fivestar

I have an 86 IROC with TPI, I changed out the fuel pump and new 22lb injectors along with adjustable regulator, now it will only run for three seconds or so then it dies. It ran fine before the change but it just won't stay started. I hear the fuel pump and I am getting fuel, regualtor at 65 lbs, Anyone have any ideas?

Fivestar

Davidgou

iTrader: (2)

Sounds to me like you're loosing fuel pressure. Is your new fuel pump maintaining the fuel pressure while the engine is running?

InjectorsPlus

iTrader: (1)

Why are you running 65 lbs of fuel pressure?

What other mods do you have?

What kind of AFPR?

Vader

The high pressure may be preventing the injector solenoids from opening the pintle valve. Drop pressure closer to normal and see what happens. An '86 (305 stock) and 22# injectors will probably not need that kind of pressure unless you're blowing it or adding NOX.

fivestar

Tried dropping the pressure down to 45 (normal) but it still runs for only a few seconds. It is a balanced and blueprinted engine and plan on adding headers and free flowing exhaust. I will adjust to about 50-55 and then measure fuel flow and find out if I am maintaining pressure after initial start. I am thinking that perhaps I have a vacum leak somewhere in one of the newly installed injectors any thoughts on this??
Thanks for all the helpful advice by the way...

Fivestar

InjectorsPlus

iTrader: (1)

Weather it's the injectors or not.....my .02 is to get bigger injectors if you need them and run the pressure at one bar. There's no advantage to running pressure that high if your injectors are sized right. All you're going to do is promote failure by compensating for an injector that is too small.

What kind of injectors are these and who sized them for you? Why do you think you need that much pressure? Somethings wrong there if you HAVE TO run that pressure.

Vacuum leak would not keep the car from starting, where would you think you have a vacuum leak with injectors?

And finally, are you bases covered? Is this car in good tune? Did you check spark?

xch3no2

Eh? one bar pressure? what did you really mean...

I see all manner of tuners running all sort of injectors at much higher pressure than stock without any "fear of failure".

I agree that 65lbs psi sounds like far too much for your setup.

Start by determining your fuel requirements based on expected HP.
Find a happy injector size that will let you both raise & lower pressure for tuning purposes & MOST important set your fuel injector constant & offsets for the size injector & pressure that you are running or it will NEVER run right.

I think the running problem you are experiencing is one of detail (mistake) in reassembly, go back over all your work, and set pressure correctly.

fivestar

I think you may be right about a fault in reassembly. Going to go back and break it down and start again. Had to make a store run and friend who was helping reassembled some of the top end without me being there and not sure if everything was put back just right...Will also drop the fuel pressure. Thanks for the feedback

Fivestar

InjectorsPlus

iTrader: (1)

I've had more than a few customers melt a piston resulting from running higher pressures than necessary.

Of course, it depends on the injectors. Like any other mechanical some will fail some won't.

FP should be used to fine tune once you get in the ballpark, not compensate for too small an injector.

spkx714

Did you try running it with the old injectors? You changed three items, three things are suspect. Injectors are the easiest to swap, pressure requlator, I hope you cut an access hole for the fuel pump. But mostly, I hope you don't have to go there.