TheTunedPort

So my '86 Vette since I've had it all of a week, has been hard to start, hot or cold, takes many cranks (3-5 cranks at 3 secs each) and often blows a puff of white/bluish smoke for a few secs upon startup. It runs strong out on the road and has enough torque to take off in 3rd... so it seems to have good compression and the oil is clean no coolant.. 103K original miles, runs like a sewing machine once running
The problem is also not getting worse or better... now I had an old 88 Camaro with a TBI 305 in it and I know all about the valve guides and seals... but the Camaro was never this hard to start I don't think.
This car has a stock L98, but the previous owner has done some sort of bypass of the fuel regulator with a rubber line and turned up the fuel pressure. Why would someone do this, and is this a problem? I feel like if the car was tuned from the factory, computer and all, to run on a regulated amount of fuel, then thats how it should stay.. am I wrong?
Is this a headgasket or a dirty Throttle Body?

65Z01

Does the rubber line connect into the intake manifold? If so that is normal.

I would use FP gauge on the Schrader valve to see how is fuel pressure both during start and during operation.

If FP is ok, steady and does not drop off it would seem normal. In which case I would pull a few spark plugs to evaluate condition.

KyleF

You have to check you fuel rail pressure while running at idle. I am not sure what you mean by bypass, but if the regulator is not getting vacuum when you hit the throttle you are not getting more pressure as the RPMs climb and would be going lean. However, you say it has power so I doubt that. It should be connected to the manifold somewhere. Regardless, this shouldn't have an effect on start up. I will say though, when you are having issues, you should always correct anything you know is wrong.

Bluish smoke is oil, you know about the valve guides and seals, so you know this happens to a lot of SBC's and it's not really a big deal. If it is only happening at start up, it is what it is.

If you search on thirdgen.org you will find and I am currently dealing with this on an 88 IROC 350, hard starts is a symptom of leaks in the fuel rail. a seal kit is about $2.99 from AutoZone and if you replace the injector O-Rings at the same time that is another $4.99. But you will need the intake gasket set which is another $20. Or, if you don't like your regulator set up, while it's apart you can upgrade to an adjustable fuel pressure regulator (AFPR) from TPIS for $80 or so and it will come with the upper intake gaskets.

I would take a good sniff around your fuel rails after you hear the pump prime.

Dt86

Please post a photo of this fuel pressure regulator bypass.

454z06

Does pumping or holding the throttle help/hurt any? Dirty or stickong idle air control...?
Theres a short vacuum hose toward the back right side of the upper plenum. It goes from the top of the fuel pressure regulator to one of the small ports on the intake.. Oil one end off, make sure its dry. Cycle the key on and off a few times. Make sure gas is not coming out of the regulator.
Do you have access to a scanner? If so, turn key on and see what your air temp and coolant temps are.
also check your sign timing. If its retarded to far, will affect startings

KyleF

Being hard to start warm points away from the IAC. However, this is an easy check and the procedure for resetting it is also pretty easy.

You should remove the IAC, Clean it and the passages. Install it, Plug it back in, ground A&B Terminals on the ALDL, key on for 30 sec, unplug IAC, Key off, then remove the jumper from the ALDL port (I used a bent section of 14ga wire). Disconnect the EST, start car, adjust idle in P to about 600 RPM with the throttle plate, or about 450-500 in D with brake on. Then confirm timing with a timing light, adjust throttle again if needed. Shut car off. This should be done while warm.

Disconnect battery to reset computer and clear codes (EST should cause a 42... if it doesn't your Ignition Control Module or PCM may be bad), plug the IAC and EST back in, reconnect batter, start and drive at different speeds for about 20 minutes.

Having a scanner to see IAC counts, Knock Counts, Codes, 02 readings, etc is very valuable. I use WINALDL.

3D-Aircrew

So you already know that the valve guide seals need replacing ... no sure what you are talking about on the fuel bypass without seeing it. Also If your fuel pressure regulator is as old as the car then it likely is toast with fuel leaking into the plenum. This can cause hard starts and also can thin your oil.

Good luck

Leaking FPR


Leaking FPR