No Start when Hot, not a problem- Thx Pelicans

[charlesbahn]

Well, my car developed it's second problem (the 1st was a loose ground wire with intermitant loss of power, also easily fixed with info from this board). This time it's a hot no start problem. After the ignition was turned off, the engine would crank but just not start. After the engine cooled down she would fire right up. Only took about 1 minute search on this BBS to figure out the most likely solution.

Replaced the fuel pump (from our host) just as described in the Tech section, and BINGO. Problem solved. No expensive mechanic, no aggrevation. This BBS and Pelican are the greatest. Thx to all.

[bigchillcar]

that's great, charles. did anyone suggest checking just the fuel pump check valve? i'm wondering if by replacing the fuel pump, you also actually replaced the fuel pump check valve in doing so?
ryan

[charlesbahn]

Hi- on this car, the valve is built into the pump assembly. But of course, it is the valve that is the problem, not keeping the fuel pressure up after the car is turned off and the system is hot. The car still runs the same, it just starts now at any time now after the engine is turned off and I don't have to sit around and wait for an hour or two.

[bigchillcar]

charles,
gotcha..just making sure you didn't spend $$ you didn't have to (like it would help now!) i wasn't sure if you had the internal check valve or the external version like i have. good deal. nice stockings, btw..
ryan

[MovOvr1]

I am having same problem on my 79 930. Is it the rear pump or the forward pump that the check valve is connected to? I had my front pump replaced about a year and a half ago.

I really like this board as well. It is a great group of people with TONS of information.

Brian

[Nitrometano]

Maybe is the warm up regulator (WUR). You said that "After the engine cooled down she would fire right up". This is a typicall sympthom of a faulty WUR. An easy and cheap test is to do the following. Start the engine and wait until he reaches the normally temperature operation. Then shut off the car. Try to start the engine. The engine will crank but not start. (This is the problem that you have). With the engine warm now you will going to test the WUR. Find cold water with ice. Soak a rag into the water until it get wet. Then, put the rag over the WUR. Wait a short time, like 1 minute. Then try to start the car. Is the engine starts, your problem is the WUR.

[charlesbahn]

Nitrometano- Thx-in this case, replacing the fuel pump with internal check valve has solved the problem, I'm not having any trouble with hot starts now. Does the 85 3.2 with Motronic even have a WUR (showing my ignorance)?

MovOvr1- My car has a single fuel pump, I think the 930 has two, and I'm not sure where the check valve is. Hot start issues are frequently caused by the check valve going bad and not allowing the fuel system to stay pressurized. Find out where the check valve is for your system and try replacing it. On some models, the check valve is integral to the fuel pump and the fuel pump needs to be replaced. On other models the valve is separate and can be replaced without the expense of replacing the pump too. This is what bigchillcar was referring to. Boy, I sure have learned a lot from Wayne's book and this BBS. Thx again to everyone who contributes to this great place.

I'm sure others more knowledgable about the 930 fuel system will chime in.

[wahoofan]

FWIW....Back in college I drove a 77 bmw 320i that had the same hot start problem that nobody could figure out. I finally took it to a shop that specialized in Porsche/VW and the mechanic fixed it in an hour for under $100 by adding another check valve in-line instead of replacing the fuel pump! Don't see why that wouldn't work on a 911.

[bigchillcar]

wahoo,
neat fix..as long as the fuel pump seems to pump okay (meaning it hasn't started to draw too many amps as they do when they age) then that sounds like a good, economical solution!
ryan