hey guys i'm new to this TPI thing so don't give me too much hell, i bought a 89 formula yesterday, automatic, tpi 305, has a few mods, headers, CAI, edlebrock runners, and a shift kit, the car sound like it's running off 7 cylinders, and it bogs down at WOT, the guy i bought it from said it needs 3 new injectors, the car did sit for2-5 years, is it common for these injectors to fail? or am i missing something?

 

It is common for the injectors to fail especially if the car has been sitting for a few year and are even multitech's . You may need to go through the complete fuel system pump and injectors. You can ohm the injectors when hot this is not a 100 % guarantee on testing them but they should be around 16-16.5 ohms. Southbay fuel injectors has some nice bosch 3 19#hr injectors.

http://www.southbayfuelinjectors.com...7&product=1500

 

it has a new pump in it, the car will shut off after idling for about 20 minutes too, has a new computer in it, dist cap, full tune up, so i'm actually hoping it's the injectors, thank you.

 

well it cranked today! it ran for about 15 minutes..once it gets warm it shuts off, in that 15 minutes it idles worse and worse, i'm not sure where to start.

 

Fuel pressure dropping?

 

Suggest you check your coolant temp sensor, intake air temp sensor and clean idle air control motor and clean passages. Somewhere in the forum someone posted a resistance vs temp table for the temp sensors. Maybe someone could post it here. Agree that the fuel pressure should also be checked.

 

Don't overlook the oxygen sensor, and remember that while at idle it is probably entering and dropping out of closed loop mode.

 

That's what happened to my old 'formy. Ohm the injectors right after it shuts down. You'll probably see that one or more are low which overheats the drivers and they stop working. The resistance drops as they warm up which is why it'll start fine but run progressively worse 'til it dies. At least that's what a GM tech told me. New injectors fixed it right up.

 

Besides potentially having a bad coil or two on your injectors, if the car sat for a couple of years they may be clogged as well. When you check the ohms check it both hot and cold if possible. If you get any reading less than 12ohm than your injectors need to be replaced.

 

i'll look over all the sensors, just put a new cap and rotor on it, i just want to knock out a few things before i dump money into injectors if i don't need them, can any shop ohm the injectors? the car only has 63k on it, it sat for almost 2 years, the check engine light isn't on, it backfires through the exhaust, smells like raw gas, so my only guess is the injectors, how do you check the fuel pressure? and what should it be at?

 

and once it shuts off or if you shut it off...it wont crank until you let it sit for a few hours.

 

you can buy a vom at any parts store or harbor freight for cheap. If the car is running that rich the fuel regulator may be damaged. You can pull the vacuum line to the regulator and check for evidence of fuel. With the engine running and the vacuum hose off to the regulator you will have 38psi with the hose connected 45psi. The test valve schrader valve is on the passenger side rear top of the fuel rail. when you say the car won't crank you turn the key to start it and it just cranks and won't start or you turn the key and no clicking of the starter ?

 

i'll turn the key to crank it, it turns over real fast and tries to fire, then i try to crank it the next morning and it fires right up.

 

you need to ohm your injectors, the 89 tpi takes longer to start than previous years with a csi because it need 8 drp to enable the injectors so when everything is working right 6-8 second cold start time.

 

i plan to get them ohmed this weekend..should i do this when the engine is cold? warm? or what?

 

do them both cold and warm, they are more likely to fail when the engine is warm. do it yourself save some money.

Good information but if you need to buy get from southbay

 

alright, i'll see how the injectors come out, expect some more posts! if i need to replace them should i get a new regulater and filter?

 

If you do need new injectors these are the parts I suggest you buy


http://www.autozone.com/autozone/par...ier=79645_0_0_



GP Sorensen/Fuel Injector O-Ring Part Number: 800-9211
(this will have a large and real small one you will not use)
mrgasket 145 or felpro MS93160
a new fuel filter GF481 or equilivent
http://www.southbayfuelinjectors.com...7&product=1500
http://www.southbayfuelinjectors.com...7&product=3054

 

i ohmed the injectors...4 of them read areound 5 or 6, the other 4 read 17 or so, i'm going to order a set from southbay soon...do these tpi 305s have any potential power wise? i drive a 78 trans am right now with a 400 4bbl...lets just say..it's gutless.

 

the poncho 400 was in the heavy smog era of low compression engines after the muscle car era. A stock 400 does suck but can be built into a good engine. The 305 has good low end torque and can rev pretty quick. you will wake that car up with new injectors

 

after sitting for so long, a little tune up may do it pretty well. i had a pretty similar problem (when it was my DD) which it wound up being my rotor was worn to next to nothing. when we checked out the parts, they were still original parts when the car was about 22-23 years old....good work GM

 

after sitting for so long, a little tune up may do it pretty well. i had a pretty similar problem (when it was my DD) which it wound up being my rotor was worn to next to nothing. when we checked out the parts, they were still original parts when the car was about 22-23 years old. had original cap, rotor, wires, spark plugs and filters....good work GM

 

Schrader valve on rear end of passenger fuel rail near distributor.
Here's the specifications

 

yeah it sounds like injector failure to me. Sitting for long periods of time can be hard on them. i want to throw fresh ones in my 86 TA but money is against me :b