This is my problem... I have a TPI system from a 91 camaro. The engine runs great and starts great, no power loss, and not running rich at all. the engine runs and act great!!! With one minor problem…
When I start the engine cold or hot and drive it around sometimes like at a gas station or a friend’s house I will go back out to start it and it fires and dies, fires and dies, and to get it started I have to feather the throttle till it stumbles and revs up to 3k-4500 rpm and then it runs great. I kind of smell fuel like it is flooded or is loaded up. I checked the fuel pressure and it holds at 41psi running and I have it at 45psi with the vacuum off. The problem does not occur every time, seems like it happens more when I drive it a short distance like 1-10 miles and turn it off and try to start it again. The last time it did it, it sat for 20 mins and I tried to start it and it stumbled for like 3 times before I feathered the throttle to get it going and it ran fine then.
New Items I replaced recently were:
Plugs Accel 437SS silver tips
plug wires 8.5mm MSD
Accel ICM
Accel super coil
MAP
CTS
Intake air sensor
Heated 02
IAC
Adjustable fuel regulator
Design III bosch 21lh/hr injectors

I have the 7730 computer with a hypertec memcal and was reprogrammed for my application. I have a RV cam on a rebuilt block and heads.
I cannot seem to figure out what the deal is... please help

 

DBR,

I know it's been about a month, but I wanted to share this with you anyways in case you are still having a problem.

I was having a similar problem recently. The TPI would start great when cold or after sitting for a long period of time, but if I drove it and tried to restart after 20 min (and less than about 4 hrs later) it would give me a hard time starting (flooding).

I first suspected a leaking injector, but my problem ended up being a small tear in the diaphragm on the fuel pressure regulator. What was happening is after I ran the car and shut it off, the pressure in the fuel rail was squirting fuel (through the small tear in the diaphragm) into the intake plenum. The fuel was going into the plenum through the small vacuum line which is connected from the regulator to the plenum.

The good thing is that it is real easy to check. Run the motor for a few minutes and shut it off. Then disconnect the vacuum line that goes from the regulator to the plenum. If the diaphragm is torn then the residual fuel pressure in the system will start spitting the gas out of the top of the regulator (where the vacuum line was).

When I did this I had to quickly put a spare vacuum line and an empty soda bottle on the regulator to catch the fuel coming out. After about 20 minutes the bottle had about 2-3 ounces of gas in it !

When I originally put fuel pressure gauge on it I wasn't seeing a very big pressure drop after shutting the motor off, which was why I suspected a leaky injector. I was very shocked about the amount of gas that was actually coming out of the regulator.


Good Luck,

Tunedport350

 

Thanks for the input... and your right, i suspected the same issue as one that may cause my problem. So I changed the diaphragm in my Holley AFPR, and still had the same symptoms.
So an update on my problem, well it still acts up I did increase the rail pressure to 47psi with vacuum off, it made a slight difference, but still died. So I tried things here and there and come to find out that my intank fuel pump is failing intermittingly. I ran the engine hard one afternoon and no problems at all till I drove right in front of my driveway and it DIED!!! Well I pressurized the rail and it started and ran for 5-10 seconds and died like three times. Then all of a sudden it started the rpm dropped a bit and it picked up again idled… so now I am installing a MSD 285lph inline fuel pump and dropping the tank and removing the in tank one.
CROSS YOUR FINGERS

 

I see that you already have a plan, but...

What was the fuel pressure when your Jeep wouldn't start? You could hook up a gauge and drive around until it dies. Sounds like it is loading up on fuel (maybe a "new"/refurbed injector is stuck open) and letting the car sit for 20 minutes is long enough for the extra fuel to evaporate.

Where did you get the injectors?

Good luck.

 

i know... and I should hook it up untill it does. I might just do that and whenn it dies and the fuel drops to 0-20psi I will know that was the problem. I did try to run it at 35psi with vac on and it died every 20 to 30 yards... I turned it up and it ran good till I really laid into the throttle and it starved itself and started to act up.

 

This was a transplant into a Jeep, yes? What did you do for the fuel pump (ie. factory TPI pump or aftermarket)? I will assume you have already replaced the fuel filter (starvation issue). If you used the tank from a Wrangler, the stock Jeep fuel pump may not be able to keep up with engine demands (pressure vs flow).

Hope this helps.

 

This indeed was a transplant into a 93 jeep wrangler with a stock 4cy MPFI fuel pump. They claim that the fuel pump for the 1992-95 wrangler is enough to run a 350 TPI but i am skeptical now, and being the stock 1993 fuel pump, that is now 19 years old might be worn out... I have replace the fuel filter about a 100 miles ago, so that is taken care of.