Decel or not to decel
 

I have a 1974 914-4 1.8L. The Haynes manual talks about a "DECEL" valve, at the right side of the engine compartment.
http://forums.pelicanparts.com/uploa...1086371006.jpg
When I got the car I got a decel valve that wasn't installed.http://forums.pelicanparts.com/uploa...1086370927.jpg
IS there a problem?

So it its the stock L-jet system? I'm pretty sure that you need it, it keeps the fuel pressure from skyrocketing which would the injectors from injecting more fuel when you get off the petal.

The decel valve routes air around the throttle plate when closed while coasting. This air promotes secondary combustion and reduces CO and HC emissions.

Thanks guys--If you look at the first picture there is a "funky" three port "thing" where the Decel valve goes does this stay or is it replaced by the Decel valve???

That is a D-Jet decel valve in the top picture. If you have a 1.8 then go with the other one in the 2nd pic.

i think the smaller one in the upper pix is a '74 decel and the bigger one uninstalled is a '75

My bad, not fuel but air. Long week (even though it was a 4 day one)

"upon further review..." whoops, in the top pix that could be the fuel pressure regulator. in the pix, it is located in the position of where the decel valve should be. the regulator is on the drivers side rear (towards rear of car) in a little mount off the engine sheet metal.

Thanks again guys--Now I have time to install the Decel valve--my clutch cable just broke--oh well, should have changed it when I had the car apart--hope I don't miss the summer driving season again!!!

I am almost positive that is a decel valve in the top pic, not a fuel pres. reg. But oh well, good luck.

Uh Uh...........Fuel Pressure Regulator

'Uh Uh' right back at ya. That is the decel valve for 1974, mine has one just like it (and the POS leaks, too). The pressure regulator is on the driver's side of the engine towards the rear, buried way down low. You can be certain that neither of the large, unclamped hoses going in and out of the decel valve in the picture carry high-pressure fuel.

That is a decel valve. You can see the fuel supply from the right engine shelf running to the fuel rales. Visible also is the >30 year old plastic return fuel line. The decel valve uses 13mm vacum lines from the breather to the plenum with a 5mm vacum line to the plenum. To decel or not to decel is a much less important question than to replace fuel lines or not to replace. Forgive me, I was reading Shakespear with my son last night.http://forums.pelicanparts.com/uploa...1086526688.jpg

to clarify a taste, the top pic is for a 74' and the bottom pic is for a 75'....there were so many changes for these engines.

more info-.....the 1.7 and 2.0 also had a version of the top pichttp://www.pelicanparts.com/support/smileys/wat5.gif

The 1st picture is absolutly, without any dought a decel valve the FPR is on the left side rear under the air flow sensor, I to have a 74 1.8 L-Jet and just changed the FPR and removed the decel valve,
Remember the FPR has fuel lines going to it!! not vacuum lines like shown in the 1st picture.

Car should run just fine without it unless you need a SMOG test.

Ken

This has been flogged to death... wonder how long we can keep this string going?

Like I said "it's a Decel Valve." ;)

I'm almost positive its a decel valve..http://www.pelicanparts.com/support/smileys/lol2.gif http://www.pelicanparts.com/support/...s/beerchug.gif

however it could be a decel valve...

UH UH...........it's not dead yet! lol

Yep, it's a decel valve and nope it's not a fuel pressure regulator :D

Next time i will refer to my shop manuals. Sorry for any wrong input, beer tends to help my confidence too much sometimes.

Cheers, Don.

(Note: I was drinking while writing this too. Damnit! Its a vicious cycle.)

Decel Valve
 

Not to beat a dead horse, but one more tidbit about teh decel valve....

Apart from the emissions benefits, it does have one very handy feature. It's nice to have if you have a lightened flywheel. If you lift off the gas completely from high revs, an engine with a very light flywheel will have a tendancy to drop revs too quickly and -possibly- stall. The devel valve bleeds air back into the intake and will slow the rate that the revs drop. A handy thing to have if you've got a very light flywheel...

Just my $0.02...

Josh2

i think the smaller one in the upper pix is a '74 decel and the bigger one uninstalled is a '75.

I think you hit it right on the nose there. The top pic shows a decel valve that was common to 1.7 and 2.0 engines as well. Leave it unless it's faulty, or bypass it if you don't want it and don't need it for smog.

If it were a fuel pressure regulator, two of those connections would be fuel lines, and it would be mounted on the engine sheet metal.

***further flogging a dead horse***