Poor Fuel Mileage '83 944 --- Help?

[3rdday]

My son was given my dad's 944 last spring. It had not been driven much the past few years due to an intermittent starting/running issue. Drove from Florida to Tennesse, averaged ~20+ mpg.

Took to a mechanic and had tune-up items such as distributor cap, rotor, plugs and wires replaced as well as rebuilt starter and new sensors on transmission. Starts and runs great.
The problem now is extremely poor fuel mileage: around 9-10mpg along with the smell of gas. Found the hose under the rail where the fuel pressure regulator and damper are located was dried and cracked and fuel was coming out of it. I fixed that so no more gas smell but still poor mileage. Any idea if the fuel pressure reg or damper need replaced? Or if not, what else can I check?

Car is mostly driven to school ~4 miles one way on a Parkway with several traffic lights. And then the usual teen running around after school. But even when driven at highway speeds, mileage is poor.

Any insight is greatly appreciated.

[Techno Duck]

Change the fuel filter also.

Another thing that is worth just changing is the O2 sensor.

A failing dampener or regulator will cause abnormal fuel pressure, only way to check these is to check the pressure at the rail.

[SoCal Driver]

When was the last time the timing and balance belts were changed? If you don't know you need to change them NOW!

A broken timing belt will, at the least, bend the valves. Seen a few loose a piston and a head if a valve breaks off.

Check the vacuum lines to the fuel pressure reg and damper. You may get lucky and find it's a two dollar rubber elbow that needs replacing.

[Aerkuld]

Agree with Technoduck. The O2 sensor improved my mpg, but it isn't going to get you from 10mpg to over 20! There is something more than that. If you can get hold of a fuel pressure gauge and check the fuel rail pressure (check this site: http://clarks-garage.com/ and look under "Garage Shop Manual" for the "Fuel Pressure - Checking" section you should be able to tell if the pressure regulator is the problem. You may also want to check the injectors to make sure they are working correctly and you don't have one sticking open. Try taking the fuel rail off with all the injectors in place. Put the business ends injectors (still attached to the fuel rail) into four containers. Cutting the bottoms off four clear plastic soda bottles would do. Turn the engine over for a few seconds with the key and see if all four injectors are flowing about the same. It will give you a rough idea.

See if that helps. It might also be worth checking for leaks around the fuel pump.

That site, if you haven't found it already, is very useful. Add it to your favorites I guarantee you'll need it again!

[Aerkuld]

Originally posted by SoCal Driver
When was the last time the timing and balance belts were changed? If you don't know you need to change them NOW!

A broken timing belt will, at the least, bend the valves. Seen a few loose a piston and a head if a valve breaks off.

Check the vacuum lines to the fuel pressure reg and damper. You may get lucky and find it's a two dollar rubber elbow that needs replacing.

SoCal is THE expert on this board (isn't that right SoCal!). He doesn't know how many times his advice has helped me. But timing belt is a must.
I picked my 944 up nice and cheap thanks to someone who didn't think they needed to replace theirs every 30k. It's not a difficult job and timing belts are cheap. A complete set of valves and a top end rebuild is NOT!
Search on here for details, there are always people that are willing to offer advice.

[3rdday]

WOW!!! thanks for all the replies. I will try to look into this over the weekend.
When we got the car, I asked about the TB and was told it had been done within 10-15k. I will find out for sure, though. I have a VW TDI and know how important it is to change the TB.

[SoCal Driver]

I'm only an "expert" because all of the bad stuff has already happened to me. Broke two timing belts. Don't ask.

[Razorback1980]

Pull the vacuum hoses off the fuel pressure and dampner and see if there is fuel in them. If there is, then they need to be replaced. When I first picked up my 87, gas was running past the fpr and into the vacuum line which goes straight to the intake manifold. This dumping of the gas also allowed gas to sit in the J boot which caused it to break and creating a vacuum leak there.

[3rdday]

Razorback1980 - yes, there is fuel in that line. Do I need to replace both units?

[speedracing944]

I would replace both the dampener and pressure regulator both of which should be able to be purchased form Pelican. When my FPR went bad I had a 100psi guage on the front of the fuel rail and the guage spiked. I had black soot pouring out of the tailpipe and the darn thing would barely idle or run.

On a side note you just missed the pelican Parts meet at the Tail of the Dragon last weekend.

Speedy

[3rdday]

speedracing944 - looks like I will be ordering the damper and regulator. There is black soot coming out the tail pipe also.

Yeah, I saw the thread about the Tail of the Dragon. I have never been there even though I live so close - a couple hours away, I am guessing. Maybe next time!

Everybody - Thanks for all the advice. I will start with replacing these two parts and see what happens.

[Razorback1980]

Be sure and check the condition of your J boot at the same time. If it's cracked or has damage on the inside (right about where it bends), then you should replace it too. This was caused by fuel running down there from the FPR and sitting in the J boot at the low spot. This can cause vacuum leaks and the engines in these cars are very sensitive to vacuum leaks. I think you are doing the right thing by replacing both...at least that is what I did. Not cheap I know, but they play an important part and if one is bad, then probably both are.

[3rdday]

I have already replaced the J boot. It was very dry and developed a crack. Car wouldn't run at all!

I will check the inside of it, though, and clean it if needed.

Thanks again.

[SoCal Driver]

When you replace the FPR and damper don't use the body of the fuel rail for leverage. Use the hex flange on the units. Otherwise you will crack the fuel rail where the mounting brackets are welded. Also get a fresh set of o-rings for the injectors. In most cases you don't need the plastic parts but you will get them in the re-seal kits too. The top o-ring is the most important as it seals out the fuel. Should one of these develop a leak you most likely will have an engine fire. The bottom o-ring seals the intake. Should it be leaking it's just a vacuum leak.

[3rdday]

Thanks for that advice, SoCal Driver. With my luck, I would have done just that and destroyed the rail! Will replace the O-rings as suggested.

Thanks!

[shikzachaser]

I have an 84 that I let sit for over 5 years before I decided to get it going again. I had a very similar problem and it definately turned out to be the FPR. I replaced it and it ran great for a couple thousand miles until I decided to really do some things to the car. I have since gone w/ a Lindsey adjustable system and as such no longer have a use for the stock parts. I have the new FPR and Damper still on the old rail. You can have them if you have not purchased them already. PM your address and I will get them out to you. You can just pay me the postage after you get them. I have quite a few stock parts that I no longer need to include a fuel pump, fuel rail, coil, air filter, plug wires, bumpers, and a lot of other stuff I can't think of right now. Let me know what you need as the 84 and 83 are identical.

Steve

[shikzachaser]

Oh yeah, I jave an O2 sensor also.

[3rdday]

Thanks, Steve.
I have sent a PM.

steve

'83 944 - son's daily driver
'73 914 2.0 - in need of restoration
'91 Westfalia - getting an engine replacement
'96 Passat TDI - my daily driver