Fuel pressure drop......regulator or injectors???

[im4darush]

Situation is a hard start after the car has been sitting a while warm. It will crank longer than usual and when it does fire, I see some black smoke in the exhaust. Logically I am thinking injectors, but can the regulator play a role here? Pessure in the rail goes to 0 after about 2 hours of sitting. Runs good otherwise. When running it is steady at 38(line on).

 

[bogies87]

Yes the regulator can play a role. So can the pump. Easy way to tell which end of the car its on is to pinch the return line and see if it bleeds off.
Make sure you get the rubber part of the return.

Sent from my SCH-I535 using Tapatalk 2

 

[buickGN3:16]

or u may have an injector or a few injectors staying open so pressure will cause stuck open injector to leak fuel into cylinders then when u fire it up its puffing black smoke from an extra amount of fuel in cylinders.. could be sevral diffrent things causing this,


Posted from the TurboBuick.Com mobile app

 

[aminga]

Check valve in the pump

 

[TexasT]

If you shut her down and pull the plugs I bet one or more are wet. If so, injectors. I had the same problem with my suburban. A new set of injectors cured it.

But do the other tests too. Could be a combination of things.

Posted from the TurboBuick.Com mobile app

 

[earlbrown]

You mention black smoke on startup...

Does it crank like it's like a carbed car that's almost flooded, then with it busts off a big puff of black comes out, then it clears it's throat and runs right? If so, that sounds like an injector.

A bad FP check valve can't put gas into the combustion chamber. A leaky FPR could possibly put raw fuel into the vac line running to the throttle body but that doesn't really match your description of the running condition.

 

[im4darush]

Earl, that is exactly what is happening. Car runs great. Starts great cold, starts great hot if don't let it sit too long. But if you let it sit for an hour or so, it will crank long, fire and spit black smoke out the exhaust. The smoke clears right away and car runs great after. I think the fact that I have raw fuel in the cyl means one of the injectors is leaking as you said. Don't really see how the other items would create black smoke on start.

 

[earlbrown]

walk out to the car when it's cold and crank it just long enough so that it WONT fire up. Then pull all 6 plugs. If one of the plugs is gloss black and 5 of them are tan or white, you found the injector.