1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72freak · 04-11-2014, 02:07 PM

We have a weird loss of power thing going on at higher RPM's. 135,000 miles and its all stock. Its had a complete tune up in the past 10K miles, there are no check engine lights or codes, fluids are full, fuel pressure is right where it should be at all RPM's, the catalectic converters have been tested and are NOT stopped up. It runs fine until you accelerate hard and it falls on its face. There is no popping or roughness...simply no power. One of my mechanic friends doubts its the spider injection because there are no codes and no fuel smell but I have no idea. UPDATE. Another one of my mechanic buddies asked if the fuel gauge jumps around than the fuel pump is aerating despite what the fuel pressure gauge says.

Any thoughts.

Tropical Snowstorm · 04-11-2014, 04:14 PM

My daily driver 1998 1500 does the same thing, 2WD/5.0/3.42s when I put my foot all the way down north of about 3500 rpms. It does better half throttle at the same RPMs and I thought it was just me missing the worked over 5.3 in my other truck but it's definitely worse than when I first got the truck in 2007...

I keep thinking it might be a fuel pump (mine is original with 160k) not keeping up but really haven't been able to track it down. The pressure is right but the screen could be messed up in the tank or something else causing a volume issue, not a pressure issue.

I'm open to ideas too, let me know what you find!

speedygonzales · 04-11-2014, 09:19 PM

Valve springs

72freak · 04-12-2014, 06:17 AM

Quote:

Originally Posted by speedygonzales

Valve springs

More details would be appreciated. Have you had this experience with a Vortec and it turned out to be "valve springs". To tight?

speedygonzales · 04-12-2014, 09:43 AM

Do a search on valve spring tension. You'll figure it out. It's easy enough to change them on the vehicle IF it turns out that's the problem.

1badgmc · 04-12-2014, 11:38 AM

My '98 Suburban would fall on its face at higher throttle. If I kept my foot in the upper 1/3 of the pedal, it would be fine, but if I pushed much past that it would get pissed off. I changed the fuel filter and all was well with the world.

83GMCK2500 · 04-12-2014, 11:55 AM

x2, would also think fuel filter. All it takes is one bad fill-up to plug one or restrict one. I changed the filter on my '99 Tahoe every 10k-12k and I never had an issue with power or the poppet injectors.

Tropical Snowstorm · 04-13-2014, 04:38 AM

Never heard of any issues with valve float but that would make since given the symptoms. It's not the fuel filters on mine at least, changed with any hint of a problem since they're so cheap and easy.

Tom · 04-13-2014, 04:09 PM

My 98 did this when the fuel pump wasn't making enough pressure. I had like 5psi less then minimum at idle. Would drive fine until 35%+throttle then stumble on its face. Ran like that for over a month too before I checked the pressure.

72freak · 04-13-2014, 04:42 PM

Quote:

Originally Posted by Tom

My 98 did this when the fuel pump wasn't making enough pressure. I had like 5psi less then minimum at idle. Would drive fine until 35%+throttle then stumble on its face. Ran like that for over a month too before I checked the pressure.

everything keep s going back to fuel pump. We tested the pressure and it was fine but that doesn't read volume. Im probably going to have to just replace it and see what happens.

speedygonzales · 04-14-2014, 07:33 AM

Quote:

Originally Posted by 72freak

Im probably going to have to just replace it and see what happens.

Get a gauge that has a hose and either hang it in the window or tape it to the windshield. If your pump were not keeping up, the pressure will show it. Drive it and get the problem to show up and see if the pressure is low at that time.

Incidentally, the stock injectors are supposed to have 60 to 66 pounds at full prime.

The replacement (MP) injectors are supposed to have 55 to 62 at the same point.

Don't concern yourself so much with numbers as much as what the pressure is right before the "event" and during the "event".

Incidentally, there is now away to clean the injectors professionally on the engine with a snap-on cleaner.

72freak · 04-14-2014, 08:47 AM

Quote:

Originally Posted by speedygonzales

Get a gauge that has a hose and either hang it in the window or tape it to the windshield. If your pump were not keeping up, the pressure will show it. Drive it and get the problem to show up and see if the pressure is low at that time.

Incidentally, the stock injectors are supposed to have 60 to 66 pounds at full prime.

.

Already done this...all good.

speedygonzales · 04-14-2014, 08:52 AM

So your saying the pressure never changed from before there was a problem to when the problem occurred while driving it?

If that's the case, a pump change will not work.

72freak · 04-14-2014, 01:29 PM

Quote:

Originally Posted by speedygonzales

So your saying the pressure never changed from before there was a problem to when the problem occurred while driving it?

If that's the case, a pump change will not work.

Yep, drove it for several miles with gauge on the windshield with it acting up and fuel pressure was consistent and correct.

72freak · 04-20-2014, 08:52 PM

Culprit was the fuel filter. Changed it out and back to normal.

83GMCK2500 · 04-24-2014, 11:44 AM

Thank you for posting up the solution to what you experienced, may help someone down the road. Happy for you it was probably the most affordable of options.

04-11-2014, 02:07 PM	#1
72freak Rottenwood Garage Member Join Date: May 2005 Location: Marietta, Georgia Posts: 4,321	1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? We have a weird loss of power thing going on at higher RPM's. 135,000 miles and its all stock. Its had a complete tune up in the past 10K miles, there are no check engine lights or codes, fluids are full, fuel pressure is right where it should be at all RPM's, the catalectic converters have been tested and are NOT stopped up. It runs fine until you accelerate hard and it falls on its face. There is no popping or roughness...simply no power. One of my mechanic friends doubts its the spider injection because there are no codes and no fuel smell but I have no idea. UPDATE. Another one of my mechanic buddies asked if the fuel gauge jumps around than the fuel pump is aerating despite what the fuel pressure gauge says. Any thoughts. __________________ 2004 Chevrolet Suburban C1500 2001 Chevrolet 2500HD Crew 6.0 1999 Harley Davidson Electra Glide 1972 Chevrolet C-20 Custom Camper "Dump Truck" 1972 Chevrolet C-20 Suburban "Big Green" 1969 Chevrolet C-50 Wedge Hauler "Leonidis" 1966 C-10 2x4 short fleet 327 4 speed "Race Truck" 1952 Plymouth Cranbrook "Rican" (my grandfathers) 1931 Ford Model A Coupe "Black Beauty" 1930 Ford Model A truck "Club Cab" 4x4 Rottenwood Garage and Speed Shop.....where everything must be racy! *It's not just a hobby..It's a LIFESTYLE!!!* Thanks for nothing Barrett-Jackson You cant fix stupid or teach accountability! Time wasters, looky Lous and tire kickers are everywhere! Last edited by 72freak; 04-11-2014 at 04:13 PM.

04-11-2014, 04:14 PM	#2
Tropical Snowstorm Lurky lurky Join Date: Sep 2005 Location: Maryville, TN Posts: 553	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? My daily driver 1998 1500 does the same thing, 2WD/5.0/3.42s when I put my foot all the way down north of about 3500 rpms. It does better half throttle at the same RPMs and I thought it was just me missing the worked over 5.3 in my other truck but it's definitely worse than when I first got the truck in 2007... I keep thinking it might be a fuel pump (mine is original with 160k) not keeping up but really haven't been able to track it down. The pressure is right but the screen could be messed up in the tank or something else causing a volume issue, not a pressure issue. I'm open to ideas too, let me know what you find! __________________ Current slooooow build 1972 Cheyenne Super 1972 C10, sold thread 1970 Camaro RS Family Heirloom

04-11-2014, 09:19 PM	#3
speedygonzales Registered User Join Date: Jan 2006 Location: Smithfield, VA Posts: 1,501	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? Valve springs __________________ 99 Z71 (98 body style) Pride and joy

04-12-2014, 09:43 AM	#5
speedygonzales Registered User Join Date: Jan 2006 Location: Smithfield, VA Posts: 1,501	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? Do a search on valve spring tension. You'll figure it out. It's easy enough to change them on the vehicle IF it turns out that's the problem. __________________ 99 Z71 (98 body style) Pride and joy

04-12-2014, 11:38 AM	#6
1badgmc Registered User Join Date: Feb 2000 Location: Wichita Falls, Texas Posts: 3,153	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? My '98 Suburban would fall on its face at higher throttle. If I kept my foot in the upper 1/3 of the pedal, it would be fine, but if I pushed much past that it would get pissed off. I changed the fuel filter and all was well with the world. __________________ '91 GMC RC Sportside '98 Chevy Suburban '88 Chevy Crew Cab Dually Last edited by 1badgmc; 04-12-2014 at 12:03 PM.

04-12-2014, 11:55 AM	#7
83GMCK2500 Registered User Join Date: Sep 2009 Location: Beaverton, OR from WA State Posts: 1,515	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? x2, would also think fuel filter. All it takes is one bad fill-up to plug one or restrict one. I changed the filter on my '99 Tahoe every 10k-12k and I never had an issue with power or the poppet injectors. __________________ Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96

04-13-2014, 04:38 AM	#8
Tropical Snowstorm Lurky lurky Join Date: Sep 2005 Location: Maryville, TN Posts: 553	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? Never heard of any issues with valve float but that would make since given the symptoms. It's not the fuel filters on mine at least, changed with any hint of a problem since they're so cheap and easy. __________________ Current slooooow build 1972 Cheyenne Super 1972 C10, sold thread 1970 Camaro RS Family Heirloom

04-13-2014, 04:09 PM	#9
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,690	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? My 98 did this when the fuel pump wasn't making enough pressure. I had like 5psi less then minimum at idle. Would drive fine until 35%+throttle then stumble on its face. Ran like that for over a month too before I checked the pressure. __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

04-14-2014, 08:52 AM	#13
speedygonzales Registered User Join Date: Jan 2006 Location: Smithfield, VA Posts: 1,501	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? So your saying the pressure never changed from before there was a problem to when the problem occurred while driving it? If that's the case, a pump change will not work. __________________ 99 Z71 (98 body style) Pride and joy Last edited by speedygonzales; 04-14-2014 at 09:00 AM.

04-20-2014, 08:52 PM	#15
72freak Rottenwood Garage Member Join Date: May 2005 Location: Marietta, Georgia Posts: 4,321	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? Culprit was the fuel filter. Changed it out and back to normal. __________________ 2004 Chevrolet Suburban C1500 2001 Chevrolet 2500HD Crew 6.0 1999 Harley Davidson Electra Glide 1972 Chevrolet C-20 Custom Camper "Dump Truck" 1972 Chevrolet C-20 Suburban "Big Green" 1969 Chevrolet C-50 Wedge Hauler "Leonidis" 1966 C-10 2x4 short fleet 327 4 speed "Race Truck" 1952 Plymouth Cranbrook "Rican" (my grandfathers) 1931 Ford Model A Coupe "Black Beauty" 1930 Ford Model A truck "Club Cab" 4x4 Rottenwood Garage and Speed Shop.....where everything must be racy! *It's not just a hobby..It's a LIFESTYLE!!!* Thanks for nothing Barrett-Jackson You cant fix stupid or teach accountability! Time wasters, looky Lous and tire kickers are everywhere!

04-24-2014, 11:44 AM	#16
83GMCK2500 Registered User Join Date: Sep 2009 Location: Beaverton, OR from WA State Posts: 1,515	Re: 1999 Tahoe Vortec 5.7 loss of power at higher RPM's??? Thank you for posting up the solution to what you experienced, may help someone down the road. Happy for you it was probably the most affordable of options. __________________ Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.