection spider kit. It includes the injectors, metering body, the FPR, retaining plate, and all internal orings. If you did need to replace any of the orings, they are the same as those used in the current metering body.

The bracket is exactly the same as the one in your engine.