I solve one problem, now another...91TR | FerrariChat
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I solve one problem, now another...91TR

Discussion in 'Technical Q&A' started by Shamile, Mar 4, 2006.

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  1. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
    Full Name:
    Shamile
    #1 Shamile, Mar 4, 2006
    Dear Ferraristi,

    I have a new problem on my 91 Testarossa. I had posted previously about my alternator as I was having a lumpy idle and sounded a little "off " . Anyway, the lumpy idle is back.

    I think I have something going on with the fuel pumps. Here is what is happening. I start the car and drive for about an hour...all normal. After that I start to get a high pitch buzzing sound coming from inside the cabin. When the buzzing starts, my idle gets very lumpy and sound like the car is missing.

    I don't think it really is missing as it revs fine, lots of power and smooth sound to redline. Also when this happens, my return idle undershoots and almost sounds like it will stall but recovers. This only happens when I get this buzzing. If I turn the car off and back on, same symptoms. If I let the car cool down for a few hours, start it up....all normal once again....no lumpy idle, no buzzing, no undershooting.

    The buzzing was driving me nuts as I couldn't locate where it was coming from. It almost sounds like a high pitch fan...not loud....only audible at idle. I pulled into the garage when it was doing this and stuck my head in and out everywhere. I finally discovered it was coming from the fuel pump area. I'm thinking fuel pump as the there isn't any other mechanical devices in that area. Again this pattern of symtoms fall in place together like clock work. It took me a long time to figure out that they were all all tied together.

    Is this buzzing sound indicitive of a failing fuel pump?

    Why does this only happen after about an hour of driving?

    If it is the fuel pump, can an intermited pump cause the lumpy idle?

    Why after a few hours, is everything normal again?

    Is there anything else in the fuel delivery system that can make the fuel pump buzz? (meaning, it's not the pump but something else going on making the pump buzz)

    As always, your help is greatly appreciated.

    Shamile

    Freeze... Miami Vice!
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,232
    Mount Isa, Australia
    Full Name:
    Pap
    #2 PAP 348, Mar 4, 2006
    I have a mate who had the same problem in his Toyota Supra. The pump would make a buzzing noise,clearly audiable inside the cab also. After around 30mins,the car would splutter and then stall. Let it cool down for a few hours,then its all good again. We put a new fuel pump in it and solved the problem. We pulled the old pump apart and it seems that when the pump was getting hot,the bush area in the pump expanded and the vanes in the pump on the shaft were rubbing,causing the buzzing noise on the inner body of the pump. As it cools down of course,it returns to normal. As it also gets hot,it expands and basically loses performance and thats why you get the lumpy idle as there is little or no fuel pressure or fuel flow to the engine/injectors. My mates pump lost around half its fuel pressure when we flowed/pressure tested it before we replaced it. Get the pump/s flowed and pressure tested when its hot and has the crap idle and see how you go from there brother. :)
     
  3. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
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    Shamile
    #3 Shamile, Mar 5, 2006
    Dear Ferraisti,

    Does anyone know a good cross reference for a 91 Testarossa fuel pump ?The units are bosch and should be able to be matched.

    Shamile

    Freeze....Miami Vice !
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,932
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #4 Steve Magnusson, Mar 5, 2006
    Just buy the Bosch fuel pump directly from someplace like www.importeccatalog.com (just search on the Bosch 10-digit PN at the importec site)

    TR Fuel Pump
    F PN 121727
    Bosch 0 580 254 947
    (Bosch USA 5-digit PN 61947)

    Have you determined it is a fuel pump problem? I had previously replaced one for being "buzzy" (but it worked OK).
     
  5. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
    Full Name:
    Shamile
    #5 Shamile, Apr 9, 2006
    Dear Ferraristi,

    Well, it was definately one of the fuel pumps. I would get this buzzing sound in the cabin after about one hour of driving and the idle would go "off"

    I changed both pumps and noooo buzzing and no "off" idle.

    One thing though, I had a hard time getting the hose for the tank to pump. I got some cloth braded hose like the original but the wall was much thinner. Ferrari wanted $200.00 per foot of the thicker wall hose. Anyone know where I can find some? I'm using the thinner stuff for now. I won't leave it like that and if no match, I will pony up to the Ferrari-Pimp.

    Shamile

    Freeze....Miami Vice !
     
  6. sparky p-51

    sparky p-51 Formula 3

    Aug 8, 2004
    1,375
    klamath falls, Or.
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    steve
    #6 sparky p-51, Apr 10, 2006
    Sounds like aircraft fuel/oil hose to me. Try any aircraft parts house. Lots of airplanes down there....should be somewhere to get it. Sells for about 2.00-3.00 per foot.
     
  7. Mark 328

    Mark 328 Formula Junior

    Nov 6, 2003
    510
    Orange, Ca
    Full Name:
    Mark Foley
    #7 Mark 328, Apr 11, 2006
    Shamile:

    When you changed fuel pump(s) did you also clean the fuel inlet strainer inside of the tank? A friend of mine is a mechanic and he said that when fuel pumps make noise they are buring-up because the fuel strainer is becoming clogged and the pump is cavitating--this may cause the bearings to run tight like the other post described.
    On my 328 the pump started to make noise and I cleaned the strainer out and the noise went away. That was almost 5 Yrs ago. When I took the strainer out you couldn't see light thru it, but when I cleaned it in laquer thinner light was visible.
    The new pump may be just masking the root cause of a partially clogged strainer.

    Mark
     
  8. shaikhzeep_212

    shaikhzeep_212 Karting

    Apr 13, 2006
    85
    Saudi arabia
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    HAM
    #8 shaikhzeep_212, Apr 13, 2006
    Good day,

    You are all right.

    Replacing the pumps and checking the pumps suction strainer and also you need to check the suction hoses for the pumps.As i found one of them is so tight internally that almost fuel wont come to pump suction causing it finally to fail.

    And of course in the end you will find you TR performance different
     
  9. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
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    Shamile
    #9 Shamile, Apr 14, 2006
    Dear Ferraristi,

    Wow, such great ideas! I have to admit, I didn't pull the strainer. I guess I'll do that when I find the thicker wall cloth braided fuel line. ( from tank to pump ) I like the lacquer thinner idea also.

    I've been driving the car about 2 weeks since the change and the car really runs smooth.


    Shamile


    Freeze...Miami Vice !
     

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