Any ideas?

CanadianZ71 · July 16, 2002

Hey guys, I'm a new user and a newer Chev truck owner. I bought a 1997 Z71 (5.7L)about two months ago and love it. Recently, however, it started to act a little funny. It (intermitenly) runs laboured - the engine sounds like it's running about 2000 rpm more than it really is - and there is just not the normal power behind it. At first I thought the tranny was slipping but the rpm's don't spike. The truck has 100K miles on it but has been well maintained and normally runs like a top. The problem arises more when towing (only small loads, ie. boat) and when the outside temp is high. Any similar experiences and/or ideas? Oh yeah the SES light has not come on once since I've owned the truck. Thanks.

CanadianZ71.

sincityZ71 · July 16, 2002

My old 96 GMC with the 5.7 did something similar to what your saying. It seemed like it was straining, but wasn't hitting high rpms. It turned out to be the fuel pump and the fuel pump sending unit. Got that replaced and it has run smoothly ever since (my dad now drives it.). Might want to look into that.

Colorado Kid · July 16, 2002

I'll bet that it's just the fan clutch engaging. All the clues point to it. When the clutch engages the fan (but not the engine) speeds up quite a bit, the fan takes power so the power seems to drop off and it happens more often when towing and when it's hot out.

CanadianZ71 · July 17, 2002

Colorado Kid, is this normal - the loss of power is quite substancial.

Off Road Red · July 17, 2002

Welcome aboard, Finally another Canadian member, wherebouts in Canada do you live?

CanadianZ71 · July 17, 2002

Edmonton, Alberta.

Colorado Kid · July 18, 2002

Well, I can't say much more than I did before...it does take power to run the fan...also since the fan engagement depends on the temp of the air at the fan it can tend to engage right after the A/C compressor engages (adding heat to the airstream), which also takes power.

The fan clutch engaging is perfectly normal, you benefit fromt he reduced load and noise the entire time it is disengaged, and it only kicks in when it's needed.

Is the amont of your power loss normal? I'd have to drive it to know, and E town is a long way from the Mile High City. If you want to bring it down here I'll be happy to check it out. ;) Or, even better, if you'd like to pay for a family of 4 weekend in Edmundton (Airfare and Hotel Accomodations included) we'll be really, REALLY happy to check it out for you!