Cpi and nut kit replaced, still problems

[leadalto]

When I have time, I'd like to connect the results of my efforts to previous postings but to expedite matters,
I'd like run a few things before the experts to see what track I'm on.

I just replaced the CPI and Nut Kit (parts from Cadillac dealership in Oak Park, Il).

The problems I had were Rich fuel mixture, won't start without priming through air intake, hunting for idle speed, black carbon deposits from exhaust, failed emissions test because of excess unburned fuel.

After replacing the CPI and Nut Kit, It still will not start. I need to use starter fluid! As a matter of fact, it’s even worse than before because I need to use starter fluid even after its been running.

What is different is:

When running in “closed loop” it used to be rich 100% of the time. Now it’s rich 50 % of the time. The acceleration is like it was when the car was new. There is no more hunting for an idle speed. Idle is smooth (no hunting) even after panic stops.

Before, using a pressure meter, the fuel pressure at the valve fluctuated (dial indicator vibrates at least 15 psi or more) when the engine was running. Now, there is very little movement of the dial indicator (it vibrates slightly at about 55 psi)

I get an SES light that turns on and off periodically (No correlation to anything that I can see while driving).

Checking the error code with a jumper (OBD I), gives Code 23. This code is not listed for a 93 S-10 Blazer in my Clilton’s manual!!!

Obviously, there was something wrong with my previous CPI, but I always thought that I had more than one problem.

It’s still not right (but better). What do I look for now???

[corning_d3]

Code 23 means "Manifold Air Temperature, Low Temp Indicated", which would point to your problem. Replacing it will more than likely fix your problem. I am assuming 15psi of fuel pressure is a typo?? Your system requires 54 to 64psi of pressure..

[leadalto]

The picture below shows the New 17113673 Injector and 17112705 Nut Kit installed in my 93 S10-Blazer, 4.3 Liter, VIN W engine with CMFI fuel injection, prior to installing the upper intake manifold assembly.



Getting the retainer for the input and return fuel lines, held on with a T30 screw, was a real challenge because you can’t see the screw and getting it off and then on again is done by feel. Knowing ahead of time that it would be a problem (from previous posts), I bought a T30 ¼” drive socket. I couldn’t break the screw loose with the ratchet handle but the straight bar which is only 3/4 “ longer gave my weak fingers just enough additional torque to crack the screw loose. Yes, you have to use your fingers because you can’t grab the wrench with your hand. A pipe over the ratchet handle would do the same trick. Wouldn’t you know it though, the last time I cleaned the garage, I threw out an assortment of pipes that were taking up space for the last 35 years.

One thing I would do differently is to re-use the original T30 screw (assuming it didn’t get lost in some unreachable nook or cranny behind the engine). The Nut Kit comes with a new screw which has thread lock on the threads near the screw head. This made it very difficult to tighten and draw the retainer plate against the block. Why make it any harder than it needs to be?

I would also like to clarify some points from my previous post.

Originally Posted by leadalto

Before, using a pressure meter, the fuel pressure at the valve fluctuated (dial indicator vibrates at least 15 psi or more) when the engine was running. Now, there is very little movement of the dial indicator (it vibrates slightly at about 55 psi)

What I meant was that the indicator needle vibrates very rapidly over a range of about 15 psi, i.e. from around 45psi to 60 psi.

Originally Posted by leadalto

I get an SES light that turns on and off periodically (No correlation to anything that I can see while driving).

I inadvertently left the jumper that I was using to check “open loop” operation in the scan test connector when I took off for a road test. That’s why the SES lamp kept flashing on and off while I was driving.

Originally Posted by leadalto

Checking the error code with a jumper (OBD I), gives Code 23. This code is not listed for a 93 S-10 Blazer in my Clilton’s manual!!!

As I said, the Chilton’s manual does not list Code 23 nor does it show up in the diagnostic troubleshooting charts. The 93 model has something called an Intake Air Temperature (IAT) sensor mounted in the rubber air ducting just before the throttle body which does the same job as a Manifold Air Temperature (MAT) sensor typically mounted in the intake manifold. When I started the car after completing the job, the air ducting was not in place and the IAT connector was disconnected. I thought it didn’t make a difference because there are no codes in my manual covering the IAT. The book obviously does not have a complete list of codes. This morning, I cleared the codes, connected the IAT, ran the engine and got no codes.

The engine would not start without a shot of starter fluid. One thing that I noticed, which was previously being masked by black smoke, was a small amount of white smoke and some water dripping from the tailpipe. There was also a slight miss that went away after 10 – 15 seconds.

[leadalto]

There are a couple of things that I forgot to mention about the installation of the CPI and Nut Kit. I measured the resistance of the regulator coil. The two electrical contacts on top of the regulator.

After connecting the regulator cable, and before buttoning-up the unit, I checked (at the connector on the cable going into the plenum) to see that I had a good electrical connection by measuring the same resistance. On a 200 ohm scale, it measured 2.1 ohms. Not much, but then, it's a coil winding.

Another item where I needed to buy a special tool, which I did not have, was a 5/8" Hydraulic line wrench. Both fuel input and return lines were on very tight and I didn't want to chance rounding the nuts (because of their location). They miked to 16 metric but I could not find a wrench of that type in 16 metric. The 5/8" went on tight but worked.

After searching this forum (and others), I notice that almost all posts refer to a fuel pump which whines. My fuel pump produces an almost inaudible "fluttering" sound during "key on" priming (2 sec.). I get the same thing if I connect the pump directly to the battery through the connector that's provided in the cable harness. Is this the symptom of a weak fuel pump and the cause of my hard starting problem?

I've read several articles about fuel pumps that won't keep up pressure when voltage drops during starting, but run without problems if the engine is primed with gas or starter fluid.

Hard starting was my original problem which got sidelined by rich mixture, black exhaust, bad idle, etc. After replacing the cpi and nut kit which fixed those problems, I'm still left with hard starting. Has anybody had a similar hard starting problem that was the result of a weak fuel pump?

[ZL1power69]

i ran into a pickle when i went to install the new nut kit on my jimmy. i had already replaced the cpi the day before but when i went to remove that 30 torx, it was completely striped/rounded out. allens wouldn't remove it, u can't get a drill in there to use a screw out. i had to buy stud removers, hammer one into a socket, then yank on that thing extremely hard to get it off. other than that i had no major issues.

[leadalto]

Originally Posted by ZL1power69

i ran into a pickle when i went to install the new nut kit on my jimmy. i had already replaced the cpi the day before but when i went to remove that 30 torx, it was completely striped/rounded out. allens wouldn't remove it, u can't get a drill in there to use a screw out. i had to buy stud removers, hammer one into a socket, then yank on that thing extremely hard to get it off. other than that i had no major issues.

Sorry to hear about the problems you had. For me, being an older guy, it was physically demanding to apply any force to anything between the engine and firewall. I probably would have elected to remove the lower intake manifold even though it's a big PITA because of removing coolant, hoses, and a host other things. The only plus would be installing new intake gaskets even though the old ones were intact (knowing Murphy, the new ones would probably leak).

[leadalto]

Originally Posted by leadalto

After searching this forum (and others), I notice that almost all posts refer to a fuel pump which whines. My fuel pump produces an almost inaudible "fluttering" sound during "key on" priming (2 sec.). I get the same thing if I connect the pump directly to the battery through the connector that's provided in the cable harness. Is this the symptom of a weak fuel pump and the cause of my hard starting problem?

I've read several articles about fuel pumps that won't keep up pressure when voltage drops during starting, but run without problems if the engine is primed with gas or starter fluid.

Hard starting was my original problem which got sidelined by rich mixture, black exhaust, bad idle, etc. After replacing the cpi and nut kit which fixed those problems, I'm still left with hard starting. Has anybody had a similar hard starting problem that was the result of a weak fuel pump?

I replaced the fuel pump and guess what? No more hard starting!

The new pump has a solid sounding (soft whine) instead of a “flutter” from my old pump.

The key pressure parameters are that my old pump would come up to 60 psi, but somewhat grudgingly. It might take several tries with the key to bring it up. The new pump jumps to 60 psi instantly.

When cranking, with the old pump, pressure would drop from 60 psi to around 45 psi. The new pump maintains 60 psi while cranking.

Hard starting problem solved!