swap350tbi

OK here my problem, I have a 91 RS Camaro that was a 305 TBI, 700R4 trans. car. Now it has a 93, 350, TBI, 700R4 trans. truck engine in it. I had it running but the fuel pump went out and had to replace it. Now that everything is back in the fuel system the car will not start. I checked the timing and it is on 0° mark, I checked the fuel pressure (13/15psi) and it is OK, the next thing I did was to put a piece of paper towel under the injectors to see if I get the two squirts of gas on first turn on (before you try to crank), there was none, when I tried to start it there is more gas than I need. I rebuild the TBI and the fuel regulator everything is OK and no gas on crank with the injectors unplugged. I checked to see if I had a short in the return lines on the injectors but there was not. I made a led light to check the pulses at the injectors during cranking and it looks like it has a steady stream of pulses at both injectors. I know that you will get a pules on crank with every plug fire and that the left will squirt and then the right. But I think I am getting to much gas (flooded). I have a 1228746 ECM and a ANTS prom. Help!!!!!!!!!

TonyC

iTrader: (1)

If it's indeed flooding on startyp, hold the gas all the way down when you're cranking it. This will put the ECM into flood clear mode and should get it started.

swap350tbi

Tony, what about the first two shoots of gas when you first turn on the key (before you start to crank). When I say flooding I mean alot of gas (looks like both injectors are on all the time). The only thing that would make the injector turn on all the time would be the ECM turns them on.
John

Rknrs_92

I had the same problem, the fix was that I had broke one of the "O" rings that go around the injectors. Be careful and check your engine oil for fuel. I dumped about a gallon of fuel into my crank case.

TonyC

iTrader: (1)

Understood, but when you floor the pedal on startup, the ECM will tell the injectors to fire a LOT less fuel. Give it a shot, it sounds like you have other problems, but starting it up like this may help you to diagnose what's going on. Try rebuilding the injector pod, new O-rings, injector filters, etc.

Tony

swap350tbi

All,
The TBI has been rebuilt from one end to the other, all the o-rings are good because if I disconnect the injectors from the ECM and try to crank the car no gas and no flooding. I think the ECM is gone west. Again I connected an LED test light to the input of the injectors and I have a steady light (no blink). Is there anything that would tell the computer to turn on the injector all the time. Oh yes I disconnected the coil and tried to crank the car ofcourse it would not crank, but the LED test light did not come on or blink.
I'm starting to lose what hair I have.
John

TonyC

iTrader: (1)

Did you try flooring the pedal and starting it?

swap350tbi

Tony,
Yes I did try flooring the pedal and cranking it. I didn't have the injectors connected but had the LED test light pluged into the left injector and with the pedal to the floor you could see the light blinking. Does anyone know what the timming setting for a 1993 TBI 350 truck would be, right now I have it a zero.

John

TonyC

iTrader: (1)

Try it with the injectors plugged in.

dimented24x7

iTrader: (2)

What happens when you floor the gas is the ecm sets the desired AFR to 20:1 to lean out the motor and allow teh flood to clear. Doesnt always help if things are really far off. What works better for me is to just cut the fuel entirely when in flood clear mode. With the stock ecm just unplug the injectors and crank the engine to run all the fuel out.

Flooding out on startup is a pretty common problem. I lived with it for a year or so. The ecms are set up on the rich side and when you have a new motor and larger injectors, there is just too much fuel and it floods. The solution is to change the calibration in the prom. Assuming youve gotten the VE tables corrected, the main things to look at will be the crank AFR, the initial and choke AFR and its decay multiplier, the filter coeff. for bringing in the spark advance, the IAC park position and run positions, and probably a few other things Ive forgotten.

Theres a whole mess of stuff that inderectly effects the startup as well, but those are the things that are directly related to it.

The crank AFR defines how rich the mixture will be while cranking. They set it pretty high at the factory. The filter coeff for the SA controls how fast the timing can come in. This was too slow for me and the motor would catch, come up to around 1200 rpms, and then drop like a brick. With the rich AFRs, this would cause a stall and the motor would flood out.

The IAC park position is also pretty high so most of your air will pass around the throttle blades, leaving the fuel to drip on the intake floor. The solution to that is to open the blades to the pont where the IAC is just open enough to allow the ecm to control the idle when fully warmed. You can then close the IAC down when it parks and allow more air to pass through the throttle blades while cranking. Also improves fuel dist. when the engine is running.

Theres alot more to it then this, but this will help for starters.

dimented24x7

iTrader: (2)

Hmmm... That is interesting. Only thing I can think of at the moment is to check the CTS sensor and make sure the resistance isnt infinite. The ecm will see that as being very cold. This can cause the inejctors to have a very high duty cycle. Although you should still be able to see them turn off momentarily when firing.

swap350tbi

All,
I just solved my problem, I think the hard problems are when you don't have a problem. I connected everything like it should be and put just a little starter fluid on both sides of the TBI. Believe it or not the thing fired off and ran. I drove it around the block for the first time in almost a year. I would like the thank the ones that responded to my problem on net.
Drive hard, keep it between the white lines and again thanks (TonyC, rknrs_92, and dimented24x7).
John (swap350tbi)

TonyC

iTrader: (1)

Good to hear man, it always feels great to get it going again after a while

dimented24x7

iTrader: (2)

Ive had similar problems caused by the lifters going flat over time. The real acid test for startup, though, is leaving it out over a cold night. If it starts, then your in the clear.

bodyman57

I have had this very same problem.. Make sure the ignition temp control switch is working. it's right by the thermostat housing most have 2 wires.
disconnect tan wire for timing.. chevy says set the timing at 0 degrees, ( I advance mine to 6 degrees ) plug back tan wire. start it by pumping gas paddle 3 times as your cranking it and hold to floor.
This tells the computer it's flooded and lets the engine clear out the gas. let off the key but don't turn off and wait. keep paddle on floor though. try it again it should start.
once you get it started clean out the extra fuel in the cyclades and let idle. advance timing to 4 or 6 degrees by unplugging the tan wire and set it, Plug tan wire back up.
let it get cold once again hit key to start (BUT DON'T TOUCH THE PADDLE) it should start right up.. hope this helps,

Tuned Performance

iTrader: (92)

bodyman57

yeah well I am new to this. and didn't see the date.. so shoot me..lol
Maybe it will still help someone..

hugh.g.rection

helped me today