1990 suburban shut down

[duduca]

Hello,
I am looking for help! I'm in Brazil and I have a 1990 suburban 3/4 5.7 and a big problem. Here in Brazil we have only 4 burbs of this model and we have no tecnical people to fix this cars. When I'm driving the engine service light turn on and the fuel injection ends. When my car shut down the head light doesn't work I don't hear the fuel pump (when ok every time I pre start ignition I hear the fuel pump working) the sound doesn't work but ignition runs ok, the eletric door look runs ok. I send to 2 eletric shop and they say thats its all ok my mechanic say that is ok. Sometimes when shaking the problem occurs and sometimes shaking the car back to work fine some times with the door opened the problem occur, and I ever know cause every time thath the problem shows the interior main light shut down. Please help me I don't know what to do .Some times I get the car back to working spraying lub oil into injection and the same time I spray I turn the ignition on i half throtle.
Thanks

[Autotec]

Sound like you have a bad connection from the battery. I would start aT THE BATTERY to make sure the connection are OK and clean. If that check good I would start doing a voltage drop test on all battery cables. Check also for loose connection at the starter and the engine battery ground and chassic grounds. If that all check OK then remove the cover at the passager firewall you see an electrical power strip with wire running off of it, make sure that all nuts on the power strip are good.

[duduca]

hello,
I've tried but I find no problems

[twistedtech]

Lot's of could be's and your gonna have to try them one at a time till you get it. The large wiring harness that's bolts to the plug going threw the firewall may be lose or bad.