Cold start issues on a Maserati | FerrariChat

Cold start issues on a Maserati

Discussion in 'Technical Q&A' started by JasonMiller, Feb 12, 2011.

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  1. JasonMiller

    JasonMiller F1 Rookie
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    #1 JasonMiller, Feb 12, 2011
    Last edited by a moderator: Sep 7, 2017
    First of all I am very thankful for this community and all the sharing of information regarding these quirky cars and thanks in advance for any input on my problem.

    This is a Maserati 4.9 engine with four weber carbs. The car is a 1982 Quattroporte. On the dash is a button for a back up fuel pump and of course a pull choke.

    When this car has sat for a few days or even overnight it’s a bear to get started, when it has sat for a week or longer (like this winter) I will literally crank for 15 minutes before it finally starts. Once the car is running I can drive it to work or wherever and it starts right up.

    I feel it’s a fuel problem so I usually choke the car and put on the auxiliary fuel pump for a minute and then start cranking, but that doesn’t help..
    Is there a procedure for starting this beast?

    Today I decided to spend some time trying to figure out this problem. When I opened the hood before trying to start the car the clear fuel bowl was ¼ full of fuel. I started the auxiliary fuel pump which makes A LOT of noise and I do notice some bubbling in the fuel bowl but it seems to fill slowly like an inch in 10 minutes.

    When I crank the car the bowl fills with fuel faster and eventually fills up.

    There is a pressure guage on the fuel line which after thinking about it I am figuring (please correct me if I am wrong) that the fuel pump needs to build some pressure before the carbs get enough fuel to start which would explain the time it takes cranking to get it to start… Am I right?

    BTW did I mention it starts immediately if I pour some fuel in the carbs but dies shortly after.

    So some questions,

    1. Why is there a pressure gauge on the fuel line? When the car is running this gauge is around on the 15. (See pic)

    2. Should my auxiliary fuel pump be used to cold start it? And if so should it fill the glass bowl and build up pressure on the gauge? If so maybe my auxiliary pump is bad it makes a lot of noise and can be heard from 10 feet away from the car, but seems to move little fuel…

    The car hasn’t been started in over a month and today I spent 15 min cranking and finally decided to stop, the starter was HOT and Battery was HOT. I obviously need to figure out the problem before I destroy something else…

    Thanks for your input.
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  2. 2NA

    2NA F1 World Champ
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    Sounds like your carbs aren't getting fuel.

    This can be a result of:

    bad fuel pump/s

    clogged filter

    some other blockage

    Sounds like your pumps run (or at least make noise) so it's not electrical.

    Weber carbs typically operate at pretty low fuel pressure (2-4psi) but they won't supply fuel to the engine if their not full.

    That glass bowl is actually part of a pressure regulator/filter. One possibility is that the filter element is clogged, another is that the pressure is set too low. When you turn on the key, the glass bowl should fill right up and stay full.

    The original Facet pumps on that car typically have their own filter elements built into a removable cap. They could be plugged. There is also probably a "sock" filter on the fuel pickup inside the tank. If the tank has never been cleaned out, it could be a problem.

    The pressure gauge is just an accessory that someone installed (maybe because they were having trouble). There should never be 15 psi anywhere in that fuel system. Are you sure it isn't 1.5?
     
  3. fatbillybob

    fatbillybob Two Time F1 World Champ
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    I had an 84 qporte and it would fire instantly on key turn better than any car I ever owned. I never understood why. Anyway, I would start by seeing what the output of fuel is aft of the 4 carbs. You can see the flow on the returnline to the tank just after the last carb. There is a wsm spec for that. You can also avoid the long crank by using some starter spray to light off the stored car but then the fuel should be flowing in a properly tuned car and it shold be running fine.
     
  4. JasonMiller

    JasonMiller F1 Rookie
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    Yes 1.5 sorry, You state the gas bowl should fill with the key on, it doesn't, if I turn the key on nothing happens (as far as the glass bowl is concerned). That's what I thought the backup pump was for. When the engine is cranking it begins to fill up.
     
  5. 2NA

    2NA F1 World Champ
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    If nothing happens when you turn the key on (you should hear it) you likely have a dead pump.
     
  6. JasonMiller

    JasonMiller F1 Rookie
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    All I hear is a bunch of annoying 1980ish buzzers :)

    Would this be the pump in the tank, or the one located beneath the engine?

    thanks





    .
     
  7. 2NA

    2NA F1 World Champ
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    Does your car have a mechanical pump? The cars I am familiar with have two electric pumps.

    Of course a mechanical pump only works when the engine turns.
     
  8. JasonMiller

    JasonMiller F1 Rookie
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    According to my repair manual, both pumps (the main and auxiliary) are located next to each other under the car. I will just replace both of them and see what happens.

    When the key is on there is no sound from the "pump" area. When I turn on the auxiliary pump the noise is so loud it can be heard from 10 feet away and the glass bubble barely gurgles..

    Both pumps are identical so my bet is both of them are not working from this car sitting so many years.

    Of course this doesn't explain why when I crank the car, the glass slowly fills up and why once its running it runs fine and starts fine..
     
  9. Pantdino

    Pantdino Formula 3

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    I think you are right-- the main pump is completely dead and the auxillary is barely functioning.

    Webers require something very close to 3.0 psi to operate. Any more than 3.5 or so and you run the risk of fuel overflowing into the intake system, causing rich running. If the engine is off and the pump is running the fuel will run down the intake system and fill a cylinder. Then when you turn the car over you will "hydraulic" a piston and bend a rod.

    If there is too little fuel the engine will run lean and possibly burn a piston.

    Under the cover nut on that filter / fuel pressure regulator there is a screw or nut (I forget which) that you can turn to adjust the fuel pressure. You should adjust it so it is at 3.0 with the engine at fast idle.

    Just went thru all this with my Abarth vintage racer.
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
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    post picture abarths are cool
     
  11. staatsof

    staatsof Nine Time F1 World Champ
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    +1

    All the vintage V8 Maseratis should start very easily once you let the carbs fill.
    From your description of the symptoms I would go through the above checklist before you start replacing pumps. The facet pumps are easy to get and inexpensive if you buy them from the right places. $80-$90. The secondary backup pump on your car might be something weird or just one of those small solid state pumps.

    Typically I let the carbs fill, give the throttle 2 or 3 good stabs and then the car usually starts. I never use the choke.

    I might add checking to see if your accelerator pump circuits in the carbs are working. If not then cold starts are going to be difficult. You can look down the top with a flashlight and see that. If not, it might be dirt or quite possibly just a new set of accel. pump diaphragms. That's a relatively easy repair. Your car should also be stumbling or hesitating once under way if the diaphragms are bad.

    Bob S.
     
  12. afwrench

    afwrench Formula Junior

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    If tha main pump makes no noise with the key on check to see if you have power at the pump. Bad wire or fuse possible.Simple things first. Mike
     
  13. JasonMiller

    JasonMiller F1 Rookie
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    Thanks all,

    I will check wires and fuses first, yes the car starts fine with fuel in the carbs and runs fine once its started..

    Are there aftermarket pumps available or a cross reference?

    Thanks
     
  14. JasonMiller

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    What am I looking for with the flashlight?
    thanks
     
  15. staatsof

    staatsof Nine Time F1 World Champ
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    Well given your response it might help to read a bit about the operation of a Weber DCNF.

    Basically, there's a pump diaphragm inside of a chamber on the driver's side of the carb I think. You'll see a plastic cam on the end of the throttle linkage on that side and as you open the throttle the cam operates a level that pushes the diaphragm. When you're looking down the barrel of the carb from the top you should see a nice stream of gas being sprayed as you open the throttle. Like Tom Thumb is pissing in your carb ... :)
     
  16. 2NA

    2NA F1 World Champ
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    Accelerator pumps don't work too well unless the carbs are full of gas. Probably get the pump thing going first.
     
  17. staatsof

    staatsof Nine Time F1 World Champ
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    Car won't run at all if the pump doesn't work. It does run but starts hard. At least I thought that's what he said. But he should go through your complete list.
     
  18. staatsof

    staatsof Nine Time F1 World Champ
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    If you need a pump just call up Facet. They're in Elmira, NY. They can tell which pump it takes and they are so easily available why bother with something that needs special fitting?

    These guys won't know which one you need but they'll probably have it once you know which one to get.
    http://www.yachtsupplydepot.com/mechanical-supplies/fuel-pumps/cat_697.html


    So it runs OK no problems once it's started? Doesn't sound like a fuel problem then.
     
  19. bundas

    bundas F1 Veteran
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    take the fuel line loose at engine side of main fuel pumps with ign. on and see if you have flow. if not take line loose on intake side to check for flow restriction. You will be buying a starter soon if you do not stop excessive use. you may have a line restriction. a very easy problem to solve. all the best
     
  20. JasonMiller

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    Great advise, will do that tomorrow, we are having highs in the 50's here in PA, just like spring so I can tinker with the cars without freezing to death.
     

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