1993 Vortec won't start

I have read nearly every post that has to do with the fuel system, but I am still not able to solve my problem. I bought the Jimmy late last year, it seemed to be running fine for about a month, although it idled a little rough. Then, the gas mileage started to severely drop (5 miles per gallon), there was black smoke coming from the exhaust and a very bad gas smell, and the idle was really rough.

At that point I changed the O2 sensor, the plugs, wires, distributer cap. It still didn't get better. I took it to AutoZone and although the code read that it needed a new EGR valve, which was fairly expensive, he suggested I take it to a shop and put it on a diagnostic machine. I did that in early March and he agreed it was the EGR valve and the other valve, TPS etc were fine. After replacing it he indicated that he also had to change the oil as it was full of gas and replace the plugs that were fouled. After doing this, it increased my mileage (about 10 miles per gallon), some of the smell was gone, and the smoke decreased. He stated that because it was still idling rough he tested to see if the CPI injectors was bad and stated it was not working correctly on the drivers side. I knew it would be costly and told him just to leave it and took it home.

I continued driving it for a few days and it lost compression, I found that to be from the #1 plug wire, which he apparently didn't put back on all the way, it was arcing. I shot carb cleaner into it and continued driving it for about another week or two until one morning I went out, it started and then within a few minutes stopped. It would crank over but didn't start. I figured the CPI unit had totally gone out. Yesterday, I put a new unit in, about with the plenum gasket, and noticed a fuel line leak (recommended by AutoZone to check before putting it back together) in the intake. Since it was late, with no where to get the part, my son put a piece of high pressure hose with a clamp inside the intake to replace the fuel line (one side of the nut kit).

After putting it all back together, it will crank, but not start. We shot starter fluid in it, it will stay running for a few seconds and then die. After reading these posts, I see I should probably properly replace the nut kit, but I don't think that is why it is not starting. Also, the fuel pressure is reading correctly and I can hear the pump running.

We have checked all the connections and the vacumm lines and they seem to be okay. Any other suggestion would be appreciated. I now believe that my starting problem may have been something other than directly related to the CPI injectors. I am wondering if changing the plugs and oil again might help or ????

Thanks,

A regular piece of hose will not work for the nut kit. You're putting 60 psi through that hose so more than likely it's still dumping fuel and not allowing the proper pressure to open up the poppets on the CPI unit. You need to get the nut kit, not a half baked patch job to make it run right.

Yip, do the job properly, or don't do it at all.

Yip, do the job properly, or don't do it at all.

Thanks for all your help. I did end up replacing the nut kit and then the fuel pump and sending unit after testing the pressure. So far I have replaced the 02 sensor, EGR, the CPI, the nut kit, the gasket, the fuel filter, pump and sending unit, the plugs, wires, oil change, and relay
So now nearly ever part of the fuel system has been replaced except for the tank and that ended up leaking a little after the job was done.

The truck was running great, passed emissions test with flying colors, gauges are reading great, no check engine light anymore but now for the last two weeks it itermittantly dies at idle and I can't get it restarted. This also happened to me once when I had driven to work in the morning and didn't try to start it again until late afternoon and it took about 20 minutes before it would crank to start. Every once in a while, sometimes when I am driving on the highway, it will slightly miss, like it is starving for fuel, but it only has died when I am at idle or coming to a stop like in traffic or at a light.

I would almost think something is getting "hot" and causing it to shut down EXCEPT for the fact that one time it wouldn't crank and it had been sitting for nine hours. It turned over about 20 minutes after I began trying.

I have been reading the posts but can't get clear direction on this problem. I thought maybe it was a defective fuel pump and it was working sometimes but not others, but I can hear it whiring when I turn the key.

I am really frustrated, love my truck, when it is working and need some advice. Please help...I am tired of being stranded. Thanks.

Check the plug wire going to the coil. Look for white corrosion.

Check the plug wire going to the coil. Look for white corrosion.


Okay well it happened to be the control module inside the distributer. I changed it and it started right up. Thanks.

man i went thru similar fuel system headaches as tinlizzy above...but now a few months later the vortec is choking AGAIN...not getting fuel at times. stalled at a stop sign so I pushed it to athe same garage that accurately diagnosed my troubled CPI a few months ago. they had a hard time but decided it is the inector electrical connector that is loose, possibly inside the intake, possibly pinched..he said he simply wiggled the wire and then it started and the resistance went from 20k down to the proper 1.5k ohm. the truck seems to be fine now but i guess i should take the upper intake off and hope to figure out if the wire is just loose or if the whole connector needs to be replaced...
the mechanic also made me concerned about the CPI unit I bought online..whether it was new or rebuilt...I think it's new...but ya never know w/ ebay...
wish me luck.


Check the plug wire going to the coil. Look for white corrosion.

Just make sure you use a fresh upper plenum gasket and torque the nuts down accordingly.

Even though the (four month old) gasket remained on the lower half unscathed, replace after removing upper plenum?
Better safe than sorry I guess.

I have to ask a question that I may know the answer to: THe left half of my lower plenem is washed clean, the right half is dirty and carbonated. I just installed a (supposedly new) CPI four months ago. Is it likely this has something to do w/ a faulty CPI? ( I have pictures but I'm sure you know exactly what I'm talking about.)

Ought I attempt to clean the (four month old) EGR valve while it is easy to get to?

My injector electrical connector is not tight where it connects to the CPI, I think this is what was causing my truck to hesitate here and there and finally give-up at a stop sign. I hope to solve it by slightly pulling tight on the outside of lower plenum and secure w/ electrical tape. Unless I find the connector is cheap and not a pain in the arse to replace.

Thanks


Just make sure you use a fresh upper plenum gasket and torque the nuts down accordingly.

Yes, replace the gasket every time you remove the upper plenum cover.