low fuel pressure problem

K

Ken Seegers

SCCoA Member
I currently have a low fuel pressure problem in my 93SC. At no vacuum or boost, I have about 32psi of fuel. Also after a couple of minutes the fuel pressure drops off. I have changed the fuel pump, fuel filter, fuel rail, injector "o" rings at the rail, and fuel pressure regulator. I have 42llb injectors in the car. I searched for any ideas, but I am still stumped.

Thanks
Ken
 
Couple minutes while running or after key off?

How much does it drop?

Is the tank (cell?) vented properly?
 
Smell any fuel on the dipstick?

If not, I'd say it's not your lucky day w/regulators...
 
Sounds like a low fuel pump voltage issue. If you had a leaking injector or regulator, pressure would drop almost instantly, so i doubt that is the issue.

David
 
I get 30psi with regulator line disconnected and it doesn't seem to drop when I have power on. My voltage off the alternator is 13.2 volts. Also the car seems to burn pig rich at idle you can smell gas and when I get into boost I am blowing black smoke out the the tail pipes. I check the oil and no gas, plus the oil is clean
I am still puzzled
Ken
 
Last edited:
You would have to verify voltage at the pump.

Regulator should hold rail pressure at 39 psi with the vac line disconnected and engine idling. Below that means either the regulator is bad, or the fuel pump is under performing. I know you said you replaced the regulator so.

You said it seems rich, that wouldn't be happening if you're running low on fuel pressure. Are you sure your gauge you measure fuel pressure with is accurate?
 
sts70004 said:
Did this happen overnight, develop over time, or after an upgrade or repair?
Click to expand...

I have had the problem for awhile. I change from a 190lph to 255lph pump. After changing the regulator and fuel rail, I decided to change the pump because that the low fuel pressure. I will try and test the voltage at the pump later this week.

Ken
 
I just the fuel pressure... I am getting 32psi at idle with the line off. I would hate to think another regulator or pump is bad. Well I am only getting 9.76v to the pump. I guess now I have to out why.
Ken
 
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