Ok to start its a 93 sedandeville has 93k just chanded plugs, wires, cap, rotor, air filter, fuel filter, did fuel injection cleaning multiple times(sea foam product) and did a ckeck for visibly broken vacuum hoeses. All this and i am still getting 9.8 mpg highway and city combined. I can smell a strong odor from the exhaust and the car runs kinds rough at times. I do not wanna spend tons of money finding the problem so any advice o where to go next would help a lot thanks.

No large puddles of flammable liquids laying around on the driveway, eh?

I agree with you that this is NOT normal. In fact, that kind of mileage is pathetic. You must be closing in on the poorhouse real fast with the number of times the tank needs your attention.

So, in the absence of any obvious leaks, could the fuel sending unit be shot? I suppose it's possible that your pissing raw fuel out the tailpipes at an alarming rate, because you did mention a strong odour from them. But you'd have to be losing a significant amount on an almost constant basis, to arrive at those numbers.

Others will be along that are more adept at this type of troubleshooting than I, but rest assured that you're at the right place to find a solution to this issue.

And welcome to our forum!

Any trouble codes?

I suspect the O2 sensor went out. Maybe FPR is shot?

Check the FPR.

Check the fuel pressure at the shrader valve. It's located at the extreme front of the engine on the driver's side. It's kinda underneath a plastic cover - one or two small screws hold it on - but you can attach the fuel gauge without having to remove the platic cover. There's a cap covering the scrader valve, just screw it off. (A schrader valve is the same as a tire valve that you fill a tire with air) You can get a fuel pressure gauge at any auto shop for pretty cheap.

It should be around 40 psi. Make sure the engine is off and cool before you put it on and have a big towel handy to sop up any spilled fuel. Then, when you've securely attached the fuel pressure gauge, fire up the engine.

If the pressure is much more than 40, have the FPR (Fuel Pressure Regulator) checked.

The FPR is not very expensive, but can be a real bitch to replace because one of the bolts points down towards the engine block leaving you with about one inch for your wrench and it's in the 'V' between the cylinder banks so there's no way to get an open-end or box wrench in there - you need a special tool to get at it. I just took it and a new FPR to a local-yokel mechanic who replaced it for cheap.

Thanks THU I will give it a shot. Someone else told me the same thing. I was think o2 sensors as well and those are fairly easy to change as well. I am a decent mechanic just not good at diagnosing problems that are past normal. More of a parts changer if you will.

If the fuel rail pressure is not to spec, then there is plenty of postings here on how to check the FPR.

Tech Tips section has a post on how to check and replace it.

Thanks THU I will give it a shot. Someone else told me the same thing. I was think o2 sensors as well and those are fairly easy to change as well. I am a decent mechanic just not good at diagnosing problems that are past normal. More of a parts changer if you will.

If you can change the plugs the o2 sensor should be a breeze. The 4,9 93 like mine only has one o2 sensor in center back of the engine bay straight down in the exaust. I did replace mine in about 20mins.

I was getting about 9 mpg light city and changing that took me to 14ish, Now that it usually gets driven a bit longer distances I average 19-20 after new wires. I would look at the 02 sensor soon. Its about 20 dollars to get a new one, but if you wait like me it could foul up a few more componets.

If you can change the plugs the o2 sensor should be a breeze. The 4,9 93 like mine only has one o2 sensor in center back of the engine bay straight down in the exaust. I did replace mine in about 20mins.


Lol this couldn't be further from the truth. I go to change the 02 sensor and darn thing wouldn't budge. So we get the manifold nice and hot and the o2 sensor comes out. We is me and my brother who is a better mechanic than I am. Well upon inspection of the o2 sensor it had mega carbon buildup and the threads were stripped. So we tried to install the new one and it would not thread in.
We tried using a thread chaser to clean the manifold with no luck whatsoever it wouldn't thread either. Next step we got a thread chaser and forced it in the manifold and then had to put the o2 sensor in the same way.
Long story short I will be having the manifold tapped and installing a new o2 sensor next week but the car is driveable and i am getting 17.2 mpg in city. Thanks for all the advice.

Well glad you got it, Mine wasnt stripped out fortunately. Wasnt the easiest thing to remove but not the hardest. Look like a pretty nice increase in mpg aswell