Crank no start?

Hello,

A good first step would be to check the fuel pressure you plan to do.
With the key on and engine off it should have 55-62 PSI of fuel pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

One thing you can do is to spray starting fluid into the intake and try to start. If it starts and runs for a little bit, then you will know the issue is fuel delivery.

https://www.2carpros.com/articles/car-cranks-but-wont-start

It is not impossible to have a faulty crank sensor, but you want to rule out the fuel first before taking a deeper dive.

Let me know what you find with the fuel pressure or if you have any questions.

Thank you.

The good news is it won't be a crank sensor. The bad news is the new fuel pump is only producing 30 pounds of pressure at the rail. Tried to test it at the filter because there's a fitting there but the tester wouldn't connect solidly enough to test it. Runs good on gasoline poured directly into the throttle body. I want to check the fuel filter before I go ahead and assume I have a bad pump since its brand new. Any thoughts on this ?

Just a little more information it pumps to 30 pounds but then falls off so I think it's a weak pump not a filter.

It could be a weak pump or bad fuel pressure regulator. If you were able to test the pressure at the filter or anywhere before the regulator, it can help you determine if it is the regulator or a weak pump.

I'm going to rig up something so I can test straight out of pump.

The pressure directly off the pump is over 100 pounds. Here are some pictures and a video. I believe it falls off was my fitting was leaking.

Right the pressure from the pump would be higher than what it supposed to be, that is why the regulator brings it to the correct pressure.
So if the pressure is stable at the pump the regulator could be the culprit.

I don't know about stable but it sure is strong I didn't try with cranking because I didn't have the feed line hooked up to the engine tested directly off pump.

I don't know about stable but it sure is strong I didn't try with cranking because I didn't have the feed line hooked up to the engine tested directly off pump

So, if you have good pressure from the pump but not at the injectors, the issue could be a bad regulator. As you have also said, the pressure tends to fall off at the port.

I'll be trying a replacement known to be working regulator tomorrow and I'll keep you posted. Thanks for the help.

Sounds good. I will look out for it.

There seems to be adequate pressure at the rail I haven't tested it but it squirts forcefully out of the Schrider. But still no fire unless I feed it gas through the throttle body. Could it be a TPS?

Rail pressure 60 pounds but falls off and stabilizes low. Also checked injector pulse which is good on all 8 cylinders. Also checked to see if I have 3 second fuel prime and more fuel delivered while cranking. Everything checks out. Clogged injectors? Engine tried to fire even with all 8 injectors unplugged.

Hi Jeff,

I noticed you haven't been contacted in a couple of days. Have you been able to make any progress? Also, I read through the conversation you had. Based on everything you indicated, it sounds like it may be an injector issue. If you remove the fuel pump fuse, see if it starts for a couple of seconds and then stalls. If so, it may actually be flooding.

Also, here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Let us know your status and what we can do to help.

Take care,

Joe

Engine did not fire. Proceeded to remove plugs. All 8 black, several were wet. Not sure gas or oil. Hoping gas. Majority of wires broke off connectors even when leveraging on boot or heat shield. Haven't tested spray or no spray from injectors. 20 degrees today. Is it necessary to use the heat shields?

Hi,

Wow, the plugs aren't in good shape. As far as the ones that were wet, chances are it was fuel. Which wires were broken? Was it the wiring to the injectors?

I just went back through your conversations. The idea that the fuel pressure reached specification and then dropped before it stabilized leads me to think you have injectors leaking or a faulty fuel pressure regulator. If you remove the vacuum hose from the regulator, is there any evidence of fuel in the vacuum hose?

Also, yes, reinstall the heat shield or you could end up with a hydrostatic lock in the fuel system.

Let me know what I can do to help.

Take care,

Joe

Spark plug leads to torn off connectors when removing. No other wires are broken. Regulator was bad, put a used one in from a running engine. Falloff may have been due to gauge connection, was seeping fuel. No fuel in vacuum line. Old regulator only gave 30 psi at the rail. Will be replacing plugs, wires. Also, will check injectors and clean them. Weather depending.

Thanks for the update. Before you even try starting it, confirm spark at the plugs. That will prevent you from having to remove them again if it doesn't start.

Take care and I'll be here when you get it done. I'm interested in knowing what you find.

Joe

Truck would run when gas was poured into the throttle body so spark must be present as well as crank sensor must be okay. Engine sounded great for 250,000.

Hi,

That makes sense. If you have fuel pressure and you have spark, then it is likely the injectors are not getting power or there is no ground path for them.

Each injector will have a pink wire to it. See pic 2. With the key on, each injector should have 12v at the pink wires. Confirm that. If there is no power, check fuses 55 and 56 in the under-hood fuse box. See pic 1 below.

Also, note there are two splices that may need to be checked. I circled them in pic 2.

If they do have power, here is what I need you to do. Disconnect one at a time. In addition to the pink B+ wire will be one that is a different color at each injector.

Take a test light and clamp the alligator clip of the light to the battery positive. Probe the different color wire at the injector connector and have someone crank the engine. The test light should flash on and off. If that happens, that indicates the PCM is providing a ground path to the injector. At that point, I would remove the injectors and inspect them for operation.

If the light doesn't flash, the PCM or connector/wiring to the PCM is suspect.

Let me know what you find.

Take care,

Joe

See pics below.

Used noid light already and all 8 have pulse.

Hi,

If you have fuel and spark, it should run. Since it started when primed with fuel, that tells me the fuel isn't getting into the engine via the injectors. Have you removed the fuel injectors to see if they are working?

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Let me know.

Joe

That's my next step, weather depending here in Wisconsin.

Sounds like a plan. If you have a chance, let me know how things turn out for you. I'm interested in knowing.

Take care,

Joe

I removed all the injectors and tested them. They all seem to have about 9.4 ohms. That seems a little low I think spec is 12. Also tried to rig up a system to spray carburetor cleaner through them as I triggered them with the 12 V supply but haven't been successful at that yet. Nothing at all came out initially so I assume they are plugged. Also, initially one bank of injectors had 14.3 ohms but then reread and all are 9.4. I don't know the accuracy of my multimeter because when I touch the leads together it read 11 ohms? Seems like a lot. Would this throw off the test? I can get 8 new upgraded injectors, AC Delco for around $40.00.

Hi,

If your meter indicates 11. Ohms of resistance when you touch the leads together, something is off. It should be 0. There shouldn't be any resistance if they are touched together. So, I'm not sure what is happening.

Let me know. Can you get your hands on a different one just to recheck?

Joe

The injectors that came out are Delphi part no. 25317628. The original part no. AC Delco 17113698. The first is called upgrade. Are these interchangeable and are the connectors the same? It appears there has been some work done on the injectors or wiring as there is a different type of tape wrapping around the connector on a couple.

Hi,

Yes, they are the same injectors for the same GM vehicle. See part interchange below. GM used the Delphi part but gave it a GM part number. That is what you have.

Take a look and let me know if that helps.

Take care,

joe

See pic below.

I noticed that different wires are used with Delphi coils. Is there any reason you can't just use any wires for the 5.3l?

Hi,

They shouldn't require anything different. They are to be a direct fit. Could you take a few pics of what you are seeing as far s the wiring and upload it for me to see?

Joe

Your site won't let me add pics. Rockauto shows two different sets of AC Delco wires. One says for use with Delphi coils.

Hi,

I'm not sure why the wiring would be different. I looked up both brands and the connectors and pins look the same on each one.

Are you planning to replace all of them? If that is the case, just go with whichever brand you use.

Let me know.

Joe

We are talking about spark plug wires. They show two different part no. depending on type of coil.

Hi,

Okay, but I'm still not sure why they would be different. Anything is possible, but it doesn't make sense.

Do you see anything different in pics?

Joe

Just an update. I installed new injectors but had to bend the pins a little to get the connectors to fit but it should be alright. Installed new iridium plugs. Need to install the spark plug wires but it's -4 and snowy here. Big winter storm warning through the weekend. Hopefully it will fire up, I'll let you know.

Hi,

We are getting the same storm starting tomorrow. Ugh!!! I miss summer. If possible, let me know how things turn out for you. I'm interested in knowing.

Take care and I wish you and your family a Great Christmas.

Joe

Merry Christmas and Happy Holidays.

New pump and sending unit, repaired small fuel line leak, used fuel pressure regulator, new plugs, wires, and injectors. She fired right up. We're having a heat wave, supposed to be 27 tomorrow.

Hi,

Thank you for the update and I'm glad to know it's fixed. LOL That is always a good thing.

I hope you enjoyed Christmas. I was lucky enough to lose heat Friday morning when the storm started and temperatures dropped, and not get it back until Monday at 10 AM. Ugh!!!

Regardless, take care and feel free to come back anytime in the future.

Joe