New fuel pump + accumulator = Hot start issue

[lostinthemarket]

1977 911s

I'm kind of a newbie here but have spent a lot of time searching. I've kind of run into a wall and am looking for some advice.

I've replaced both of the major items that seem to cause the problem for most. The fuel pump was noisy anyway so I thought it wouldn't hurt.

Just to recap for anyone not acquainted with the issue: starts fine when cold, runs great. If I shut the car off after it's been warmed up it will start right away. If I wait 5 to ten minutes, it cranks and cranks but does not fire. I can smell gas so I assume it is being flooded.

What else could it be? Do I have leaky injectors? When I got the car over a year ago, i had no problems. To me this would point to a sudden failure of a component. Is it possible that I have a defective new check valve or accumulator?

[Bob Kontak]

All you need is one small leak to bleed the rest pressure down. To test it's sealing correctly you need a set of pressure gauges. Worth the investment and also lets you know for sure how your fuel pressure system is working. However, you know the problem - a leak - now to find it.

Start the car up and shut it down. Just a few seconds to build rest pressure but not long enough to warm the engine up to where the cold start valve is disabled. Alternatively, turn the key on (but no start) and lift the air sensor - that will pressurize the system - probably safer this way also. Pull out the injectors one at a time and look for leaks. I would pull them loose and re-install before you start the test procedure so you are not wrestling with them during the rest pressure bleed down time window - Let's assume it is one minute for discussion. Check one bank of injectors then start it up and shut it down again (or lift air sensor) to build rest pressure before testing the other bank.

I have never seen a leaking injector but I bet it will be pretty obvious.

Get a four or five inch mirror and a flashlight. Look behind the engine for leaks at the fuel system connections.

If your cold start valve is leaking I don't think you can tell from casual observation, which is a bummer. You have to remove it from it's mounting point to check.

If you use the air sensor pressurization - only lift it for a second. All injectors are spraying when you lift but they stop when you let it back down.

Doubt the failure of the new parts.

[ossiblue]

Originally Posted by lostinthemarket

1977 911s


Just to recap for anyone not acquainted with the issue: starts fine when cold, runs great. If I shut the car off after it's been warmed up it will start right away. If I wait 5 to ten minutes, it cranks and cranks but does not fire. I can smell gas so I assume it is being flooded.

You may wish to check for spark during the times the car won't fire. It certainly could be a fuel issue but since you do smell gasoline, it appears fuel is being delivered. What kind of CDI do you have--stock Bosch or Permatune or something else? How about the coil? Simply put, it sounds like you would be able to replicate the failure fairly easily. I'd suggest you do so, and then do a quick check for spark. If nothing else, it could eliminate a potential cause for your condition and you could focus on fuel delivery.

[boyt911sc]

Originally Posted by lostinthemarket

1977 911s

I'm kind of a newbie here but have spent a lot of time searching. I've kind of run into a wall and am looking for some advice.

I've replaced both of the major items that seem to cause the problem for most. The fuel pump was noisy anyway so I thought it wouldn't hurt.

Just to recap for anyone not acquainted with the issue: starts fine when cold, runs great. If I shut the car off after it's been warmed up it will start right away. If I wait 5 to ten minutes, it cranks and cranks but does not fire. I can smell gas so I assume it is being flooded.

What else could it be? Do I have leaky injectors? When I got the car over a year ago, i had no problems. To me this would point to a sudden failure of a component. Is it possible that I have a defective new check valve or accumulator?

losinginthemarket,

Bob K. and Larry J. have given you good and sound suggestions. These are the kind of sage advises we all should expect. Meaningful and well thought procedures to troubleshoot the problem. While everyone is encouraged to participate in the discussion, once in a while comes some out ragious or not well thought ideas to try. So be cautious and be very selective who you listened too.

While I have a couple of things for you to consider, I'll hold up at this point. The above suggestions should be sufficient to locate and determine the culprit/s. Keep us posted.

Tony

[lostinthemarket]

Thanks so much for the great replys.

I've had my eye on a CIS injection tester for a while. I think I'll pick one up soon.

The car has an MSD ignition so I would assume this replaces the CDI box? I hear these are pretty bulletproof but I will check for spark at the next opportunity.

One question about pulling the injectors: are they held in in a manner similar to more modern injectors with O-rings? When pulling them out should I worry about what is sealing them into the intake manifold?

[edgarcia737]

I strongly suggest the tester. Its the only way to know for sure. In my situation, it was the WUR. system would not hold residual pressure. I sent the Fuel Distributor and Warm Up Regulator to Fuel Injection Corp in California for bench testing. My FD was fine but my WUR needed to be overhauled. It's been fine ever since.

[brd]

I had a similar problem on a 1981 SC engine... try disconnecting the cold start injector. I was a leaking injector and was a pain and causing flooding.
I have left it disconnected for the moment and all fine. Not sure what it'll be like in winter... wait and see

[Bob Kontak]

Originally Posted by lostinthemarket

When pulling them out should I worry about what is sealing them into the intake manifold?

Each injector is held in place with a chubby little o-ring. The injectors will pop right out with a brisk tug. The o-rings should be pliable. If not, buy a new set. If they are tired don't sweat it for the fuel leak test.

Separate from your probable fuel leak, the intake runners have two o-rings. One is described above and the other is unseen and around the outside diameter of the orange sleeve that fits into the intake runner with a crimp type fit. Both o-rings get tired and can allow air to get sucked into the system past the air sensor. To remove the orange sleeve thingie, you have to dremmel the little crimp depressions (crimps are in the intake runner) out and then the sleeve comes out. Replace in reverse and then re-crimp with a suitable drift tool and hammer.

See page 43 of 403 - parts 27 and 28. And page 46 of 403 - part 44. Buy all 18 parts when you get down to the "fix".

http://www.porsche.com/all/media/pdf/originalparts/usa/911_USA_74_77_KATALOG.pdf

Also check this:
FUEL INJECTION TESTER FOR CIS-K-JETRONIC BOSCH SYSTEMS - JCWhitney