Silverbishop

I couldn't find a thread directly addressing flow rate and what issues it can cause if you have the incorrect flow rate injectors. I currently have found out that the injectors I have upgraded to in my 89 Camaro are not the correct flow rate that is recommended for the upgrade from 305 tbi to 350 tbi. I used GP Sorensen injectors that would fit a 1994 k1500 with a 350. The flow rate from what I gather is 55 lb/hr for them while the ones recommended are the Caprice police interceptor ones that have a 65 lb/hr injector. At the time I did not realize there were differences between the 350 tbi injectors as I'm new to all of this. What problems could having a lower flow rate cause besides making the car run lean as mine seems to be doing?

DynoDave43

iTrader: (11)

Lean and it's associated conditions are probably it.

Can you tell us a little about your engine, so we know what you are trying to feed?

What fuel pressure are you running? Do you have a gauge, and an adjustable regulator?

Fast355

iTrader: (2)

Truck 350 injectors (Orange/Black color code) are around 61 lb/hr @ 12 psi. The 305 injectors (Green/White color code) are about 50-55 lb/hr depending on your source.

Silverbishop

My car was originally a 305 swapped to 350 prior to me buying it. I have swapped everything that was not swapped over to 350 components such as the electronic spark control, chip, and injectors. I recently tested my fuel pressure and it read right at 11 pounds but my adapter needed new o-rings as it was leaking so i'm not sure if that was accurate and I also do not have an adjustable regulator. The pump I'm using is the stock pump that would have come with the car and from what I've read should be enough to run it properly.

Schurkey

11 psi at idle, or 11 psi under heavy load?

Silverbishop

11 psi at idle.

Schurkey

If fuel pressure is low at idle, it's bad. If fuel pressure is OK at idle, it can still be bad under load.

Test the fuel pressure with the engine at high RPM with the throttle pedal on the carpet. Going uphill in high gear would be ideal. This tests not only the pressure, but the volume as well.






For the record, why do you think the engine is running lean? How old is the O2 sensor?

Silverbishop

I don't have any problems with it when it's driving. Drives fine. The O2 sensor is maybe a year old. I'm going to be changing it before I change the injectors. Also my snapon scanner tells me that the car is running lean. Also had a certified mechanic inspect it and he also said the car was running lean. I'm really just trying to find out what effects fuel injectors with a lower flow rate than required would have. Everything I find says I need injectors with a higher flow rate than what the current injectors I have in it are.

Schurkey

It runs good, and you haven't mentioned anything about it setting a "lean" code.

How lean can it be? Sounds like you're getting worked-up over nothing.

If you're still concerned, jack the fuel pressure up and see what happens. Might require disassembly of the regulator, and shimming/stretching/replacing the regulator spring.

dmccain

iTrader: (2)

Gt a TPI pump and a 14psi spring bet that cures it.

Silverbishop

I didn't mention anything about a lean code because I was curious about injector flow rate and had not really thought about mentioning the code at the time. However I never thought about the pump and spring not being enough for the required pressure. So more than likely the 350 injectors I used aren't the problem and the pump and spring in the regulator are the issue?

Also admittedly I probably am a little worked up. I've been struggling with this car for probably a year now.

Silverbishop

So I took the advice of you both. I put a 14 psi spring in it and just got the fuel pump changed to a TPI pump. I won't know for sure if it's fixed until Friday but the spring did seem to help some already as I replaced it about a month prior to having the pump changed.

Silverbishop

The fuel pump did end up helping alot. It goes through its rich lean cycles now according to the scan tool though I do still have some problems with the car, they are not nearly as bad as they were and it is driveable now.

Schurkey

Thanks for the update.

Silverbishop

You're welcome and thank you for the help.