1990 GMC Jimmy Q&A

1990 GMC Jimmy Question: trottle body backfires and loseses pressure and cuts off

my 1988 gmc jimmy backfires through the throttle body and looses pressure when driving , and cuts off. can anyone help me? -
Answer 1
is the check engine light flashing ? if it is count the flashes write then down those are your codes then you can take it from there. -
Answer 2
Had the same problem with my 1990. Check ur distributor cap and button.One or the other might be bad. -
Comment 1
i just put a new cap, button, wires, plugs, fulfiller, EGR, and cat. what can it be -
Comment 2
My 88 jimmy is currently in the shop now for the same thing. The exhaust valve seats were bad but that didn't fix it 100%... But there was some broken grounds... If u figure it out I would lik to know what it was -
Comment 3
remoove valve covers.Cech valve hieght.If rocker to loose on exhaust when intake opens the cylinder pressure release through intake causing backfire through throttle body.Seen this many times Doug dkmazur@telus.net -
Answer 3
Pull valve covers.Jimmy is good for broken rocker [real cheap to repair] push rod comes partially through causing exhaust valve to not vent. On intake when intake valve opens pressure releases through intake.Seen this often -