Xvetteowner

My car, an 84 Euro S is finally after 6 months of ownership on the road as of today, Just doing local around town driving to start off. It goes straight, stops fine... but damn if it doesn't feel like its fighting vapor lock after fully warmed up ( Its 90 today) I thought I check that the transmission goes into 1st gear ( No place local to floor it) so I jumped the kick down switch , backed out of the drive way, shifted into gear and was on my way ( Starting off going down a pretty steep hill) no sooner do I come to the end where it flattens out (going 2000 rpms) my car starts acting like its running out of gas, bucking to the point that I thought it may stall. So I give it more gas and the bucking continues to around 3000 rpms then she really jumps with just a small amount of bucking. I got home, shut it off and waited about 30 seconds to she if it would restart, a few seconds of cracking without touching the gas she started right up with just that little missfire I can't seem to fine between 1200 and 2000 rpms ,,,then under a minute later the missfire is much worse. I think the 1st thing to check would be the fuel pressuse, is there a place to hook up a gauge? Heat's got something to do with this problem. I just got to find it. Thanks in advance for an help.

depami

No, they do not suffer from vapor lock but there are many other possible fuel issues. Checking pressure is a good place to start. Check the front of the passenger side fuel rail for a cap where a gauge can be connected.

Edit: Oops. Just noticed you have '84 Euro. Not sure where gauge connects.

Mrmerlin

install new ignition wires,
and rebuild the MAF,
also inspect the fuel dampers and FPR vacuum line for fuel smell ,
inspect the timing of the twin dizzy make the rotors are lined up to the hash marks with the engine at TDC

bronto

If you search this forum you will find that they DO suffer from vapor lock under certain conditions, but your situation doesn't sound like it. I get vapor lock at very high altitude on very hot days. Apparently the fuel rail passes too close to an exhaust manifold and the fuel can boil. The solution is to put some insulation or heat reflecting foil around the troubled area.

Xvetteowner

I never thought to check to confirm the PO installed the twin dizzy belt correctly.... From some of his past post here it would be wise for me to check this. The wires look good no light show at night...but I bet there from 1984.The MAF was rebuilt some years back from a company called Renn Tech in N.Y But that doesn't mean its still good, Gee I hate to think the fact I used two 944 caps has something to do with this?

Mrmerlin

the things I listed are the most probable for poor running on the 84 Euro

Landseer

They actually are a pair of 944 caps, so that shouldn't be the problem.

Xvetteowner

So today I thought I start it and without warming it up try driving it ( Note as a collector I'm a 500 mile a year driver of the cars I have) Anyway going around the block cold it runs a hell of a lot better. Not good but better.. while yesterday when fully warmed up there was a time I thought I would get stuck. (The block is 1 mile around) Seems heat could has something to do with. As it gets hotter it losses its power.. sounds like a race car cold while reving it ( a quick 4000 rpms) Hot, not so much like a race car LOL. Did I read somewhere here that if you turn the car to on and then move the throttle by hand you should hear a micro switch click. If so I hear the same "click" with or without the key on. Since the MAF has so much input as to how these cars run I'm thinking that could be the issue ( Or a weak fuel pump) Since it seems like a really lean condition after its under load I just need to find out why. P.S the new plugs look black but for the last 6 months it was just idling for 20 minutes 1 time a week. At least I enjoy this stuff

SeanR

+1, and if you have a bad FPR or damper this will make it worse.

dr bob

Why not attach a fuel pressure gauge, then look at the readings ad you go through the cold-warm-hot conditions under which you are having problems? There are a few options for a pressure gauge on the front of the pass side fuel rail. Don't leave one installed longer-term as they can ultimately be a fire hazard. Roger and Carl both have had fuel pressure gauge kits.

It's way eady to spend a lot of time and $$ throwing parts at problems. A little bit of diagnostic work can systematically defione or eliminate whole classes of possible causes. Fuel pressure gauge is a good start, to identify or eliminate a fuel system problem.

Bill Ball

Symptoms sound like a lean fuel condition. So, as mentioned, fuel pressure, MAF and perhaps large vacuum leaks (although that should screw up the idle as well) would be high on the list of suspects.

j.kenzie@sbcglobal.net

They do suffer vapor lock:


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Better question might be "do you ever drive on days hot enough to need or want air conditioning?"

The history of the fuel cooler starts with a problem seen on many CIS cars (not just Porsche cars) used in warmer climates. For instance, sitting in raffic here in Los Angeles, or after a brisk sprint into the Sierras in the summertime as the tank level dropped, my CIS-equipped car would vapor lock due to heat added as fuel passed repeatedly through the hot engine bay and back to the tank. Eventually the fuel in the tank got so hot that it would boil in the suction of the fuel pump. So Bosch learned that they had to figure a way to strip the added heat from the system.

Don't take it out.
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