*fixed* ANOTHER fuel pump/pressure question 03 Yukon Denali

[hushko]

Welcome to the forum.

Is the engine flex fuel or gas? What engine? Possibilities are 4.8, 5.3 and 6.0. For the sake of moving on I am going to assume a 5.3L. All 03 Denali's do not have the same parts.

Agree with @PNWTahoe about a possible injector problem. How old are the ignition components? Pull the plugs and inspect. Post pics of them here. That is just to react to fuel pressure but that 35 psi is not enough.

Flex fuel: https://www.rockauto.com/en/moreinfo.php?pk=7056044&cc=1415551&pt=10147&jsn=893

Gas: https://www.rockauto.com/en/moreinfo.php?pk=1300750&cc=1415551&pt=10147&jsn=892

Fuel pressure regulator-flex fuel: https://www.rockauto.com/en/moreinfo.php?pk=344238&cc=1415551&pt=6124&jsn=904

Fuel pressure regulator-gas: https://www.rockauto.com/en/moreinfo.php?pk=1029862&cc=1415551&pt=6124&jsn=90

 

[Fless]

Thanks. This is a 5.3 gas, not flex. I removed all of the plugs and they were all clean, tan colored and the center electrodes not eroded. Gaps all at 0.040”. The plugs and wires have around 65-75k miles. I use Sea Foam in the gas occasionally, and in the crankcase frequently. The fuel pressure regulator is new BWD. It’s an ‘02 Silverado with a later revision ‘03 engine (no EGR valve). Fuel pressure ranges from 48-50 psi.

Is the above response in the right thread? Seems out of place.

 

[CBIII]

Is the above response in the right thread? Seems out of place.

I see him c/p vietvet's response with all the links on my end.

BTW. replaced with an ac delco regulator and all is well again.. As far as fuel issues are concerned. Now to figure out why it's only getting up to 185f

 

[Fless]

If the radiator's been replaced, the new radiator needs to have a restriction in the small hose that dumps into the surge tank. Having too much flow there can cause overheating or underheating. Obviously check thermostat and temp sensors first.

 

[CBIII]

If the radiator's been replaced, the new radiator needs to have a restriction in the small hose that dumps into the surge tank. Having too much flow there can cause overheating or underheating. Obviously check thermostat and temp sensors first.

Yeah, that's what I've been reading! Some folks put a valve in-line, others PLUG their WATERPUMP (tf?). I actually just replaced my radiator this week as the old one was cracked and finally blew out. The innards of the oil cooler portion came out when removing the fittings (my 03's lines/fittings were slightly diff than the ones on the 05 core support assembly I grabbed) so I wound up bypassing that also. I'd not been paying attention to temp previously, figured it was fine where it was until someone pointed out it was running too cool. It has a motorad thermostat (not sure why I didn't take a picture of it. ADD/brokenbrain) that I THOUGHT said 165, but got tunnel-vision and tossed it back in after deciding it was *probably* ok. The waterpump threads decided to give out when reinstalling said thermostat, but I found a longer bolt and it's tight.. enough. Not keen on yanking IT off at the moment. I'll prob be swapping to e-fans this weekend as well, so there's a lot going on around the cooling system now...

TL;DR: I absolutely agree with ya about the replaced radiator/restriction at this point, @Fless. I'm just not sure which method I'm going to use to resolve it, but I may just tweak fan settings in my HPT and see if I can force it to warm up more before replacing even more parts.

 

[OR VietVet]

You can use a small hose clamp and tighten to restrict flow on the hose and see if that takes care of the concern. If it does, you know you found the problem and can do a better fix, like a restriction in the hose itself instead of the clamp.

 

[CBIII]

You can use a small hose clamp and tighten to restrict flow on the hose and see if that takes care of the concern. If it does, you know you found the problem and can do a better fix, like a restriction in the hose itself instead of the clamp.

I didn't think about using a hose clamp.. Good idea! I was going to burp it again tonight after I got home as well. I did see a puddle under the truck when leaving this morning though, so not sure what that's about yet. I'm hoping it was just runoff from my sloppy radiator swap.