i have an 89RS 305 TBI. i just got it out today for the first time after the winter. i drove it about 12 miles with no problems then all of a sudden i hit the gas and it started studdereing like it was missfireing and it back fired alittle. i was able to get it where i was going but i had to be real easy on the the throttle.

i took the air cleaner off and when i hit the gas hard it back fired up through the throttle body with a little fire ball. if i slowley press the gas to higher RPMs it seems to be fine. but if i step on it it just jerks all around and wants to stall. i ilde seems ok but just alittle rough but not to bad.

i tried the sea foam thing because i thought it might be gas but it didnt seem to help

any suggestions would be great!

 

Try changing the fuel filter. Make sure your ignition is up to snuff as well.

 

i just got done changing the fuel filter. seems to run good so far. i have not drove it yet to make sure but it reves fine now and seems to ile alot smother.
thanks for the input

 

well i drove that car a couple times with no problems (estimated about 50 miles). even got new gas in the tank. then today it started doing it again. i had to get it home by shifting it manualy because if it would shift into over drive or the next gear it would bog the engine abit then start backfireing and sputtering. if i used the gears manualy and slowly got on the gas i could get up to speed with no problem

could it be a fuel pump maybe? if so what is the fuel pressure supose to be?

my dad seems to think it might be a timing issue but i dont think it is because i can rev it high with no problem as long as i give it slow steady throttle but if i jump on it it back fires a studders.

idle seems alittle rough but not bad... it will stay running by ist selt

any help will be great thanks

 

i still have the same problem. i have looked all over the internet to see if anyone had the same problem. i found alot of cases of the same problem but all seem to end with out the problem fixed. i saw one did say and O2 sensor fixed his.

what should my reading be on a scanner so i know if it is that.

the car only has this problem after i drive the car for about 30 min.

Any help?

 

well i changed the coil and it seemed to fix it. no problems so far

 

hey man, i was having almost the exact same problem! i changed the fuel filter, the fuel pump, the spark plugs, the wires and the distributor cap. nothing fixed it. so i took it to a shop and he said it was the MAF sensor. he disconnected it and it ran almost perfect! but on any normally running car, if you disconnect the MAF it will run just a little bit worse than normal. but this solved the problem for me, because when it was connected, it was completely screwing up my idle and throttle because it was giving out or gone altogether!

so... if you have a MAF, try that!

 

TBI does not use a MAF. One thing I have seen a few times on TBI systems is a broken FPR spring. The FPR is built into the TB and can be disassembled and rebuilt. The spring is exposed to atmosphere with a poor seal to keep moisture and oxygen out. The ones I have found broken were rusted and had basically crumbled. The broken spring caused a severe loss of fuel pressure so that the engine would idle poorly and drivability was almost nil.

This can be checked by testing fuel pressure. FP should be about 9-13psi at idle. A quick visual check can be done by watching the spray pattern at idle. It should be a wide cone pattern and clearly hit the inside of the throttle bore and mist slightly on throttle snap.