Very interesting no start issue need help

[putsk]

Hello guys this is the first time I placed in the post, but I spent time on the forum quite a while. My brother and I need your help. One day last summer he drove his truck home shut it off and the next morning it cranks but would not start at all. He tried working on it when you got time last year but have more time now to work on it. He thought it was the injection pump so he replaced it still no go. Also has tried three different PMD's still will not run. He tried putting a new crank sensor on it. Hasn't worked. Lift pump works. The injection pump came with a new shut off solenoid it's working. had new Optical sensor. Nothing happened with that. Has replaced batteries with two new ones has also tested the red wire off the IP to see if there was power and for a Split Second it does have power while cranking and goes out right away. It gets fuel up to injection pump but still no go. Also has no codes in the computer. I forgot to mention the specs on the vehicle are it is a 1999 GMC Sierra 1 ton with a 6.5 L four by four automatic trans new turbo during installation of fuel pump as seals were leaking. He has put it in a PMD relocate kit and cooler plate. It has the latest version of the PMD on it now less than a year old. Have but and tried another new PMD as well.. also have taken to relocate harness out of the equation as well and put the directly to the fuel injection pump.

I would really appreciate it if we could get some help trying to figure this out it's obviously something electrical being and shuts down the signal from the red wire. We are at a complete loss and do not know where else to try. Any advice would be greatly appreciated. As I do not work on it if you guys need any other information I will have to ask him and get back to you. Thanks for your help, Keith

[quvia1]

Need to fill in your profile. What year engine etc. Do you have fuel at injectors? Could be ign. switch. Also check your grounds.

[putsk]

Hi, thanks for the reply. I never thought about the ignition switch either but I will let my brother know to check that. Not sure where all the grounds are? There is no fuel at the injectors the injection pump just isn't letting the fuel through for some reason.

[grancito]

quvia1 could have something here, don't worry where the grounds are, jumper cable engine to body. Bypass the ignition switch with a jump wire from the "ignition" fuse to the battery.

[putsk]

Hi, thanks for your reply could you tell me which fuse he needs to do this with there's like three different fuses or possibly more that it could be what is it labeled as? He would go from the fuse terminal to the battery? If I'm understanding you correctly he wouldn't even need to use the ignition switch at all to start it then? He has also put a jumper wire from the Block to the firewall already.

[grancito]

Sorry for replying late, lot of business to complete yesterday. You see in my list of vehicles, 2 GMCs one year apart, and the fuse system is completely different. The later one has a fuse box under the hood, and there is a fuse labeled IGN, I use that to power the lift pump. At the back of the box are 2 large live posts, no need to wire to the battery. The earlier GMC has all of the fuses inside by the drivers door, more wire needed for a jump cable. You could check for a live fuse when the ignition is off, like windows, or lights, and jump that to IGN.

[putsk]

Hey guys, thank you very much without your advice we would not have been able to figure it out it was ignition switch. Without your help we would have never figured it out. My brother was getting so frustrated he was willing to scrap out the truck. Once again thanks guys from both my brother and I.

[grancito]

Thanks for the success feed back. Ignition switches from 1995 on, fail a lot, mine did recently, but only gave intermittent electrical problems. Have fun installing it.

[putsk]

Hi guys, You bet grancito, my brother was just having a alot of fun getting out.. *not* when he gets the part installed I'll let you know for sure what happened. thanks guys

[putsk]

Hi guys it seems that we have the no start issue finally figured out but we have one more that we just can't get over. When he did all the other replacing of parts do you replace the injection pump as well it will start runs a little rough but it will not do the time cycle. We read many articles that's what you needed scan tool which we do not have anyone have any ideas how we can get it workout? It idles at 1200 RPMs and will not come down even after many relearn Cycles could this also be because of the new crank sensor as well? Anybody could help me on this issue I would greatly appreciate it if you need to be more informed please let me know and I will possibly get a video of what the truck is doing to show you. Once again I greatly appreciate the help