fuel pressure, please help, cpi?

[demotim00]

I have a 94 Jimmy with the 4.3L vortec CPI and it is showing most of the signs of the CPI unit leaking. I really do not want to replace it though unless it absolutely needs it because I can not do the work myself as I am not that familiar with that kind of work, can not handle the summer heat and have no one to do it for me, and the cheapest shop I found is $500(including labor). I can have the fuel pressure tested for $65, if I am correct wouldnt that so whether it is most likely leaking or not, as if it is leaking, the fuel pressure would be lower than it should be? Or would I be better off to just go ahead and have it repaired, since they do have a tendency to go bad? Keep in mind it is a 94 with a 164xxx miles, I have only owned it several months and am not sure what all has been done to it, that I have had the entire fuel system, including egr valve cleaned, the fuel filter, air filter, pcv valve, spark plugs, spark plug wires, distrubutor cap, and ignition rotor repaired.

[rlith]

You can test the pressure yourself rather easily. Go to autzone and get a fuel pressure tester from their loan-a-tool. It will end up being free.

Attach the fuel pressure gauge to the shrader valve on the back of the intake (looks like a bicycle tire valve only a little thicker).

Turn the ignition to the run position for 10 seconds, then turn it off. The gauge should read 56-60. It should hold at that for at least 15 mins. If the gauge starts falling rapidly or doesn't achieve that pressure then you have a leaking CPI or nut kit.

Now. If you have a cheapie socket wrench set you have the tools to change the CPI by yourself. It's actually quite simple.

[demotim00]

I decided I would just take off the vortec cover, and use a flashlight to look down through the IMTV, and to my suprise the CPI & Nut Kit was leaking. Also I agree with Blazer LT in one the other posts, you need to stop telling people to take off the upper plenum as it is not needed, because with a flashlight you can easily see through the IMTV.

P.S. ANYONE READING THIS NEEDS TO BE AWARE OF THE FACT THAT YOU DO NOT NEED TO TAKE THE ENTIRE UPPER PLENUM OFF TO SEE THAT THE NUT KIT OR CPI EITHER ONE IS LEAKING. JUST USE A FLASHLIGHT TO LOOK DOWN THROUGH THE IMTV, IN WHICH I AM SURE EVERYONE OWNS A FLASHLIGHT.

[rlith]

And as I've said time and time again, you can't always see everything through the imtv...This has been proven time and time again. So I'll keep reccomending it. You have your opinion, I have mine.

[demotim00]

Well I just got my Jimmy back from the shop today. Had the CPI and Nut Kit, and had my oil changed, ended up costing $525 total. It took care of the missing, took care of my rough idle, the gas smell, and the surging when accelerating at low speeds. It still has like a rattle noise when accelerating at low speeds(which I believe has to do with the catalytic convertor because appearantly the CPI has been leaking for the past several months while I was driving the vehicle, and who knows how long before I bought it). However atleast it is to where I can drive it decently and I am not wasting 1/4 tank of gas in 25 miles of driving because at the end when I took it to the shop I went through 1/4 tank of gas(5gallons) in about 25 miles, along with it was missing so bad I couldnt even accelerate really and was stuck to keep it under 25mph. Hopefully my problems are taken care of now. Figured I would repost to let everyone know I did take care of my problems, atleast for now. IF ANYONE DOES HAVE ANY OTHER IDEAS WHAT COULD BE CAUSING RATTLE NOISE FROM MY EXHAUST(SOUNDS KINDA LIKE THE HEAT SHEILD IN THE MOTOR LOOSE OR CRACKED, EVEN THOUGH THAT AINT IT AND ITS COMING FROM RIGHT AT THE CATALYTIC CONVERTOR) PLEASE POST IT FOR I CAN CHECK IT OUT OR LOOK IN TO IT.

[rlith]

Well considering you've been dumping so much fuel, probably your cat is breaking up.

[demotim00]

Thanks for your reply on that. Thats what I was figuring to is the cats probably bad from the fuel dumping like it was. Do you know if there is anyway to actually find out if the cat is bad without costing a shit load of money, or replacing it? Obviously I cant really afford to replace parts unless I am 100% positive it needs it.

[rlith]

Stop by a local muffler shop... The can test it for ya. Usually at no charge.

[demotim00]

Aight, I wasnt sure if a an exhaust shop could test cats or not, because I wasnt sure if there was a way to even test them, but thanks for the info, and I'll look in to that and post any results for anyone that reads the thread will know what the outcome in in case they have the same probs.

[wildcatsua]

[quote=rlith]You can test the pressure yourself rather easily. Go to autzone and get a fuel pressure tester from their loan-a-tool. It will end up being free.

FYI - I tried to borrow a fuel pressure tester from Autozone and they don't have them around here. Even their website doesn't show them available.

http://autozone.com/in_our_stores/lo...oan_a_tool.htm

Good luck!

[blazee]

Originally Posted by wildcatsua

FYI - I tried to borrow a fuel pressure tester from Autozone and they don't have them around here. Even their website doesn't show them available.

http://autozone.com/in_our_stores/lo...oan_a_tool.htm

Good luck!

I've heard a lot of people say that. I don't think I've seen anyone get one, yet.

[demotim00]

Originally Posted by demotim00

Aight, I wasnt sure if a an exhaust shop could test cats or not, because I wasnt sure if there was a way to even test them, but thanks for the info, and I'll look in to that and post any results for anyone that reads the thread will know what the outcome in in case they have the same probs.

Alright, I finally got around to going to an exhaust shop and having my exhaust system looked it. It is truly indeed my catalytic converter thats broke up on the inside from all the fuel dumping through. My muffler is also beginning to show signs of replacement, so since I want custom exhaust anyway I am just going to go ahead and have the cat replaced with a highflow cat and have the muffler replaced with a flowmaster 40 series single inlet and dual outlet with stainless steel tips. Just figured I would let everyone know of what the rattling noise turned out to be.

[BlazerLT]

Don't get a flow40, install a Ravin Z55.

Trust me, you will love it.

[demotim00]

Originally Posted by BlazerLT

Don't get a flow40, install a Ravin Z55.

Trust me, you will love it.

You may personally like Ravin Z55, but 3 of my friends have Flowmaster 40's, and one of them actually have them installed on a 92 Blazer. Personally I like the sound of them, and have heard nothing but good things from them as far as friends, so I'm just going to go ahead and go for the flowmaster.

[BlazerLT]

Originally Posted by demotim00

You may personally like Ravin Z55, but 3 of my friends have Flowmaster 40's, and one of them actually have them installed on a 92 Blazer. Personally I like the sound of them, and have heard nothing but good things from them as far as friends, so I'm just going to go ahead and go for the flowmaster.

Sure, do what you want, but a Flow40 flows almost worse than the stock muffler so don't expect a performance gain from it.



The Ravin has a straight through flow design that doesn't hinder exhaust flow whereas the Flow40 has deflectors and dividers throughout causing foor exhaust flow.

Flow40 will give you sound whereas Ravin will give you sound plus performance.

Listen to the sound clips of mine here:

At the bottom of the page...

http://www.cardomain.com/ride/519698/2

The Z55 I have installed is not even the loudest option from Ravin either. There is a Z33.

I have flow40's on a 4.3L right next to my truck and everyone could hear the difference and hands down liked the Ravin better.

Be different and be smart, getting something because all your friends have it when you have data showing you a better option would be your choice, but not the best one you could make.