Car is a 95 Z28 with a 396 Stroker LT1 9:1 Compression with an ATI procharger pushing 8 psi of boost. Here is the problem.

It has a hard start. It will turnover and over and then after 30 seconds start. The tuner says they think the injectors are leaking (50lbs/hr MSD part # 2013). They tested them at a shop and the guy said some of the injectors where off. SO I got them back and tested them myself at another shop and the flow test said they where dead on. So I sent them back. The car was built by mistake with 13:1 compression so I thought this is the reason for the hard start. Well the new 9:1 compression motor is in and they are still having a hard start problem. So they said they think its still the injectors. They said they pressure tested the fuel system and it is not holding pressure. So they then said it is either a leaky injector or a defective Fuel pressure regulator. But he said he is leaning towards leaky injectors because it is having some issues on the dyno at high RPM. So my question to you Fuel system experts is do you think they are the injectors? What are the odds of 3 brand new MSD 50 lbs/hr injectors out of 8? DO you guys think it is more likely the injectors rather then the Fuel Pres Regulator? Also will a leaky injector cause a hard start? I would say 1 out of 10 times it starts right up otherwise it turns over for 15 seconds or more then boom fires up.
Any input would be greatly appreciated. I guess I can send all the injectors back to MSD and have them test them????

 

i'd lean towards a bad regulator. I'd check fuel pressure on up the rpm band and see if it's holding pressure. I'd check the fuel pressure w/ the ignition key on but, don't start the car. With the S/C I suspect your fuel pressure might be higher than "normal". If the injectors are leaking, remove the fuel rail w/ the injectors connected. wipe off the tips and turn the ignition on. Check for fuel leaking out . there should be no fuel dripping or "wetting" the tips for 30 seconds. good luck.

 

They said it was leaning out in on the dyno in high RPM. He said he pulled off one of the tubes tot he fuel Pressure Reg and it was pissingout fuel. I guess this is not suppose to happen? Any way he says he is noe 95% sure it is the regulator because of this. Man I hope so!

Thaks again for the input.

 

If the fuel was "pissingout" of the vacuum compensation line, you have a ruptured diaphragm in the regulator. That would cause it to be difficult to maintain fuel pressure at startup, and would have dumped fuel into the intake the whole time it was running, at shutdown and again on startup. Seems to explain the problems, including the lean out.

Seems fairly obvious, but maybe I'm overlooking something, or don't have all the facts.

PS: Please don't use the "quote" button to duplicate your original post in the responses, or the thread get a little cumbersome......

thanks,
Fred

 

I agree with Fred. I had a hard start issue and it turned out the FPR was not holding fuel pressure. I would try replacing it.

-Alex

 

Thanks Fred and Alex. They have changed the FPR and I am just waiting for a call to find out if that fixed the problem. I should get a call within 24 hours. I hope it is only the FPR!

 

That looks like a nice set up in your signature Jason

In hindsight I should have just sent my car to ARE rather then do it myself.

 

97TA-WS6-Con, I would have to say that last year I would not have recomended ARE but now I am very happy with them. The "new ARE" is nite and day compared to before. There is a lot to my story but I will keep it short and say Wade (the new sole owner of ARE) and Barry are very capable and have awsome customer service.

 

Have you had a chance to pull the plugs and see if they are fouled? I know when I had a leaky injector, that plug was black and the rest were normal. So, I swapped out the stock injectors with SVO 30lbs. and no more fouled plug.

Talking about AFPR, is it suppose to hold pressure with the key in the ON position, but not running? I just notice on my electric FP gauge, that it bleeds down to 0. BTW, I have an Aeromotive AFPR.

Thanks,

Jody J.

 

The stock fuel system should hold pressure..... there is a check valve in the stock in-tank pump, and the FPR should close down to prevent leakage via the return line. But not all aftermarket systems will hold pressure without the pump running.

 

freds got it right. be sure to let us know if the new FPR fixes ya.

 

I had no idea there had been a change. Is Nick still there? I would assume not.

PS where in Canada are you? I'm in Surrey BC

 

Yes you are correct. Nick is no longer there. Now as for if the change in service is due to that I am not going to comment since I am not that type

I am from Ottawa Ontario

By the way your set up looks very nice! With that new rear end of yours slicks will are going to make such a huge difference. I am glad the compression of my motor was lowerd to about 9:1 so I can turn up the boost a bit

 

If you could call it running then yes LOL. A calculation mistake and inturn a lot of head aches trying to understand why so much detonation and running like a year 1903 Ford Model-T LOL. They took the time to tear the motor apart and find the problem after so many head aches. I cant wait to drive this car this summer after not having it for 3 summers.

 

Update:
Well I called ARE today and after replacing the AFPR the hard start problem has disapeared. It now starts right up. Its goes on the dyno tomorrow so I will let you guys know if the lean out in high RPM is also gone.