kary4th

Any amazing thoughts on short term aids? Stalling in the second lane of I-495 in rush hour is a little unsettling.

James Bailey

Vapor lock ?? with CIS fuel injection , doubtful . Guess again .

dr bob

Kary--

Permanent solution for many of the early cars is a higher-pressure fuel pump. The CIS metering unit manages the actual pressure so no worries about mixture, but the higher pressure upstream of the metering unit will help a lot with your vapor locking.

In the near term-- A full or close to full tank will keep the fuel cooler for longer. Heat is added as fuel passes through the metering unit in the engine bay, and is routed back to the tank. Having the tank full also increases the suction head and therefore the pumping efficiency of what you have now. Early CIS Saab and BMW cars were notorious for this, never designed for stop-and-go traffic with AC on in 100º+ conditions. Higher-capacity FP's seemed to make a big difference. Later cars have a fuel cooler in the return line from the AC evaporator to strip heat out of the fuel before it gets back to the tank. There was a good reason why that was done.

Also- resist the urge to open the gas tank cap, especially if your vapor system is well sealed. The tank will pressurize with the heat. I've had to go clawing through the roadside brush to find the gas cap after the first CIS vapor lock I experienced. All the time the cap was off, waves gas vapors were roiling out of the tank. An explosion waiting for an ignition source. Got the cap back on, iced down the metering unit, started the car and kept the ice on it for a while with the hood open to gain a little running room to go get the tank filled.

Good luck with the interviews!

James Bailey

Ah so that is why the fuel chiller was added to later cars to reduce the temperature of the excess fuel going back into the tank ! Seems I was mistaken about vapor lock I had always heard that on carbureted cars with mechanical fuel pumps mounted on the block.

kary4th

Yeah, mine's only got one fuel pump, so if I move down here, adding a second (it was wired for a second when new) or changing to a higher flow model would apparently be a requirement.

So would fixing my AC. Holy crap, is it hot in traffic.

Shark Attack

I lived down their for a few years.. The 15 min drive to work was usually 1.5 hrs. I used to work late, put in an extra hour at the office and only get home 15 min later than I would have if I left at 5. I worked in Beltsville and lived in Germantown.... So I moved to Adams Morgan ( near downtown DC, my drive was only 15 min then,,, flowing against the traffic while everyone else was trying to get into the city I was cruising out of the city.

svp928

Kary I had good luck wrapping a piece of metal-backed insulation around the fuel lines where they pass by the exhaust manifolds as well- its available at most speed shops...don't know about any in DC area. All the other advice here is worth doing as well!

Steve

dr bob

Don't worry, only crazy people live in DC in the summertime. It's a swamp with some fill poured in to make it look like a nice place. There's a really good reason why the gov't takes summer recess.

bronto

Yes, one thing I didn't mention about my drive through vegas was the vapor locking I was experiencing. I feared I wouldn't be believed with injected fuel. Sure felt like it to me, and it started happening almost as soon as I got off I-15 and into heavy traffic on the strip. Had to start it about a dozen times just to get it OFF the strip and away from traffic. The guy at Black Sheep Auto confirmed that this is what it was, and living in Vegas he'd know. He said that you *want* to keep the AC on because it is tied in to the fuel system to prevent this, but as Jim said that might have been a later addition. His one recommendation to me was to leave the key on for about 30 seconds prior to starting it to get the fuel pump to circulate the hot fuel back into the tank and cooler fuel into the lines.

He also told me something else I didn't know. If your temp gauge is jumping it's a sign of air in the cooling system. The guage doesn't read steam, so every time a "bubble" hits it the needle will jump.

GregBBRD

You're not the only one that learned something today, Jim. I would have never guessed that these things could vapor lock with a 7 bar pump pushing, from the rear of the car. I knew that the fuel cooler was on the return line, but I figured that this was just to keep the fuel in the tank from getting too warm and expanding too much.

Thanks, Dr. Bob!

hagen454

Kary I put about five hundred miles on the car today. You will be happy to know I had ZERO problems in good old NY weather.

Also, I talked to Darren and the job was posted Thursday.

Good luck with the interview!

kary4th

Before I ever got the car on the road, I noticed that it was wired for a second fuel pump. Before then, I need to find some insulation.

I pissed off a half million people yesterday by blocking the beltway (twice) and Connecticut Ave. (once).

SpeedBump

Well someone has to do it, wait until you see the beltway during a thunderstorm.

fraggle

You've hit a hot week here. Best way to avoid this is not to drive into DC. The metro rocks.

Stay in touch, hope to see you at frenzy or earlier!

Dennis Wilson

This has been brought up before and yes, the CIS systems can vapor lock. This is why Porsche put the second in tank pump on the 928's destined for hotter climates. Some options to remedy this problem are to replace the standard Bosch pump with a 6.5 bar Pierberg, install an intank pump (the wiring is in place) or insulate the fuel lines in the engine compartment.

Dennis