Engine problem. I have no idea what I'm doing.

[I-r-welder81]

I'm having problems with engine power and fuel consumption on my 95 Yukon 5.7L. It starts fine. Idles fine. But when I'm on the hwy or going up hills (any size) I have no power to accelerate. The engine bogs down like its flooding. I've changed the rotator, cap, plugs and wires. Also EGR and EGR Solenoid. The cat is clear. My concern is the injectors. They look to be squirting not spraying fuel. The exhaust smells badly of un burnt fuel too.

Any suggestions would be appreciated.

 

[lesterl]

Might change the fuel filter, check fuel pressure, run some injector cleaner?

So the spray pattern is droplets and not a fine mist?

 

[lesterl]

DUP POST, See...

http://www.tahoeforum.com/showthread.php?t=526117

 

[Jens99tahoe]

Hi I just had these exact same issues with my 99 Tahoe 5.7L

Let me ask u.. Is ur service engine soon light on? if yes, what code(s) is it throwing

If none I agree check your fuel filter. I would also say you could have a leaky fuel injector, and or need to replace FPR (fuel pressure regulator) etc etc.
Just make sure and check ur fuel pressure.

Get back to us and let us know how it goes

 

[aznpersuasion]

what about the TPS? i had the same problem with a motorcycle and it turned out to be the throttle position sensor

 

[SouthJerseyTahoe]

Bad coolant temp sensor will make the injectors dump fuel. check resistance across the injectors to be between 1.2 and 2 ohms

 

[montess85]

Yea had same problem with my 90 K5. Bad coolant temp sensor was the culprit. Mine would idle fine but any load on it and it would just dump fuel and stall out. Very easy to change.

 

[blairian]

If it isn't the coolant temp sensor I'd look at the fuel filter, fuel pump, and injectors. Somewhere along the line something isn't functioning like it should, and usually with an issue like this it is delivery related.

 

[SouthJerseyTahoe]

The spray pattern on TBI injectors does look like droplets but you can also use a timing light aimed directly at the injection to see if its a nice inverted V pattern.
Its very rare i get one of these old OBD1 trucks in my shop anymore but it just so happens I got an 89 Chevy K1500 this week that failed inspection for high hydrocarbons meaning its got too much unburnt fuel in the exhaust. Upon further inspection I noticed its not going into closed loop and the O2 sensor isnt switching so its running rich. I tested the signal wire and ground all the way back to the ecu and I checked the ground at the exhaust manifold and then bench tested the O2 with a torch and a graphing meter. It turned out to be a bad ECU so he has been driving around in open loop all the time burning too much fuel.
Get your truck on a a scanner and make sure the O2 is switching and not throwing a code 13. Also make sure the engine temp is reading accurately. Not on your gauge but on the scanners datastream. The truck has a sensor for the gauge and a seperate sensor for the ecu. You cant just watch it idling either the old one wire sensors have to be driven at 4% throttle at full operating temp. for at least 1 minute to put it in closed loop.

 

[Bigbill]

Sounds like a clogged catalitic converter

 

[SouthJerseyTahoe]

Sounds like a lot of things but until you put a scan tool on it your guessing and wasting money. You can easily jump the A an B terminals in the diagnostic connector under the dash and get any flash codes that may be stored.

 

[I-r-welder81]

So it's been a while and I have figured out the whole issue(with all of your input). I bought a seal kit for my TBI and fixed the droplets forming and It turns out the timing on my truck was way off. I put a timing light on it and set it back to factory and its running a lot smother with decent power. Thank you all for the great input.