I'm working on a '99 for a customer. Its a really long story about what happened. Anyway, at first the truck would start and surge really hard for about 3 seconds and go dead. I found that the lift pump was not running right (it would pump its 25% duty cycle during cranking with no prime cycle), so I replaced the timer module. I wasn't sure if the timer shuts down the IP or not but I was pretty sure the module was causing problems because the chimes were acting crazy too. In the mean time, the customer calls and says "Oh yeah, you might check the fuses because my son worked on it and was shorting some wires down by the ECM and I saw some sparks" . If I would have known this I probably wouldn't have taken the job. I did find a blown fuse when I started on the truck and had already replaced it. After I replaced the module the lift pump still did the same thing. I had another engine out back, so I put the ECM from it on the truck. Lift pump worked then, but it wou;ldn't start at all. If I ctracked an injector line I would get a large volume of fuel but no pressure. I told the customer he needed a pump (VP44) and a ECM. He says he'll get 'em himself, I'm already kinda aggravated at this guy so I say "whatever" . Well, he gets used stuff from somewhere. I go ahead and put it all on and now I'm getting the same thing. No fuel from #1, large volume from 3 and 4 no pressure to speak of. I haven't checked any of the rest. Is it the VP? I cant see how it can be anything else. I have checked all relays and fuses. No codes. Please help me get out of this nightmare. I want to tell him this used pump is junk, but I need some reassurance that it can't be anything else.

 

Ok, just found a "mismatched VIN" code in the ABS module. Do I need to reflash this ECM? I have that capability. I don't want to do it if I don't need to.

 

I have a 99 with a simular problem, starts fine when cold, but warm it up and no start until cools back down, when this whole then started, the ABS and parking light came on and hasen't left....no codes will come up...some say its the VP electronic, but sometime (rare) it will start when warm (just as I turn the key off starter in fires)...any help

 

Well, I just called the customer and told him to get me another pump. I thought about it after my last post, i have swapped engines many times and left the ECMs alone, so that shouldn't make any difference. Anybody know anything about the security system on these trucks is there any way it can cause this? I would think there would be no fuel at all if that was the case.

 

Fixed it. I reflashed it. I suspect it had something to do with the timer module. I replaced the pump with another that I knew was good. Still wouldn't start, but I got fuel out of all six. It's funny that I cant find much info on how the timer/security system works on these trucks.