So this has been an issue popping up for a while now. It started happening during the winter, I was at a 7-11 and went inside for coffee. Came out, and the truck just would not start. It would crank over, and sort of start then die out.

I originally thought it was the aftermarket alarm (also remote starter) so I switched it into valet mode and the problem stopped. Its one of the DEI alarms with the satellite remote start relay. I have installed a similar one in my Honda Accord, a Python unit so I am familiar with it and the wiring.

Anyways, recently this issue came back. The truck would be sitting for a couple of days, and I go to start it and same thing. Would kick over for not even half a second and die out. Sometimes, give it a little while and will start right up. Sometimes, give it a day and it will start.

So out of advice on the forum, I went and bought a fuel tester gauge. Now I did the original test of checking the fuel rail nipple to see if there was fuel, and oh yes there was. So after a no start I ran to autozone, picked up the tester, came back and right before installing the tester (I must of leaked out some fuel trying to get the damn thing on) the truck started. Since then, no problem!

I also picked up a spark tester, but since I am not having the problem right now I can't diagnose it. I did run the fuel tester and it was reading over 60 pounds, and I know when it is not starting the fuel pump is going on from the sound, and the fact that there is fuel in the rail.


So my question is, whaaaaaaaaat is wrong? Kyle has mentioned numerous times the ignition switch which I am ordering through a friends shop, and also gonna install a new coil to be safe. I am going on the beach on July 4th and don't want this to come up.

Noticeably, when it does this type of thing the security light does not go on. I have read that is the usual suspect with the ignition switch. Well, the security light never goes on. I do not know if the truck is equipped with passlock, the only way to tell besides getting a spare key made or ripping the column apart to look for either a spare key taped to the ignition or the bypass. I do notice that there is a light for Security, but it never lights up.


What do ya guys think? I really would like to rewire the alarm, but I don't have time and that remote starter is not properly installed. The RPM line must be messed up because the truck keeps cranking once its started. That, will not be installed.

Good question to ask - does the truck's security system have a fuel injector cut off? Or is that possible for an aftermarket alarm to trigger? I know most alarms either have a starter cutoff relay or a fuel pump cut off relay, but it just seems either the injectors are not triggering or their is no spark. I sprayed some carb cleaner in the throttle body to try to get it to turn, nothing. FYI - The fuel spider has been changed

Truck info, 99 4 Door Blazer, 4x4.

I know its a lot of info, but those of you know me know I type a lot to be detailed so :-P

 

it def sounds alarm related, its cutting the fuel to the truck possibly only way to test it is to completely unhook it, and see what happens

 

your standard gm anti-theft passlock system will cut the fuel also since there is an aftermarket alarm that throws another wrench into the works, if the passlock is cutting the fuel you should see the security lamp illuminated, you need to check fuel pressure with the engine cranking if you have not done it that way already 60-66 psi with engine cranking, not a reliable test just turning the key on I had a "weak" fuel pump had exactly 60 at the test port with key on but dropped to 50 with engine cranking, not enough to start this engine. testing the fuel pump directly at the fuel filter should get you 80-90 psi none less.

 

Yea, I think the alarm has a large piece in this. I do not like having a vehicle with an alarm installed in it already because you do not know how they wired it. When it comes with electronics, I only trust myself doing it. If something goes wrong, I know where to look as I did it.

I bought a new coil and new ignition switch, and I am going to take the alarm out and redo everything. At least then I will know whats going on.

I don't know if its the fuel cut off though. Normally, when there is a fuel cut off doesn't it shut off the pump? I have never seen them cut off the injectors, which is a pretty cool thing to be honest.

I do not know if the alarm is going off, or it is a bad connection with the alarm, or that stupid key bypass is screwing things up - wont know until I have all that non oem crap out.

 

I am not real sure on this but I think the fuel pump prime is a seperate circuit through the relay than the signal from the pcm to the relay to run the pump, which is what gets interupted by passlock, thats why it still comes on when you turn the key but will cut off after you start to crank, also some models need to see oil pressure from the sending unit or fuel pump is cut off.

 

The passlock system kills the injectors, not just the pump. Whenever the key is turned on, the pump will prime, regardless of whether the passlock system is triggered or not.

I would bet that it is something with the old starter/alarm system that is causing this issue and would start by removing all modifications to the wiring. Hopefully they did not butcher the electrical system under the dash too much.