Hello!

I've been researching this problem for a little while now, and I'm just getting into trying to fix these problems myself so I'm a bit new to this.

My Jimmy has two problems which may or may not be related. When I start it up, it surges when idling and at times it even has trouble starting. When the truck warms up it runs great, although I eventually get a 'running rich' code, 45. Getting about 200 miles to a tank which I think it could be doing better.

I think it may be the EGR valve that's causing the surging, but haven't checked it yet. I'm not sure if that could also be causing the poor fuel economy. Due to other problems with the truck beforehand, I have replaced the knock and oxygen sensors which made it run better than it did before. This is the only problem I have left.

It is a W type engine, 4.3L vortec, only around 119k miles.

Any suggestions would be most welcome!

 

My 92 is doing something similar, but it wants to idle real high. It threw a 45 code. I pulled the computer to check some wires that seemed to check out OK. I replaced the TPS and it still does it. Since them it has not threw the code again, yet if I drive it and get it warmed up it idles very high.

The weather has had me shut down and unable to fool with it the last several days.

For what its worth I've been told that a code 45 can be anyone of these.

Fuel pressure, injector leakage, HEI Ign shelding, canister plurge valve. coolant sensor, map sensor, tps sensor, 02 sensor contamination, Egr Valve stuck open and large vacumn leaks.

 

I would take a close look at the fuel pressure and leak down. The CPI engine is notorious for having fuel leaks internal to the plenum.

A vacuum leak can also cause a surging idle as can a clogged EGR valve.

 

Took it to a guy who has more tools than I do, and we found that the pressure is indeed 50psi so there's part of the problem. He suggests to replace the entire spider unit. At least I feel like I'm getting closer though

Thanks for all your replies, they've been very helpful!

 

Here you go, I just bought this a few hours ago myself. $177 for a remanufactured spyder. http://www.oreillyauto.com/site/c/de...2521&ppt=C0024

Take the vortec thing as well as the other thing off the top of the plenum and look inside and see if one side of the plenum is shinny. My regualtor side was but I replaced it 2 years ago so even if it is the regulator I said screw it and paid $125 more for a completely remanufactured spider so I don't have to worry about it insted of getting another $50 regulator. Also replace this, just incase it goes bad, http://www.oreillyauto.com/site/c/de...1512&ppt=C0024

Also, the 2 inches of fuel line between the fuel pump and sending unit is also probably bad and leaking pressure so after you check the spider if there is still pressure loss I would check that. And don't make the mistake I did and undo the bolt holding the drivers side bracket ontop of the fuel tank otherwise you will bend you sending unit fitings that are probably rusted anyways.

 

Just wondering.

How do you know that the lack of pressure isn't caused by the fuel pump? My W engine vortec 92 Blazer was holding about 48 pounds, I replace the fuel pump, it cured the problem.

 

I agree about the internal fuel leak; I checked the oil and it does smell like fuel, and the dipstick shows it as being overfull. We just had the oil changed not too long ago so I hadn't noticed it earlier. I suppose it is possible that the fuel pump could be going out as well. Once we get the spider and the oil changed, we'll try it out and see. I'll post what happens once everything is done.

Those links will be extremely helpful as I hope to be getting the spider tomorrow, thanks!

 

I just wanted to post that the problem has been resolved, it was the spider all along. Everything works great now, thanks a lot to everyone who helped out!

 

Stellar. Its a big problem for us on these older trucks. If you were to ask for that part at the GM dealer they would want 880 bucks for a new spider, what a joke.

 

Got a quick question. I replaced the spider unit and it's running great. I had the oil changed of course. The oil still smells like gas though but it is not overfull. Could this be a bit of gas from the old oil getting into the new oil, or is the problem still not resolved?

Thanks again!