I have an 88 TA 5.7L. 148K Mi. Recently installed a Hypertech thermo chip, I added some fuel injection cleaner to a fresh tank of gas and within a couple miles my fuel pump started humming like crazy (although I have heard these can be operating just fine while making alot of noise). Next I noticed on freeway I was bogging down at anything over 3,000 RPM when I put my foot into the throttle. I first thought that somehow the additive with the new Hypertech chip was creating a problem so I drained my fuel out and added some fresh gas. When Vehicle was cold I took the car out onto the freeway and I had power back with good throttle response, but humming was still coming from fuel pump. I then parked the car for the night. When I drove it the next day I had power loss again and it seemed to get worse (not sure if it was there right away or after temps reach 190). I thought the cleaner may have broken up rust out of tank and clogged fuel filter so I put in a new filter in and tested car while it was still warm and it was still bogging down. So I am wondering, why would it have regained power after adding new gas and then fall back off again (could there be an internal tank screen or filter). I know I need to check fuel pressure to see where that is at. But due to not having the equipment or cash to have this done right now I was wondering if anyone has ideas on what possible problems this could be? I also think my Catalytic converter may be nearing its end could that be a culprit?

 

ummm...yes, all of the above.

First i'd try it without that chip and see what happens.

But a failing fuel pump or a clogging cat could do all that as well.

 

I forgot to mention after changing fuel filter I did change chip back to the stock one and it had no effect. As for the cat, I realize the later ones with an O2 sensor after the cat will give feedback to the engine and act like a rev limiter which seems to be whats happening, can a broken down or partially clogged cat without the second O2 sensor do the same thing?

 

OMC,

If the cat converter is coming apart, pieces of the matrix can be clogging the cat, limiting your RPM and power output.

 

Thought I'd give an update on this. Changed the converter went with a Catco universal and had it welded in. Changed my o2 sensor and pcv valve. Runs like a champ again. My fuel pump is still humming although for some reason not as loud. Next on my list when money becomes available I will put in a fuel pressure gauge, hopefully inside with an isolator so I can keep track of the fuel pump situation. Oddly enough through all this my SES light never came on. It does come on when starting motor so I know the lights good

 

Even if you just pick up a diagnostic fuel pressure gauge, you'll be able to tell. Yeah riding around and watching fuel pressure all the time would be ideal, but if you're worried about the pump, drop the $40 for the diagnostic gauge. Mine is a Sunpro, from Pep Boys. Whenever I have a strange problem, the gauge is one of the first things I throw on the car. 5 minutes with that gauge and I can reassure myself that the fuel system is in perfect working order. (And so far, twice, it hasn't been. TWICE! Stupid pumps.)

 

I have seen the diagnostic gauges for about $40 but I have also seen where I could buy a small (about 1") gauge and mount it directly to the fuel rail for about the same. I may end up doing this just for the cost saving (over the isolator and in cab gauge), Then I could get a hose and tape the gauge to the window for temporary under load test. Not sure which way I will go yet. Not looking forward to the day when I have to change my fuel pump.
Any way to check to see if my SES light is operating properly?