Fuel accumulator test

Thanks for more great info, Steve.

 

I misspoke. I am assuming the WUR is good. We just put that in. I was going back to my old assumtion that warm start problems were either accumulator or check valve. I stand corrected. I will post progress this weekend.

 

Robert,

Glad to hear the new check valve had the washers.

You may be able to see the connection point of item #29 with a mirror and a flash light placed behind the ignition coils.

 

I'll be going after it this weekend thanks for the tip.

 

You can hear the accumulator, if there is no leak in it, or elsewhere, it would emit a kind of "creak" every couple of minutes for 20 minutes after stopping the engine as the diapragm gradually moves back. If it makes one long creak after stopping, there is a leak. At least this is the case with the vent open to air. I guess with the vent connected to a tube the sound might be subdued.

 

That's interesting, so if I unplug that hose what should come out over what period of time.
If gas then _____
if vapor then ______
if creaking is intermittent=good
if creaking is one long creeeeeak=bad

and no creaking?

 

Nothing should come out. In theory a small amount of air would come out when the fuel pump starts and then a small amount of air gradually sucked back in after its stopped but this would not be noticeable I think.

 

Well this has been interesting. A fail on the pressures. It is obvious to me that it is dangerous for me to have purchased the tester gauge. Not a single measurment was the same as the manual. Warm, cold made no diffrence, I was in over my head having never done this before. It was almost comical in a sense. I started by checking for vacuum leaks per manual. Actually found two. One was a crack in the vacuum line to the ECUs by the plenum the other on a line I had found one on before on the other side by the cold start injector. Of course now the engine was warm. Delay. And this was how it went, back and forth. Frustrated I decided to go about this in a monticarlo fasion. Using the tips about sound etc. I just had the car tuned and other then the warm start issue was running pretty good so I was hesitant to change anything anyway. So, no groans, creaks or anything from the accumulator, removed the hose in question, which does return to the tank and was rewarded with a nice steady stream of fuel. Yikes, really wasn't expecting that. Cleanup on isle 3. Delay while fumes evaporated and left garage. Since the wheel well cover was off I decided to adjust the clutch pedal and call it quits. Spending a day and a half futzing with the gauge was interesting but I would need to be guided through this live before attempting it again. So got the lines reattached and leak free and will make appt. to have the accumulator and checkvalve replaced. Without a lift I saw no way to access these things unless the tank was out maybe. Thank you all for the insights but I will leave this diagnostic procedure to the pro's for now. I must admit that this defeat tasts awful.

 

Definitely shows that the accumulator is bad so you know that that's money well spent.

I know it seems frustrating now, but that's how we all gain experience...

 

Sounds like a success to me, a definite fault found!

 

You should be able to remove the accumulator and the fuel pump with just jack stands. I believe the QV has the same setup as the 328 and the two units are mounted to a fairly easily removable metal triangle plate. Once you have the plate loose and the lines disconnected the entire assembly should easily fit out through the bottom or wheel well. Make sure you drain the fuel tanks first.

I know you said you were going to take it in for service but I thought I would give you some food for though about DIY.

 

Dan, thanks for the encouragement but it just looked so tight in there. Perhaps I will get past this gumption trap and go at it myself. Next weeekend perhaps.

 

Trial by fire. I am discouraged but haven't totally given up yet. Now that I have had some exposure I need to consult the manuals and prepare a flow sheet for myself. Trying to find values in the garage with things in a bit of disarray was the wrong way to approach this. For a first time I think I need to verify what I have before attempting to make any changes etc. I was just caught off gaurd I guess expecting this to be simple. Wrong. But, on the good side, two vacuum leaks fixed, verified bad accumulator and a pedal adjustment. If Dan is correct perhaps I will give it another go and replace the accumulator along with the checkvalve next weekend.

 

Thanks Andyww! It was a small one but I will take it.

 

Robert, if you need some phone assistance PM me and I will give you my number.

 

I'm glad to find this thread, because I have an issue along the same lines. I have an 84 QV that runs perfectly, except it has the hot start issue that requires pressing the throttle, and significant cranking, to catch. I pulled the accumulator vent tube and found fuel, so I thought I found it. I had an independent Ferrari mechanic replace the accumulator, dial in the FD (because of someone messing with it in the past for smog reasons), and check the pressures. The car runs alot better with the FD set like it should be (no more surging), but the hot start persists. The mechanic said all the pressures are correct, so I'm not sure the check valve will change anything. It seems to be overly rich, because of the need for throttle, and the slight puff of black smoke when it does fire. The cold start injector was also checked by pulling the plug, but no voltage was found when warm, and it didn't change the starting issue. Could it be leaky injectors, or possibly a WUR issue? Any suggestions would be greatly appreciated. Thanks, Scott.

 

If the pressure after engine shutoff drops to the correct value and stays there for the specified times = correct, nothing wrong with the check valve, and, if your mechanic confirmed that the warm control pressure was correct, that generally exonerates the WUR.

That verifies that something electrical isn't causing the cold start injector to (wrongly) open during a warm restart, but it could still be leaking fuel (when the voltage is zero and it's supposed to be fully closed). The test would be to remove the cold start injector (so that you can observe the business "squirting" end) and unplug the safety switch and turn the key "on" (so the fuel system pressurizes) -- if fuel leaks out = bad CSI. How consistent is the warm restart problem -- everytime, only sometimes?

Have you tried unplugging the safety switch during a warm restart to see if there's any difference in behavior?

 

Thanks for the reply Steve. That is a very good thought on checking the CSI. I will try that next chance I get. As for the consistency of the problem, it happens every time on a warm restart, and I always have to give it throttle to fire. While I was at the shop, we did try to start it with the safety switch disconnected. It didn't change much, and if anything, it made it a little worse. That's why I'm suspecting a rich condition. If this helps point to any other possible culprits, please let me know.

Scott

 

I was able test the CSI today, hoping that was the issue, but all seems OK. When I removed the injector after driving the car, the end was dry. Also, it did not leak or spray while testing with the pump running. One thing I noticed while starting the car warm was that it would try to catch immediately upon cranking, but then have to continue cranking for several seconds before coughing to life. And, this is with the throttle pressed about halfway. This seems pretty uniform, on every warm start. Hopefully, this info might help pinpoint the culprit, or something else to check. I'm wondering if experimenting with the WUR wouldn't be a bad idea? Any other suggestions would be welcome. Thanks in advance, Scott.

 

It could be the WUR going bad or not properly set. You may want to call Larry Fletcher who rebuilds these units and ask him since it appears you have ruled out most of the likely components. I was thinking fuel pump check valve but you stated the pressures checked out okay.

Here is Larry's contact info www.cisflowtech.com

I am certain Steve will have some additional insight. He is the guru with these issues.