Engine quits when i tyurn on headlights!

[BadBowtie]

Hey guys, i finally got my truck insured again so i went to drive it tonight and it ran good even though it sat for a bout a month without being driven. Anyhow as soon as i turn on the headlights the motor dies. THe truck is a 87 s10 blazer 4x4. It used to have a 2.8L auto nots isa 5.7 auto. If anyone has any ideas why its doing this it would be appreciated. before the truck sat it never had this problem.

[bohn333]

i\'m thinking that your alternator is junk. When you turn on the lights it draws to much juice and doesn\'t have enough to run the engine. Easy way to tell is start it up, and unhook the positve to your battery. if it dies then the alternator is junk..if it stays running your problem lies somewhere else.

[BadBowtie]

i had a problem with the truck a couple months back that the altenator was junk but it wasnt it was just the exciter wire for it wasnt working. so the alternator is still good. i can drive all day and it wont die, its when i put my lights on thats it!

I was wondering if there is somewhere typically that might give me a problem with the wiring harness for the lights that im not thinking of?

[IceQueen]

Do the headlamps come on fine are they bright or dim? you may have a short in the system and its killing of the engine..? just an Idea.. http://www.s10v8.com/images/smilies/icon_biggrin.gif

[BadBowtie]

i figured out the problem. i have a bad wire somewhere between the ecm and the fuel pump relay. If i run a power wire directly to the test connector for the fuel pump it works fine. and the headlights are all good too! so ya im gonna run a power wire and a switch to the test connector for now until it warms up a bit around here then i\'ll figure out the real problem!

[IceQueen]

Sounds strange to me! http://www.s10v8.com/images/smilies/icon_biggrin.gif

[4more]

i take it your using the stock fuel pump , it might be going out some times they can draw a ton of amps also and by using a totally different feed it might not interfer with your headlights chek amp draw of the fuel pump to see but it does soundweird to me but hard to tell online good luck

[BadBowtie]

ok i thought i had the problem fixed, but i obviously dont. i ran apower wire from the battery to the test connesctor and the truck would start and run fine, no headlight problems or anything. but then i got about 1/8 km from the house when the truck stalled on me. so i played with my power wireand started it up again. then another 1/8 km it stalled again and wouldnt restart. i had to push the truck home with my dads pickup. This is really starting to piss me off. That was saturday night and i havent tried to figure it out yet cause it was too dark when the last senario occured.