Question: Running too rich

[English Guy]

I think my 89 is running too rich (smell of gas but no leaks, harder to start and only 12-14 mpg town driving:ugh) is there a straight forward solution to fix this? Many thanks for any advice folks.

 

[ex-x-fire]

1st place to start is pull the vacuum hose to the fuel pressure regulator, prime the fuel press. by cycling the ignition. Then watch the regulator to see if any fuel leaks at the vacuum connection.
If you don't see anything there, you'll have to get a fuel press. tester to make sure you are losing psi. Possibly the injectors are dirty & not closing all the way.

 

[muddywaters]

My 88 acted the same, it was the injectors, they ohmed ok but leaked down.

 

[Toms007]

Sounds like FP regulator. My Silverado (although it was an LS series engine) was doing same thing. I pulled the vacuum line off and gas ran out. Replaced it and problem solved. I don't know if the gen I SBC had the same issue or not.....just a thought. Injectors leaking would cause a hard start, strong fuel smell as well.

 

[English Guy]

1st place to start is pull the vacuum hose to the fuel pressure regulator, prime the fuel press. by cycling the ignition. Then watch the regulator to see if any fuel leaks at the vacuum connection.
If you don't see anything there, you'll have to get a fuel press. tester to make sure you are losing psi. Possibly the injectors are dirty & not closing all the way.

Hi, where is fuel regulator located?( Injectors are recon bosch with about 700 miles on them) Thanks

 

[ex-x-fire]

Its on the fuel rail, under the plenum. The regulator is back near the dist. cap, you can unhook the hose there.

 

[English Guy]

Its on the fuel rail, under the plenum. The regulator is back near the dist. cap, you can unhook the hose there.

I pulled vac pipe on regulator and she fired up on first turn and no leaks and no gas smell. service engine light still flashing but no codes shown,weird.Also backfires sometimes when cranking, not big bang more loudish pop.

 

[WhalePirot]

I'd check for a vacuum leak. At idle, no load, the full idle vacuum will reduce fuel pressure, as it should, for reduced fuel required. With an adjustable FP regulator, a MAX value is set with the hose off.

Less than appropriate vacuum a the FP regulator, and hence to the injectors, will cause rich running.

Either the regulator (as the above addressed) or the supply line may be leaking. Looking for fuel, as above, addresses a failing diaphragm.

 

[English Guy]

Fp reg checks out fine so inspected O2 sensor which was very sooty and looked like it had been fitted some time ago. Replaced with new sg-5 unit and the improvement was amazing! Much better response, more power and quick again like she used to be. Engine check light is still on thoad, but still the best £25 I have spent for a while!
Many thanks to all that replied, cheers.