i have a 91 z-28 with a vortec tpi 350 engine. it has about 15k on it. i just had the spark plug wires replaced, the timing set, and the fuel pressure set about a week ago.

now here is the problem.........

last week i went to pick up my kids and as i was pulling out on the highway and started to accelerate the car just died. it started missing and backfired and ran horrible. the oil pressure, temp, volts etc all read fine. i managed to limp home doing about 25mph. any thing above and forget it. the car was also seemed very quiet. i openned the hood and could not see anything wrong.

next day i start thinking i may have a problem with my cat. i crank the car and stand behind it and cannot feel any exhaust comming out the tail pipes. (i have a shorty headers, singel cat with 2.5 exhaust and hooker cat back system) hmmmm, maybe i found the problem. next day i get my trusty sawsall out for some surgery and cut the exhause loose in front of the cat. outside of being loud it runs fine. i'm thinking problem found.
i cut the cat out and gut it. several of the pieces that came out looked blocked so now i am convinced as to where the problem is or should i say was.

hook everything up and start the car.....so far so good. i head down the street and yeeeeeeeeeehaaaaaaaaaaaw!!! this thing is a monster. it runs GREAT!! no sheet, i picked up nearly .5 sec from 0-60 on my stop watch. nothing like the smell of burning rubber at 10pm!! after 30 minutes i head home and sleep with a smile on my face all nite long.

next day i get up drive the car to the store and to my business, to another store and back to my business again. at 3pm i go get my kids pull back on the highway in the same place and start to accelerate and guess what.....the same thing happens again. i limp home doing 20-25mph.

besides high explosives, does anyone have any suggestions?

 

I'm going to go fishing here, but maybe some on the crap that was plugging the cat has made its way to the muffler? Thats my guess.

 

possible i guess. there just aren't any real small holes to plug in that hooker muffler though. and now exhause seems to be comming out the tail pipes, where before nothing was comming out.

the thing that kills me is how well it ran right up until it did it again.

thanks for the suggestion though.

 

i can't seem to spell exhaust to same my life!!!

 

did you check the fuel pressure? fuel filter?

 

fuel filter has about 1k on it. i plan to check the pressure tomorrow as well as any other ideas that come up.

thanks!!

 

hmmm,

today i went out and started the car and it cranked up fine, but i did not drive it. it got me to thinking back when i had a 76 caddy seville. it was fuel injected to. it developed a similar problem everytime it got hot. i finally figured out it was vapor lock.

COULD THIS BE VAPOR LOCK?

 

of course it could be vapor lock.

old secret is to wrap tin foil around the fuel lines to keep the heat away, rather it works or not, i do not know..

can u smell gas?

 

no i have not smelled gas before.

i used clothes pins on the fuel line of the caddy to get home.

i had never heard of a tpi with 'vapor lock' is why i was asking. the fact i had the car at idle for about 10 minutes while picking up my kids is what made me wonder. you can get a ton of heat build up in 10 minutes at idle.