Fuel Accumulator

[longhornchris04]

Where is the part number located on the fuel accumulator? I didn't see it when I looked.

I ask because my car (chassis) is a '75, but the engine is a '79. Additionally, the accumulator and filter aren't bolted together like in the tech diagrams, so its possible that the 3.0L upgrade included swapping of the fuel system parts. I don't have a good vehicle history... (yeah, I know)

The '79 and '75 use different part numbers. Since I'm having a warm-start issue and the fuel pump works fine... I'm hoping its the accumulator and want to order the correct part.

Thanks in advance.

[ossiblue]

Couple of questions: First, does the current accumulator (on the car) have a hose connected to the bottom? If so, it's a later version where the bottom hose connects to the fuel return line to the tank and a failed accumulator will leak fuel back into the tank without obvious dripping. I believe the original to the 75 had only two ports (no hose from the bottom) and would account for the different part numbers. (Not an expert on this, so I may be corrected by someone who knows for certain when the accumulator changed.)

Second, you say your fuel pump is fine, but have you checked the residual pressure with a fuel gauge set? The pump may maintain proper pressure/flow but if the check valve is bad it won't hold pressure after shut down and you will have warm start problems.

[longhornchris04]

The unit on the car has 2 ports on top, 0 on bottom, and there's no signs of leakage.

I don't have a set of fuel gauges to check the residual pressure. Its possible the fuel pump check valve has failed... is there any way to test this w/o gauges.

The onset of warm-start issues has been fairly sudden. 30min to 1hr of sitting still and it takes a couple extra seconds to crank. If the engine sits for 2-3 hours after getting hot, then I've got a problem.

Part of it may be wishful thinking on my part... the fuel accumulator is easier to get to than the pump. I've had the heat backdated, so I can get my whole head in next to it as long as the engine is cool.

[ossiblue]

Sounds to me like the accumulator is probably o.k. The only way I know of testing the check valve is with a fuel gauge set. I believe the pump on a 75 is by the left, rear wheel well. If so, you might try this: Start the fuel pump to fully pressurize the system. Using a suitable clamp, clamp off the fuel feed hose to the pump immediately after shut down of the pump.
Now, carefully remove the fuel feed line from the pump. If your check valve is working, there should be very little to no fuel dripping from the pump once the line is disconnected. You can further this test by removing the inlet hose to the accumulator and blowing air back through it toward the pump. You should not be able to expel fuel from the line if the valve is good.

Note: This test is assuming the valve is internal to the pump. Some pumps have the valve as part of the banjo fitting. If yours is part of the fitting, simply remove the fitting and try to blow backward through it, using compressed air. Regardless of your set up, use care and have a fire extinguisher close by.

[longhornchris04]

gracias

[Flat6pac]

The 3.0 should have the line to connect the bottom of the accumulator or the injection and fuel lines has to have been changed to accomplish the early accumulator interface.
Bruce

[sobamaflyer]

I have an identical setup to yours and am having identical problems, except that I have cold AND hot start issues. It can take a couple of minutes to get mine running when cold, it will start back up VERY easily after a 5 minute drive, it will take a couple minutes to restart after a good long drive and an hour or so cool down. (The car runs wonderfully after it's started)

I also do NOT have the bottom nipple on the accumulator, original ('75) fuel pump, accumulator, etc. From my research here, I was on tonight to order a new accumulator, but now the advice above has me 2nd guessing that? Can it really take that long to re-build pressure if the pump's check valve is bad?

Is there another suspect area for the issues we are experiencing?

[ossiblue]

Originally Posted by sobamaflyer

I have an identical setup to yours and am having identical problems, except that I have cold AND hot start issues. It can take a couple of minutes to get mine running when cold, it will start back up VERY easily after a 5 minute drive, it will take a couple minutes to restart after a good long drive and an hour or so cool down. (The car runs wonderfully after it's started)

I also do NOT have the bottom nipple on the accumulator, original ('75) fuel pump, accumulator, etc. From my research here, I was on tonight to order a new accumulator, but now the advice above has me 2nd guessing that? Can it really take that long to re-build pressure if the pump's check valve is bad?

Is there another suspect area for the issues we are experiencing?

CIS can drive you crazy. The key is to eliminate the likely suspects first and that takes diagnosis. Please remember, the OP doesn't have a fuel gauge set which is one of the basic tools for dealing with CIS issues. With the gauge set, you can readily identify or eliminate the check valve as a possible suspect. My advice, in the perfect world, would be to test the residual pressure first to see if it is even part of the problem. To answer your question, of course there could be another suspect but avoid speculation and needless parts purchases by doing a step-by-step investigation to narrow down the possibilities.

BTW, your cold start issues my be related to too high cold fuel pressures--something that could be checked with a pressure gauge set as well. IMO, anyone who wants to work on a CIS engine needs to make an investment in a gauge set.

[boyt911sc]

Originally Posted by longhornchris04

Where is the part number located on the fuel accumulator? I didn't see it when I looked.

I ask because my car (chassis) is a '75, but the engine is a '79. Additionally, the accumulator and filter aren't bolted together like in the tech diagrams, so its possible that the 3.0L upgrade included swapping of the fuel system parts. I don't have a good vehicle history... (yeah, I know)

The '79 and '75 use different part numbers. Since I'm having a warm-start issue and the fuel pump works fine... I'm hoping its the accumulator and want to order the correct part.

Thanks in advance.

Chris,

It is imperative that you use a fuel pressure gauge kit to diagnose fuel injection problem/s. All CIS components in 911 could easily be bench tested by DIY'ers. So to save time and money stop the guess-work and do a systematic investigation of your problem. Do not replace CIS component/s unless verified defective. Unless you want to spend money unnecessarily or doesn't care as long as to make the car run.

By just knowing the residual pressure of your system you could conveniently pin point possible source of the problem. Or you could install a new fuel accumulator and still have the same problem or be lucky to fix the problem by chance. BTW, two (2) or three-port fuel accumulator will work on your engine. So without knowing the fuel pressures, your guess is as good as anybody.

Tony

[Tbone425]

I also have a 76 trying to transplant a 3 liter into, trying to figure out how to safely eliminate the need for the bottom line on the FA so that I can continue to use the 2 port FA... any help would be appreciated. Can it be as simple as capping the line off? If one of you has a set-up that can shoot a photo would be outstanding, while not super easy based on location.

Chris

[Tbone425]

The old engine is out....looking to move the new one in ASAP.

[boyt911sc]

Originally Posted by Tbone425

I also have a 76 trying to transplant a 3 liter into, trying to figure out how to safely eliminate the need for the bottom line on the FA so that I can continue to use the 2 port FA... any help would be appreciated. Can it be as simple as capping the line off? If one of you has a set-up that can shoot a photo would be outstanding, while not super easy based on location.

Chris

Tbone,

If you want to use and stay with the two-port FA, simply plug the 3.0 liter FA return fuel line. Since you are using a bigger 3.0 liter engine why not simply get a replacement three-port FA and be done with it? You are not saving much by being frugal. Plus the newer 3-port FA is easy to troubleshoot and safer than the older FA. In case the 2-port FA starts to leak, where do you think the fuel will drip? Droplets of leaking fuel on hot areas like heat exchangers or headers could result to something unimaginable!!!!

It is your car, you could do want you want to save a few bucks. I use a 2-port FA on my CIS bench tester but never in any of my cars. The decision is all yours. Stay safe.

Tony

[Tbone425]

Point taken Tony...getting one today. Do I need to get the longer S shaped line as well, since mine is a ver short elbow from the FA to the filter? Or is there room to reconfigure the mounting position of the filter (I assume the FA has to stay flat as it works on gravity.

Thanks,
Chris

[BoxsterGT]

I am happy to help with CIS lines in general, like injector or WUR lines. I can only buy the single fittings new, not the compound ones w multiple connections. For any of the feed or return lines I must have your original fittings to build from.

Also, the rubber covered Polyamid tube is NLA. I can only buy the basic Poly tube itself w/o the rubber cover.

For questions, please email me only. I cannot send photos via PM and my box is almost always full.

Len at Autosportengineering dot com