Will not start after replacing the fuel pump

Hi,

If there is no spark, have you confirmed there is power to the coil? At the distributor, the connector should have a red wire. With the key in the run or start position, that wire should have power.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

I'm struggling to connect the fuel pump replacement causing this, but we'll figure it out.

Let me know about the power to the coil. Also, if you have a live data scanner, see if there is an RPM signal when cranking.

Let me know what you find.

Joe

There is power at the coil with key on. I do not have a scanner. There is power at the injectors. I am going to check all the grounds to neg terminal next, maybe that will turn up something. I get a fuel filter today and will install it. I haven't tested for any vacuum as I can't imagine it would prevent spark. Thanks again

Oh, there is no security light lit on dash.

Hi,

I attached a couple of pics below that you may find helpful. One other thought. Did you check the 10 amp fuse in the under-hood fuse box (fuse 11) that is specific to the ignition? Also, have you checked the ignition control module?

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below. Also, pic 3 shows the fuse I'm referring to. When checking, make sure there is power both to the fuse and from it.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Fuses are all good and reseated. The ICM is brand new but put the old one back in just in case, but no change, just a continuing turnover. There is spark going to the coil but none out! Testing negative post and one on the positive post of the coil results in 1.5ohms. Put the old coil back just to try. Checking both from side terminal and one in the center high tension terminal gives just above 8k ohms. One change has occurred when the key is turned on - security lights up and then goes out and the check engine light stays on. I borrowed a reader. I plugged it in and turned the key on. The reader goes through a self-check, checks the VIN and starts counting in percentages, quitting at 50% and displaying error message that it cannot continue - no other message. I am truly stumped. I got the PCM (flashed to my VIN) from FlashMasters off eBay. When I got it, plugged it in and the car fired right up, took it for a 10-15 minute ride and noticed the car did not get up to power and idled rough and would shut off. Pulled into the garage waiting on the new fuel pump. After the fuel pump was installed is when it wouldn't start. Stumped!

Just for the heck of it, take the distributor cap off and have someone crank the engine. See if the rotor moves. Also, resistance seems high on the coil. If I recall, 1 ohm should be max.

Also, take a look at the three pics below. Each one is a different diagnostic flow chart. Each of these three codes can cause a no-start condition due to spark.

You are certain the fuel pump is running, correct?

Let me know if that helps in any way.

Take care,

Joe

See pics below.

Distributor moves okay with the key and pressure at rail is 50PSI and holds. I will run down the DTCs in the morning. Thanks

Hi,

You are very welcome. Hang in there. We'll get it going.

Take care,

Joe

Tried a different reader and it quit after 50%, so I am returning the PCM and having them send another. They will diagnose the return and let me know what went wrong, etc. Will post more later. Oh we installed the steering column with the correct nr 9 resistor key, and it made no difference. Another pointer that its the PCM VATS failure.

Hi,

It sounds like you are on the right track. Let me know what happens. I'm really interested in knowing.

Take care and I hope you have a great Christmas.

Joe

The flashmaster tech says my friends Hypertech device is not a reader but a programmer and must be defective as the PCM I returned no longer responds. Waiting on the new PCM. Will update later.

Hi,

I'm not really familiar with Hypertech, but I do know they make programmers.

Regardless, let me know if that takes care of it. I'm interested in knowing.

Take care,

Joe

Will do.

Hi,

I noticed it has been a couple of days since I heard from you. Have you been able to make any progress or tied up due to the holiday? LOL

Just checking in to see if you need anything.

Take care,

Joe

I got the new PCM today. Connected it and turned the key on only to get a solid security light (not blinking). Went ahead and tried to turn it over. No fire. Disconnected the battery. waited five minutes and tried again. This time it fired right up, started it down the driveway to ease it around for 20 minutes as Chevrolet suggests for the PCM to set. Halfway down the driveway I had to give it a little gas to avoid bogging down in the sand - it quit as soon as I actuated the gas pedal and would not refire. Towed it home, washed my hands and sat stupefied and sent you this... The resistor on the original key was 2.8ohms. The key set was lost by the last owner who had a 2.8 resistor inline from the ignition to the PCM, which we were previous to the gas pump exchange firing a-okay. So, with the new PCM which was flashed to the VIN of the vehicle, could the imbedded resistor setting be different than before making the 2.8 inline resistor incorrect? Too many things for my pea brain...

Hi,

They can be confusing. Also, anytime people modify things, it usually leads to problems.

So, I need you to try something. Turn the key to the run position so the security light turns on. Allow it to sit for approximately 10 minutes. Does the light turn off and will the vehicle then start?

Let me know. Also, you were worried about getting stuck in the sand. I wish I lived there. LOL

Take care,

Joe

Oh, the sunshine and 77 degrees will make for an excellent round today. Got a list of the keys numbered with their ohms. Will go up the chart an try all settings. I have already got through to 3.0. Will post later.

Hi,

I noticed it has been a couple of days since I heard from you. Have you been able to make any progress? I'm interested in knowing.

I hope you have a great New Year!!!

Joe

Weekend off to the beach. Just got back. Will update tomorrow night about getting a VATS and PCM from a 95 Z28 that got sandwiched broadside, but still starts every time. My friend is going to pull everything from the wreck while I pull it from my car.

Sounds like a plan. I hope you had a good time at the beach.

Take care,

Joe

Didn't work. Pulled the wiring from the fuel system and laid down new wiring. Examined old wiring and did not find a scrape, break or rust in it, but it is absolutely unbelievable - runs great. Dyno'd at 366hp. Guess someone worked on the bottom end. Going to put headers and a nit kit to get near or just over 400. Be fine for daily driver. Thanks for the sounding board.

Hi,

Sounds great. Was it the wiring to the pump that was the problem? Interestingly, the actual wire covered with the rubber insulator can break inside and the insulation looks perfect. I wonder if that is what happened?

Let me know.

Joe

Curious too, so I stripped back the insulator wrap from pump head going forward and didn't find any breaks. There were a couple of flat spots where wire retainers were tight around the wire. I remain baffled but happy that it is running.

I'm glad you got it running as well. It sounds like it's running really well, too.

As far as the wire, I have had similar issues where the internal wire has broken but the insulation wasn't damaged, so it was very hard to find. The only indicator was there was no continuity from end to end on the wire until it was moved around. It can be very frustrating.

Regardless, I'm glad it's fixed. Take care of yourself and feel free to come back anytime in the future. You're always welcome here.

Joe

Just as a courtesy (since the car started the same systems all over again two days later) I want you to know that the basic problem was in testing methods of the ignition control module and the coil. Even though we had power on the 12v line, and the grounds were good we failed to establish what ohms readings we were getting met the thresholds necessary to sustain constant power flow. The ohms reading on the original coil read 4.2 and on the new coil it read 4.28. Looking at specs in the service manual revealed that this reading was within tolerance. On a hunch (and connecting with a local speed shop who agreed) I went I got a coil for a 95 vette and tested it with a reading of 10.1 ohms. Install the vette coil and the car started immediately. Apparently the 95 Z28 and the 95 vette have the same power specs. Moral - if you have an engine that is the same engine used in a vette, use vette components your Z28.

Hi,

Thanks for that update. It is interesting that the specifications indicated you were good but in reality, it wasn't. Regardless, thank you for the update. I'm sure it will help others.

Take care of yourself,

Joe